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PSL 310 > Endocrine Physiology > Flashcards

Endocrine Physiology Flashcards

1
Q

Endocrine glands are____________glands

A

Ductless

They secrete hormones into the blood
Which affect target cell function (the hormones site of action, the hormone influences)

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2
Q

The endocrine system is a _________ system; it regulates the function of target cells

A

Control

The nervous system is also a control system

The nervous system is faster acting but it’s effects are shorter lasting than hormones

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3
Q

Since hormones travel in the blood they can reach (or potentially affect) ____ cells

A

All

But cells only respond to a hormone if they have receptors for the hormone

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4
Q

How are the two control systems (nervous and endocrine systems) interrelated

A

The hypothalamus of the brain is a very important link between the 2 systems- it controls the pituitary gland

The pituitary gland secreted many hormones and those hormones control many functions

The hypothalamus controls the pituitary gland secretions (both anterior and posterior)

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5
Q

Steroids

A

Ringed lipids derived from cholesterol

These are the sex hormones and adrenal cortex hormones

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6
Q

Peptides

A

Chains of amino acids- these are most hormones

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7
Q

Amines

A

From amino acid tyrosine-these are thyroid hormones and catecholamines are epinephrine, norepinephrine, and includes dopamine-these are adrenal medulla hormones

Dopamine is also released from the hypothalamus- it is prolactin inhibiting hormone (PIH)

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8
Q

Catecholamines

A

Epinephrine, norepinephrine, and dopamine

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9
Q

How do hormones cause their effects

A

1st bind to target cells receptors-in diff location for lipid soluble/ lipid insoluble hormones

The hormone binding to the receptors affects cell proteins
A.) can change activity of proteins already present in cell (enzymes)
B.) can cause synthesis of new proteins by activation of genes (or can do the reverse-can cause inhibition of genes and decrease protein synthesis)

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10
Q

Where are the receptors found for lipid insoluble hormones and why

A

These hormones can’t get through the cell membrane so their receptors are on outer surface of the membrane

They are hydrophilic hormones=peptide hormones + catecholamines

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11
Q

Where are the receptors found for lipid soluble hormones and why

A

The receptors are found within the cell because they are lipophilic hormones

Steroid+ thyroid hormones

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12
Q

As a rule, ——————— hormones alter the activity of proteins already present in the cell

A

Hydrophilic

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13
Q

As a rule, ————— hormones affect genes and synthesis of new proteins

A

Lipophilic

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14
Q

How do lipid soluble hormones cause responses?

A

Signal transduction causes the response

  1. Hormone diffuses through cell membrane
  2. Hormone binds to receptor inside cell
  3. Hormone and receptor together bind to DNA
  4. Hormone and receptor binding activates genes
  5. Activation of genes causes protein synthesis
  6. New protein cause hormone effect/ response

Could be opposite where decrease in protein synthesis occurs (eg. cortisol turns off genes involved in inflammation)

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15
Q

How do lipid insoluble hormones cause responses?

A

Most use a second messenger (messenger inside the cell)
First messenger is the hormone

Many use cyclic AMP as second messenger

  1. Adenylyl Cyclase is activated (after the hormone binds to the receptor and series of steps in the membrane which involves a G protein occurs)
  2. Adenylyl cyclase makes cAMP from ATP
  3. CAMP activates a protein kinase
  4. The kinase phosphorylates/ activates proteins
  5. Activates protein causes the response dictated by the hormone
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16
Q

Parts of the pituitary gland

A

Part of the pituitary gland develops upward projection of the pharynx; this is the adenohyppphysis (which contains glandular epithelial cells)

This is known as anterior pituitary

Part of the pituitary gland develops as downward growth of the hypothalamus; this is the neurohypophysis (which has nerve fibers and nerve endings)

This is the posterior pituitary

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17
Q

What is the brains relationship with the pituitary gland

A

The neurohypophysis (posterior pituitary) connected by a stalk to the hypothalamus

