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Neural and Hormonal Control > Pituitary Gland with focus on oxytocin and ADH > Flashcards

Pituitary Gland with focus on oxytocin and ADH Flashcards

1
Q

Where does the pituitary gland lie?

A

In the sella turcica at the base of the brain

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2
Q

What connects the pituitary gland to the hypothalamus?

A

The pituitary stalk (hypophysial stalk)

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3
Q

What are the two parts that make up the pituitary gland?

A

Anterior pituitary (adenohypophysis)
Posterior pituitary (neurohypophysis)

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4
Q

What are the six hormones secreted by the anterior pituitary?

A

Growth hormone (GH)
adrenocorticotropin (ACTH)
Thyroid-stimulating hormone (TSH)
Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH)
Prolactin (PRL)

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5
Q

What is the function of growth hormone?

A

Promotes growth of entire body by affecting protein formation cell multiplication and differentiation

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6
Q

What is the function of adrenocorticotropin?

A

Controls secretion of hormones from adrenal cortex. Affects metabolism of protein, glucose and fats

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7
Q

What is the function of thyroid stimulating hormone?

A

Stimulating gland to control the secretion rate of thyroxine and triiodothyronine. Control the rate of intracellular chemical reaction of entire body

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8
Q

What is the function of follicle-stimulating hormone?

A

Control growth of gonads and hormonal and reproductive activities

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9
Q

What is the function of luteinizing hormone?

A

Control growth of gonads and hormonal and reproductive activities

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10
Q

What is the function of prolactin?

A

promotes mammary gland and milk production

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11
Q

What are the two hormones secreted by the posterior pituitary gland?

A

oxytocin
Antidiuretic hormone (ADH)

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12
Q

What is the function of antidiuretic hormone?

A

control rate of water excretion into urine (maintain water concentration in body fluids)

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13
Q

What is the function of oxytocin?

A

Helps for delivering milk from glands of breast to the nipples during suckling. Helps with baby delivery at the end of gestation

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14
Q

What are the different types of tissues that make up the anterior pituitary?

A

Somatotropes
Corticotropes
Thyrotropes
Gonadotropes
Lactotropes

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15
Q

What do the somatotropes help secrete?

A

Growth hormone

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16
Q

What do corticotropes help secrete?

A

adrenocorticotropin

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17
Q

What do thyrotropes help secrete?

A

Thyroid-stimulating hormone

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18
Q

What do gonadotropes help secrete?

A

gonadotropic hormones: follicle-stimulating hormone and luteinizing hormone

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19
Q

What do lactotropes secrete?

A

Prolactin

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20
Q

What controls secretion from the anterior pituitary?

A

Controlled by hormones; hypothalamic releasing and inhibitory hormones

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21
Q

What controls secretions from the posterior pituitary?

A

Neural control; nerve signals sent from the hypothalamus

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22
Q

What is the cascade of events that leads to the release of hormones from the anterior pituitary?

A

The hypothalamus receives signals from sensory sources in the nervous system.
Hypothalamic releasing and inhibitory hormones are synthesized in special neurons in the hypothalamus.
The endings of these neurons connect to the median eminence in the hypophysial stalk
The releasing and inhibitory hormones release from the neurons into tissue fluids.
These hormones are absorbed into the hypothalamic-hypophysial portal vessels and are carried to the sinuses of the anterior pituitary gland

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23
Q

What are the six hormones produced in the hypothalamus that control the release of anterior pituitary secretions?

A

Growth Hormone Releasing Hormone (GHRH)
Growth hormone inhibitory hormone (GHIH)
Corticotropin-Releasing hormone (CRH)
Thyrotropin-Releasing hormone (TRH)
Gonadotropin-Releasing hormone (GnRH)
Prolactin inhibitory hormone (PIH)

24
Q

How many amino acids make up growth hormone

A

191 amino acids in a single chain

25
Q

How does growth hormone promote growth in babies and muscle size increases in adults?

A

GH can increase the physical size of cells
GH can increase the number of cells
GH can increase the amount of protein inside of a cell

26
Q

How does growth hormone promote protein synthesis?

