3. 1. Controls homeostasis
2. Maintains water balance
3. Controls uterine contractions
4. Controls milk production
5. Regulates ions (calcium, sodium, potassium)
6. Regulates metabolism and growth
7. Regulates heart rate and blood pressure
8. Monitors blood glucose levels
9. Aids the immune system
10. Reproductive functions
Functions
4. 4
Components of Endocrine System
Endocrine glands:
secrete their product directly into blood stream
Chemical signal:
molecules that are released from one location, move to
another location, and produce a response
5. Types of Chemical Signals
Chemical signals or Ligands
- Molecules released from one location that move to another
location to produce a response
• Intracellular:
produce in one of part a cell and move to another part of
same cell
• Intercellular:
released from one cell and bind to receptors on another cell
5
6. • Autocrine:
- released by cells and a have local effect on same cell type
- Ex. Eicosanoids (released in response to inflammation)
• Paracrine:
- released by cells that affect other cell types in close proximity
- Ex. Somatostatin (inhibits insulin secretion)
• Neurotransmitter and neuromodulators:
- secreted by nerve cells
- Ex. Nervous system function
6
Types of Intracellular Signals
7. • Pheromones:
- secreted into env’t and modify behavior and
physiology of other individual in same species
- Ex. Women and menstrual cycles
• Hormones and neurohormones:
- secreted into blood and bind to receptor sites
- Ex. Epinephrine and insulin
7
8. Autocrine
Paracrine
Neurotransmitter
Endocrine
Endocrine
Hormone
NeurotransmitterNeuron
Paracrine
Chemical messenger
Chemical messenger
Autocrine
Thyroid hormones,
growth hormone, insulin,
epinephrine, estrogen,
progesterone, testosterone,
prostaglandins
Secreted into the blood by
specialized cells; travels some
distance to target tissues;
results in coordinated
regulation of cell function
Produced by neurons;
secreted into a synaptic cleft
by presynaptic nerve terminals;
travels short distances; influences
postsynaptic cells
Acetylcholine, epinephrine
Somatostatin, histamine,
eicosanoids
Eicosanoids (prostaglandins,
thromboxanes, prostacyclins,
leukotrienes)
Produced by a wide variety
of tissues and secreted into
extracellular fluid; has a
localized effect on other tissues
Secreted by cells in a local
area; influences the activity
of the same cell from which
it was secreted
Classes of Chemical MessengersTABLE 10.1
Chemical Messengers Description Example
9. 9
Components of Hormones
• Receptor site:
location on a cell where hormone binds (lock)
• Target tissues:
group of cells that respond to specific hormones
• Specificity:
specific hormones bind to specific receptor sites
10. 10
Receptors
Chemical signals bind to proteins and glycoproteins (RECEPTORS)
Specificity – Tendency for each receptor site to bind to a specific
chemical
12. Hormones
• Hormones are distributed in the blood to all parts of the body,
but only its corresponding target tissue respond to each type of
hormone
• Influences target cells by chemically binding to their receptors.
• 2,000-100,000 receptors for a particular hormone
• Hormones that pass in the blood and act on distant cells are
called Circulating hormones or ENDOCRINE
• PARACRINE - Hormones that act on neighboring cells
• AUTOCRINE – Acts on the same cell
• Local hormones usually are inactivated quickly
13. 13
How does this work?
1. Hormones are secreted by endocrine glands directly into
bloodstream
2. Hormones travel to all parts of body
3. Hormones (key) bind to receptor site (lock) on target tissue
4. Response occurs
14. 14
How do Hormones cause change?
• Alter cell activity of target tissues by increasing or decreasing cell’s
normal processes
• Change permeability of cell membrane by opening or closing ion
channels
• Synthesis of proteins
15. Membrane-bound receptors
Extend across the cell membrane,
with their receptor sites outside the
surface of the cell membrane
Responds to chemical signals that
are large, and water-soluble
Intracellular receptors
Chemical signals DIFFUSES and bind
to the intracellular receptor located
at the cytoplasm or nucleus
16. 16
Types of Hormones
• Water soluble:
- includes proteins, peptides, amino acids
- most common
- Ex. Growth hormone, antidiuretic, prolactin, etc.
• Lipid hormones:
- includes steroids and eicosanoids
- Ex. LH, FSH, androgens
17.
