Animal Form and Function-1
COMMUNICATION_III
The Endocrine System and Chemical Messenger
Lecture Content:
1-Introduction of chemical messenger
2-Chemical Messengers
3-Biochemistry of hormones
4-Characteristics of hormones
5-Feedback control of hormone secretion
6-Mechanism of hormone action (I,II)
1. Endocrine System and Chemical Messenger
Lec-1
Mr. Hassan Hameed
University of Education Lahore, Pakistan
(Multan Campus)
2. Lecture Content
Introduction of chemical messenger
Chemical Messengers
Biochemistry of hormones
Characteristics of hormones
Feedback control of hormone secretion
Mechanism of hormone action (I,II)
3. Introduction of Chemical Messenger
Communication
Maintenance of homeostasis in an animals
body.
Body’s response to various stimuli
One time of chemical messenger is a hormone
Only those cells that have specific receptors
for a hormone can respond to that hormone
4. Hormones work with nerves to communicate,
coordinate, and integrate activities with in the
body of an animal
Almost every invertibrate produces hormone
The major endocrine glands of vertebrates
include; Hypothalamus, Pituitary, Thyroid
parathyroid, Adrenals, Pineal, Thymus,
Pancreas and Gonads.
5. Various other tissues, however, such as the
kidneys, heart, digestive system and placenta
also secrete hormones.
6. Chemical Messengers
The development of most animals commences
with fertilization and the susequent division of
zygote
Further development then depends on continued
cell proliferation, differentiation and growth.
Integration, communicationn and coordination of
all physiological processes such as metabolism,
respiration, excretion, movement and
reproduction, depends on chemical messengers.
7. The chemical messengers are the molecules that
are synthesized and secreted by specialized cells.
Categorized;
- Local chemical messengers
(Lumones, Histamine)
- Neurotransmitters
(acetylcholine)
- Neuropeptides
- Hormones (thyroxin, insulin)
- Pheromones
11. Feedback control of hormone secretion
Feedback system is defined as the system in
which the controlling mechanism is itself
controlled by the product of the reaction it is
controlling. e.g iron
The endocrine system is controlled by complex
feedback mechanism in which the secretion of
a hormone is turned on or off (depends on its
concentration)
It may be Positive or Negative.
12.
13. Mechanism of Hormone Action
Fixed-receptor mechanism;
Endocrine cells > secrete > water soluble hormone>
at target cells > hormones binds specific receptor
site on target cell membrane > comlexed formed >
hormone-receptor complex > complex activate
adenylate cyclase > convert ATP to AMP cyclic >
AMP then activate protein kinase > phosphorylates
cell specific proteins > that tiger biochemical
reaction> lead to cell respose.
14. After function > phosphodiesterase inactivates
cyclic AMP.
Meantime, receptor on the plasma membrane
loses the first messenger and now becomes
available for new reaction.
15.
16. Mobile-receptor mechanism;
Steroid hormone molecules diffuses from blood
to a target cell > in cytoplasm binds to receptor
protein > steroid-protein complex >carries to
nucleus > trigers transcription of specific gene
region of DNA > mRNA translated to protein in
cytoplasm> this new protein the mediate the
cells response.
22. Hormones of Adenohypophysis
6 different hormones
Two types of hormone;
- Tropic (Primary target > another EG)
(TSH, ACTH, LH, FSH)
- Non-Tropic
(GH, Prolactin)
23. Tropic hormone
TSH; > thyroid gland > thyroxin
ACTH; Hypothalamus>CRF> pituitary>ACTH
Female; LH>stimulate ovulation > mature ova,
LH also stimulate corpus luteum > ovaries, in
response release sex hormone > estrogen and
progesterone.
FSH…..?
LH; (Male) stimulate> leyding cells >
testosterone.
FSH,LH; Gonadotropins
24. Non-Tropic Hormone
GH; (Somatotrophic hormone), Affect all
body part concerned with Growth, induces cell
division.
Influence protein synthesis, RNA synthesis,
ribosome activity.
Prolactin; Role in reproduction such as
- stimulate reproductive migration
- mammary gland development, milk
production
26. Pineal Gland
Third eye
Darkness makes PG to produce melatonin.
Wake/sleep and seasonal changes modulation
Light inhibit enzyme need for melatonin synthesis
Affect our physiological process to adapt to
seasonal and diurnal cycles
In human, decreased melatonin secretion, triger
puberty onset
Regulate sleep pattern
30. Adrenal Glands
Two gland top of kidney
Eeach gland have two part(cortex and medula)
Adreanl Cortex; secretes three hormone
1. Glucocorticoids; Cortisol > regulate
metabolism, blood sugar, also function as
defense against infection
2. Mineralocorticoids (Aldosterone) > maintain
solute conc. In extracellular fluid
3. Sex hormones (androgens, estrogens)
33. Pancreas
Synthesize,store and secrete hormone insulin
and glucagon
Somatostatin; inhibit glucagon and insulin
secretion
Pancreatic polypeptide >inhibit somatostatin
secretion
34.
35.
36. Testes
Male > testosterone secrete, which act with
LH and FSH > spermatogenesis
Testosterone necessary for growth and
maintenance of male sex organs, sex behavour,
stimulate growth of facial and pubic hair.
Testes also produce inhibin which inhibit FSH
secretion
37. Overies
Estrogens; regulate menstrual and estrus
cycle,mammary gland development, sec.sex
character
Progestin; placenta formation
Relaxin; soften uterus opening in delivery
Inhibin; inhibits FSH
38. Thymus
Behind breastbone
Role in immune and endocrine system.
Active until puberty
Produce hormone thymosin > stimulate WBC
development (T-cells).