Stalk is known as infundibulum

The posterior pituitary is thought of like an extension of the hypothalamus

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18
Q

Steps of how hypothalamus produces the hormones secreted by posterior pituitary

A
  1. Hormones are made in cell bodies in hypothalamus
  2. Are transported in vesicles down axons, stores in terminals in posterior pituitary
  3. On an appropriate signal are released by exocytosis

This hormone release into the blood is triggered by action potential from hypothalamus (excitatory postsynaptic potentials in the cell body in the hypothalamus will cause action potentials in the axon that goes to the posterior pituitary)

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19
Q

What 2 hormones are from posterior pituitary

A

ADH=vasopressin

Oxytocin- stimulates uterine contractions in delivery of a baby

is also the hormone for milk letdown; causes milk to be ejected into the ducts of the mammary glands so that the baby can remove the milk by nursing (baby cant remove milk without reflex)

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20
Q

Milk letdown reflex

A

Shows how nervous and endocrine systems are interrelated it is a neuroendocrine reflex

Suckling causes impulses to go to the brain and then the hypothalamus of the brain and then the posterior pituitary- which causes oxytocin release.

Oxytocin travels through the blood to the breast and causes contraction of myoepithelial cells (contractile epithelial cells - with actin and myosin in these special cells - that surround the alveoli) causes milk let down

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21
Q

What can affect milk letdown

A

Psychological stress can prevent the reflex

A crying baby can cause nursing mother (who feels for the crying baby) to leak milk

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22
Q

Anterior pituitary glands relationship with the hypothalamus

A

The hypothalamus secretes hormones which control anterior pituitary hormone secretion

These hormones from the hypothalamus (which control the ant pit) are called hypophysiotrophic hormones or simply releasing and inhibiting hormones

23
Q

How do hypothalamic hormones get to the anterior pituitary

A

Capillaries in the hypothalamus lead to hyothamamo-pituitary (or hypothalamic-hypophyseal) portal vessels which pass down the pituitary stalk lead to capillaries in the anterior pituitary

Portal vessel- connects two capillary beds

24
Q

Hormones from the hypothalamus control the anterior pituitary through a ______link

A

Vascular (the portal system)

25
Q

Hormones from the hypothalamus control the posterior pituitary through a ______link

A

Neural (nerve fibers from the hypothalamus end in the posterior pit)

26
Q

Hypothalamus hormone: Growth hormone releasing hormone GHRH

A

Effect on anterior pituitary

Simulates secretion of growth hormone

27
Q

Hypothalamus hormone: growth hormone inhibiting hormone (GHIH) (or somatostatin)

A

Effect on anterior pituitary

Inhibits secretion of growth hormone

28
Q

Hypothalamus hormone: Prolactin inhibiting hormone PIH

A

Effect on anterior pituitary

Inhibits secretion of prolactin

29
Q

Hypothalamus hormone: Prolactin releasing hormone PRH

A

Effect on anterior pituitary

Stimulates secretion of prolactin

30
Q

What is growth hormones effects on metabolism

A

Anti insulin antagonist effects
Increased growth hormone causes increased fat breakdown (increased fatty acids in blood) increased blood glucose, increased protein synthesis*, increased movement of amino acids into cells and increased synthesis of proteins from amino acids, increased cell division

*this is like insulin

31
Q

Growth hormone stimulates release of _______ from the liver also other cells

A

IGF-I

causes mitosis or cell division

32
Q

Prolactin

A

Another anterior pituitary hormone

Promotes lactation; promotes breast gland development

Prolactin release increases with suckling/nursing

33
Q

The rest of the anterior pituitary hormones stimulate (or regulate) secretion of another hormone and are called ________ hormones

A

Tropic

Growth hormone acts like tropic hormone when it stimulates IGF-I release from liver

Tropic hormones target is endocrine gland

Of anterior pituitary hormones, only prolactin is not at all tropic hormone

34
Q

ACTH

A

controls secretion of cortisol from the adrenal cortex

Anterior pit Tropic hormone

35
Q

TSH

A

Anterior pit. Tropic hormone
stimulates secretion of thyroid gland’s thyroid hormones
Also stimulates thyroid gland to grow (can cause goiter)

