I sacrifice to read students whose under medical trainees and also those under health science studies

1. **Course title: Human biology.
What is human biology?
Human biology is a branch of science that deals
with the development & the function of human life
aspects; it is closely related to the medicine….**So,
• Human biology interact with other disciplinary
components of knowledge, such as *genetics,
anatomy & physiology, cell-biology…etc..
1

2. *As introductory: Homeostasis & the control system.
* The term homeostasis, Its literal concept is about *A dynamic
constancy of internal environment of the body, this dynamic
constancy{i.e. a continuous activity} is an interactions between the cells of
the body & Extracellular environment. {i.e. watery environment outward the
cells}…*Thereby, in biological system, these interactions are usually achieved by a process
called: Control system (it is a regulatory mechanism that maintain or keep-up this continuous
activity as its steady level).
So, the extracellular envir/t surrounding the cells of human body consists of: a- Fluid compartment, in
which molecules are dissolved (ie,carbohydrates, proteins, & lipids & the P/membrane associated SRTs)
& b- A matrix of polysaccharides & proteins.
As example, at extracellular environment include all constituents [i.e. essential parts] of the
body functions [i.e. cells of the body..like, Growth & development], because cells receive nutrients from,
& release their waste products into E.C.E..*such as the different cells of a tissue, or the cells
of different tissues within the organs, *or the cells of different organs interact with each
other through a chemical regulators secreted into ECE.
And finally:- the compartments[parts]of E.C.E is as follows:[Either fluid or matrix]
As next page…
2

3. a- Fluid compartment..[body fluids]
*The water content of the body is divided into two portions *approximately 67% of
the total body water is contained within the cells [intracellular comp/t]..the remaining
33% of the total body water is found in E.C.E, * about 20% of this E.C.fluid is contained within
the vessels of cardiovascular system, where it compose the fluid portion of the blood..[i.e. blood
plasma]* whereas the remaining 80% of E.C.fluid makes-up the tissue fluid..[so, called
interstitial fluid]…So, this fluid is contained a gel-like of matrix composed of Glycoproteins &
proteoglycan that form a supportive structures of basement membrane…i.e. below the cell’s
membranes….
E.C.E
I.C.E
3
*
.
.

4. 1.1.*Distribution of body water between E.C.C & I.C.C.{ie, ratio of water volume}
As earlier, approximately two-third of the total body water is contained within the
cells of body, and so called:*ICF; whereas the remaining one-third is in ECF,
So that, about 20% of this fluid accounts to the blood plasma, *due to this, the
distribution balance of water between interstitial fluid & the blood plasma is
determined by an opposing forces acting at capillaries…(Blood capillaries)…..
*for examp/ *B/pressure promotes formation of interstitial fluid from plasma, *whereas
osmotic forces draw water from the tissues(ie, interst/space)..into the vascular system.*Thereby
the total volume of IC & EC fluid is normally maintained a constant balance for *water loss &*water
gain.
1.2. *As Second example: signal transduction….[cellular level]
Cell signaling refers to * how cells of the body communicate with each other in
certain specialized cases….
Mostly, the cells signal to, Each other by releasing chemicals into E.C.E.
The signal pathway of cells can be divided into three general categories.
a- paracrine signaling. b- synaptic signaling. & c- endocrine signaling.
*these are all examples of, a dynamic constancy*
* Osmotic pressure is a force to prevent the inward flow of water..[draw back]
4

5. *Chap/1th Endocrine systems…[biology]
The nervous system and endocrine system work together to regulate the activities
of other systems of the body, Both systems use chemical signals, when they
respond the changes…ie, take action that threaten the homeostasis, *however, the
nervous system is composed of;*Neurons, *So, In this system, Sensory receptors
detect[sense to ]the changes in internal & external environment..(ie, sense the body
temp/…& out side changes)…and finally: the CNS..[ie, part of the brain that maintain the
body temp..then integrates..[receives]..an In-put information & responds by stimulating
muscles and glands..[cutaneous glands] ….(ie, functional targets).
• **As endocrine system is largely composed of glands, that secrete hormones,
carried by the bloodstream to the target cells……
• So endocrine glands are contrasted with exocrine glands, *Exocrine glands have
ducts and secrete their products into a passage…*as exmap/*The salivary
glands send saliva into the mouth by way of ducts….
• **Endocrine hormones are bind to receptors with their target cells….*either
extracellular receptors..[ie, group of membrane proteins act as receptors]..or *intracellular
receptor…
*A simple chart of regulation of nervous system ... Shows next slide.
As next slide.
*Homeostasis/communication with in the body is controlled by;* regulatory mechanism…
(Nervous & endocrine systems)….
5

6. *this is about a simple chart for regulation of Nervous system…{to their functional units}
*
*
*
*Interaction components of homeostatic control.
*
*
*
6

7. *The major/selected endocrine glands & location within the body.
7

8. A] the action of Hormones. {*as commonly}
* The major action of hormones to influence, the activity of certain tissue cells.. (ie,
body cells)..Is about an effect that induces..(bring-on)..*Either to increase or
decrease; *such as, up-take of particular substances..(as glucose) or Ions..(as
calcium)….*Other effects bring about an alteration of cell’s structure…like growth
hormones….**Growth hormones are peptide hormones that include *proteins,
*Glycoproteins…etc.
*They are modified from AAs. **Growth hormone is a protein produced and
secreted by the anterior pituitary gland…..***As steroid hormones are derived
from cholesterol….
I- The action of peptide hormones. (some of, promotes signal transduction, some
of, promotes protein synthesis…some of, initiates energy metabolism)….etc.
The actions of peptide hormones can be different, in some ways *As example:- when
they target on muscle cells…..
**In muscle cells; after epinephrine hormone binds to a receptor in plasma
membrane, so the reception of epinephrine leads to break-down of Glycogen to
glucose, which provides energy for ATP production. The immediate binding
results formation of cyclic adenosine monophosphate(cAMP)…& then the cAMP
activates a protein kinase enzymes in the cell..{in active prot/enzymes] *Once these
enzymes activated, they break down glycogen….glucose and enters the blood..
Water soluble
**AS this example..
8

9. • **And finally; *many molecules of glycogen are broken down to glucose and enters the blood
stream…..***As this FIG: shows…..15.4.
FIG: 15.4
*
9

10. • II- The action of steroid hormones.
• Only the adrenal cortex, Ovaries, & the testes produce steroid hormones.
• Thyroid hormones are amines and act similarly to steroid hormones..[ie,it is
biogenic amines..or monoamines that are involved removal of carboxyl group….
(functional group)..and has nonpolar ring…
• Steroid hormones do not bind to plasma membrane receptors…but they are
able to enter the cell….**So, once inside, the steroid hormone binds to a
receptor in cytoplasm…and then the hormone-receptor complex diffuse into the
nucleus and bind with DNA, & activates certain genes..(ie, regulatory proteins)
…that initiates formation of mRNA….
• The mRNA then moves into the cytoplasm……**As example of steroid hormone is
aldosterone, which is produced by adrenal glands, **Aldosterone targets the kidneys
where it helps to regulate the salt-water balance of the blood….
*Question:- * Why second messenger systems are needed for peptide
hormones?
Question:- Explain, how homeostasis of plasma osmolality is maintained?
***As next slide shows..
10

11. **Effects of steroid hormone……..
11

12. *partially-
12

13. • 2.1- Hypothalamus and pituitary gland.
• The hypothalamus acts as the link between the Nervous and endocrine
systems, * It regulates the internal environment through communications..[ie,
chemical messengers] ….*as example:- *It helps to control body temp/..,*water-salt
balance…*& also controls the glandular secretion of pituitary gland.
• a. The pituitary gland: Is a small gland about 1cm in diameter, it is connected
to hypothalamus by stalk-like structure….* It has two portions:(the posterior…so
called:- neurohypophysis… & the anterior…so called:- adenohypophysis)
• b- Posterior pituitary gland….[neurohypophysis]
• *Neurons in hypothalamus called:-*Neurosecretory cells produce the
hormones..*antidiuretic hormone[ADH]…and *Oxytocin…these hormones pass
through axons into the posterior pituitary…*where they are stored in axon-endings..{ie,
the posterior part of pituitary gland is stored the axon(fibers) terminals of hypothalamus….and
carries- out releasing action}
• Certain neurons in hypothalamus are sensitive to, Water & salt balance of the blood…
• As examp/:- When the blood become too concentrated…..*ADH is released into the
blood, Upon reaching the kidneys…..*& the hormone causes more water to be
reabsorbed by the kidney cells into the B/capillaries{B/stream}….*As the blood
becomes dilute…***ADH is no longer released…**This is an example of control by negative feed
back….[term negative….reduction of intensity(ability)..or opposite to changes….[stable, homeos/]
(NB:*ADH is more sensitive to, changes in blood osmolality)…
13

14. *FIG:- shows the two hormones produced by neurosecretory cells of hypothalalmus.
*
*
*
.
.
14

15. *Hypothalamic control:- * by way of regulatory hormones…
*
*Posterior pituitary.
*ant/pituit.
. .
15
Hypothalamic-releasing
And hypothalamic-
inhibiting hormones..
*Portal
system.
*Neural control.
Is under adrenal
Medulla….

