Pituitary Gland Flashcards
How many hormones are secreted by the anterior pituitary gland
6
Name the 6 hormones secreted by the anterior pituitary
1- GH
2- adrenocorticotropin (ACTH)
3- thyroid-stimulating ( TSH)
4-Follicule-stimulating (FSH)
5- Luteinizing hormone (LH)
6- prolactin (PRL)
What is the second name of GH and role
1- somatotropin
2- promote growth by affecting protein formation (cell multiplication/differentiation)
Second name ACTH and role
1- corticotropin
2- control secretion hormone by adrenal cortex, affect metabolism glucose/protein/fat
Second name TSH and role
1- thyrotropin
2- stimulating thyroid gland to control rate secretion
Role FSH
Control growth gonad and hormonal + reproductive activities
Role LH
Control growth gonad and hormonal + reproductive activities
Role PRL
Promotes mammary gland and milk production
Hormone secreted by posterior pituitary
1- antidiuretic hormone (ADH)
2- Oxytocin
Second name ADH and role
1- vasopressin
2-Control rate water excretion into urin
Role oxytocin
Help delivering milk from gland breast to nipple during sucking + help baby delivery
Mechanism of secretion of anterior and posterior pituitary
Ant. = adenihypophysis ( hormonal control)
Post. = neurohypophysis ( under neural control, neuron goes directly into lobe)
Parts of pituitary
Anterior + posterior pituitary lobe attached to hypothalamus through pituitary stalk
Lays in sella turcica in brain
5 cell type + % found in anterior pituitary
1- somatropes (30-40%)
2- corticotrope ( 20%)
3- thyrotropes (3-5%)
4- gonadotropes ( 3-5%)
5- lactotropes ( 3-5%)
Role somatotrope cell
Secrete GH
Role cortitotropes cell
Secrete ACTH
Role thyrototropes cell
Secrete TSH
Role gonatotropes cell
Secrete gonadotropic hormone = LH + FSH
Role lactotrope cell
Secrete PRL
What is a controlling factor
Hormone released from hypothalamus and are transmitted into ant. Lobe by portal vein
What are the 6 controlling factor
1- GH releasing hormone ( GHRH)
2- GH inhibitory hormone ( GHIH)
3- Corticotropin- releasing hormone (CRH)
4- Thyrotropin-releasing hormone ( TRH)
5-Gonadotropin-releasing hormone ( GnRH)
6- Prolactin-releasing hormone (PIH)
Role growth releasing and inhibitory hormone
Cause secretion or inhibition GH hormone
Role corticotropin-releasing hormone
Cause secretion adrenocorticotropin
Role thyrotropin-releasing hormone
Cause secretion TSH
Role gonadotropin-releasing hormone
Cause secretion LH + FSH
Role prolactine-releasing
Cause inhibitory secretion of PRL
How does controlling factor work
1.Signal from sensory NS is sent to hypothalamus
2. Hypothalamus synthesized controlling factor
3. Controlling factor release hypophysial stalk area
4. Are absorb in hypothalamic- hypophysial portal vessel
5. Carries hormone to trope cell
6. Trope cell receive controlling factor on their receptor and release hormone in anterior pituitary
4 effect of GH
- Promote growth baby + promote m. Size inc. in adult
- Inc. number cells
- Inc. physical size cell
- Inc. amount protein inside cell
3 aspect on what GH as effect on metabolism
- Fat metabolism
- Protein metabolism
- Carbohydrate metabolism
How does GH Affect metabolism (4)
- Promote protein synthesis
- Enhance fat as a source for energy
- Decrease use glucose for energy
- Decrease protein for energy
How does GH promote protein synthesis
- GH inc. amino acid transport through cell membrane = inc. concentration amino acid in cell = inc. protein synthesis
- Inc. formation RNA= Promote protein synthesis by ribosome in cytoplasm = inc. transcription DNA in nucleus
- Reduce breakdown protein cell
How GH enhance fat as a source of energy
- Mobilization of fat requires time
- Excessive amount may cause ketosis + fatty liver disease
- Cause triglycerides to breakdown into glycerol + free fatty acid = release fatty acid from adipose tissue = inc. concentration fatty acid in body fluid = enhance conversion fatty acid = acetylcoenzyme A (acetyl+coA) use for energy
How does GH decrease use protein for energy
Promoting use of fat for energy = protein not use for energy = protein can be use to inc. m. Mass
How does GH decease the us of glucose fo energy
- Inc. fatty acid conversion to energy = -v feedback to block breakdown glycogen to glucose = enhance deposition glycogen inheptic/ m. Cell = glycogen accumulate
2.Dec. Uptake glucose by cell = inc. blood glucose concentration = hyperglycemia may occur - Excess Gh inc. blood flow concentration glucose to 50%+ (pituitary diabetes)