18. Regulation of Hormones
• Blood levels of chemicals:
Ex. Blood glucose levels (insulin)
• Other hormones:
Ex. TSH signals thyroid gland to release thyroid hormone
• Nervous system:
Ex. Epinephrine and fight or flight response
• Negative Feedback:
tells body when homeostasis is reached
23. Hormones of the Anterior Pituitary
1. Growth hormone
2. Thyroid-Stimulating Hormone (TSH)
3. Adrenocorticotropic Hormone (ACTH)
4. Gonadotropins
A. Leutinizing hormone (LH)
B. Interstitial Cell-stimulating hormone (ISCH)
5. Prolactin
6. Melanocyte-Stimulating Hormone
24. • Stimulates the growth of bones, muscles, and other organs by
increasing protein synthesis.
• Resist protein breakdown during periods of food deprivation
• Secretion of growth hormone is controlled by 2 hormones from
the hypothalamus (releasing and inhibitory hormone)
• Daily peak levels during sleep, also increases during fasting
and exercise
Target tissues: most
Abnormalities:
Too much GH causes giantism
Too little GH causes pituitary dwarfism
Growth Hormone
25. In gigantism - ACROMEGALY - facial features and hands
become abnormally large
Somatomedins – Protein chemical signal which together
with Growth hormone to bind to the receptors of bone and
cartilage tissues to stimulate growth
26. Target tissues: thyroid gland
Functions: regulates thyroid gland secretions
Binds on Membrane-bound receptors of the thyroid gland, causes
to secrete thyroid hormones.
Abnormalities:
Too much TSH, thyroid gland enlarges
Too little TSH, thyroid gland shrinks
Thyroid-Stimulating Hormone (TSH)
27. Adrenocorticotropic Hormone (ACTH)
• Binds on Membrane-bound receptors on the cells in cortex of
adrenal glands.
• Increases secretion of Cortisol ( hydrocortisone), which keeps
the adrenal cortex from degenerating
• Binds to melanocytes and increase skin pigmentation.
• ↑ ACTH - Darkening of the skin
28. • Binds on Membrane-bound receptors of the gonads. Regulates
growth, development and of functions of gonads
• LH (Luteinizing) for females:
- Target tissue: ovaries
- Function: Ovulation of oocytes and the secretion of estrogen and
progesterone from ovaries
• LH for males / Interstitial Cell-stimulating hormone (ISCH)
- Target tissue: testes
- Function: stimulates interstitial cells (sperm cell) of the testes
to secrete testosterone.
GONADOTROPINS
29. • FSH (Follicle-Stimulating) for females:
- Target tissue: follicles in ovaries
- Function: follicle maturation and estrogen secretion
• FSH for males:
- Target tissue: seminiferous tubules (testes)
- Function: sperm
GONADOTROPINS
30. • Binds on Membrane-bound receptors in the cells of the Breast,
during pregnancy and stimulates the production of milk
- Target tissues: mammary glands and ovaries
- Functions: milk production
Prolactin
Melanocyte-Stimulating Hormone
Binds on Membrane-bound receptors on melanocytes and causes
them to synthesize melanin.
↑ ACTH - Darkening of the skin
31.
32. • Binds to Membrane-bound receptors and increases water
reabsorption by kidney tubules. Resulting to less water lost in urine.
• Can cause blood vessels to constrict (vasopressin)
• Target tissues: kidneys
- Functions: conserve water
- Abnormalities:
Diabetes insipidus:
- low ADH
- kidneys to produce large amounts of
dilute (watery) urine
- can lead to dehydration and thirst
Antidiuretic Hormone (ADH)
33. • Binds on Membrane-bound receptors and causes Uterine
contraction and milk ejection (milk let-down)
• Target tissues: uterus
• Functions: increases uterine contractions during labor
Oxytocin
34. • Made up of 2 lobes connected by the isthmus
• Located on either side of trachea, just below the larynx
• Largest endocrine gland
• Thyroid follicles – small spheres with walls that consist of simple
cuboidal epithelium
• Each follicle is filled with protein to which thyroid hormones
attached.
• Requires iodine to function
• Thyroid hormones:
- Target tissues: most
- Functions: regulates metabolic rates and in needed for growth
Thyroid Gland
35.
36. Thyroid Hormones
Binds to intracellular receptors in cells and regulate the rate of metabo
Participates in normal rate of growth and development.
Hypothyroidism
Infants – Cretinism - Mentally retarded and short in stature, with abno
Adults – reduced rate of metabolism
sluggishness, reduced ability to perform
routine task.