16. • *Cont:-
• Inability to produce..ADH, causes diabetes insipidus….(ie, excessive urination that causes
inadequate of ADH hormone….ie, antidiuretic hormone, also called vasopressin) or the lack of the
normal response by the kidney to ADH)….*So, a person with this type of diabetes
produces excessive urination results in severe dehydration & a loss of
important ions from the blood….*this condition can be corrected by administration
of ADH…..
So the other hormone made in hypothalamus(oxytocin)causes uterine contraction
during childbirth…& milk let-down when a baby is nursing[feeding]……
***C- Anterior pituitary gland….[adenohypophysis]
**NB:-the hypothalamic control of pituitary gland is by two ways…
**Neural control…(hypothalamic terminal axons[fibers] stored in posterior pituitary)….
*& hormonal control…(anterior pituitary)
So, The hypothalamus controls the anterior pituitary by producing:*(hypothalamic-
releasing & hypothalamic-inhibiting hormones)….These hormones pass from
hypothalamus to anterior pituitary by way of *portal system(entrance)….
*So, four of the seven hormones produced by anterior pituitary have an effect on
other glands…….as example;
16

17. • **Thyroid-stimulating hormone[TSH]..stimulate the thyroid to produce its
hormone…*Adrenocorticotropic hormone[ACTH]..stimulates adrenal cortex to
produce cortisol…***Gonadotropic hormones..(FSH/LH]..stimulates the
gonads..[testes in male, & Ovaries in female]..to produce gametes…
• NB:-*So in each instance[case]..a negative feed back controls, a way of hormones
are secreted into the blood….[ie, Either inhibiting/releasing]….
*
*This is an examp/: of anterior pituitary.
*hypothalamic-
*
*
1-
2-
*
3-
*hypothalamic-inhibiting hormone.
17

18. • *Cont:-
• The other three hormones produced by anterior pituitary do not affect other
endocrine glands…such as*prolactin[PRL]…causes the mammary glands in breasts to
develop & produce milk; * it also plays a role in carbohydrate & fat metabolism.
• **Melanocyte-stimulating hormone[MSH]…*NB:-In-general causes…Skin color changes in
many fishes, amphibians…& reptiles having melanophores..(ie,special skin cells produce color
variations)….*The concentration of this hormone in human is very low!!
• &* Growth hormone[GH]….this hormone promotes skeletal & muscular growth.
• It stimulates the rate at which amino acids enter cells and protein synthesis occur.
• It also partially promotes fat metabolism…*as opposed glucose metabolism…
• NB:-*The production of insulin-like growth factor 1.[IGF-1]..secreted by the liver is stimulated
by growth hormone…**and it takes part the Growth & development….
• In 1980s growth hormone become a biotechnology product, it was possible to
treat short children..{ie, slow progress/delayed}..**& those diagnosed as pituitary dwarfs…
• Because of; a growth hormone blood test can be done to tell, if a child is under a low value of GH..
• And can be injected GH as medication….
• **Effects of GH. **The greatest quantity of GH is produced during childhood &
adolescence…**So , if too little of GH is produced during childhood….the child has
(pituitary dwarfism) *** If too much of GH is secreted, person become giant.{over-size}
• **giants have usually poor health…..**GH has effect on blood sugar level, causes illness
**diabetes mellitus..*this disease is characterized by inability of body cells to take-up glucose….
*dwarfism:-ie, Short stature..or small size…(underdevelopment of body)
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19. • **Thyroid Gland:-*the thyroid gland is located in anterior part of neck…*it is
on the trachea….*& inferior to the larynx…it consists of two lobes…connected
by connective tissue called; Isthmus…***The parathyroid glands are
embedded in the posterior surface of Thyroid Gland…..
19

20. • **Cont:-
• The thyroid gland is composed of a large number of follicles..(each follicle is a small
spherical structure made of thyroid cells….**Filled with Triiodotyronine[T3]…which contains three
iodine atoms…**And Thyroxine[T4]..which contains Four iodine atoms…..
• **Effects of Thyroid hormone….
• To produce triiodothyronine(T3) and Thyroxine(T4)…ie, thyroid hormone is actively
requires iodine….**if iodine is lacking in the diet, * the thyroid gland is unable to
produce thyroid hormones…**So, the thyroid hormone increases the metabolic rate…*It
stimulates all cells of body to metabolize….(ie, more glucose is broken-down..and more
energy is used)….**So, If the thyroid fails to develop properly, brings a condition called:-
*Congenital hypothyroidism…**Individuals with this condition are short and have
hypothyroidism..(ie, under-secretion of thyroid hormone)..since infancy or childhood…
• Unless treatment begun within the first two months of life…*mental retardation results.
• SO, in adults…**the hypothyroidism produces the condition called:- Myxedema..(ie, a
condition associated;* including , weight gain, mental dullness, and sensitivity to cold &
lethargy..(ie, state of being drowsy)…etc.
• **As condition of hyperthyroidism…(ie, over-secretion of TH)….this condition results or
forms Goiter…*Exophthalmic goiter…(ie, eyes protrudes…,a person becomes nervous,
and usually suffer from insomnia….
• ****As next slide shows..
20

21. * This disease was being
discovered In 1835….& *clarifying
in 1956…..**Begins deficiency of
iodide….
*Exophthalmos…ie, exo = out
[protrude]…as*ophthalmos = eyes.
21

22. • **Calcitonin…(a hormone produced by the thyroid gland that lowers the levels of calcium and
phosphates in the blood and promotes the formation of bone..( 32-amino acids….polypeptide)
• Calcium ions..(Ca++)..play a significant role in both nervous conduction &
muscle contraction, they are also necessary for blood clotting.
• The blood calcium level is regulated in part by calcitonin, * it is a hormone
secreted by thyroid gland when the blood calcium level rises, **The primary
effect of calcitonin is to bring about the deposit{ie, put-down}of Ca++ ions in the
bones…***It also temporarily reduces the activity of; *Osteoclast..(Gr term….
osteoclasia; ie, Reabsorption & destruction of a bone tissue)……………..
*Decreases B/ca++.
*Increases B/ca++
*
.
*as Physiology.
*PTH major regulator
of B/Ca++ level.
22

23. *The bone cells include:-*Osteocytes, Osteoblasts, Osteoclasts, & *Osteogenic cells (stem
cells )…*Osteoclasts:- are very large multinucleate cells that are responsible for the
breakdown of bones. The breakdown of bone is very important in bone health because
it allows for bone remodeling...*Osteoblasts:- are bone cells, responsible for formation
of new bone. Osteoblasts deposit a collagen matrix and release minerals that combine
to make the bone mineral.**Osteoblasts are much smaller;**And derived from the
differentiation of osteogenic cells in the tissue that covers the outside of the bone, or
the periosteum and the bone marrow….*Osteocytes :-are osteoblasts which have
become trapped inside of the bone matrix.[middle ]
As further.
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A bone tissue cells..
*
*Differentiation.

24. • **Parathyroid Glands.
• Parathyroid glands are four small glands located at posterior surface of thyroid
gland…*& produced parathyroid hormone that causes the blood calcium level
to increase…..*A low blood calcium level stimulates the release of PTH..(9.4mg/100ml)
which promotes the activity of osteoclast(reabsorption) & the release of calcium from
bones.
• PTH also activates vitamin D in kidneys..{some times called; calcitriol}..*Then promotes
calcium reabsorption by the kidneys..*& absorption of ca++ from intestine(GTI)
• NB:- in many years ago, the four parathyroid glands were mistakenly removed
• During thyroid surgery….because of, their size & location……*Gland removal
caused insufficient of PTH secretion..and results:*hypoparathyroidism….*it brings
• a blood calcium drop in low…**Followed by excessive nerve excitability..[ie,signal is on
without rest]….**So, without treatment of this condition causes, heart failure, seizures.
• {convulsion}…& death….**(many factors influence bone formation…*(PTH,calcitonin, &
Vit/D….)
• ***Adrenal glands.
• The adrenal glands are at the top of kidneys….*Each gland consists of, inner
portion(adrenal medulla)…& outer portion(adrenal cortex), **These portions
are two functionally distinct……*the adrenal medulla is under nervous control.
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*Vitamin D [ a fat-soluble vitamin]…increases intestinal absorption of ca++,
mg++, PO4 and zinc… .Vit/D is synthesized by skin cells..[as Vit/D3] and send to
the kidneys, where it is changed into calcitriol.....acts as pro-hormone and
activates kidneys & intestinal absorption….

