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Physiology I > Endocrinology S1 > Flashcards

Endocrinology S1 Flashcards

1
Q

Homeostasis

A

A dynamic steady state of maintaining a constant internal environment despite changing conditions

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2
Q

Negative feedback

A

Initial stimulus occurs and initiates a response that decreases the stimulus. Stabilizing effect

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3
Q

Positive feedback

A

Stimulus starts a response that further stimulates it. Must be turned off by an outside factor and is reinforcing.

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4
Q

Gap junctions

A

Local communication. Holes connecting neighbouring cells for free-passage of small ions and molecules

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5
Q

Contact-dependent control

A

Membrane proteins binding to membrane proteins of another cell. Local communication

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6
Q

Autocrine control

A

Molecules move through interstitial fluid to communicate with cells a short distance away. Local communication

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7
Q

Long-distance communication

A

Occurs in the endocrine system or nervous system (neurohormones)

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8
Q

Simple reflexes

A

Reflexes mediated by either the nervous system or endocrine system

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9
Q

Complex reflexes

A

Reflexes mediated by both system and go through several integrating system

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10
Q

Differences between neural and endocrine reflexes

A

Have different specificity, nature of the signal, speed, duration of action, coding for stimulus intensity

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11
Q

Exocrine glands

A

Secrete chemicals into an external environment

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12
Q

Endocrine glands

A

Secrete chemicals directly into the bloodstream

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13
Q

Primary endocrine organs

A

Main function is releasing hormones

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14
Q

Secondary endocrine organs

A

Have a primary function and release hormones in addition to the primary function

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15
Q

Hydrophilic hormone characteristics

A

Water-soluble, dissolve in blood, can’t cross the plasma membrane, not lipid-soluble

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16
Q

Hydrophobic hormone characteristics

A

Not water-soluble, can’t dissolve in plasma (have carrier-protein), lipid-soluble, cross plasma membrane by diffusion

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17
Q

Hydrophilic hormone examples

A

Peptide hormones, protein hormones, catecholamines

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18
Q

Hydrophobic hormone examples

A

Steroids and thyroid hormones

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19
Q

Protein/peptide hormones

A

3+ hydrophilic AAs made in advance and stores in vesicles before release to bind to membrane receptors. Short half-life

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20
Q

Preprohormones

A

Can contain many copies of the same hormone or more than one type. Cleaving separates them

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21
Q

Steroid hormones

A

Made from cholesterol and made on demand. Long half life

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22
Q

Amine hormones

A

Made from tryptophan or tyrosine and behave based on synthesis

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23
Q

Tryptophan derivatives

A

Behave like peptides or steroids. Ex, melatonin

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24
Q

Tyrsosine derivatives

A

Catecholamines behave like peptides and thyroid hormones behave like steroids

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25
Q

Hypothalamus function

A

Sends hormones to the anterior pituitary to secrete its own hormone

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26
Q

Anterior pituitary vs posterior pituitary

A

Only the anterior pituitary can synthesize and release its own hormones

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27
Q

Synergistic effects

A

Caused by multiple hormones that act together for greater effect

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28
Q

Permissive effects

A

One hormone enhances the target organ’s response to a second hormone (both are required)

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29
Q

Agtagonisitic effect

A

One hormone opposes actions of another

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30
Q

How is hormone secretion regulated?

A

Endocrine cells send signals to hypothalamus and anterior pituitary which also sends signals to hypothalamus to stop secretion. Negative feedback

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31
Q

Properties of receptors

A

High affinity, saturable, specific, reversible

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32
Q

Intracellular receptors

A

Bind lipid soluble hormones and can be in the cytosol or nucleus to alter gene transcription

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33
Q

Hormone response element

A

Hormone receptor complex binds to response element DNA sequence to elicit response

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34
Q

G Protein-coupled receptors

A

Large multisubunit-protein membrane-spanning proteins. Use lipids as second messengers to open ion channels and alter enzyme activity in the cytoplasm

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35
Q

Gs mechanism

A

1) signal molecule binds GPCR to activate Gs
2) G protein activates adenylyl cyclase to convert ATP > cAMP
3) cAMP activates protein kinase A
4) PKA phosphorylates proteins, leading to a cellular response

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36
Q

Gq mechanism

A

Activates phospholipase C to convert membrane phospholipids into diglyercol so IP3 can diffuse into the cytoplasm and release Ca++

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37
Q

Gi mechanism

A

Targets adenylyl cyclase and inactivates it

38
Q

Off switch membrane receptors

A

Receptors can be endocytosed by a clatherin-coated pit, trapping receptors. Triggered by a ligand

39
Q

How is Ca+ stored in bone?

