14. • Sensory receptors
– Detect changes in the external environment
• Found in eyes, nose, ears, tongue, skin
15. - Detect changes in the internal environment
Located in specific internal organs
16. • Examples of external environment receptors:
– Light sensitive cell in the retina
– Temperature and touch receptor in the skin
– Vibration sensitive cells in the ears
17. • Examples of internal environment
receptors :
–Cells sensitive to level of carbon dioxide in the
blood, blood osmotic pressure
19. • Intergrating centre
– Intergrating centre is the central nervous system
( brain, spinal cord)
20. Intergration happens when information from the
receptors is interpreted to bring appropriate
response
21. • Effectors
– Carry out the responses to stimuli
– Effectors – muscle cells, glands
22. Sensory receptor is
stimulated , nerve
impules are
generated
Impulse carried along
the afferent pathway through
the afferent nerves
Impulses arrive at the
intergrating centre
Integration centre sent
response in the
impulse form
Impulses is carried by
efferent pathway through the
efferent nerves to effectors
Reponse to the
stimuli take place
23.
24. Pathway involved in detecting and responding to
change in the internal environment
Change in the
blood temperature
Detected by temperature
sensitive cells in hypothalamus
Impulses are carried by
afferent nerves to the
thermoregulatory centre
in hypothalamus
Integration occur in
thermoregulatory centre
Impulses are carried
from hypthalamus
to the effector through
efferent nerves
Effectors – smooth
mucles of the arterioles,
sweat gland, etc
44. • Damage to this area can cause specific defect –
speech impairment, reading difficulty, paralyse
45. • Cerebellum
– The coordinating centre for body movements
– Receieves information from sensory receptor from
all parts of the body and from the cerebrum
46. – Evaluate infromation and relays the need for
coordinated movements back to the cerebrum
– Cerebrum then sends appropriate commands to the
muscles
47. • Medulla oblongata
– Function –
• regulates the internal body processes that do not require
conscious effort – heartbeat, breathing, vasoconstriction
48. • Reflex centre for vomiting, coughing, sneezing,
hiccupping, swallowing
49. • Hypothalamus
– Function – homeostatic regulation
– Coordintion centre for regulating sleep, hunger,
thirst, body temperature, water balance, blood
presure
53. • Thalamus
– Function –
• sorting the incoming and outgoing information in the
cerebral cortex
• Enhancing and blocking signals from the sensory
receptors to the cerebrum
54. The spinal cords and it functions
• Spinal cord is surrounded by cerebrospinal fluid
-shock absorber and provide nutrients
• Consist of white matter and grey matter
67. • The spinal cord :
– Processes sensory information and send out
responses through the efferent neurones
68. – Contains neurones that transfer signals to and from
the brain
– Neural pathway for reflexes
69. receptor Neuron afferent Spinal cord
brain
Neuron efferent
Effectors
/muscle
Pathway off the impulse
70. The neurones
• The nervous system is made up of millions of
nerve cells calls neurones
• Neurones transmit nerve impulses to other
nerve cells, glands, muscles
71.
72.
73. • Three types of neurones:
• Afferent neurones
• Efferent neurones
• internuerones
74. • Afferent neurones
– Carry sensory information from the receptor cells to
the brain and spinal cord
78. • Interneurones
– Convey nerve impulses between various parts
of the brain and spinal cord
– Transmit nerve impulses between afferent
neurones and efferent neurones
– Transmit nerve impulses from one side of the
spinal cord to the other side or from brain to
the spinal cord
82. Receptors pick up
the ringing of
doorbell
Nerve impulses
from the
receptors moves
in the afferent
neruones
Nerve impulses
transfer from the
afferent to the
interneurons
Interneurones
sent impulses
to the brain
Brain interpretes
impulses, give order
in the form of
impulses
From the
interneurones
impulses is
transmitted to
the efferent
neurones and then
to the muscles
The muscles in the
arm carry out response
83. The transmission of information along
the neurones
• The transmission of information along the
neurones is through electical signals known as
nerve impulses
84. • Impulse – positive charges that travel along the
axon to the synaptic terminal
85. • A neurones will not transmit impulses if the
stimulation is not strong enough
87. Receptors pick up
the ringing of
doorbell
Nerve impulses
from the
receptors moves
in the afferent
neruones
Nerve impulses
transfer from the
afferent to the
interneurons
Interneurones
sent impulses
to the brain
Brain interpretes
impulses, give order
in the form of
impulses
From the
interneurones
impulses is
transmitted to
the efferent
neurones and then
to the muscles
The muscles in the
arm carry out response
88. The transmission of information
across synapses
• Neurones are not connected to each other
89. • Beyond the synaptic terminal there is synaptic
cleft (narrow space) that separate synaptic
terminal from the dendrite of a receiving
neurones
Synaptic cleft
Synaptic terminal
dendrite
90.