25. • **As adrenal cortex is under the control of:*corticotropin-releasing hormone(CRH)
**Adrenal medulla.
The hypothalamus initiates nerve signals that travel by way of the brain stem,
spinal cord, and preganglionic sympathetic nerve fibers{ie, Plexus from autonomic
nervous system}….to adrenal medulla…..*these signals stimulate adrenal medulla to
secrete its hormones….like:*Epinephrine(adrenaline)…and norepinephrine{NE}
*Both hormones rapidly bring about all changes that occur when individual reacts to emergency
situation..{fight/flight}
**Adrenal cortex:- *the adrenal cortex secretes steroid hormones called: *Corticosteroid,
(cortisol)…*In general; they are three categories…*mineralocorticoids,*glucocorticoids,
&*adrenal androgens..{ie, a very weak hormone that supplement a sex steroids by gonads}
*But the two major hormones like*glucocorticoids….(regulates metabolism of
glucose)…& *mineralocorticoids…(regulates Na+ & K+ balance)….
I- Glucocorticoids:- *Raise the blood glucose level in two ways; 1)*they promote
the break-down of muscle proteins to amino acids, then taken-up by the liver
from B/streams…& then converts to glucose which enters the blood…..****
***** Secondly…….
25

26. • 2)* they promote the metabolism of fatty acids rather than carbohydrates…
(this spares glucose) ….NB:- glucocorticoids also counteract..(ie, opposite to)..the
inflammatory response that leads (pain & swelling)…because they suppress the body’s
defense system….
***Mineralocorticoids.
Aldosterone is the most important mineralocorticoids, It targets the kidneys and
promotes renal absorption of sodium ions(Na+)…& renal excretion of potassium ions
(K+)…..***The secretion of mineralocorticoids is not controlled by anterior pituitary,
• As example:- * when the blood sodium level and the pressure become low…*the
kidneys secrete renin…*Renin is an enzyme that converts the plasma proteins of
angiotensinogen, into angiotensin 1, *then angiotensin 1 is changed to angiotensin II
by an enzyme found in B/capillaries…**And finally angiotensin II stimulates adrenal
cortex to release aldosterone…{the effect of this system called:- Renin-angiotensin
aldosterone system} …..
• **This system raises the B/P in two ways…**angiotensin II constricts the arterioles…
**& the aldosterone causes the kidneys to reabsorb sodium ions…*thus..when the
blood Na+ level rises , water is reabsorbed…{ie, blood pressure increases to normal}
NB:- in case the blood pressure rises dueto Na+ reabsorption, the atria of heart
are apposite to stretch, **b/cause of, a great in B/Volume….**Then the cardiac cells
secrete a chemical substance called:- *Atrial natriuretic hormone..[ANH]…..
**This substance inhibits secretion of Aldost/..**& caused by ,natriuresis..[ie, excretion of
Na+/s}
*part of kidney cells..(in area of nephrons) sense reduced B/P…
*
26

27. Supplies blood.
.
*
*Have receptors…sense reduced
Blood Pressure in arteriole.
Lumen…
.
27
*
.
Peritubular capillary.
*
*

28. A
B
*B/P rises.
B/cause of high B/P.
*B/P low.
28
*Plasma proteins..
angiotensinogen

29. • ***Malfunction of adrenal cortex..[abnormality]
• *When adrenocortical hormones are too low, …ie, hypo-secretion acquired & a person
may develop, **Addison disease ..(a destructive disease marked by insufficient of
adrenocortical hormone and characterized by extreme:- weakness, loss of weight, low
blood pressure, gastrointestinal disturbances, and brownish pigmentation of the
skin……..(Thomas Addison ..1860 English physician)
29
*

30. Ie, discomfort, *& pain in muscles.
**When the level of glucocorticoids is high dueto **Hyper-secretion….**a person may
develop..(Cushing syndrome)…**Cushing syndrome a metabolic disorder caused by over-
production of cortico-steroid hormones by the adrenal cortex and often involving obesity
(ie, Fatness)….and high blood pressure.
NB:-**Excess glucocorticoids results in a diabetes mellitus…{Inability of body cells take up Gl}
*muscle protein is metabolized and subcutaneous fats is deposited in the midsection….
The result is swelling…..**Moon face… and obese..(ie, overweight)..with arms & legs……
The cushing syndrome may be treated by using of…..*Cortisol-inhibiting drugs…
*As this slide shows.
(loss of appetite)
*Vitiligo = a condition in which the pigment is lost from
areas of the skin, causing whitish patches,
30
*Congenital adrenal hyperplasia (CAH)..excessive or deficient
*
*amyloidosis..Collection of proteins forming fibrils.

31. • ***The pancreas:- *Is an organ that stretches across in abdominal cavity, it lies
behind(under)the stomach & near duodenum…*It is composed of; *Two types
of tissue…[*Exocrine tissue..produces & secretes digestive juices that go by way
of ducts to small intestine(duodenum)]…***& Endocrine tissue, called;
pancreatic islets(islets of langerhans)….produces & secretes the hormones…
*insulin & glucagon directly into Blood….
• The pancreas is not under pituitary control, Insulin is secreted when the blood
glucose level is high, which usually occurs just after eating, *Insulin stimulates
up-take of glucose by the cells, *especially: Liver cells, muscle cells, & adipose
tissue cells…..*in liver & muscle cells glucose is stored as glycogen…. 31
*acquired cushing syndrome.
*after treatment.

32. • *Cont:-*In muscle cells, glucose supplies energy for muscle contraction…**So,
in various ways, insulin lowers the blood glucose level…
• Glucagon is secreted from the pancreas, usually b/ween eating, when the
blood glucose level is low….*the major target tissues of glucagon are:*Liver &
*adipose tissue…**Glucagon stimulates the liver to break-down glycogen into
glucose, **It also promotes the use of fats & proteins to glucose as source of
energy…..**and finally:- Glucagon raises blood glucose level….
32

33. • **Types of Diabetes….
• There are two types of diabetes mellitus: * the type 1..(pancreas is not producing
insulin)..this condition is believed to brought on, by environmental agent..most likely a
virus…*Whose presence causes cytotoxic T cells, *because they destroy pancreatic
islets…*and the body turns to, metabolism of fats, which leads the build-up of ketones
in blood..[acidosis]…that results to Coma & death…**at most cases the blood sugar
level may swing between…*Hypoglycemia[low blood glucose level…90mg/100ml]…*Or
Hyperglycemia[high blood glucose level]……NB:- it is difficult to certain both conditions…
• *Symptoms are similar…..*perspiration, pale skin, shallow-breathing, anxiety…..
• **If the problem is hypoglycemia….***treatment is two glucose tablets + Orange juice
• **If the problem is Hyperglycemia…..***treatment is insulin….**It is possible to
prevent….**a low fat diet, **low sugar diet[refinery]….**exercise…etc…
• So, the long term complications of both types of diabetes can lead……**kidney
disease, cardiovascular disorder..[including…atherosclerosis, heart disease, stroke, &
reduced circulation…..
• Later on, **gangrene…..in arms & legs….[scar/wounds]…..etc.
NB:- incase 100 grams of glucose follows(food)…..the blood glucose level rises..*If diabetic
…Glucose appears in the urine…..***As this diagram shows…
33

34. *Incase the oral glucose(food) follows 100 grams…
..the blood glucose level rises..
**Other endocrine Glands.
**Testes and Ovaries:- **the activity of testes and ovaries is controlled by Hypothalamus
& pituitary gland……**the testes are located in scrotum; as the ovaries located in the
pelvic cavity……**The testes produce androgens(testosterone)…..male sex-
hormone….**As ovaries produce(estrogen/progesterone)..female sex hormone.
34
.
*

35. • **These hormones are controlled by hypothalamic secretion….called:-
gonadotropin-releasing hormone[GnRH]…..**Under the influence of
gonadotropic hormone….*testes begin to release increased amount of
testosterone at the time of puberty…*So, this male sex-hormone stimulates &
also maintain a male secondary character…**Including: Growth of facial,
*Promotes to enlarge larynx & vocal cord, *activates Oil & sweat gland of skin
(ie, cutaneous glands)…it also responsible for body odor….
**As the female sex hormones..[estrogen/progesterone]..*both have many effects *
***estrogen secreted at the time of puberty, *It stimulates growth of uterus..
*and also necessary for egg maturation…*and largely responsible for female
secondary character…**and finally; both are required for regulation of uterine cycle..
[includes; menstruation[bloody discharge from uterus)
35

36. • **Thymus gland.
• The thymus gland lies beneath(under) the sternum….*this organ reaches its
largest size and is most active during childhood,..*with aging, the organ gets
smaller & becomes fatty….*NB:- Lymphocytes that originate in bone marrow, pass
through the thymus and transformed into T-lymphocytes,..**The epithelial cells of
thymus gland secrete hormones called:*Thymosins….*these hormones aid in
differentiation of lymphocytes packed inside the thymus…..
• **Pineal gland.
• Pineal gland is a small gland located in the brain……**It produces a hormone: *
• *melatonin…..*Melatonin involves in;* sleep-wake cycle….
36
***Hormones from other organs & tissues:
**Some Organs..(not by endocrine glands)…secrete hormones…
Such as *the heart produces **atrial natriuretic hormone/peptide..{ANP}
Secondly:- *Stomach & *small intestine{duodenum}…produces
peptide hormones (local hormones)….*gastrin hormone..released by
G cells in stomach.{pyloric area}……etc.
THE END.