A

In crystals called hydroxyapatite (have calcium and phosphate)

40
Q

Osteoblasts

A

Bone forming cells

41
Q

Osteoclasts

A

Break down bone, multi-nucleated by fusion of multiple cells

42
Q

Osteocytes

A

Previously osteoblasts that are surrounded by bone matrix and maintain bone nearby

43
Q

Osteoclast mechanism

A

Secrete HCl and proteases to break down bone and release Ca++ into the blood

44
Q

How do osteoblasts and osteoclasts interact?

A

Osteoclast precursors communicate with osteoblasts through RANK receptor on the precursor and RANKL on the osteoblasts. Both coming together creates mature osteoclast

45
Q

Osteoprotegerin

A

Osteoblasts secrete OPG to block RANKL/RANK interaction by binding to RANKL which reduces osteoclast activity

46
Q

Parathyroid hormone

A

Released by cells on the back of the thyroid gland to increase plasma Ca++ when low

47
Q

Parathyroid sensing

A

Have a Gq coupled receptor that inhibits PTH synthesis when calcium is bound

48
Q

PTH mechanism

A

1) On bone, it increases cAMP > increases RANKL and decrease OPG > stimulates osteoclast activation
2) In kidneys, PTH increases Ca++ reabsorption at distal tubule, increases calcitriol

49
Q

Calcitriol (vitamin D3)

A

Targets intestine, bone, and kidney to increase plasma calcium through reabsorption and mobilization from bone

50
Q

Calcitriol formation

A

Skin has precursors that become inactive vitamin D3 when hit by UV > become another precursor in liver > PTH creates active form in kidneys

51
Q

Calcitriol signalling

A

Lipophilic hormone that binds vitamin D to form a heterodimer to enter the nucleus and bind vitamin D response element that eventually creates calcium channels

52
Q

Blood phosphate regulation

A

1) PTH increases phosphate release from bone and decreases reabsorption in kidney
2) Calcitriol increases phosphate absorption and reabsorptiomn

53
Q

Calcitriol vs PTH

A

Calcitriol wants to make bone, PTH wants to increase blood Ca++

54
Q

Calcitonin

A

Peptide hormone secreted from C cells of thyroid to reduce osteoclast activity

55
Q

Nephrons

A

Excretes waste, regulates blood volume, controls electrolytes, blood pH and vitamin D (via PTH)

56
Q

Nephron function at sections

A

Water is reabsorbed in loop of Henle > ions reabsorbed before distal tubule > variable water/solute reabsorption in cortex medulla

57
Q

Vasopressin

A

Synthesized in hypothalamus, secreted from posterior pituitary to increase water reabsorption in the kidneys by regulating permeability (increases it)

58
Q

Vasopressin regulation

A

If there is high plasma osmolarity, vasopressin (ADH) is released by osmoreceptors. Low blood pressure detected in the heart also stimulates the release

59
Q

Vasopressin mechanism

A

Inserts water pores into the distal convoluted tubule and collecting duct of cell membranes in nephrons. Aquaporin water pores inserted into the apical membrane

60
Q

Aldosterone

A

Steroid synthesized in the adrenal cortex to regulate sodium through Na+ reabsorption and K+ secretion

61
Q

Aldosterone regulation

A

Stimulated by high K+ concentration in plasma and angiotension II via blood pressure. Inhibited by high Na+ in ECF

62
Q

Aldosteron mechanism

A

Acts in the distal tubule and collecting duct to initiate the synthesis of protein channels and pumps for increase Na+ reabsorption and K+ secretion

