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Biol 1412 > Topic 7 > Flashcards

Topic 7 Flashcards

1
Q

Endocrine system regulates 3 things..

A

growth, reproduction and metabolism

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2
Q

Endocrine glands and tissues secrete..

A

hormones which travel in blood to target cells (bind to receptors and change cell activity)

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3
Q

Receptor proteins found on either..

A
  • cell membrane

- intracellular

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4
Q

2 types of hormone types

A
  • water soluble

- lipid soluble

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5
Q

Water soluble hormones

A

peptides, proteins, catecholamines (1st messager)

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6
Q

Steps for a water soluble hormone

A
  1. hormone binds to cell membrane receptors (don’t enter cell for their actions)
  2. hormone receptor complex activates membrane proteins
  3. G proteins activates 2nd messenger systems
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7
Q

Example of cAMP as 2nd messenger

A
  • hormone binds to cell surface receptor and activate g proteins
  • g proteins activates adenylate cyclase (membrane protein)
  • adenylate cyclase converts ATP to cAMP (2nd messenger)
  • cAMP activates protein kinases
  • protein kinase acts on the proteins to alter their activity
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8
Q

Why use 2nd messenger systems

A
  • hormone can’t enter cell (water soluble)
  • rapid acting (enzymes already present- just activate)
  • 1 hormone molecule so many enzyme molecules activated so multiplies signal
  • limited, messenger broken down or removed
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9
Q

Lipid soluble hormones

A

steroids and thyroid hormones, trigger protein synthesis so takes time therefore slow but long lasting

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10
Q

Steps for actions of the lipid soluble hormones

A
  • enter target cell and bind to intracellular nuclear receptors in cytosol or nucleus
  • hormone receptor complex binds to a specific region on DNA (Activates genes) starts gene transcription. produces mRNA
  • mRNA attaches to ribosomes to produce proteins (translation)
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11
Q

Stimuli acting on an endocrine can be either ..

A
  • humoral stimulus
  • neural stimulus
  • hormonal stimulus
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12
Q

Humoral stimulus

A

stimulus = ions/nutrients (something other than hormones)

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13
Q

Ex of humoral stimulus

A

increase blood glucose (after eating carbs): pancreatic B cells detect glucose and release insulin which lowers blood glucose

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14
Q

Neural stimulus example

A

1 heart rate: resting heart rate (surprise) –> SNS preganglionic directly to nt = ACh –> adrenal medulla (epineph. +NE) –> increase heart rate and force of contraction

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15
Q

Hormonal stimulus example (-‘ve feedback)

A

metabolism: low metabolism –> hypothalamus (thyrotrophin releasing hormone) –> ant. pituitary (thyroid stimulating hormone)–> thyroid gland (thyroxine T4) –> T4 to T3 –> increase metabolism

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16
Q

Stress

A
  • any extreme external or internal stimulus
  • triggers a set of body changes called general adaption syndrome
  • all coordination directly or indirectly by the hypothalamus
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17
Q

Phase 1 of stress (Alarm Reaction)

A

(fight or flight). immediate =NS. CNS (sensory input- detect change) –> hypothalamus (RAS increase alertness) –> SNS –> organs or adrenal medulla –> epi and NE (prolongs response)

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18
Q

Effects of NS and hormones

A
  • increase blood glucose (energy). SNS inhibits insulin release. epi, NE trigger conversion of glycogen to glucose in the liver
  • increase HR, force of contraction
  • decrease blood flow to skin, abdominal viscera so more available to skel and cardiac muscle and brain
  • decrease digestion, urine production
19
Q

Phase 2 of stress: resistance reaction

A

long term (endocrine) permits recovery from tissue repair OR response to longer term stress. hypothalamic hormones initiate phase 2

20
Q

Growth hormone

A

stimulates growth

21
Q

Cortisol

A
  • release within 30 seconds of the stress but the response not for hours. steroid hormone, acts as nuclear receptors.
  • inhibits insulin release
22
Q

Release of hormones causes..

A
  • increase blood hormone
  • inhibition of immune system, bonds formation, formation of CT
  • release aldosterone and antidiuretic hormone
23
Q

increase blood glucose causes ..

A
  • liver stimulated to produce new glucose from lots and later from proteins.
  • little insulin so glucose not taken up well, special by skel. muscle and adipose tissue
  • glucose spared for use by NS
  • metabolism of non nervous tissue directed to fats for NRG
  • if stress continues, cortisol inhibits GH release and proteins are then used
  • overall increase blood FA and AA for energy
24
Q

Release of aldosterone and antidiuretic hormone reduces..