37. • Chapt:- 2nd ;**The sensations..(act of conscious )..& sensory receptors…
37
*Sensory receptors are dendrites, * specialized to detect certain types of stimuli…(*Changes)
*The two divisions of nervous system. *Sensory receptors…can be;
*sensory cells…+ sensory
nerve fibers(*Somatic &
**Visceral fibers)
*In general
*

38. • Cont:-
• Extroceptors are sensory receptors that detect stimuli from out-side the body,
such as:*taste, smell, vision, hearing…etc…{ie, this is a stimulus from out}
• *as interoceptors receive stimuli from inside the body; *interoceptors include:
*baroreceptors..that respond to, changes in blood pressure,*and osmoreceptors
• that monitor the body’s water-salt balance, ***chemoreceptors are interoceptors
that monitor the pH of the blood…..**Interoceptors are directly involved in
homeostasis and regulated by a negative feed back…**for examp/..*when the
B/pressure rises baroreceptors signal..{ie,send impulse}..to a regulatory center in the
brain….*and the brain responds by sending out, Nerve signals to arterial walls…
**causing their smooth muscle fibers to relax…*& then B/pressure falls….(NB:- all
blood vessels…..*(except capillaries)….their walls consists of:**three coated layers[ie,
tunica]…..*tunica externa, *tunica media….(composed of smooth muscle fibers)…&
tunica intima…)
• ***Types of sensory Receptors.
• Sensory receptors in human can be classified into *Four categories:-
*chemoreceptors, *photoreceptors, *mechanoreceptors, &* thermoreceptors.
• **Chemoreceptors….**Are sensory receptors that respond to..(ie, sense to)..a chemical
substances instantly like a taste,….****The chemoreceptors that monitor the blood pH
are located in the carotid arteries and Aorta…
38
*Chemoreceptors can be….*External receptors……**or Internal receptors….
*baro..[Gr ]…related to pressure[ie, stimulated by changes in pressure]…*As the
thermo[Gr] related to heat….[ie, sensitive to the heat]

39. • Cont:-
• Type of chemoreceptors called; *nociceptors(pain receptors)..are dendrites that
respond to chemicals released by damaged tissues..(cells)
• **Photoreceptors..*are receptors that respond to light energy[rays]…*In human
eyes contain photoreceptors that sensitive to the light…*& provide us sense of
vision….*these photoreceptors are known as..*rod cells..results in *Black-&-white
vision…., **Others known as..*cone cells….results in color vision….
• ** Mechanoreceptors: Are receptors detect to mechanical forces..(things results in pressure
..it can be by *deep pain…*or a sound waves in Air)…..
• **As examp/..*when we hear or listen to, An air sound waves are converted to, a fluid
waves that detected by mechanoreceptors in the innermost of ear.
• NB:- this means; a process of hearing begins, **when a sound waves enter the auditory
canal…& then sound waves travel/across to tympanic membrane..**as the tympanic
membrane vibrates[quiver]…& then vibrations move along auditory ossicles….**& then
the pressure/vibrations pass into a fluid within the cochlea…
39

40. 40
.
.
*

41. • Cont:-
*Proprioceptors are type of mechanoreceptors that respond to, *the movement &
muscular contraction...*They are associated with joints, tendons, & Ligaments.
**Thermoreceptors located in hypothalamus & skin, *they stimulated by changes
in temperature…*& divided into..*warmth receptors & * cold receptors…
**How sensation occur. *Sensory receptors sense to environmental changes.
(Either; internal envir/t, *or external envir/t)…by generating a nerve signals, *and the
nerve signals arrive at the cerebral cortex of brain…& finally; at this point, a
conscious perception occur….
**Some of sensory receptors are free nerve endings[ie, naked dendrites]..*and some of are
encapsulated nerve endings….**Others are specialized cells closely associated with
neurons…
**NB:- the plasma membrane of a sensory receptors contain receptor proteins that react
to the stimulus…..*as examp/…*The receptor proteins in plasma membrane of
chemoreceptors bind to certain chemicals…., *when this happens, * Ion channels open,
& then Ions flow across the P/membrane, & then nerve signals begin and carried by a
sensory nerve ending/fiber[PNS] to [CNS]……..
*And finally…all sensory receptors initiate nerve signals, *as the sensation results, depends
on part of brain receiving…..signal……
41
As this fig: shows..

42. 42
1-
*
*Moves along nerve fibers..(PNS)
(photoreceptors)
*

43. 43

44. 44
**Cont:-
Before sensory receptors initiate nerve signals, *they also carry out:*Integration..**so, One
type of integration is called:*Sensory adaptation..(ie, a decrease in response to stimulus)..
*As examp/…some scientists believe, when sensory adaptation occur;* sensory receptors
have stopped sending impulses to the brain….**& others believe that the reticular
activating system (RAS) has filtered out the ongoing stimuli….[just , stored & recognize later]

45. • ***Proprioceptors, **Cutaneous receptors, and **pain receptors…
• NB:- sensory receptors in the muscles, joints, tendons, Other internal organs &
skin send nerve signals to the spinal cord…*from there, they travel up the
spinal cord in tracts to somatosensory area of cerebral cortex…**So, these
sensory receptors are categorized into three types..[proprioceptors, cutaneous
receptors & pain receptors]
45
*It is where sensory information arrives..(skin, skeletal muscles)
*
*

46. • **Proprioceptors…
When a muscle stretched, the muscle spindle sends:-*1- Impulses along sensory
nerve to the spinal cord, and then to the brain,**2- then the brain sends impulses a
long motor nerve through spinal cord into muscle,….**And then the muscle contracts…
46
**As this example….

47. 47
• **Cutaneous receptors….
• The skin composed of Two layers….*Epidermis &*dermis…*the epidermis is stratified
squamous epithelium….*cells become keratinized..(dried-up) as they rise[go-up]to the
surface{outer most}…..*as the dermis is a thick connective tissue layer, *The dermis
contains Cutaneous receptors…*which make the skin sensitive to touch, pain, pressure,
& temperature..etc.****Three types of cutaneous receptors are sensitive to fine touch..
• Like:- *meissners corpuscles, *merkel disks,(epidermal-dermal junction)..*& root hair plexus….
2
1
*
3
.
.
.
Onion-shaped recep/
Encapsulated N/fibers

48. 48
• **Pain receptors:- **Like the skin, many internal organs have pain receptors…
and so called: nociceptors…..these receptors are sensitive to chemicals released
by damaged cells[tissues]….*when inflammation occurs dueto, thermal[burning]
Or toxic substances, cells release chemicals that stimulate pain receptors, **Aspirin &
ibuprofin reduce pain……
**Senses of Taste & Smell… **Taste and smell are called:*chemical senses
…because their receptors are sensitive to molecules..[food/air]..
**Sense of taste…[ie, tongue]
**In human[adult]…approximately, 3000 taste buds are located on the tongue…..many
taste buds lie along the walls of papillae..[ie, small projections on tongue]..**So these small
Elevations on the tongue are visible….**There are four primary types of taste….(sweet,
sour(acidic taste), salty(saline), and bitter)….NB:- the fifth taste, called:- *Umami…
.(gives savory flavor of certain….cheeses, beef,..etc.
NB:- The four taste buds are; *at the tip of tongue…[sensitive to sweet]
**Margins of the tongue….[salty & sour taste]..
**And the rear[back] of tongue……[bitter]
NEXT SLIDE..

49. 49
*The taste buds open to taste pore….*taste pore have supporting cells & Number of elongated taste cells
..that end microvilli….**So, when molecules bind receptor protein of microvilli….Nerve signal generated.
* * *
*
a
a.1
**signal reaches at Gustatory[taste] cortex..
.

50. • **Monthly assignment…
• *Structural questions.
• 1- How does the action of peptide hormone differ from that of a steroid
hormone?
• 2-Discuss, how the negative feed back relationship, among the hypothalamus,
anterior pituitary, and other endocrine glands?
• 3-How neuroendocrine system work with other systems to maintain
homeostasis?
• 4-Besides the blood pH mentioned, What other homeostatic conditions are
monitored by chemoreceptors?
• 5- What is a sensory adaptations?
• 6-What type of imbalance, would result the lack of aldesterone into the blood?
• 7- briefly explain, differences of PTH & calcitonin in blood pH?
50

51. 51
(Ie, Epithelia)
Lamina propria..
*Onion shaped neurons
*
*
*
*Sense of smell: **Approximately 80-90% of what human perceive as “taste”
is actually results the sense of smell…..***so, the sense of smell are between 10-
20 million Olfactory cells, located within Olfactory epithelia…**Olfactory cells are
modified Neurons…*Each cell ends in a tuft of Olfactory cilia..[hair-like STRs], which
bear receptor proteins for Odor molecules….***Each olfactory cell has several
hundred different types of receptor proteins….*As the fibers..{filaments}..of
olfactory cells attached to Neurons in olfactory bulb….**And the odor substance
contains many odor molecules which activate & combine receptor proteins…
*
*

52. ***The Sense of Vision.
Anatomy & physiology of the Eye.
*The eye ball is about 2.5 cm in diameter, *It has three layers or coats:*the sclera,
the choroid, & the retina…{as this FIG..shows}
52
* The cornea is the front part of the eye(transparent) that covers the
iris , pupil, and anterior chamber(*It does not have blood vessels)
*aqueous humor.
1
2
*
.

