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psl201: physiology > 4 week 22 > Flashcards

4 week 22 Flashcards

1
Q

what is energy metabolism? what are the 2 metabolic pathways?

A
  • energy metabolism = the way our bodies store and utilize energy
  • anabolic pathway: synthesis of larger biomolecules from smaller ones
  • catabolic Pathway: breakdown of large biomolecules into smaller ones
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2
Q

name the form stored + storage site + % of energy stored for…

a) carbs
b) proteins
c) fats

A

a) form stored = glycogen, site = liver + skeletal muscle, % = 1
b) form stored = proteins, site = skeletal muscle, % = 22
c) form stored = triglycerides, site = adipose tissue, % = 77

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3
Q

diff bw absorptive vs postabsorptive states?

A
  • absorptive: input > output. after a meal, anabolic pathways, nutrients in bloodstream, glucose = fuel.
  • postabsorptive: input < output. bw meals. catabolic pathways, maintain glucose / fat breakdown.
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4
Q

describe carb metabolism in the absorptive vs postabsorptive states

A
  • absorptive: glycogenesis (synthesis of glycogen from glucose) + excess glucose converted to triglycerides.
  • postabsorptive: glycogenolysis (breakdown of glycogen to glucose) + gluconeogenesis (glucose synthesized from non-carb sources).
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5
Q

describe glucose uptake, utilization, and storage (5)

A
  1. uptake (via transporters)
  2. oxidized to co2, h2o…
  3. metabolized to ATP
  4. glycoegenesis
  5. glycogenolysis
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6
Q

describe protein metabolism in the absorptive vs postabsorptive states

A
  • absorptive: protein synthesis from amino acids (used for gluconeogenesis) + conversion of excess amino acids to triglycerides.
  • postabsorptive: breakdown of proteins to amino acids + careful not to catabolize proteins at expense of cellular functioning.
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7
Q

describe protein uptake, utilization, and storage (4)

A
  1. uptake (by cells)
  2. protein synthesis
  3. catabolized to energy (ammonia)
  4. breakdown (into amino acids)
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8
Q

describe fat metabolism in the absorptive vs postabsorptive states

A
  • absorptive: lipogenesis (synthesis of triglyceride from fatty acids, final common pathway for all nutrients).
  • postabsorptive: lipolysis (breakdown of triglycerides to fatty acids and glycerol) + gluconeogenesis (glycerol from lipolysis can be converted to glucose) + glucose sparing (cells will use fatty acids for energy and spare glucose for the CNS).
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9
Q

describe fat uptake, utilization, and storage (6)

A
  1. breakdown of triglycerides into monoglyceride and fatty acids by lipoprotein lipase enzyme
  2. uptake
  3. oxidized to co2, h2o…
  4. combined fatty acids + glycerol form new triglycerides in adipose tissue
  5. breakdown (lipolysis)
  6. catabolized for energy
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10
Q

how does the pancreas regulate metabolism?

A
  • alpha cells secrete glucagon
  • beta cells secrete insulin
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11
Q

how does insulin promote absorptive processes?

A
  • most tissues: glucose + amino acid uptake, protein synthesis
  • adipose tissue: fatty acid synthesis
  • liver and muscle: glycogen synthesis
  • liver: fatty acid synthesis
  • GH release
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12
Q

which transporters does insulin-mediated glucose uptake depend on? why?

A
  • GLUT4
  • insulin stimulates translocation of GLUT4 from intracellular sites to plasma membrane
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13
Q

what does glucagon do?

A
  • promotes energy mobilization (promotes glycogenolysis, gluconeogenesis, ketone synthesis, protein breakdown, lipolysis)
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14
Q

insulin ___ blood glucose, glucagon ___ blood glucose

A

insulin decreases, glucagon increases

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15
Q

what is type i vs type ii diabetes? cause and treatment?

A
  • type i: insulin secretion reduced or absent, treated by insulin injections or insulin pumps.
  • type ii: defect in insulin secretion and target cell responsiveness, treated by diet, exercise, oral medications (sometimes insulin injections).
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16
Q

which hormones does the thyroid gland produce? (3)

A
  • t3
  • t4
  • calcitonin
17
Q

which thyroid hormone is most abundant? which is most bioactive?