A

salt and water loss at kidney to maintain blood volume

25
Q

Long term effect of stress

A

decrease weight, increase bp, increase HR, immune suppression (cortisol) decrease bond density, increase risk of type 2 diabetes

26
Q

Phase 3: exhaustion

A

results from depletion of body resources, loss of K+, damage to organs

27
Q

Functions of testosterone

A
  • development of organs of male reprod. tract of +2 sex characteristics
  • stimulate bone growth at epiphyseal place (convert E to stop growth = closure of plate)
  • promotes protein anabolism
  • directly stimulates spermatogenesis
28
Q

FSH

A

stimulates -1 to become 2 follicle, inhibited when increase progesterone (P) (so FSH increase when P decrease)

29
Q

LH

A
  • stimulates estrogen production from theca and granolas cells of follicle
  • surge in LH therefor ovulation and formation of corpus luteum from remnants of follicle
  • in follicular phase: E from 2 follicle rises for a few days then stimulus LH release then stimulus follicle to increase E secretion (+ve feedback) leads to LH surge
  • luteal phase - P inhibits LH release
30
Q

Estrogen

A

required for ovulation, development of 2 sex characteristics, stimulates growth, endometrium, increase bone growth, closure of epiphyses

31
Q

Progesterone

A

from corpus lute, prepares uterus for pregnancy

32
Q

Day 1-14 of ovarian cycle

A

Ovary: Follicular (preovulatory) phase
Early on: P low ∴ LH, FSH secreted - some 10 follicles → 20 follicles due to FSH
- follicles secrete E ∴ blood E rises
Later on: one (usually) 20 follicle becomes vesicular follicle

33
Q

Day 1-14 of uterine cycle

A

Uterus:
i) Menstrual phase (days 1-5):
- stratum functionalis shed (outer layer of endometrium) + denuded areas bleed
∴ menstrual flow = blood, cells, secretions ii) Proliferative phase (days 6-14):
- E → repair + proliferation of stratum functionalis (due to mitosis in stratum basalis)

34
Q

Day 14 of ovarian and uterine cycle

A

ovulation due to LH surge
LH triggers:
a) completion of meiosis I → 20 oocyte
b) rupture of vesicular follicle with release of 20 oocyte

35
Q

Days 15-28 ovarian cycle

A

Ovary: Luteal phase

- high P from corpus luteum inhibits GnRH (∴ LH + FSH) ∴ no follicles develop

36
Q

Days 15-28 uterine cycle

A

Uterus: Secretory phase

  • P from corpus luteum:
    i) prepares endometrium for implantation - becomes vascular, thick + stores glycogen
    ii) inhibits uterine contractions
37
Q

If fertilization occurs:

A

a) placenta secretes human chorionic gonadotropin (hCG)
- hCG maintains corpus luteum (similar structure to LH)
b) corpus luteum → P, E (for about 6 weeks, then placenta takes over (secretes P, E))
c) FSH, LH inhibited by high P (no new follicles develop)

38
Q

If NO fertilization occurs:

A

a) corpus luteum → corpus albicans (no hCG, low LH)
b) ∴ P, E ⇓ ∴
i) no longer inhibit LH, FSH → LH, FSH ↑
ii) no longer maintain endometrium –> menstruation

39
Q

3 types of contraceptives

A
  • oral
  • implants
  • morning after pill
40
Q

Oral contraceptives

A

high E + P → inhibit GnRH secretion ∴ low FSH, LH (mimics luteal phase) - no follicle maturation, no ovulation

41
Q

Implants

A

e.g: progestin- similar mechanism to oral

42
Q

Morning after pill

A
  • high E and progestin or progestin only (= Plan B)

- prevents implantation, ovulation or fertilization

43
Q

Placenta

A
  • formed from chorion (fetus) and endometrium (maternal)

- blood vessels of mother and fetus close proximity (no blood mixing)

44
Q

Placenta functions to..

A

1) exchange site:
- gases, nutrients/wastes, hormones, antibodies (passive immunity) - drugs e.g. alcohol, morphine, nicotine
- viruses - measles, polio
2) secretes hormones:
a) E + P
b) hCG
- maintains corpus luteum for ∼ 6 weeks post-fertilization - detected by pregnancy tests
- stim. testosterone secretion by fetal testes

Biol 1412 (15 decks)

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