53. • Cont:-
• The outer layer(sclera) is a white & fibrous..*except cornea..which is made of
transparent collagen fiber,…and it is known the window of the eye….
• *the choroid is a thin middle coat, *It has an extensive blood supply..& its dark
pigment absorbs stray (ie, get lost) light rays that photoreceptors have not absorbed..
• (it helps visual acuity)…**The choroid becomes a doughnut-shaped the IRIS…
• **The iris regulates the size of Pupil..[a hole in center of iris….which light enters Eye]….SO,
*Behind the iris, the choroid thickens and forms the circular ciliary body…..NB:- Ciliary
body contains smooth muscle fibers, which controls the shape of lens for[near/far vision]
• **The lens is attached to ciliary body by suspensory ligaments & divides the eye into
two compartments…[ie, anterior compartment is in front of lens, and the posterior
compartment is behind the lens]…..**The anterior compartment is filled with a clear,
watery fluid called:*aqueous humor…[NB:- a small amount of aqueous humor is continually
produced each day…**& it leaves the anterior compartment by way of tiny ducts…[lacrimal duct]
**Incase a person has glaucoma..**these drainage ducts are blocked and aqueous humor increases..
**If not treated glaucoma..*it results to compresses the arteries that serve[around]..the N/fibers of
Retina…{where photoreceptors located]…and begin to die…..[causes blindness]
**The third layer is retina….located at posterior compartment, **this area is filled with a
clear, gelatinous material called:- *Vitreous humor….**The vitreous humor supports
retina & lens….*as the retina contains photoreceptors called; *rod cells,*cone cells…
**rod cells are sensitive to the light,,*as the cone cells sensitive to different wave of light &
Also require bright light…..[it is an ability to distinguish colors]…… 53

54. 54
*Function of the lens:-**The cornea, assisted by the lens and the humors, *Images are
focused on the retina….**Focusing starts with the cornea and continues as the rays pass
through the lens and humors….*The image produced is much smaller than the object…..
because light rays are bent{refracted}…**And the image on retina is inverted(upside down)
and reversed from left to right….*Visual accommodation(ie,put up ) occurs for close vision,
*During visual accommodation, the lens changes its shape to bring the image into focus on
retina…{NB:- the shape of the lens is controlled by ciliary muscle, within ciliary body}…..
*When view a distant object, ciliary
muscle..relaxed…
A
*
B
*
*when view a near object, ciliary
muscle….contracted..
*visual acuity…depends
on variation in curvature
of either ….* Cornea or
lens…*or in the overall
shape of the eye….
{astigmatism,hyperopia,
& *myopia[shortsighted]

55. • **The function of photoreceptors….
• The structure of photoreceptors called:*rod cells & cone cells..*Both have an
outer segment joined to inner segment by a short stalk..* pigment molecules
are embedded in the membrane of many disks present in the outer segment,
So, Synaptic vesicles are located at synaptic endings of inner segment…*the
visual pigment in rods is a deep purple pigment called:-*Rhodopsin….(* Is a
complex molecule made-up of protein(opsin)..& a light absorbing molecule called:[retinal]…**it is
derivative of Vit/ A…**When a rod cells absorbs light, *rhodopsin splits into Opsin &
retinal……So, this leads to a series of reactions..& the closure of ion channels in the
plasma membrane of rod cells….*as the release of inhibitory transmitter molecules from
Rod’s synaptic vesicle, ceases[absorbing light]…*thereafter, signals go to other neurons.
55

56. 56
*Cont:- ** in the retina..(*rods are very sensitive to light)…*Rod cells are
plentiful through out the entire Retina, **except Fovea,….**and finally:- **rods
also provide with *peripheral Vision..[marginal] & *perception..[insight]…
**The cones are located in the Fovea..**and activated by bright light….*they
detect the color of an Object..***NB:- Color vision depends on three different
types of cones, Which contain pigments called:**B(blue) **G(green) *& *R(red)….
So, each pigment is made up of; * retinal + *Opsin..(ie, rhodopsin)

57. 57
**The function of retina:- **The retina has three layers of neurons…*the layer closest to
choroid contains *rod cells &*Cone cells…, *A layer of bipolar cells covers the rods & cones.
**The innermost layer contains ganglion cells(N/Cells), *whose sensory fibers become the
Optic nerve…{only rod cells & cone cells are sensitive to light}…***The rod cells & Cone
cells synapse with bipolar cells..*next, Signals from bipolar stimulate ganglion cells, whose
axons become the Optic nerve….**So, as signals pass to bipolar cells & ganglion cells….
*
.
.

58. 58
Additional slide.
**Process of
phototransduction path way

59. • **Integration occurs, **Therefore, processing occurs in retina before ganglion
cells generate nerve signals….[NB:-the ganglion cells converge to form Optic
nerve, which transmits information to Visual cortex….
**From retina to visual cortex…
• So, to reach the visual cortex….*The Optic nerves carry nerve impulses from
the eyes to optic chiasma..[*Optic chiasma is an X-shaped space, where Optic nerve fibers
crossing over..}
59
* *

60. • Cont:- **then, The optic nerves continue as optic tract. **so, fibers from the
right retina,(Rt Eye) half of each data..(information)..converge and continue in the
right optic tract, **as the fibers from the left retina…half of each go on the left
optic tract…**traveling to the brain.
*The optic tract sweep around the hypothalamus, and most fibers synapse with
neurons..[ie, nerve cells within thalamus]…..**and finally:- *Axons from thalamic nuclei form
optic radiation[rays]…*that take impulses to the visual cortex within Occipital lobe….*and it is
where an image is split-on.
**Abnormalities of the Eye..
**Color blindness & misshapen(malformed) eyeball..{bulbus oculi}..are two common
abnormalities, **So, Color blindness is extremely rare and is caused by a genetic
mutation…..NB:- in most instances[case in-point]…*Is about one type of cone cells is
defective[out] or deficient in number….*this abnormality accounts 5/8%...
**Others can be:- *Cataracts[when the lens of eye become cloudy {ie,overcast]..and
glaucoma..[a fluid pressure builds-up in side the eye]…both decrease in vision…
60
*Iris overcast

61. 61
*Healthy Eyes
*Abnormal
*

62. 62
*Long eye ball.
*short eye ball.

63. • **Sense of hearing.
• The ear has two sensory functions:- (i.e, hearing & balance)…So, the sensory receptors
for both of these are located in the inner ear, *each consists of hair cells. {i.e, STRs seen as
hair-like}….that sensitive for mechanical stimulation…..
• **The structure of ear.
• The ear has three divisions: *outer, middle, & inner…..**The outer part
consists of; Pinna..[external flap]..and auditory canal…*the opening of auditory canal is
lined with fine hairs and sweat glands..[secrete earwax, a substance against entrance of
foreign materials….
• **The middle ear begins at tympanic membrane and ends at a bony wall containing
two small openings covered by membranes…..* these openings are called:-*oval
window..& *round window, **Three small bones are found between the tympanic
membrane and oval window….**Collectively, they are called**Ossicles(malleus..[hammer]
incus & stapes..[i.e, smallest seen as U]..* the malleus adheres to tympanic membrane…and
the stapes touches oval window…**An auditory[eustachian]tube extends from middle
ear to nasopharynx….*it permits equalization of air pressure…as examp/…* chewing,
swallowing helps air move through auditory tube, *as this occurs, we often feel the ears
“pop”……* and finally; the outer/middle of ear contain air, as the inner filled with fluid..
**The inner ear has three sub-areas[divisions]…*semicircular canal, vestibule are concerned
with equilibrium[balance], & cochlea concerned hearing[tons]…..
63

64. • **The structure of human ear:-**outer, middle, & inner…[ie, sense of hearing occur at inner part]
64
*
*
a
*
Spiral orgn

65. 65
*
**From cochlear to auditory cortex…
*the cochlear has three canals[ducts] *the sense organ for hearing so called: *spiral
organ[organ of corti]…**It is located in the cochlear canal…* the spiral organ consists
of; little hair cells and a gelatinous material called; tectorial membrane, the hair
cells sit on basilar membrane…and their steriocilia[projections] embedded in
tectorial membrane….***So, when the stapes[smallest bone]..strike the membrane of
Oval window, then the pressure moves from vestibular canal to tympanic canal across to
basilar membrane….*& then basilar moves up/down..and then steriocilia of hair cells bend
*
*
.

66. 66
**And finally; a nerve signal begin in cochlear nerve and travel to the brain….**as it
reaches to auditory cortex in temporal lobe….*****& interprets as sound….[tone]
*Cochlear region [*Vestbular,*Organ of
corti, & *Cochlear duct]
*

67. • **Pathway of sound wave..[i.e, act of hearing]
• **When the sound waves entered the external auditory canal..[external acoustic meatus]
• Then it pass or across to tympanic membrane….*as the tympanic membrane vibrates,
this vibration causes movement of ossicles…*and the foot of stapes moves like a piston
on the oval window…transmitting the effects of sound waves into a pressure wave….*
and then this pressure wave from an oval window travel through perilymphatic duct of
innermost[i.e, a fluid within the inner part]….So, at this point, the pressure wave converted
to fluid pressure…..that causes a hair-like cells within the cochlear duct to bend…and-
initiates a nerve signal
67
*As physiology.
Initiated nerve signal….

68. 68
*Pathway of sound..[act of hearing]
*

69. 69
• Chap/3rd :- Muscular system.
• Human have three types of muscle tissues:*Smooth, cardiac, & *skeletal.
• The cells of these tissues are called; muscle fibers…[or fascicles….]
• **Smooth muscle fibers are shaped like *narrow cylinders[rolled]..with pointed ends,
Each has a single nuclues[uninucleated]….**the cells are usually arranged in parallel lines,
forming sheets, *smooth muscle is located in the walls of internal organs(visceral organs)
and blood vessels…and cause these walls to contract, * Contraction of smooth muscle
is involuntary without conscious control…[i.e, slower than skeletal]
• ** Cardiac muscle.
• This muscle forms the heart wall, *Its fibers are generally uninucleated..[single nuclues],
Striated, & branching. **The fibers are interlock like by intercalated disks, *the plasma
membranes at intercalated disks contain gap-junctions..[ionic space]…that permit
contractions to spread quickly through the heart…**The contraction of cardiac muscle
is rhythmic[self beats]….i.e, it contracts without nervous stimulation.
• **Skeletal muscle……*Their muscle fibers are multinucleated, striated, and attached to
skeleton….*their fibers[muscle cells]run the length of the muscle and quite long
**Three classes of muscles in human..