A
  • most abundant = t4
  • more bioactive = t3
18
Q

colloids are found in thyroid follicles. what do colloids contain? (3)

A
  1. thyroglobulin (a protein)
  2. enzymes
  3. iodide (must receive from iodine in diet, transported by follicular cells from blood)
19
Q

describe the 7 steps of the synthesis of thyroid hormones

A

1) thyroglobulin (TG) is converted to MIT and DIT
2/3) DIT and MIT form t3 and t4 and are stored
4) TSH binds to receptor and activates follicular cell proteins
5) uptake of iodinated TG into follicular cells
6) TG molecules fuse with lysosomes
7) t3 and t4 are released into the blood (hydrophobic, carried by proteins)

20
Q

actions of t3 and t4? (4)

A
  1. metabolism:
    - increases basal metabolic rate (BMR)
    - increases oxygen consumption, energy expenditure and heat generation
  2. cardiovascular:
    - maintains responses to sympathetic stimuli
    - increases the number of beta adrenergic receptors
  3. growth:
    - required for normal growth
    - stimulates growth hormone release and targeting to tissues
  4. nervous system:
    - required for normal brain function in adults
    - role in brain development
21
Q

how do thyroid hormones exert their wide-ranging effects?

A
  • bind to nuclear receptors in target cells
  • bind onto DNA at thyroid response elements (TRE)
  • alter gene transcription and protein synthesis
22
Q

causes of hyper vs hypothyroidism? treatments?

A
  • hyper: causes = tumours or thyroid-stimulating immunoglobins, treatments = removal of part of thyroid gland, t3/t4 synthesis blockers, t3/t4 conversion blockers
  • hypo: causes = lack of dietary iodine or under active thyroid gland, treatments = exogenous t4
23
Q

what does iodine deficiency lead to? (3)

A
  1. thyroid gland unable to produce t3 and t4
  2. lack of negative feedback leads to excess TSH secretion
  3. TSH stimulates growth of the thyroid gland, producing a goiter
24
Q

where are the adrenal glands located?

A

on top of kidneys

25
Q

which hormone does each zona of the adrenal gland release…

a) zona glomerulosa
b) zona fasciculata
c) zona reticularis
d) adrenal medulla

A

a) aldosterone
b) cortisol, androgens
c) cortisol, androgens
d) epinephrine

26
Q

what are adrenal hormones synthesized from? are the hydrophilic or hydrophobic?

A
  • cholesterol
  • hydrophobic (lipophilic, membrane soluble!)
27
Q

what does aldosterone do? (3) what is it stimulated by? (2)

A
  • opens existing channels, synthesizes new channels, synthesizes Na/K pumps (acts on principals cells)
  • hyperkalemia (low Na, high K), RAAS pathway (low BP)
28
Q

what is the RAAS pathway?

A
  • renin angiotensin aldosterone system
  • liver produces angiotensinogen which is cleaved by renin to get angiotensin I which is cleaved by ACE to get angiotensin II which is converted to aldosterone via adrenal cortex activation
29
Q

a) how do stress and your circadian rhythm lead to cortisol secretion?
b) what is cortisol stimulated by?
c) what does cortisol do and rest vs above rest vs as a drug?

A

a) stress + circadian rhythm stimulate hypothalamus to release corticotropin releasing hormone (CRH), which stimulates anterior pituitary to release adrenocorticotropic hormone (ACTH), which stimulates the adrenal cortex to release cortisol
b) noxious stimuli (eg surgery, burns, infection) also strenuous exercise, anxiety, temperature extremes
c) REST = maintain catabolic enzymes, ABOVE REST = enhance energy mobilization, AS DRUG = inhibits inflammation + allergic responses, suppresses immune system

30
Q

cushing’s syndrome vs addison’s disease?

A
  • cushing’s: excess cortisol secretion = hyperglycemia, hypertension, bone/muscle loss, face fat deposition
  • addison’s: low secretion of adrenal steroids (autoimmune destruction) = hypoglycemia, poor stress tolerance, Na/K loss leads to arrhythmias
31
Q

a) what is epinephrine/adrenaline derived from?
b) what is it stimulated by?
c) what are its effects?

A

a) tyrosine (hydrophilic)
b) fight or flight activation (sympa)
c) mediates stress responses, gluconeogenesis, all ForF responses

32
Q

how do epi-pens counteract the symptoms of anaphylactic shock? (3)

A
  1. promote bronchodilation
  2. promote vasoconstriction of intestines, skin, kidneys
  3. promote vasodilation of skeletal and cardiac muscles

psl201: physiology (21 decks)

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