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Neural Biology 1 > endocrinology > Flashcards

endocrinology Flashcards

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1
Q

what does the endocrine system control ?

A

. it’s one of the bodies two main control systems
it control
1. reproduction
2. growth and development
3. maintenance of electrolyte, water and nutrient balance of the blood
4. regulation of cellular metabolism and energy balance
5. mobilisation of body defenses

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2
Q

what do endocrine glands secrete ?

A

. they secrete hormones into the systemic circulation

. hormones are transported in blood to a tissue where they have a specific function

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3
Q

what is the difference between exocrine and endocrine glands ?

A

endocrine glands secrete internally
exocrine glands secrete outside the body
e.g. lacrimal , sweat

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4
Q

what is a hormone ?

A

. a chemical substance which is secreted by a specialised endocrine cells directly into the blood to exert an effect on distant target cells
. only cells that.have right receptor in their plasma membrane will respond to hormone

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5
Q

what are local target cells referred to ?

A

they are referred to as paracrines or autocrines

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6
Q

what are hormones made of ?

A

. amino acid based
1. polypeptides- cannot pass through plasma membrane by diffusion
. water soluble
. e.g. TRH , TSH , GnRH , FSH , LH , insulin , glucagon
2. modified amino acids
. small , cannot pass through plasma membrane by diffusion
. water soluble
. e.g. thyroxine

steroids
. synthesised form of cholesterol
. small , fat soluble , can pass through plasma membrane
e.g. cortisol , oestrogen , testosterone

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7
Q

what are the 3 types of stimuli that stimulate hormone release ?

A
  1. humoral stimulus
  2. neural stimulus
  3. hormonal stimulus
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8
Q

what is humoral stimulus?

A

. hormone release caused by altered levels of certain critical ions or nutrients

stimulus - low concentration of Ca
response - parathyroid gland secretes PTH which increases Ca

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9
Q

what is neural stimulus?

A

. hormone release caused by neural input

  • Stimulus: action potential in preganaglionic sympathetic fibres to adrenal medulla
  • response- regulate secretion of adrenaline by adrenal medulla cells
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10
Q

what is hormonal stimulus?

A

. hormone release caused by another hormone

stimulus - hormone from hypothalamus
response - anterior pituitary gland secrets hormones that stimulate other endocrine glands to secrete hormones

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11
Q

explain negative feedback ?

A
  1. Gland A secretes hormone A in the blood stream
  2. hormone A stimulates secretion of gland B
  3. gland B secretes hormone B
  4. hormone B has action on target organ
  5. at certain periods levels of hormone B increase in the blood stream
  6. hormone B inhibits secretion of gland A
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12
Q

what are the main endocrine glands in the body ?

A 
Pineal - sleep wake cycle
Pituitary-Growth/lactation/thyroid
Thyroid- Metabolism
Thymus- T-cell maturation
Adrenal-stress response
Pancreas-glucose metabolism
Ovaries-ovulation
Testis-spermatogenesis
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13
Q

what is the pineal gland ?

A

. sits right in the middle of the brain
. secretes melatonin which peaks at night
. cause :
drowsiness and low body temperature

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14
Q

how does pineal gland regulate wake sleep cycle ?

A

. in the retina we have photoreceptor cells , this sends nervous innervation to pineal glands which secretes melatonin
. the neural stimulus goes through suprachiasmatic nucleus in hypothalamus

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15
Q

what is the function of the hypothalamus ?

A

. receives input from higher brain centres- limbic system= detect emotional changes
. receive input from visceral and somatic sense via brain stem
. the release of hormones from the pituitary is regulated by different stimuli acting on the hypothalamus initially

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16
Q

What is optic chiasm?

A
  • Bundles of nerves coming from back of eye ( optic nerve)
  • cross middle line of brain
  • sits directly above the pituitary gland
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17
Q

what is the hypothalamus a part of ?

A

. hypothalamus is part of CNS
. hypothalamus regulates pituitary gland and pineal gland through suprachiasmatic nucleus thus using neuroendocrine system
. hypothalamus links the CNS to the endocrine system

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18
Q

What is the pitutiary gland?

A

-lies close to optic nerves
-has a bony cup and grows upwards
-have 2 regions:
-anterior lobe- larger
-posterior lobe
the two regions secrete different hormones and innervated differently by the hypothalamus

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19
Q

what is the function of the anterior lobe ?

A

. secretes hormones

. contains multiple cell types , each cell type secretes a different hormone

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20
Q

What are the anterior pituitary cells?

A
  • Somatotrophs- growth hormone
  • Lactrotophs- prolactin
  • Corticotrophs- ACTH
  • Thyrotrophs- TSH
  • Gonadotrophs- FSH and LH
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21
Q

what does the posterior lobe secrete ?

A

secrets oxytocin and vasopressin

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22
Q

What is the relationship between neuroendocrine hormones from hypothalamus and the hormones that are
released from the anterior pituitary?