70. 70
**The three classes of muscles in human; **These muscles have different characters…
*

71. 71
**The basic structure of skeletal muscles:-**the skeletal muscles contain bundles of
muscle fibers called;*fascicles; * within the fascicles, *each fiber is surrounded by a
connective tissue..[endomysium]..*as the muscle fascicle[tissue] is surrounded by a
connective tissue ..[perimysium]…*and the whole muscle organ is covered by a fascia…[a
type of connective tissue]..that becomes its tendon.*NB:-(a band like STR that connects bone ,muscle)
**When a muscle contracts,* it pulls on the tendons at its insertion and the bone moves…
*Arranged as; *muscle organ,
*muscle fascicle [tissue],
*Muscle fibers[cells],
& myofibrils..[cont/filament]
*Muscle cell.
*
*Membranous
wrapped over
muscle tissues.

72. **The criterion or the standard that muscles are given by names, depends on:- * their size, *& the
region lay over, **Their attachments,….etc.*As the terms used to indicate size, is about …*Longus,brevis,
bbreives,..etc.
72

73. • **Skeletal muscle fibers[contraction]
A muscle fiber is a cell containing the usual cellular components, *but special names have
been assigned to some of these components; **as Examp/:- *plasma membrane called,
(sarcolemma)….*the cytoplasm…sarcoplasm…& *Endoplasmic reticulum….sarcoplasmic reticulum.
**The sarcolemma has invaginations called T tubules….*It encases hunderds/thousands of
myofibrils, *each about 1µm in diameter, *Myofibrils are contractile portion of muscle
fiber/cell…..**Any other organelles, such as MTCH are located in sarcoplasm between
(myofibrils)….* it also contains glycogen..[ie, Stored energy; provides for muscle contraction].
73

74. • **Myofibrils and sarcomeres..[ie, a division of myofilaments]
A muscle fiber/cell is about cylindrical in shape, *Grouped inside a smaller STRs,.. Called;* myofibrils,
*Myofibrils are composed of a tiny thread like STRs called; myofilaments…. *so, myofilaments are
protein molecules of two types(*myosin & *actin)
74
Muscle cell.
myofilament

75. • **Cont:- *myofibrils are divided [fasten] into sarcomeres,**as
sarcomeres extends between two dark lines called:* Z lines or discs. *the I bands on
either side of Z lines are thin filament(actin)…*as the A band is a thick filament(myosin)
*Centered zone within the A band is a vertical [*H zone] this zone is only myosin filaments.
75
.
*

76. • So, the thick filament composed of several protein molecules
called: Myosin…*this portion of filament is a straight chain ending a
globular heads..(cross-bridge)…the cross-bridge occur on each side of
sarcomere…..***As the actin filament(thin) consists of; *two intertwining
strands of protein molecules…& two other molecules called; *tropomyosin &
*troponin…..
• **The sliding over of filaments begins, when muscles are stimulated, {NB:-
*electrical signals travel across the sarcolemma and then down to T tubule…..And
finally; these signals are released calcium from sarcoplasmic reticulum…*and the
muscle fibers are contracted…..as myofibrils are shorten…..
76
Actin.
Myosin.
*Z discs/lines.
*Action is as this

77. 77
*END.

78. *Chap/4th :- Nervous system…The nervous system has two major divisions **the CNS…
..Consists of; *the brain & spinal cord…..[regulating part] ***And PNS..[coordinating part]
78
*
*

79. 79
• **The nervous system has three specific functions:- **Receiving sensory input.
• {ie, sensory receptors/organs responds by generating nerve signal that travel by way of
PNS to CNS}
• **The CNS performs information processing, *Integration,{combination} & *stores…
• **The CNS generates motor output, ie, a nerve signal from CNS go by way of PNS to the
muscles, glands, and organs…etc.
***Nervous tissue….**The nervous tissue contains two types of cells:*neurons,
& *neuroglia..(neuroglial cells)…..**Neurons are the cells that transmit nerve impulses
between parts of nervous system….*As neuroglia support & nourish neurons
* *
*Neuron..
*
*
*
*Neuroglia
Ie, out-put information.
*four types

80. 80
*Neuroglia are cells that supports and nourish to neurons, they do not have long
extensions…{ie, axons or dendrites}…..**Neuroglia found in the brain are; *microglia
*astrocyte, (provide nutrients to neurons and produce a hormone known; *Glial-derived
neurotrophic factor[GDNF]…it is a growth factor…. & *Oligodendrocytes,,[forms myelin
sheath of fibers in brain & *spinal cord..…As **PNS…neuroglia are schwann cells…
etc..[a myelin sheath around N/fibers]…..
**Neuron Structure…
Neurons are three types according to their function;*Sensory neuron,
**motor neuron, *& *Interneurons…
**A sensory neuron takes nerve signals from sensory receptor to CNS…
**Interneurons lies entirely within the CNS, **Interneurons receive input from
sensory neurons and also from other neurons in the CNS[ie, act of signal
communication]….
**As motor neurons take impulses away from CNS to effectors..[glands, muscle
fibers, or organs]…….***Neurons can be different in appearance, but all of them
have three parts;(cell body[neuron], dendrites, & axons…[a portion conducts nerve
impulses….it can be long,… and termed…*N/Fiber…..or *a nerve.
***As sensory neurons have a very long axon carries signals from dendrites
associated with receptors,.. to CNS…{**NB:- This axon is interrupted by the cell
body{sensory neuron}, interneurons, & motor neurons…..etc.
*STRlly …multipolar,[most common] *Bipolar, & *unipolar
*As the slide….I…shows.

81. 81
• In further:- *Neurons come in many shapes and size, but they share certain basic
features….(cell body, dendrites, & axons)….*the cell body called *Soma, & it is enclosed by a
plasma membrane, & contains cytoplasm surrounding nucleus…[ie, control center of neuron]….
• As the cytoplasm within cell body….called:- *perikaryon. ***Dendrites are small process that
branch off the cell body… **Axon is N/fiber, *It is a longer portion that neuron make contact to
other neuron….or effector,….(NB:- the first part of axon is triangular region…called Axon hillock, *
as the cytoplasm within an axon called…Axoplasm, **the plasma membrane of axon …axolemma,
*It has other extensional STRs…called; axon collateral…**& finally:- terminal edge of
axon…telodendria….{bulb-like STR….*synaptic vesicle}
A
*
*
*
*As next slide.

82. 82
B
Axon collateral
*
.
*

83. 83
**Three types of neurons..(**as functionally)
I

84. *Myelin sheath.
• Many axons are covered by a protective myelin sheath, **In PNS the myelin
sheath is formed by a type of neuroglia called(schwann cells)….So, the myelin
sheath develops when schwann cells wrap themselves around an axon many
times, **the gap where there is no myelin sheath called:*nodes of ranvier.
AS the signal is an information[stimulus]convey by the nerves within the
nervous system….
• SO, this signal or signal transmission is initiated, when resting potential of
neuron is changed into action potential…
• Ie, Neuron has potential energy….**So, when a neuron is not conducting a nerve
impulse..this energy called:-*resting potential,….**whereas the conduction process of a
neuron..called:- *Action potential…
• Thereby;* this process happen, when stimulus activates the neuron and then, signal
transmission begins….
• **The whole parts of a neuron has functional segments of(4 segments); *Receptive
segment..{*includes; *dendrites & cell body, it is a region of neuron that receive stimuli
to excite[electrify]just neuron}
• **Initial segment:{*this area composed of, axon hillock….it contains both
voltage-gated channels…(Na+/K+)..
84
*Nodes of Ranvier,** it is where the axonal membrane is exposed to the extracellular space,
and highly enriched *ion channels, that participate to regenerate the action potential
*Myelin is a fatty white substance that surrounds the axons.
***As physiology..
***

85. • **Conduction segment:-{*it is the longest part of axon}
• &**Transmissive segment:-**Synaptic area…[Ca++ channels]….SO,
85
*In action potential; begins when a neuron is stimulated or receive a local stimulus in the
receptive segment of neuron, and then, a chemical-gated channels are open, allowing specific
type of Ions across the plasma membrane, it creates a local current that causes flow of Ions
along the plasma membrane of an axon..[axolemma]..which then influences an action potential
….that results Transmission of signal pathway…….
*ie, Pain neurons in skin stimulated..
when they receive signal, *signal
causes …………. {action potential}
*
.
*
*
(Initial segment)
Synaptic..