A
  • GH can enhance transport of most amino acids through cell membrane to the interior of cells ==> increase the concentration of amino acid in cells ==> increase protein synthesis.
  • GH increases the formation of RNA ==> promotes more protein to be synthesized by ribosomes in cytoplasm ==> increases transcription of DNA in nucleus.
  • GH mobilizes large amounts of free fatty acids from adipose tissue ==> in turn the free fatty acids are used to supply most of energy for body cell ==> reduces the breakdown of cell protein.
27
Q

How does GH enhances fat as a source of energy

A

*GH causes release of fatty acids from adipose tissue ==> increase the concentration of fatty acids in body fluids ==> enhances conversion of fatty acids to acetylcoenzyme A ( acetyl-CoA ) used for energy.

*GH mobilization of fat requires time ( hours to occur ).

*GH at excessive amounts of may cause ketosis and fatty liver disease.

28
Q

How does GH decrease the use of glucose as an energy source?

A

*GH increases fatty acids conversion to acetyl-CoA, ==> negative feedback effect to block breakdown of glycogen to glucose ==> enhances the deposition of glycogen in hepatic or muscle cells ==> glycogen accumulates

*GH diminishes the uptake of glucose by cells ==> increases the blood glucose concentration ==> hyperglycemia might occur if GH is excessive

*If excessive GH chronically increases blood concentration of glucose increases to 50% or more above normal, called pituitary diabetes ==> GH over-stimulating islet of Langerhans to secrete extra insulin ==> diabetes mellitus may develop ( diabetogenic effect ).

29
Q

What affects regulation of growth hormone secretion rate?

A

Promoted by starvation, malnutrition, anorexia, bulimia (low concentrations of glucose and fatty acids lead to secretion of GH)
Promoted by exercise (after 2 hours of strenuous exercise)
Promoted by sleep (after 2 hours of sleep)
Promoted by trauma (

30
Q

What is the cascade of events leading to the control of GH secretion?

A

One of the two factors are secreted from hypothalamus ==> travel down the hypothalamic hypophysial portal vessels ==>reach the anterior pituitary gland ==>attaches to receptors on the somatytrope ==> activates adenyl cyclase system inside the cell ==> causes short and long term effects.

31
Q

What is the cascade of event for short-term GH effects?

A

Increase Ca ions transport into cell ==> fusion of GH secretory vesicles with cell membrane ==> release of GH into blood.

32
Q

What is the cascade of events for long-term GH effects?

A

Increase transcription in nucleus by the genes that cause new GH synthesis.

33
Q

What are the five different abnormalities of growth hormone secretion that can occur?

A

Panhypopituitarism
Dwarfism
Gigantism
Acromegaly
Aging caused by decreased secretion of GH

34
Q

What is panhypopituitarism?

A

Decreased secretion of all anterior pituitary hormones
It can be congenital or occur during life
The lack of GH results in abnormal growth
The lack of other pituitary hormones cause a multitude of other issues

35
Q

What is dwarfism?

A

Results from specific deficiency of GH alone or it can be due to a special case of panhypopituitarism dwarfism from childhood.
* Body develops in appropriate proportion to one another but rate of development decreased greatly
* age of 20 looks like 7 - 10 years old.
* Panhypopituitary dwarf does not pass through puberty.
* No sufficient gonadotropic hormone for developing sexual function
* 1/3 of dwarfs resulted from deficiency of GH alone can develop mature sexual function.
* Pygmy people are born with a defective GH response

36
Q

What is gigantism?

A

Excessive amounts of GH produced caused by a tumour on the pituitary gland
Body tissue grow rapidly

37
Q

What is acromegaly?

A

Acidophilic tumour occurs after adolescence
Soft tissue continue to grow, bone grow thickness

38
Q

What is aging caused by decreased secretion of GH?

A

Decreased secretion of GH ==> accelerates aging process.
Result from decreased protein synthesis in body tissue and increased deposition of fat.

39
Q

The posterior pituitary gland is composed of what?

