assist prof. of medical physiology. to do its action, the hormone must bind to specific molecules on...
TRANSCRIPT
![Page 1: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/1.jpg)
Assist prof. of Medical Physiology
![Page 2: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/2.jpg)
![Page 3: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/3.jpg)
• To do its action, the hormone must bind to specific
molecules on the cells called receptors.
![Page 4: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/4.jpg)
![Page 5: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/5.jpg)
• Hormone receptors are 2 types according to its location;
Cell surface or cell membrane receptors
Intracellular receptors
![Page 6: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/6.jpg)
![Page 7: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/7.jpg)
– Water soluble hormones e.g. peptide hormones,
catecholamines bind to cell membrane receptors
on the surface of target cells
1. Activation of a membrane-bound enzyme.
2. Rise of intracellular Ca++ concentration:
3. Increase in cell membrane permeability to
Na+, K+ and Cl-.
![Page 8: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/8.jpg)
• Membrane-bound enzymes include adenyl cyclase
• Activation of this enzyme generates a intracellular 2nd messenger (e.g. cyclic AMP) → biological response
![Page 9: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/9.jpg)
• The hormone-sensitive adenyl cyclase system
has 3 components:
i) The receptor:, stimulatory or inhibitory (Rs or
Ri).
ii) G protein: guanine nucleotide (GTP) – binding
protein (Gs or Gi).
iii) Catalytic component (C): enzymatically
converts Mg2+-ATP to cyclic AMP.
![Page 10: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/10.jpg)
1. Receptors 1. Receptors
2. G 2. G protein protein
3. Catalytic 3. Catalytic subunit subunit
![Page 11: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/11.jpg)
• It is a guanine nucleotide – binding protein • It may be Gs or Gi
a) Gs mediate the action of the hormones that
stimulate adenylyl cyclase activity,
b) Gi mediates the action of hormones that
inhibit adenylyl cyclase activity.
• Gs and Gi are heterotrimers comprised of a unique
-subunit (s or i) and similar and subunits.
![Page 12: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/12.jpg)
![Page 13: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/13.jpg)
βγ
Catalytic subunit
G protein
ATP
C-AMP
Activate enzymes
α
Adenyl-cyclase systemReceptor
![Page 14: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/14.jpg)
Binding of the hormone to the receptor
activate G-proteins
dissociate the α-subunit
change the activity of membrane-bound enzyme
"second messenger
mediate the action of the hormone
![Page 15: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/15.jpg)
![Page 16: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/16.jpg)
– This occurs by 2 mechanisms:
i- Increase Ca++ influx,
– by activating ligend gated Ca++ receptors.
ii- Release of Ca++ from
– endoplasmic reticulum,
– mitochondrial membrane.
![Page 18: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/18.jpg)
![Page 19: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/19.jpg)
![Page 20: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/20.jpg)
• ↑ free cytosolic Ca++ produce the following:
1. Changes in cell motility
2. Contraction of ms cells.
3. ↑ed release of secretory proteins.
4. Activation of regulatory enzymes.
5. Ca++ binds to specific calcium – binding proteins, such
as;
Calmodulin in smooth ms
Troponin C in skeletal ms
![Page 21: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/21.jpg)
• Binding of hormone to its membrane receptors
↑es membrane permeability to Na+, K+ and Cl-.
![Page 22: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/22.jpg)
![Page 23: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/23.jpg)
Cytoplasmic Cytoplasmic Receptors Receptors
Nuclear Receptors Nuclear Receptors
Steroid HormonesSteroid Hormonese.g. vit D and e.g. vit D and
retinoids retinoids
Thyroid Hormones Thyroid Hormones
![Page 24: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/24.jpg)
Mechanisms of interaction of lipophilic hormones, such as steroids and thyroid
![Page 25: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/25.jpg)
![Page 26: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/26.jpg)
![Page 27: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/27.jpg)
![Page 28: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/28.jpg)
![Page 29: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/29.jpg)
– It is a secretion released by a nerve cell &
reaches the endocrine glands via blood vessels
or nerve fibres.