86. 86
*
*
.
.
Presynaptic neuron

87. • **Propagation of action potential….
• Propagation of action potential can be different in axons….(N/Fibers)
* If an axon is unmyelinated, the conduction system along the entire axon become
rather slow….**As the action potential of myelinated axons is much faster,
because of an action potential at one node of ranvier causes an action
potential at the next node…and the conduction system so called; *saltatory
conduction….
87
**As this animation.
Unmyelinated axon.
*Myelinated axon

88. • Part I:- *The central Nervous system…
• The spinal cord and the brain make up the CNS,[where sensory information is
received and motor control is initiated]….*Both the spinal & brain is protected by bones,
[skull & vertebrea]…**As the brain and spinal cord both are wrapped in protective
membranes known as:-*Meninges….**The space between meninges are filled with
*Cerebrospinal fluid…[CSF]…**Cerebrospinal fluid is also contained within the ventricles
of brain & in the canal of spinal cord…*The brain has four ventricles,{as further:- *ventricles
are cavities within the brain and derived from neural canal[tube] in embryonic life…*All ventricles
are lined with ependymal cells….**Two lateral ventricles are in the cerebrum, separated by a thin
partition called;(*Septum pellucidum)..*Within the diencephalon is a third ventricle..[smaller/thinner]
*Each lateral ventricle communicates with the third ventricle an opening called;[*Interventricular foramen]
88
*
*
*
1
.
.
*
As continue
.
.

89. • Cont:- ** NB:- A narrow canal called; *Cerebral aqueduct passes through the
midbrain and connects the third ventricle with fourth ventricle….**AS the
fourth ventricle is located between the pons & cerebellum……
**Spinal cord.
*The spinal cord extends from the base of brain through a large opening called;
(*Foramen magnum)..in the skull…and proceeds[continue]inferiorly in the vertebral canal…
*So, in a cross section of spinal cord shows, (*a central canal, gray matter, and white matter)
89
Spinal cord.

90. 90
.
*
.
*
*
.
.
*
*
*
Spinal
cord.

91. **Cont:- *the spinal nerves project from the cord through intervertebral formen.
The central canal of spinal cord contains cerebrospinal fluid, *the gray matter is
centrally located and shaped like,{H letter}…**Portions of sensory neurons and
motor neurons are found in gray matter; *the dorsal root of spinal nerve contains
sensory fibers entering the gray matter…**As the ventral root of spinal nerve contains
motor fibers Exiting the gray matter….**NB:- Both join before the spinal nerve leaves
the vertebral canal…**Spinal nerves are part of PNS… *So, **The white matter of
spinal cord is in area around the gray matter…..*This area contains ascending tracts
taking information to the brain…[located posteriorly]…..& descending tracts taking
information from the brain…[located anteriorly]………etc.
91
*
*Corticospinal tracts.
*spinal cord communicate PNS & the Brain….
& also it has a center for coordinating signals..

92. • **The functions of spinal cord.
• The spinal cord provides a communication between the brain and Peripheral
nerves…*Ie, Transmission of nerve signals from the motor cortex to the body, and from the
afferent fibers of the sensory neurons to the sensory cortex. It is also a center for coordinating….
[manage]….many reflexes (and contains reflex arcs) that can independently control reflex..
• *as examp/…*Sensory receptors generate nerve signals that pass through
sensory fibers to spinal cord and go up the tracts to the brain…. NB:- the pain
message can be allowed to pass directly to the brain or can be prevented reaching the
brain… *Because the tracts in spinal cord have Gates that control the flow of pain
messages from PNS to the brain….**the peripheral nervous system has centers at which
a pain stimuli can be regulated. {ie, an area in dorsal horn of spinal cord involved in
receiving pain stimuli from fibers, so called; *laminae,} and also there is a non-
nociceptive fibers that indirectly inhibit the effects of the pain fibers, ie, closing a gate
to the transmission of their stimuli.{Ronald Melzack and Patrick Wall….* in 1965}……
92
As this exampl {*Area of gate control}

93. 93
*
*(Laminae).**non-nociceptive neurons..*Acts as **Interneurons…
*In-put information.
*
*Afferent pain receptors (nerves)..two groups
*Spinal neuron.

94. ****IN FURTHER:-
*An afferent pain-receptive nerves, those bring signals to the brain, include at least two
kinds of fibers:- *a fast & thick, myelinated "Aδ" fiber that carries messages quickly with
intense of pain,(such as; *cold, pressure and some pain signals)….* and a small, unmyelinated,
slow fiber, called:- *C fiber that carries the longer-term throbbing pain[simple]…**there is
also “Aβ fibers” are non-nociceptive that interfere & inhibit the effects of firing by Aδ and C fibers,
..(the peripheral nervous system has centers at which pain stimuli can be regulated…it is in dorsal
horn..[laminae]
94
*This is an example of
Spinal gate control..

95. **The brain.
*The human brain consists of three parts;* the cerebrum, *the brainstem, and
*the cerebellum. It controls most of activities of the body,*Such as; *
processing, integrating, and coordinating the information it receives from the
sense organs, and making decisions as to the instructions sent to the rest of the
body, *and also coordinates activities of other parts of the brain…etc.
** The cerebrum; *Is the largest part of the human brain. It is divided into two
cerebral hemispheres by a deep groove called; longitudinal fissure..[Lt+Rt]…*The
two cerebral hemispheres communicate via, *corpus callosum..[it is about bridge of
nerve tracts]… FIG:-13.8 **As FIG 13.8 :- shows….
** A shallow grooves called; sulci..[suluc]..divide each hemispheres into lobes;
*1-the frontal lobe is anterior…..behind the forehead,
*2 the parietal lobe is posterior to frontal lobe.
*3 the occipital lobe is posterior to parietal lobe..[at back]
*4 as the temporal lobe is inferior to frontal + parietal lobes…..et.[as FIG 13.9 shows]
**The cerebral cortex….
*The cerebral cortex is a thin, convoluted outer layer of gray matter that covers the cerebral
hemispheres, **The cerebral cortex contains over 1 billion cell bodies, **it is a region of
the brain that accounts for sensation, voluntary movement , and all process associated
with conscious…… 95
**As slide 95 shows..

96. 96
*
FIG: 13.8
1*
2* 3*
*(at the base of brain..)

97. 97
FIG:- 13.9
*
*
*
*
1-
.
*
2-
.
3-
. #
#
4-
5-
6-
.
‘
*

98. • ***Primary motor and sensory areas of the cortex.
The cerebral cortex contains motor areas and sensory areas, *the primary motor
area is in the frontal lobe…{it is where anterior to central sulcus}… **Voluntary
commands to skeletal muscles begin in the primary motor area……ie,* at this area is
controlled all structures that carry out movements…..**like, the muscles that control
facial movements…swallowing, salivation, expression….**& also hand movements..*
*together these two STRs command; two-thirds of primary motor cortex….
***AS the primary somatosensory area….**Is posterior to central sulcus in the
parietal lobe, **Sensory information from the skin and skeletal muscles arrives
here;**Ie, the primary sensory cortex is dedicated to all body areas with sensation..
[face & hands]…..*Reception areas of other primary sensation, …Like; *taste, *Vision,
*hearing, and smell……Are located in other areas of cerebral cortex…**The primary
taste area in the parietal lobe (Pink)…accounts for taste sensation…….
98
*
.
*
.
(As next slide)
convoluted
(As earlier slide)
23rd /08/17

99. • **Cont:- **Visual information is received by the primary visual cortex..(blue)..
It is in the occipital lobe, **The primary auditory area in the temporal lobe..(dark-
green)….**And finally:- *Smell sensations are travel in the primary olfactory area…..
(yellow)…*& found on the deep surface of frontal lobe……
99
*as FIG: 13.10..shows
*
(*In frontal lobe)
(*In parietal lobe)

100. • **Association areas…**Are about integration occur and memories are
stored. *Anterior to the primary motor areas is a premotor area….**Premotor
area organizes motor functions…such as; walking, talking…etc. *{**incase, a
momentary..[temporarily]…become inadequate of Oxygen during birth can damage the
motor areas of cerebral cortex….(a condition called; cerebral palsy..is characterized}…
• **The sensory association area…..*located posterior to the primary sensory area…
• It processes, & analyzes the sensory information from skin & muscles,
• **As the visual association area located in occipital lobe, …..etc.
**Processing centers…*the processing centers of cortex receive information
from other association areas….*like, (**Prefrontal area in frontal lobe,
receives information from other associated areas..and uses this information to
**Reasoning,(interpretation), critical thinking…& formulating appropriate
[suitable] behaviors….
(NB:- the unique..[single]…ability of human to speak is partially depends upon two
processing centers:- **{Found only in Lt cerebral cortex…wernicke’s
area…located in posterior part of temporal lobe; * & Broca’s area..located in
left frontal lobe]………
100
*Wernicke’s area= region of c/cortex contain motor neurons involved
in comprehension of speech. (in 1874 by German neurologist Carl
Wernicke)…**As Broca’s area= contains neurons involved in speech
function.. (1861 by French surgeon Paul Broca)

101. **Basal nuclei…[ie, A region located at the base of the brain & composed of; **mass of neurons]
*Each of cerebral hemisphere is composed of tracts,[zones] *these are mass of gray
matter, deep within the white matter,…*so called; basal nuclei, **It regulates motor
commands & also ensure that the proper muscle groups are stimulated or
inhibited
**NB:- integration ensures that movements are coordinated & smooth…..**Parkinson
disease is believed to be caused by degeneration of neurons in basal nuclei….
**Parkinson's disease (PD) is a degenerative disease of central nervous system that mainly
affect the motor system, ..*the most obvious symptoms are; *shaking, *slowness of
movement, and difficulty with walking,..etc…**the cause of Parkinson's disease is
generally unknown, but believed to involve both genetic and environmental factors…
***The Diencephalon…
The hypothalamus & thalamus are in the diencephalon,..**a region that encircles the third
ventricle,..*the hypothalamus forms the floor of third ventricle, **the hypothalamus is a
center to maintain homeostasis…..*It regulates, hunger, sleep, thirst, body temperature,
& water balance…etc, ….*It is also controls pituitary gland…
***The thalamus…..Consists of; two masses of gray matter located in the sides and roof of
third ventricle…..*The thalamus is the receiving end for all sensory input…*except; Sense
of smell…*so, *Visual, auditory, and somatosensory information arrives at thalamus….
And it sends the appropriate portions of cerebrum………
101
*are strongly interconnected with the cerebral cortex, thalamus, and brainstem,

102. 102
Position of basal nuclei…
*
(cerebrum)
.