91.
92. • Synapse is the site where two neurones or a
neurone and an effector cell communicate
93. • Electrical signals must be transmitted across the
synaptic cleft to an adjacent cell
94. • The transmission of nerve impulses across the
synaptic cleft occurs with the help of
neurotransmitter (chemical substances)
99. Electrical impulses
reaches the presynaptic
membrane
Neurotransmitter diffuse
across the synaptic cleft
and bind to specific
protein/receptors
that attached to the
postsynaptic membrane
Binding of the
neurotransmitter to
receptors
generates a new impulses
signal
Impulses is transferred
to another neurones
100. • The transmission of nerve impulses across
synapses is an active process which required
energy
101. • Synaptic terminal contains abundant
mitochondria to generate energy for
transmission of nerve impulses
102. • After the neurotransmitter has relayed its
message
– Broken down by enzymes
– Taken up again by the synaptic terminal and
recycled
116. Reflex arc
Sharp pin pierces
the skin – sensory receptor
in the skin generate
nerve impulses
Nerve impulses transmitted
along an afferent neurone
toward the spinal cord
In spinal cord the
nerve impulses are
transmitted to the
interneurone
From interneurone the
impulses are transmitted
to the efferent neurone
Efferent neurone
carries the nerve
impulses to the
effector
Pin can be pulled
out immediately
118. - the pain is slightly delayed after the response
has been made
119. • Only involves the spinal cord, the brain is
reserved for more complex task
120. • Reflex that involves the brain
– The opening and closing of the pupil of the eye
– Automatic response, we have no control of the size
of the pupil
121. • Another types of automatic response is knee
jerk reflex
– Involves afferent neuron and efferent neurone
122. Knee jerk response
Rubber hammer
hits a tendon that
connect the
quadriceps muscle
in the thigh to a
bone in the lower
leg
The force stretches
the quadriceps muscles
and stimulate the
stretch receptors in
the muscles, triggering
nerve impulses
Afferent neurones transmit
impulses to the efferent
neurones in the spinal
cord
The efferent neurones
transmit impulses to
the quadriceps muscle,
muscle contract, the leg
jerking forward
123.
124. Reflex arc
Afferent neurones -
interneurones – efferent
neurones – effector
-- piercing of the skin
Afferen neurone – efferent neurone
-
effector
-
--knee jerk reflect
Afferent neurones – brain
- interneurone – efferent
neurone – effector
--opening and closing of
the pupil
125.
126. Involuntary action which involves smooth
muscles, cardiac muscle or glands
1. The autonomic nervous system
- controls involuntary actions involving :
128. – Connects the medula oblongata and hypothalamus
with the internal organs and regulates the internal
body processes
– Require no conscious effort
Cerebral
cortex
129. – Impulses are not transfered to the cerebral cortex –
we were not aware of the response
136. decrease the pulse rate, blood pressure,
breathing rate
-stimulate the digestive system to continue
breaking down food
137. Diseases of the nervous system
1. Parkinson's disease
- affect the muscular movements causing tremors
or trembling of the arms, jaws, leg, face
- difficulty maintaining normal postures, impaired
balance and coordination
138. 2. Alzheimer's disease
- neurological disorder causes the loss of
reasoning and ability to care fo oneself
- individuals becomes confuse, forgetful, lose
ability to read, write, eat, walk and talk
139. • The information for involuntary actions does not
involve the cerebral cortex
– No perception is generated
– We not aware of the response
140. The role of Hormones in humans
• Hormones are chemical messengers produced
by the endocrine gland
141. • Endocrine glands – ductless glands that
release hormones directly into the interstitial
fluid and then to the bloodstream
142. • Hormones only affect specific target cell
• Hormones causes the target cell to respond in a
specific manner
143. The need for the endocrine
system
• The endocrine and nervous system play
important roles in maintaining homeostasis
• Some physiological processes need both
system too work together, others only involve
the endocrine system
144. The nervous system
controls voluntary
and involuntary actions
conveys impulses
message conducted
via neurones
message are carried
between specific
location
responses or effects
are temporary
message are conveyed
rapidly
The endocrine system
controls involuntary
actions
conveys chemical signals
message are conveyed
via bloodstream
message are carried to
various destinations
responses or effects
are long lasting
message are conveyed
slowly
145. The human endocrine system
- consist of glands that contain hormones-
secreting cells
- the glands secrete different types of hormones
involved in specific physiological processes
154. Regulation of hormone secretion
