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TV2001 > Endocrine Physiology - Part 1 > Flashcards

Endocrine Physiology - Part 1 Flashcards

1
Q

What are the two major control systems for body functions? What do they control?

A
  • nervous system = rapid, precise responses

- endocrine system = slow and sustained functions, even at low concentrations

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2
Q

What are endocrine glands?

A
  • ductless glands

- secrete chemical messengers (hormones) into the blood to communicate with target cells throughout the body

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3
Q

What are some characteristics of hormones?

A
  • made in glands/cells
  • transported by blood
  • bind with target tissue receptors
  • activates physiological response
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4
Q

How do hormones travel?

A

in blood, either dissolved in plasma or protein bound

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5
Q

What is a tropic hormone?

A

regulates hormone secretion by another endocrine cell

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6
Q

What happens at the target site when a hormone reaches it?

A
  • action of hormone is amplified at target cell
  • binds with receptors
  • rapidly degraded by target cells or removed from the blood by kidneys or liver and excreted
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7
Q

What are the three classifications of hormones?

A
  1. Peptide and protein hormones
  2. Steroid hormones
  3. Amine hormones
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8
Q

What are the characteristics of Peptide and Protein hormones?

A
  • most are this type
  • hydrophilic
  • stored in secretory granules
  • have receptors on the surface of cell
  • cause their effect most often by formation of second messengers inside the target cell (cAMP - most common)
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9
Q

What are the characteristics of Steroid hormones?

A
  • primarily produced by adrenal cortex and the gonads/ placenta
  • made from cholesterol
  • not stored in the cell
  • travel in bound form with proteins (99% bound, 1% free)
  • receptors inside the target cell
  • causes activation of specific genes
  • can be given orally and absorbed by GIT
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10
Q

What are the characteristics of Amine hormones?

A
  • derived from AA tyrosine
  • two types: Thyroid hormones and Catecholamines
  • stored until secreted
  • Catecholamines have cell membrane receptors and 50% travel in bound form in blood
  • Thyroid hormones behave more like steroid hormones with intracellular receptors that activate genes
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11
Q

Describe the secretion rate of hormones

A
  • not secreted at a constant rate
  • rate varies depending on control
  • most are secreted in short bursts with little or no release in between.
  • may maniifest diurnal circadian rhythm or 24hr cyclical variation, influenced by factors such as sleep, light,etc.
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12
Q

What is a negative feedback loop?

A

a reaction that causes a decrease in a function

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13
Q

What is a prominent feature of hormonal control systems and why is it important?

A
  • negative feedback loops

- allows continuous changes and adjustments to be made to maintain an optimal concentration of a hormone.

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14
Q

What is an example of a positive feedback loop in hormone regulation?

A

surge in luteinising hormone (LH) that occurs as a result of the stimulatory effect of oestrogen before ovulation in humans

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15
Q

What are three characteristics of hormones?

A
  1. permissiveness: action of one hormone caused by another
  2. Synergism: action of one hormone complements another
  3. Competition: structurally similar substances compete for receptors (agonists vs. antagonists)
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16
Q

What do endocrine disorders commonly result from?

A
  • hypo-secretion
  • hyper-secretion
  • abnormally low target cell responsiveness to the hormone (receptor defect, intracellular cell signalling pathway defect)
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17
Q

What are the major endocrine glands in/ around the brain?

A
  • pineal gland
  • hypothalamus
  • pituitary gland
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18
Q

What are the major endocrine glands in the throat region?

A
  • thyroid and parathyroid glands
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19
Q

What are the major endocrine glands in the abdomen

A
  • Adrenal gland and kidney

- Pancreas

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20
Q

Where is the hypothalamus located?

A

below the thalamus

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21
Q

What is the function of the hypothalamus?

A
  • processes sensory info from internal and external environment and mediates responses via ANS and endocrine system
  • secretes hormones from the pituitary gland that majorly effect the secretion of other hormones
22
Q

What are the three lobes of the pituitary gland?

A
  • posterior lobe (Neurohypophysis, pars-nervosa)
  • anterior lobe (Adenophysis, pars-distalis)
  • intermediate lobe (pars-intermedia)
23
Q

How are the pituitary gland and the hypothalamus connected?