36
Q

FSH and LH

A

cause sex hormone secretion from the gonads and gamete (egg and sperm) development

37
Q

How is hormone secretion controlled

A

By negative feedback for tropic hormones

It maintains the concentration of hormones in the blood (cortisol levels)

38
Q

What is a short feedback loop and long feedback loop

A

Short
Anterior pituitary hormones inhibit the hypothalamus

Long
3rd hormone is secreted out in the body (loop back is long)

39
Q

Anatomy of thyroid gland

A

2 lobes connected (by an isthmus) it is composed of follicles. Each follicle is a ball of cells. The follicles are filled with colloid

Follicle cells secrete colloid which is mostly thyroglobulin; and enzymes

40
Q

Thyroglobulin Tg

A

A large protein which contains thyroid hormones- they are attached to Tg

Thyroglobulin stores thyroid hormones

When thyroglobulin is split up by enzymes thyroid hormones are released

41
Q

What are the two types of thyroid hormones

A

Thyroxine or T4

Triiodothyronine or T3

Number=number of iodine atoms attached

42
Q

Iodine must be supplied in the diet to make ______

A

thyroid hormone TH

It is only reason you need iodine in your diet

43
Q

Steps of synthesis and release of thyroid hormones

A
  1. Follicle cells make thyroglobulin which moves into the colloid by exocytosis
  2. Iodide is cotransported into the follicle cell with Na+ (by secondary active transport)
  3. Iodide enters the colloid
  4. MIT (with one iodine) and DIT (with two iodines) make T3; DIT and DIT make T4
  5. Endocytosis of thyroglobulin by follicle cells occurs
  6. Lysosomal enzymes break apart thyroglobulin
  7. T3 and T4 are released into the blood

Almost all steps are controlled/ stimulated by TSH

44
Q

Effects of thyroid hormones

A

With increased TH:
Increased basal metabolic rate
Increased O2 and energy use
Increased heat production

45
Q

How do thyroid hormones increase responsiveness to epinephrine and norepinephrine, and increase heart rate and contractility and cardiac output

A

They increase beta receptors on the heart

46
Q

TH effects on growth

A

TH promotes the effects of growth hormone on protein synthesis

TH is needed to synthesize growth hormone. Hypothyroid children have stunted growth

47
Q

TH effects on nervous system

A

Needed for nervous system development and growth of the nervous system.
Deficiency of thyroid hormone in infancy can cause intellectual developmental disorder

48
Q

What causes a goiter

A

An iodine deficiency

Wouldn’t be able to make normal amounts of thyroid hormones

Lack of negative feedback so increase in TRH abs TSH and TSH stimulates thyroid to grow

49
Q

Calcitonin

A

Not controlled by anterior pit. Controlled by C cells of thyroid gland

Inhibits osteoclasts (cells that breakdown bone) releases calcium

50
Q

Calcitonins effect on blood C++

A

Increased blood Ca++ causes increased calcitonin release which decreases blood Ca++

51
Q

Parathyroid hormone

A

Is very important in controlling blood Ca++

PTH increases blood Ca++

Stimulus to secret hormone is decreased Ca++

52
Q

What is hypocalcemic tetany

A

Low blood Ca++ causes it

Spontaneous tetanus muscle contractions

Low blood Ca++ causes the membrane to be leaky to Na+

Causes spontaneous depolarization of excitable membranes and potentials and contractions

If it affects respiratory muscles causes death

53
Q

What three organs does PTH have actions on

A
  1. Bone - causes release of Ca++ from bone
    Stimulates the cells that tear down bone- osteoclasts
  2. Kidney-affects rhe nephrons. PTH causes:
    Increased reabsorption of Ca++
    Decreased reabsorption of PO43- (phosphate ion) and increase PO43- excretion
  3. Intestine
    The effect of PTH is indirect through vitamin D
    The step in activation of vitamin D In kidneys stimulates by PTH
    Active vitamin D increases Ca++ absorption from the gut
54
Q

Hormones from the adrenal cortex

A

Glucocorticoids, mineralocorticoids, and sex hormones

PSL 310 (8 decks)

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