- endocrine gland release hormones more
frequently when stimulated
-
155. • hormone secretion is normally regulated to
prevent over production or under production
156. • Regulation of hormone is controlled by:
• Signals from nervous system
• Other hormones
• The level of specific substances in the body
157. The regulation of hormone secretion by signal
from the nervous system
- pituitary gland is the master of endocrine gland
because it secreters hormones that control
other endocrine gland
158. • The pituitary gland is controlled by
hypothalamus
• Posterior pituitary gland contains axons and
synaptic terminals of the neurosecretory cells
that originate in the hypothalamus
159. • Hypothalamus :
• Controlling the secretion of hormones from the pituitary
gland
• Link between the nervous system and the endocrine
system
160. • Maintain homeostasis by receiving impulses of the
internal environment
• Have specialised nerve cells called neurosecretory
161. Neurosecretory cells
in hypothalamus
ADH, oxytoxin
pass through the
axon into the
posterior pituitary
cells and stored in
the synaptic terminals
ADH and oxytoxin
are secreted into
the bloodstream
Hypothalamic releasing
hormones, hypothalamic
inhibiting hormones
These hormones are
carried in the blood
stream to the anterior
pituitary
Hypothalamic releasing
hormones stimulate the
seretion of anterior pituitary
hormones
Hypothalamic inhibiting
hormones prevent the secretion
of the anterior pituitary
hormones
168. • The release of a hormone from the target exerts
a negative feedback control
169. Thyroid releasing
hormone from
hypothalamus TRH stimulate the
anterior pituitary
to secrete TSH
TSH stimulates the
thyroid gland to
secrete thyroxineWhen thyroxine
concentration is high,
its inhibit TRH production
from the hypothalamus
and TSH from the anterior
pituitary
170. The regulation of hormone secretion by the level
of specific substances in the blood
- the secretion of hormones is regulated by the
level of specific substances in the blood
174. The involvement of the nervous and
endocrine system in a fight or flight
situation
175. Fight or flight situation
Nerve impulses from the
hypothalamus stimulate the
neurones from the sympathetic
division of the autonomic nervous
system in the adrenal medulla
Stimulate the adrenal
medulla to secrete
adrenaline and
noradrenaline
Adrenaline and
noradrenaline cause an
increase in heartbeat,
breathing rates, blood
pressure, blood glucose
level, metabolic activity
176. Fight or flight situations
Nerve impulses from hypothalamus
Stimulates the neurones from the symphathethic
Division of the autonomic nervous system in the adrenal
medulla
Stimulate the cells of the adrenal medulla to secrete
Adrenaline and noradrenaline
Adrenaline and noradrenaline cause increase in heartbeat,
Blood pressure, blood glucose level, metabolic activity
177. • The hearts contracts vigorously to pump larger
amount of oxygen and glucose to the brain and
skeletal
178. • Skeletal muscle becomes more energised and
enable a person to fight or flee immediately
from danger
179. • The nervous and endocrine system working
together to bring immediate response to cope
with threat
180. Hormon imbalance and related disease
1. growth hormone
- over secretion
– gigantism
- acromegally (adult) – bones, hand, feet, cheek
& other tissues enlarge
181.
182.
183. - under secretion :
- dwarfism
- genetically enginered growth hormone is given
to the children allowing them to attain normal
height
189. – Under secretion – diabetes mellitus
• Abnormally high level of glucose in the blood
• Body do not produce enough insulin or cannot use the
insulin that are produced
190. • Increase frequency of urination
• Large quantities are produced by genetically engineered
bacteria – injected to the patient
191. 4. ADH
- Over secretion
- high retention of water in the body
192. – Under secretion
• Diabetes insipidus
• Excrete a large amount of urine
• Always thirsty, drinks frequently
• Water lost in the urine
193. Homeostasis in humans
• The maintainance of relatively constant internal
environment is known a homeostasis
195. The excretory system
• Primary organs – kidneys
– Regulate water and salt balance – excreting more or
les salt, increasing intake or loss of water
196. – Regulate osmotic pressure and ionic level in the
bloods
– Excrete waste products
– Regulate blood pH
197. Waste products
From metabolic reactions
- urea, creatinine
(from amino acids)
- uric acids (from nucleic acids)
Foreign substances in
the diet
- drugs, toxin
198. The human kidney
• Kidneys filter blood and form urine
• Urine exits thorugh the ureter, urinary
bladder and urethra
199. • Urine consist of :
• Water
• Urea
• Disolved waste
• Exces nutrients
200. • Kidney has two region :
• Renal cortex – outer light red region
• Renal medulla – inner dark red region
201.