37. Abnormalities of Thyroid Gland
Hypothyroidism:
• Decreased metabolism
• Weight gain, reduced appetite,
fatigue
• Low temp. and pulse
• Dry, cold skin
• Myxedema in adults
• Cretinism in infants
Hyperthyroidism:
• Increased metabolism
• Weight loss, increased
appetite, nervousness
• Higher temp. and pulse
• Warm, flushed skin
• Graves’ disease (leads to
goiter)
38. • Embedded in posterior wall of the thyroid gland
• Secretes parathyroid hormone (PTH)
• Regulation of blood calcium
• Increases the absorption of Ca+ from the intestine by causing
an increase in active vitamin D formation
Target tissues: bones and kidneys
Hyperparathyroidism
Elevated Blood Ca+ results in nerve and muscle less excitable,
resulting in fatigue and muscle weakness
Hypoparathryroidism
Reduced Vitamin D formation. Nerves and muscles become more
excitable and produce spontaneous action potential. Frequent
muscle cramps or tetanus
Parathyroid gland
39. • On kidneys
• 2 regions medulla and cortex
Adrenal Medulla (inner portion):
• Epinephrine/Norepinephrine:
• Target tissues: heart, blood
vessels, liver, fat cells
• Functions: released as part of fight
or flight response
Adrenal Glands
40.
41. • Aldosterone:
- Type of mineralocorticoids
- Target tissues: kidneys
- Functions: causes Na+ and H2O to be retained and K+ to be
secreted, indirectly involved with blood pressure and blood
volume
Adrenal Cortex (outer portion)
42. Pancreas
• Organ in abdomen
• Insulin:
- Target tissues: liver, skeletal muscle, adipose tissue
- Functions:
- regulates blood glucose levels
- after a meal glucose levels are high and insulin is
secreted
- extra glucose is stored in form of glycogen
43. •
- Target tissues: most
- Functions:
Males: secondary sexual characteristics
Females: sex drive
Androgens
Cortisol
- Type of glucocorticoids
- Target tissues: most
- Functions: increases breakdown of fat and protein for energy
uses reduces inflammatory and immune responses
44.
45. Pancreas, Insulin, Diabetes
• Endocrine part consist of pancreatic islets a.k.a. “Islets of
Langerhans” – has two types of cells.
• Alpha cells – secrete glucagon
• Beta cells – secrete insulin
• A decline in the blood glucose below the normal range causes the
nervous system to malfunction (Glucose is the Nervous system’s
main source of energy)
Insulin – Released in response the elevated blood glucose levels and
increased sympathetic stimulation.
The major target of insulin are the liver, adipose tissue, muscles, and
the area of the hypothalamus that controls the appetite, satiety center.
46. Abnormalities:
Diabetes Mellitus – Result from: (1) secretion of too little insulin from pancreas,
(2) Insufficient numbers of insulin receptors on target cells, and (3) defective
receptors that do not respond normally to insulin.
Triad of Diabetes Mellitus
Polyuria - ↑ urination
Polyphagia - ↑ food intake
Polydypsia - ↑ water intake
Causes: too little insulin or faulty insulin receptors
• Symptoms: exaggerated appetite, excess urine, dehydration, thirst, fatigue
• Type I: insulin dependent (daily injections required)
• Type II: insulin independent, often found in obese people, can be treated
with diet but can turn into type I
47. • (Diabetes Mellitus)
• Hyperglycemia- Tissues cannot take up glucose effectively,
causing blood glucose to become very high.
• Polyphagia – Glucose cannot enter cells of the satiety center of
the brain without insulin, the brain responds as if there were
little blood glucose, resulting in exaggerated appetite.
• Polyuria – Excess of glucose in the blood is excreted in the urine,
thus…
• Polydypsia – Because of polyuria, the person becomes
dehydrated and thirsty, thus the need to drink often.
48. • Target tissues: liver
• Function:
• regulates blood glucose levels
• between meals glucose levels drop
and glucagon is secreted
• glucagon allows glycogen to be
broken down into glucose
Glucagon
49. • Testosterone: Main sex hormone in male
• Responsible for the growth and development of male
reproductive structures, muscle enlargement, growth of body
hair, voice changes and male sexual drives.
• Target tissues: most
• Functions: aids in sperm and reproductive organ development
and function
Testosterone:
50. • Ovaries
• Estrogen/Progesterone:
• Development of female reproductive structures and sexual
characteristics
• Enlarges the breast and distribute fat, which influences the
shape of the hips, breast, and thighs.
• Maintains menstrual cycle
• Target tissues: most
• Functions: involved in uterine and mammary gland
development and menstrual cycle
Estrogen & Progesterone
51. Thymus Gland
• Lies at the upper part of the thoracic cavity
• Plays an important role in immune system
• Thymosin – Helps in the development of T-Cells (helps protect the
body against infection by foreign organism)
• Most important in early life.
Target tissues: immune system
tissues
Functions: promotes immune
system development and function
52. Pineal Body
• Small pinecone-shaped structure located superior and posterior
to the thalamus of the brain.
• Melatonin – decrease secretion of LH and FSH by decreasing
release of hypothalamic-releasing hormones. Acts to inhibit
reproductive system