A

by a stalk called the hypophysial stalk

24
Q

How is the posterior lobe of the pituitary gland connected to the hypothalamus?

A

via a neural link through the hypohysial stalk

25
Q

How are the anterior and intermediate lobes of the pituitary connected to the hypothalamus?

A

via a vascular like through the hypophysial stalk. This is called the hypothalamo-hypophysial portal system

26
Q

how is the posterior pituitary controlled with neurons?

A

hypothalmic neurons secrete hormones which are stored in and released from the posterior lobe

27
Q

What hormones are released from the posterior pituitary?

A
  • ADH/ vasopressin

- Oxytocin

28
Q

What 7 hormones are released from the anterior pituitary?

A
  1. Thyrotroponin-releasing H (TRH)
  2. Corticotroponin-releasing H (CRH)
  3. Gonadotroponin-releasing H (GnRH)
  4. GHRH
  5. GHIH or somatostatin
  6. Dopamine
  7. evidence of GnIH in most vertebrates
29
Q

What stimulates the release of ADH/ vasopressin?

A
  • increase in plasma osolarity

- reduction in extracellular fluid volume

30
Q

What is the target of ADH/ vasopressin? What is its effect on these targets?

A
  • Renal tubules (increases water reabsorption)

- blood vessels (vasoconstrictive effect if released in large amount)

31
Q

What disorder is caused by excessive secretion of ADH?

A

syndrome of inappropriate ADH secretion (SIADH)

32
Q

What disorder is caused by insufficient secretion of ADH?

A

diabetes insipidus

33
Q

What are some causes of diabetes insipidus?

A

(iodiopathic or congenital or head trauma or neoplasia)

  • Pituitary gland does not secrete enough ADH (central diabetes insipidus)
  • ADH is secreted but kidneys do no respond (nephrogenic diabetes insipidus)
34
Q

How is diabetes insipidus characterised?

A

polyuria, polydipsia, nocturia and incontinence

35
Q

What stimulates the release of oxytocin?

A
  • cervical and uterine stretch

- suckling

36
Q

What is the target of oxytocin?

A

uterus and lactation tissue

37
Q

What is the effect of oxytocin on target tissue?

A
  • contraction of smooth muscle in uterus during parturition
  • triggers the ‘let down’ reflex (milk ejection)
  • influences social bonding (hormone of love)
38
Q

What is the prominent cell in the intermediate lobe of the pituitary gland?

A

Melanotrophs

39
Q

What hormone is released by the intermediate lobe of the pituitary gland? What is its effect?

A

Melanocyte stimulating hormone (MSH). melanin pigment synthesis, controlling skin colour (camouflage in some species)

40
Q

What clinical relevance does the intermediate lobe of the pituitary gland have for older horses?

A

common site of hyperplasia and neoplasia in older horses

41
Q

How are anterior pituitary hormones regulated?

A

regulated by hypothalamic hormones and feedback from target hormones.

42
Q

What hormone regulates growth in vertebrates?

A

growth hormone.

43
Q

Where is Growth Hormone secreted from?

A

somatotrophs of anterior pituitary

44
Q

What does Growth Hormone do?

A
  • promotes protein deposition in tissue
  • enhances fat use for energy instead of carbs by cells and raises blood glucose levels
  • increases growth of skeletal frame until growth plate closes, increases thickness of bone
  • growth effects via production of somatomedins
45
Q

How is growth hormone regulated?

A

by hypothalamus and IGF - I

46
Q

What stimulates the release of Growth Hormone?

A

decreased glucose and free fatty acids

increased exercise, stress, etc.

47
Q

What is caused by too little growth hormone?

A

pituitary dwarfism

48
Q

what is caused by too much growth hormone?

A

acromegaly. pituitary tumours

49
Q

Where is the pineal gland in lower invertebrates?

A

close to the skin and doesnt need the eye to register day/ night cycles

50
Q

What is the function of the pineal gland in mammals?

A
  • translator of photoperiods

- produces melatonin in response to darkness

51
Q

What is the function of melatonin?

A
  • allows seasonally reproductive animals to perceive day length changes
  • induces sleep in diurnal animals and promotes activity in nocturnal animals
  • plays a major role in sexual development, hibernation, metabolism and seasonal breeding.
  • can be used to increase production in domestic animals by manipulating light

TV2001 (21 decks)

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