202. The nephron
- the funcional unit of a kidney
- each kidney – about one million nephrons
-
203.
204. - consists of three major parts :
1. glomerulus and its blood vessels
2. Bowman's capsule
3. renal tube
205.
206. • Renal tube is made up of :
• Proximal convoluted tubule
• Loop of Henle
• Distal convoluted tubule
207. • Three basic processes to produce urine:
• Ultrafiltration
• Reabsorption
• Secretion
208. Ultrafiltration in Bowman's capule
- podocytes and endothelium of the the
glomerulus form a filtration membrane
-
209. permits the passage of water and solute from the
blood into the capsular space
211. • The pressure increase because the afferent
arteriole has larger diameter than the efferent
arteriole
212. • Blood enters the glomerulus
– Ultrafiltration take place
– High pressure forces fluid through the filtration
membrane into the capsular space
213. – Filtration membrane filter certain size of molecules
– Fluid that pass the filtration membrane is called
glomerulus filtrate
214. • Glomerulus contents :
• Water, glucose, amino acids, urea, mineral salts, small
molecule
• Same composition as blood plasma
• No red blood cells, plasma proteins (too large)
216. Reabsorption
- take place when substances move across the
walls of the renal tubule into the capillary
network
-
217. - Chloride ions move out passively
- reabsorption of glucose and amino acids through
active transport
-
218. - movement of solutes into the capillary network
increase the concentration solute in the
capillary network
- water moves into the blood capillaries by
osmosis
219. - Loop of Henle:
- water, sodium, chloride ions are reabsorbed
220. - Distal convoluted tubule :
- watery filtrate contains low in salt, high in waste (
urea)
- more water, sodium, chloride ions are
reabsorbed
221. - Collecting duct :
- filtrate has very little salt, 99% of water has been
reabsorbed
- only 1 % of the water leaves as urine
-
222. urine moves down the collecting duct
- some urine diffuse out into surrounding fluid
and blood ( small size )
-
223. 45% of the original urea remain to be excreted
as urine
249. Drinks too
much water
Blood osmotic
pressure drops
below normal
Osmoreceptor cells
in hypothalamus are
less stimulated
Pituitary glands
less stimulated
Less ADH is
secreted from pituitary
glands
Low level of ADH
cause the distal tubule
& collecting duct less permeable
to water
Less water is
reabsorbed into the
blood
The result – increase
the blood osmotic pressure
and return to normal
250. Low level of ADH
cause the distal tubule
& collecting duct less permeable
to water
Less water is
reabsorbed into the
blood
251. Drinks too
little
Blood osmotic
pressure increases
above normal
Osmoreceptor cells
in the hypothalamus
detect increase in
blood osmotic
pressure
Osmoreceptor cells
in the hypothalamus
stimulate pituitary
gland to release more ADH
ADH increases
the permeability of the
distal tubule and
collecting duct
More water is reabsorbed
from the filtrate into the
blood
Blood pressure return
to normal
Water content of the
urine decreases.
Urine more concentrated , dark
252. ADH increases
the permeability of the
distal tubule and
collecting duct
More water is reabsorbed
from the filtrate into the
blood
253. • The lower osmotic pressure reduces the activity
of the hypothalamic osmoreceptor cells
258. haemodialysis – the process of filtering blood by
using an artificial means that replace the
functions of a failed kidney
259. – Blood from the artery is passed through the machine
which contains a dialyser
– Dialyser has two sections separated by semi
permeable membrane
260. – Blood passes on one side of the membrane and
dialysis solution passes on the other
261.
262. – The different concentration gradient between the
blood and dialysis solution is such that the waste
molecules and excess salts can diffuse through the
membrane
263. Blood Dialysis
solution
Toxin from the blood diffuse
through the semi permeable
membrane
Required ions and
glucose are added
into the dialysis
solutin
Semi permeable membrane
264. • Another treatment for impaired kidney is the
transplant of a healthy kidney from a donor to
the patient
265. The regulation of blood sugar level
- pancreas gland is responsible for maintaining
the blood sugar level within 75-110mg/100ml
269. • Insulin reduce the blood glucose level
• Glucagon increase the the blood glucose level
270. • Both hormone work in opposition to regulate
the blood glucose level
271. • Diabetes mellitus
– Defects in production, release, and reception of
insulin
– The proximal convoluted tubule cannot reabsorb all
the glucose from the kidney filtrate
272. The regulation of body temperature
- the body temperature fluctuate
- maintains at 37 C
273. Changes in the
external temp.