103. • **The Cerebellum…
• The cerebellum lies under the occipital lobe of cerebrum, and it is separated
from brain stem by the fourth ventricle….**The cerebellum has two portions
joined by a narrow median portion…**each portion composed of white matter
NB:- In longitudinal section…*the white matter has a tree-like STR called; arbor
vitae,…..*the cerebellum receives sensory input from *eyes, ears, joints, and
muscles,….*It also receives motor output from cerebral cortex…{NB:- *after
integrating this information, the cerebellum sends motor signal by way of
brain stem to skeletal muscles}…*it maintains & coordinated the voluntary
movements….
103
*
.

104. 104
*The position of cerebellum..
*
*
. (Treelike STR.)
*White matter.
*
Brain stem. *
*
* *

105. • The Brain stem….
• Brain stem contains..**midbrain, *the pons, & *medulla oblongata,
the brain stem acts as a relay…[pass on]..station for the tracts passing between
cerebrum and spinal cord or cerebellum….**As the pons..[L] term = bridge…..
*The pons contains bundles of axons travelling between cerebellum & the rest of
CNS…
**The medulla oblongata contains a number of reflex centers for regulating heart
beat, breathing,..and vasoconstriction act…[ie, arterial pressure]….**It also
contains the reflex centers for vomiting, coughing, Sneezing, hiccup & swallow.
And finally:- Medulla oblongata lies superior to the spinal cord…*& contains also
the tracts that ascend or descend between spinal cord and higher brain centers
**The Reticular formation……*the reticular formation is a complex network of
nuclei…which are mass of gray matter, and fibers that extend the length of the
brain stem…..*the major component of reticular formation is a reticular
activating system[RAS]…**The RAS arouses..(stimulates)..the cerebrum via the
thalamus…*& causes a person to be alert…..[awake]…
105
AS the next slide: 14.11

106. 106
*reticular formation receives &
sends information to various
parts of the brain…**as the
RAS(arrows) arouses cerebrum..
*RAS
processes
sensory infor

107. • Questions….
• 1- What is accomplished by, the transmission of
a nerve signal across a synapse?
• 2- What produced by repolarization of axon
during action potential?
• 3- by what parts of a neuron receive signals from
sensory receptors?
107
OK.

108. • **The Limbic system…& Higher mental functions.
The limbic system is a structure deep within the cerebrum[ie, two cerebral hemispheres]
And surrounding the diencephalon, **It joins a higher mental functions..**Such as;
*reasoning,..*and also with primitive emotions….like; *fear & *pleasure…
108
Purple area..
*
.
*
(Cerebral cortex)
24th /08/17
*

109. 109
**Cont:-
*Two significant structures within the limbic system are; (*amygdala, &*hippocampus)..
**The amygdala…in particular, processes an experience of emotional overtones, and creates
sensation of fear…..
**The hippocampus….**is believed to play a crucial role in learning and memory…
and also acts as information gateway during the learning process….because it can
communicate with frontal cortex..[site of memory]….
***The Peripheral Nervous system.
The peripheral nervous system[PNS]..lies outside the CNS, and contains the nerves.
**Nerves are designated as cranial nerves….when they arise from the brain, **and
spinal nerves, when they arise from spinal cord….****in any case, all nerves carry
signals to,… and from CNS…**{NB:- the nerve cell bodies of peripheral nerve-
fibers are so called; *Ganglia/*Ganglion..(ie, outside CNS)..}….**as the nerve cell
bodies of the fibers of CNS….so called; neurons}…
**So, in Cranial nerves; Human have 12 pairs[Lt+Rt]..attached to the brain…**&
they are referred by roman numericals… **some cranial nerves are
sensory nerves…[only sensory fibers]….**Some are motor nerves..[only motor fibers]…
*& some are mixed nerves..[both sensory & motor fibers]….*They are largely concerned..
*as FIG; 14.14
(As slide 110)

110. **with the Head, neck, and facial regions of the body….*however, the vagus nerve(X)..has
branches to the most of internal organs..{ie, Not only to pharynx & larynx}…and it
arises from medulla oblongata(just brain stem)that communicate with hypothalamus.
110

111. 111

112. 112
**The spinal nerves of human emerge(ie, come out)from either side of spinal cord…
NB:- there are 31 pairs of spinal nerves…..{the root of spinal nerve physically separated
the axons of(sensory & motor neurons)….**It forms an arrangement resembling a letter
Y..**After the posterior[dorsal root] + the anterior[ventral root] re-join and form *Spinal
nerve…..**All spinal nerves are mixed nerves …**because of; they contain sensory &
motor fibers……And finally; each spinal nerve serves a particular region of body….in
which it is located; *Examp/:- (intercostal muscles of rib cage…innervated by thoracic
Nerves)
(Arrangement.. Y)
*
109
.
.
Lt
Rt

113. 113
**12 pairs of cranial nerves.. 110.

114. 114
*an example of your book.

115. • Questions….
• 1- For what describes in distribution of Ions on either side of
an axon, when it is not conducting a nerve signal?
• 2- what are the functions performed by the three types of
neurons?
• 3- State the divisions of PNS?
• 4-Where does the primary somatosensory areas receive
sensory information?
115
24th /08/17

116. • **The Reflex Arc…
• The human spinal cord has a center to manage any quickly
reflexes from somatic system or somatic nerves..[like; skin, skeletal,..etc]..
• As example;.*If the hand touches a sharp pin, sensory receptors
in skin generate nerve signals that move along sensory fibers
through the dorsal root ganglia towards the spinal cord.*sensory
neurons that enter the cord dorsally..(posteriorly)..pass signals on
to many interneurons, ***some of these interneurons synapse
with motor neurons whose dendrites and cell bodies are in spinal
cord…**then Nerve signals travel along these motor fibers to an
effector…* in this case, effector is a muscle, which contracts and
then, *you withdraw your hand from the pin…
• And finally:- Other various reflexes can also be like this way,
**Others can cause a deep pressure that the brain receives…
(because of, some interneurons are involved carry signals to brain)
116
**AS this slide shows…13.16.
30th /08/17

117. 117
13.16
.
*this is the only neuron lies out
side of CNS……..[spinal cord]
*
*
.

118. • **The autonomic nervous system..[ two divisions]
• The autonomic system is also PNS…and regulates the
activity of, *Cardiac, smooth muscles, organs, & glands..
• The system is divided into..[*Sympathetic..*& Parasympathetic]…
• Although their functions are different, but they share some features….
• Like; **1- they function automatically and usually in involuntary manner..
• 2- they innervate all internal organs…
• 3- they use Two neurons and One ganglion for each impulse….
• NB:- The first neuron has cell body within the CNS….& a preganglionic fiber
that enters Ganglion……**The second neuron has a cell body within a ganglion
and a postganglionic fiber that leaves the ganglion…….
A] Sympathetic division:- **Most preganglionic fibers of sympathetic divisions
arise from the middle, or thoracolumbar portion of spinal cord…and terminate
a ganglia that lie near the cord….[therefore, in this division preganglionic fiber short
But the postganglionic fiber that contact to organ is long]…..
***Their function is to inhibit Digestive organs…..etc…
118

119. 119
* *
13.17
X

120. 120
13.17
*
(long)

121. B] Parasympathetic division.
This division includes; a few cranial nerves[vagus nerve]and fibers from sacral
portion of spinal cord..**Therefore this division is referred as;*craniosacral
division of Autonomic system…* In parasympathetic division preganglionic
fiber is long…as postganglionic fiber is short…Because ganglia lie near the
organ…***This division promotes all internal respones…such as; promote
digestion of food, slows heart beat…etc……
121

122. The autonomic nervous system is divided into:- *sympathetic nervous system and
*parasympathetic nervous system .The sympathetic division emerges from the spinal
cord in the thoracic and lumbar areas(thoracolumbar area).*As parasympathetic
division has (craniosacral)..means that the cranial nerves…are ‘out flow’ oculomoto
nerve, facial nerve, glossopharyngeal nerve, and vagus nerve) and sacral..(S2-S4) spinal
cord..
122
The End.

123. • **Multiple choice….**Circle the correct answer.
• 1- which of these is a direct source of energy for
muscles:- a- ATP, b- creatine phosphate, c- glycogen.
• 2- Impulses that move down the T system of a muscle fiber is
directly caused by:- a-movement of Ions. b- attachment of
cross-bridges to myosin. c- Release of Ca++ from sarcoplasmic
reticulum.
• 3- The neuroglial cells that form myelin sheath in PNS are:-
• a- oligodendrocytes, b- ganglionic cells, c- schwann cells,
d- A & B only.
• 4- which of these are the first and last elements in a spinal reflex;
• a- Axon & dendrite, b- sensory receptor & muscle effector ,
• c- motor neurons & sensory neurons.
123
*OK.