A

cells called pituicytes.

40
Q

Where are the antidiuretic hormones synthesized?

A

in the supraoptic nuclei of hypothalamus

41
Q

Where is oxytocin synthesized?

A

In the paraventricular nuclei of the hypothalamus

42
Q

When nerve impulses from supraoptic and paraventricular nuclei reach to the nerve endings, oxytocin and antidiuretic hormones is released from nerve endings by what?

A

exocytosis

43
Q

What are the two functions of oxytocin?

A

Cause contraction of the uterus at the end of gestation to help with the birth of the baby.
Cause milk to be released from the alveoli into the ducts so that the baby can obtain it through suckling

44
Q

What is the cascade of events leading to milk release?

A

Suckling stimuli on nipple of the breast elicits signals, ==> signals are transmitted through sensory nerves to the brain, ==> reach to the oxytocin neurons in the paraventricular nuclei in the hypothalamus, ==> cause release of oxytocin from posterior pituitary gland, ==> oxytocin is carried by blood to breasts, ==> cause contraction of myoepithelial cells, ==> milk flow ( milk ejection or milk letdown ).

45
Q

What is the main purpose of ADH?

A

to maintain blood pressure by homeostasis

46
Q

What is osmosis?

A

Movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration

47
Q

What is the secretion of ADH regulated by?

A

osmosis through osmoreceptors in the hypothalamus

48
Q

TRUE or FALSE. Osmoreceptors are specialized neurons in the hypothalamus that expand when the blood is dilute, and they contract when the blood is concentrated.

A

True

49
Q

What is the cascade of events of ADH leading to regulation of the kidney

A

When the extracellular body fluid becomes highly concentrated, water in the osmoreceptor diffuses out of the cell membrane by osmosis ==> decrease the size of osmoreceptor ==> initiates the nerve impulses in the hypothalamus ==> impulses are transmitted to the posterior pituitary ==> cause secretion of ADH, water retention in kidney.

When the extracellular fluid becomes too dilute, water diffuses into the osmoreceptor ==> increase the cell size of the osmoreceptor ==> decrease the signal for ADH secretion, water excretion at kidney.

50
Q

Secretion of ADH is also controlled by the cardiovascular reflexes in response to what?

A

response to the decrease in blood pressure or blood volume

51
Q

What is the cascade of event of ADH control by cardiovascular reflexes?

A

The baroreceptor in atria can be excited by stretch caused by high blood pressure.
The reflex impulses from baroreceptors are transmitted to brain to inhibit ADH secretion.
When the blood volume or blood pressure decreases ==> increase the secretion of ADH ==> cause constriction of blood vessels.

52
Q

The luminal membrane separates blood from what?

A

urine

53
Q

What is the cascade of events leading to changes in urine?

A

When ADH is released into blood and is transported to kidney, it binds with the receptors on luminal membranes ==> cause formation of cAMP ==> cause phosphorylation of chemicals in the special vesicles ==> vesicles insert into apical cell membrane ==> increase the permeability of collecting tubules and ducts to water ==> water is reabsorbed from the collecting tubules and duct by osmosis ==> water is conserved in the body ==> producing very concentrated urine.

54
Q

TRUE or FALSE. High concentrations of ADH can also cause the constriction of the arterioles throughout the body to increase arterial pressure.

A

True

55
Q

What is the pressor response?

A

When the blood volume or blood pressure decreases, ==> secretion of ADH then ==> constriction (tightening) of blood vessels.

By making blood vessels smaller, it helps to increase the blood pressure. This works together with the renal effects, which are to bring in more water which maintains blood pressure.

56
Q

What is the process when blood pressure goes above normal values?

A

If blood pressure is high ==> ADH is no longer secreted, water is excreted by the kidney into urine, and the arterioles relax, which lowers blood pressure. Homeostasis will eventually bring blood pressure to the optimal point, as determined by continuous monitoring by the baroreceptors in the heart and osmoreceptors of the hypothalamus.

Neural and Hormonal Control (12 decks)

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