Cause initial
change in body
temp.
Changes detected by
Thermoreceptors in
hypothalamus
detect blood temp.
Thermoreceptors in
the skin detect external
temperature
Thermoregulatory centre
in the hypothalamus
Smooth muscles
in the arterioles
Sweat gland Erector muscles
in the skin
Skeletal
muscles
Adrenal,
thyroid glands
274.
275. Internal temp.
rises, vasodilation occurs
when smooth muscles around
afferent arteriole relax
Increase blood
flows through the
skin
Increase the amount
of heat radiated and loss
by the skin
Temperature rises
276. Internal temp. rises
Sweat glands secrete
sweat to the surface
of the skin and evaporate
The body cools
and the internal
temperature drops
to set point once
again
The temperature
drop beneath set point
sweating stop, body heat
conserved
277. Internal temperature
rises above the set
point
Erector muscles
in the skill relax
lowering the skin
hair, warm air is not
trapped
Internal temperature
drops below the
set point, erector muscle
contract, raising the skin
hairs, trapping layer of warm air
278. Internal temperature
rise above set point
Skeletal muscle are
not stimulated,shivering
does not occur
Internal temperature
drops beneath set
point
Skeletal muscles
are stimulated, shivering
occurs
279. Internal temperature
rise above the set point
Adrenal and thyroid
glands are less stimulated
to secrete adrenaline and
thyroxine
The metabolic rate
is low, no excess heat
is generated
Internal temperature
drops beneath below
the set point
Adrenal and thyroid
glands are stimulated
to secrete more adrenaline
and thyroxine
Metabloc rate increase,
more heat is generated
280. Practising a healthy lifestyle
• Drugs can alter brain functions and the rates at
which neurones releases neurotransmitter
281. • The abuse of drugs reuslt in a tolerance of the
drug
• More and more drugs is needed to get the same
initial effect on the person
283. • Stimulants
– Increase activity of the central nervous system
– Blocks the removal of pleasure -inducing
neurotransmitters
– e.g. - cocaine
284. • Depressants
– Slow down the activity of the central nervous system
– Slow down the transmission of nerve impulses
– e.g : alcohol
– Inhibits the release of ADH
– Large volumes of urine
285. • Hallucinogens
– LSD (D-lysergic acid diethylamide)
– See, hear and percieve things that do not exist
286. • Narcotics
– Feeling euphoria, block pain signals, slow down
normal brain function
– e.g.: heroine, morphine
– Mimick neurotransmitter binding to their receptor
sites
289. Auxins
- promote cell elongation cell lengthening
- produced in apical meristem at the tip of the
shoots
- result – increase the stem length by increasing
the rate of cell division
290.
291. • The role of auxins in phototropism:
– Growth of plants towards light is caused by unequal
distribution of auxins in the shoot
293. • When a plant is exposed to light from one
direction
• Auxin build up on the side in the shade, and
stimulate the growth of the side that do not
receive sunlight
294. • The side that do not receive sunlight divide
faster and elongate faster than the side that
receive sunlight
• Result – the shoot bending towards the lights
• Auxin result in positive phototropism in plant
shoots
295. The role of auxin in geotropism
- if the seeds is buried horizontally
- light and gravity causes the auxins to be
transported to the lower side of the root or shoot
-
296. • The auxin that accumulate at the lower side of
the shoot stimulate the elongation of the shoot
• Result – the shoot bends upwards
297. • The auxin that accumulate at the lower side of
the root inhibits the elongation of the root
• The upper side of the root elongated faster than
the lower side of the root
• The root bend downwards
298. • When the root bend downward, the auxin
distribution becomes equal on all side
• The roots continue to grow straight downwards
299. • Auxin are also used to stimulate the growth of
adventitious roots from the stem
– Used to trigger the adventitious roots for commercial
plants
300. • Induce the development of fruit without
fertilisation or parthenocarpy
• Parthenocarpy is used to produce seedles fruits
301.
302.
303. Ethylene
- a plant hormone which is synthesised during the
ripening of the fruit
- synthesised in – fruits, leaves, stem
- in the form of gas
304. - functions :
- speeds up the ripening of fruits
- stimulating the production of cellulase
- cellulase hydrolyses the cellulose in plants
making it soft
305. - promotes the breakdown of complex
carbohydrates into simple sugar
- make fruits taste sweet
306. • Placing a basket of ripe mangoes with unripe
bananas can induce ripening of banana