- Chronic pituitary diabtes (GH abuse) = overstimulate islet langerhans to secrete insulin = islet can be damage = diabetes mellitus may develop
4 regulation abnormalities
- GH secretion promoted by malnutrition, anorexia, bulimia ( low fatty acid)
- GH secretion promoted by exercise ( after 2h)
- GH secretion promoted by sleep ( after 2h)
- GH secretion promoted by trauma ( long surgery)
Controlling hormone of GH
- Growth hormone releasing hormone (GHRH)
- Growth hormone inhibitory hormone ( GHIH)
Mechanism of the GHRH and GHIH
1 factor release from hypothalamus = goes into hypothalamic-hypophysial portal vessel and into ant. Pituitary = reach receptor somatotrope = activate adenyl cyclase system inside cell = cause short/long term effec
Short term effect from release of GHIH/GHRH
Inc. Ca2+ transport in cell = fusion GH secretory vesicle with cell membrane = release GH in blood
Long term effect from release GHRH/GHIH
Inc. transcription in nucleus by gene cause GH synthesis
If regulation fails what are the 5 abnormalities of GH
- Panhypopituitarism
- Dwarfism
- Gigantism
- Acromegaly
- Aging cause by dec. GH
Explain panhypopituitarism
Infection when feotus developping
Dec secretion from ant. Pituitary = abnormal growth (mass distribution)
What is dwarfism
Result from deficiency of GH or special case panhypopituitary dwarfism from childhood
Developp with appropriate proportion
1/3 from deficiency alone develop mature sexual function
What is gugantism
Excess GH cause by tumour in pituitary = body tissu grow rapidly
What is acromegaly
Acidophilic tumour in adolescence = soft tissu continu grow + bone grow thicker
What is the aging caused by dec GH
Dec protein synthesis in tissue + inc. deposition fat
With what kind of cell is the post potuitary compose
Pituicytes cell
What is the relationship of the post pituitary and hypothalamus
- ADH ( vasopressin) is synthesized in supraoptic nuclei of hypothalamus
- Oxytocin is synthesized in para ventricular nuclei of hypothalamus
How does the ADH and oxytocin reach the posterior pituitary
Each hormone binds with neurophysin which are then transported to the nerve ending in the post pituitary ( hormone can acumulate in nerve ending = not release right away)
By which mechanism is the hormone release from vesicle into n. Ending
When AP reach n. Ending hormone is release from vesicle into n. Ending by exocytosis
What are the 2 main function of oxytocin
- Contraction uterus at end gestation to help with birth (positive feedback)
- Cause milk expressed from alveoli into duct when sucking
What is the mechanism of action of oxytocin to allow milk flow
- Baby sucking on the nipple = signal sent through sensory nerve to the brain
- Reach oxytocin neuron in paraventricular nuclei in hypothalamus = release oxytocin from post pituitary
- Oxytocin carried to breach by blood = contraction myoepithelial cells = milk flow
What is the main purpose of ADH
Maintain blood pressure homeostasis
How is the secretion of ADH regulated
Its regulated by osmosis through osmoreceptor in hypothalamus
= they expand when blood dilute/ contract when blood is concentrated
What is the mechanism of regulation of the kidney
- Extracellular body fluid become highly concentrated = water in osmoreceptor diffuse out cell membrane by osmosis( contract)
- Initiate n. Impulse in hypothalamus = transmitted in post pituitary
- Secretion ADH ( water retention in kidney)
- Extracellular fluid become dilute = water diffuse into osmoreceptor ( expand)
- Decrease signal for ADH secretion = water excretion at kidney
What else does ADH controlled by
Its controlled by cardiovascular reflex = when dec. Blood volume/ blood pressure 15-25% = secretion inc. 50x normal
What is the mechanism of regulation by the cardiovascular reflexe
- Baroreceptor in attia are stretch by high blood pressure
- Impulse transmitted to brain to inhibit ADH secretion
- When blood volume/ pressure dec. = inc. secretion ADH = constriction blood vessel
How does ADH allow kidney to retain water
- ADH promote water to going from urine back into blood
- luminal membrane of tubular cell ( urinary tract) are impermeable to water in absence ADH
1. ADH bind receptor on luminal membrane = formation cAMP
2. Phosphorylation chemical in special vesicle = insert into apical cell membrane
3. Inc. permeability collecting tubule + duct to water = water reabsorbed from collecting duct by osmosis = concentrated urine
Why is ADH called vasopressin
Because as well as affect water reabsorption it also cause the constriction of arteriole = inc. arterial pressure