63
Q

Renal Juxtaglomerular Cells

A

Secrete renin to go into the liver to cleave angiotensinogen to create angiotension

64
Q

Angiotension II

A

Created from cleavage of angiotension I in the lungs and acts on hypothalamus to stimulate aldosterone secretion

65
Q

Natriuertic peptids

A

Peptides that act as hormones to stimulate water to be released from the body

66
Q

ANP

A

Secreted by atria and neurons to decrease Na+ and water reabsoption and increases K_+reabsorption

67
Q

BNP

A

Secreted by ventricles and neurons

68
Q

CNP

A

Secreted by brain, pituitary, vessels and kidneys

69
Q

Adrenal Medulla

A

Neuroendocrine tissue that produces and secretes catecholamine and is stimulated by the SNS (short-term stress)

70
Q

Adrenal cortex structure

A

Surrounds adrenal medulla and is surrounded by a capsule

1) zona glomerulosa secretes aldosterone
2) zona fasciculata secretes glucocorticoids
3) zona reticularis secretes sex hormones

71
Q

Zona ___ hormone formation

A

All are synthesized by cholesterol

72
Q

Androgens (sex hormones) formation

A

DHEA > androstenedione > testosterone > DHT OR from androstenedione > estrone w/ aromatase enzyme > estradiol OR testosterone > estradiol w/ aromatase

73
Q

Cortisol

A

Main gluccorticoid and is secreted following a diurnal rhythm to mediate long-term stress

74
Q

Cortisol release

A

CRH released by hypothalamus > corticotropic cells stimulate anterior pituitary > ACTH send to adrenal cortex > cortisol secreted

75
Q

Cortisol regulation

A

Excess cortisol sent to hypothalamus and anterior pituitary through negative feedback to turn off ACTH and CRH

76
Q

Addison’s disease

A

Excess secretion of adrenal steroids which causes hypotension and hypoglycemia

77
Q

Cushing’s syndrome

A

Cortisol excess causing hyperglycemia, muscle protein breakdown, lipolysis, etc

78
Q

Cortisol roles

A

1) promotes gluconeogensis
2) breakdown of skeletal muscle protein for AA
3) enhances lipolysis
4) suppresses immune system

79
Q

Anabolic processes

A

Occurs in a fed state and promotes glycogenesis, lipogenesis

80
Q

Catabolic processes

A

Occurs in a fasted state and promotes glycogenolysis, lipolysis

81
Q

Gluconeogensis

A

Creates of glucose from non-carbohydrate substrates. Occurs in a fasted state but is anabolic

82
Q

Insulin

A

Anabolic peptide that binds to tyrosine kinase receptor to reduce blood glucose by promoting formation of glycogen, fat and protein

83
Q

Insulin mechanism

A

Triggers GLUT4 receptors in the liver to increase glucose in the cell and out of the blood stream

84
Q

Hexokinase

A

Activated by insulin to phosphorylate free glucose into glucose 6-phosphate to keep intracellular glucose low

85
Q

Insulin release

A

Beta-cells in the pancreas detect glucose in the blood and increase ATP to block K+ channels, preventing K+ from leaving the cell > causing a depolarization > releasing Ca++ to trigger insulin release

86
Q

Incretin effect

A

Gastrointestinal hormones cause an increase in insulin when glucose is in the small intestine

87
Q

Gluagon-like peptide 1

A

Stimulated by nutrients and parasympathetic activity to increase insulin and decrease glucagon

88
Q

Gastric inhibitory peptide

A

Stimulated by glucose and fatty acids to increase insulin

89
Q

Glucagon

A

Increases glycogenolysis, gluconeogensis and ketogensis to prevent hypoglycemia by causes GLUT2 to transport glucose into blood

90
Q

Cortisol and glucagon

A

Cortisol is catabolic and helps glucagon build up glucose by glycogenolysis

91
Q

Glucagon mechanism

A

Alpha cells secrete glucagon in response to low glucose, SNS, amino acids to increase blood glucose

92
Q

Sulfonylureas

A

Close K+ channels to treat type 2 diabetes, allowing Ca++ to enter cell, releasing insulin

Physiology I (6 decks)

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