General Physiology Flashcards

1
Q

Describe the difference between endocrine hormones, paracrines, autocrines, and cytokines

A

Endocrine hormones - released into circulation to act on target organ somewhere else
Paracrines - released hormones to act on neighboring cells
Autocrines - act on same cells
Cytokines - can act as paracrines, autocrines or circulating hormones

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2
Q

What are the 3 classes of proteins?

A
  • peptides and proteins
  • steroid hormones (cortisol, aldosterone)
  • tyrosine hormones (thyroid hormones, epinephrine/norepi)
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3
Q

What is the difference between polypeptides and proteins?

A

Both made of AAs, polypeptides up to 100 AA, >100 are proteins

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4
Q

Describe the production/synthesis of polypeptides and protein hormones

A

Produced by the endoplasmic reticulum—> Golgi apparatus to be placed into vesicles —> vesicles either released by exocytosis to release hormones or stored under cell surface for later release

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5
Q

Describe the synthesis of steroid hormones. How are these stored?

A

Synthesized from cholesterol
very little storage of steroids –> but store cholesterol –> can be used for synthesis fast

fat soluble

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6
Q

In what two places/organs are hormones derived from tyrosine produced?

A
  • thyroid gland
  • adrenal medulla
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7
Q

What is thyroglobulin?

A

macromolecule that is used to bind and store thyroid hormones in the thyroid gland

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8
Q

What plasma protein carries thyroid hormones?

A

thyroxine-binding globulin

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9
Q

What is the normal ratio of epinephrine to norepinephrine secretion from the adrenal medulla?

A

4 to 1

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10
Q

Name 2 water-soluble hormones

A

adrenaline
growth hormone

groups: catecholamines and peptides are water soluble

dissolve in plasma and freely “swim” to target tissue

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11
Q

Name 2 protein-bound hormone types

A

thyroid hormones, steroids

need to be protein-boudn to be transported to target tissues –> once at target tissues need to dissociate from the protein to become active and move into tissue

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12
Q

What are 4 ways of metabolic clearance of plasma hormones?

A
  • hepatic excretion into bile
  • renal clearance
  • metabolism by tissues
  • binding with tissues
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13
Q

How are steroid hormones mainly cleared?

A

conjugated into the bile by the liver

liver failure –> excessive plasma steroid hormone levels

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14
Q

How are catecholamines and peptide hormones cleared?

A

degraded by tissue enzymes and then excreted by liver and kidneys

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15
Q

Where are receptors located for:
* catecholamines and peptides, proteins
* steroid hormones
* thyroid hormones

A

catecholamines/peptides - cell membrane
steroid hormones - cytoplasm
thyroid hormones - nucleus

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16
Q

What enzyme catalyzes the formation of cAMP

A

adenylyl cyclase

17
Q

Explain the function of calmodulin in smooth muscle cells

A

receptor for Ca (similar to troponin C in skeletal and cardiac muscles) –> when calcium binds –> calmodulin will activate myosin light chain kinase –> activtes muscle contraction

18
Q

Explain the steps by which aldosterone promotes Na reabsorption

A
  • moves into the renal tubular cells
  • binds to cytoplasmic receptor (mineralocorticoid receptor)
  • indcues production of surface proteins that promote sodium reabsorption
19
Q

what are different words for the adenohypophysis and the neurohypophysis

A

anterior pituitary gland
posterior pituitary gland

20
Q

What part of the pituitary gland are TSH, ACTH, and GH secreted and released from?

A

anterior pituitary gland

21
Q

What part of the pituitary gland is ADH released from?

A

posterior pituitary gland

22
Q

Explain how the signals from the hypothalamus differ to the anterior versus posterior pituitary

A

hypothalamus sends signals to the anterior pituitary gland via hormones (GnRH, TRH, CRH, etc.) that move via the hypothalamic-pituitary capillary network (hypothalamic-hypophysal portal vessels) to stimulate production of hormones in the anterior pituitary

hypothalamus and posterior pituitary are connected as long cells originating in the hypothalamus and their axons reaching down and forming the posterior pituitary

23
Q

What are the 4 main effects of growth hormone

A
  • tissue growth
  • protein synthesis
  • fat mobilization
  • decreased rate of glucose utilization
24
Q

What proteins does GH utilize to mediate some of its effects?

A

insulin-like growth factors

25
Q

What are the 2 triggers for ADH release and where are these triggers sensed?

A

increased osmolality –> hypothalamus, osmoreceptors

decreased effective circulatory volume –> stretch receptors in the atria, baroreceptors in the carotid, aortic, and pulmonary regions

26
Q

Explain how ADH increases water absorption

A

ADH binds to membrane receptors (V2 receptor) –> triggers activation of adenylyl cyclase –> more cAMP in the tubular cytoplasm –> phosphorylation of vescicles which then insert themselves into the cell membrane –> aquaporin-2