Example
1.Hypothalamic releasing & inhibitory hormones
is an example of this type of control
2.Post pituitary hormones are released from
terminals of the hypothalamohypophyseal tract.
![Page 30: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/30.jpg)
![Page 31: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/31.jpg)
Hypothalamic releasing and inhibitory
hormones
![Page 32: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/32.jpg)
Posterior pituitary hormones
![Page 33: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/33.jpg)
•Usually done by autonomic fibres e.g. sympathetic control of the adrenal medulla
![Page 34: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/34.jpg)
Negative Feedback Negative Feedback Positive Feedback Positive Feedback
Most common Most common Less common Less common
![Page 35: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/35.jpg)
Trophic Gland
Target Gland
A+ +
B
_ _
![Page 37: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/37.jpg)
Hypothalamus
Pituitary g.
Adrenal cortex
CRH
ACTH
Glucocorticoids
--
--
![Page 39: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/39.jpg)
Significance:
1.Prevent overstimulation of the target glands by
the tropic hormones.
2.Adjust the rate of hormone secretion according
to the body needs.
3.Maintain hormone blood level relatively constant.
![Page 41: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/41.jpg)
Trophic Gland
Target Gland
A+ +
B
+ +
![Page 42: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/42.jpg)
• Less common
• When a target gland hormone (B) is increased, it
will increase the rate of secretion of its pituitary
tropic & hypothalamic releasing hormones (A)
• This relation increases the target gland hormone
more and more.
• When the target gland hormone reaches sufficient
level negative feedback returns again to reduce
the hormone to its final level.
![Page 43: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/43.jpg)
Hypothalamus
Pituitary g.
ovary
Gn-RH
LH
Estrogens
++
++
LH surgeEssential
for ovulation
LH surgeEssential
for ovulation
![Page 45: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/45.jpg)
Significance:
– Temporary amplification of the biological
effects of the hormone.
Example:
– The link between estrogen and LH
– Pre-ovulatory LH surge.
![Page 46: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/46.jpg)
![Page 47: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/47.jpg)
Feed-back control system may be:
A) Long loop feed-back:
– Represents the relationship of target gland H
and their ant pituitary trophic hormones.
B) Short loop feed-back:
– Relation between ant pituitary trophic H and the
hypothalamic releasing and release-inhibiting H.
![Page 48: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/48.jpg)
Hypothalamus
Pituitary G.
TRH+ +
TSH
--
Thyroid G.+ +
T3 and T4
Long Loop
--
Short Loop
![Page 49: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/49.jpg)
![Page 50: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/50.jpg)
a) Organic substances e.g.
Blood glucose level and the secretion of pancreatic H.
b) Inorganic substances e.g. blood Ca+2, Na+,K+.
Blood Ca+2 level and parathyroid and calcitonin
hormones.
Blood Na & K level and aldosterone.
Plasma inorganic substances determines the blood
osmolarity, that affect the hypothalamic release of
ADH.
![Page 51: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/51.jpg)
Def:
• Cytokines are small proteins produced by various
cell types in different physiological and pathological
states.
• Cytokines modulate endocrine functions by acting on:
•the endocrine glands and
•on the target tissues.
![Page 52: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/52.jpg)
Example:
– Cytokine hormones (e.g., leptin) produced by
adipocytes also called adipokines.
– Leptin
•suppresses GH through stimulation of
somatostatin,
•suppresses gonadotropins and
•stimulates the pituitary–adrenal axis.
![Page 53: Assist prof. of Medical Physiology. To do its action, the hormone must bind to specific molecules on the cells called receptors](https://reader035.vdocument.in/reader035/viewer/2022062805/5697bfd01a28abf838caa6bc/html5/thumbnails/53.jpg)