A 
neuroendocrine hormones in the blood and detected by anterior pituitary
. TRH stimulates TSH
. PIF inhibits  PRL
. CRH stimulates ACTH 
. GHRH  stimulates GH
. GIH inhibits GH 
GnRH stimulates FSH AND LH
RH = release
F = inhibits
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23
Q

How is the neuroendocrine gland signal getting to those cells in anterior pituitary lobe?

A

NB. secretion of hormones from cells on anterior lobe of pituitary gland is regulated by signals that the anterior lobe is receiving from hypothalamus

  1. Neuroendocrine signals/hormones such as TRH, Gn RH, PIF are released from neurons in the hypothalamus nuclei
  2. travel down portal vein
  3. act on specific cells in anterior pituitary to release hormones
    e. g. FSH , LH
  4. hormone secretion into hypophyseal vein
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24
Q

what is GnRH in females ?

A

. In females GnRH is secreted from the hypothalamus in a cyclical way leading to a cyclical secretion of LH and FSH from the pituitary which maintains the menstrual cycle

. LH acts on the ovarian follicle and it induces ovulation
.FSH causes development of the ovarian follicle and stimulates secretion of oestradiol and progesterone

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25
Q

what is GnRH in males ?

A

. GnRH causes the release of LH and FSH from the anterior pituitary
. LH acts on the testes to produce testosterone
. FSH acts on the testes to maintain spermatogenesis

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26
Q

what is the function of growth hormone somatotrophin ?

A

. has a direct affect on organs around the body
. it increase IGF which stimulates growth in the liver
. it increases number of chondrocytes - increase axial length in bone
. regulates skeletal muscle growth and protein synthesis within them
. change rate of fat oxidation

27
Q

what happens if you have an excess secretion of growth hormone ?

A

gigantism - over elongation of muscles and bones -acromegaly- especially in hands and feet

28
Q

what is TSH ( thyroid stimulating hormone ) ?

A

. thyroid gland secretes thyroid hormone into the blood stream
. TSH stimulates thyroid gland to produce
. T4 which can be converted to T3 these stimulate metabolism of almost every tissue in the body
. secretion is stimulated by TSH secreted from the anterior pituitary

29
Q

explain Negative feedback- hormonal control for TSH?

A

.TSH secretion is regulated by the hypothalamus , hypothalamus secretes TRH , excess T4 and T3 in blood will inhibit secretion of TRH by the hypothalamus

  1. the production of of TSH is regulated by T3 and T4
  2. an excess of T3 or T4 stimulates the anterior lobe of the pituitary gland to reduce TSH secretion into the blood stream
  3. this reduces T4 and T3 production in thyroid gland
  4. reduction of T4 and T3 removes block on TSH
  5. cycle repeats
30
Q

what is the function of ACTH ?

A

. acts on the adrenal cortex of the adrenal gland
. results in the production of cortisol
. cortisol is high during the morning and helps with stress response , pressure and increase blood glucose levels

31
Q

what is prolactin ?

A

. production of milk and mammary growth during pregnancy

. inhibited by dopamine

32
Q

how are hormones secreted from the posterior pituitary ?

A

. hypothalamus to posterior pituitary via nervous innervation
. neurons come from upra optic and paraventricular nuclei in hypothalamus- innervate down in posterior lobe
. hormone stored in nuclei then secreted in blood stream via posterior pituitary into hypophyseal veins
. hormones secreted are oxytocin and vasopessin (ADH)

33
Q

what are the 2 hormone from the posterior pituitary ?

A

. oxytocin

. vasopressin ADH

34
Q

what is the function of oxytocin ?

A

happy hormone

  • orgasm
  • socialisation
  • giving birth- helps mother baby bonding
35
Q

what is the function of vasopressin ?

A

ADH

  • regulate water of blood
  • increase water retention by kidneys (antidiuretic)
  • Constricts arterial walls therefore increases BP
  • regulated by baroreceptors in atria
  • act through humoral stimulus- osmoreceptors also increase ADH release to reserve water
36
Q

where is the thyroid and parathyroid gland located ?

A

the neck

37
Q

what is the function of the thyroid and parathyroid gland?

A

important for calcium homeostasis
. regulate metabolism:
protein synthesis
lipid and carbohydrate metabolism

38
Q

how many parathyroid glands are there?

A

. 4 small parathyroid gland which release parathyroid hormone

39
Q

what are the two types of cells in the thyroid gland?

A

. thyroid follicular cells produce T3 and T4
. calcitonin cells
produce calcitonin which decreases calcium uptake

40
Q

what are the thyroid gland hormones ?

A 
. T4 - main hormone secreted by thyroid gland
. T4 is a precursor to T3 
T3 is more potent and affects 
. growth 
. metabolism increase 
. body temperature regulation
. mood

thyroid hormones require iodine

41
Q

what do parathyroid glands have ?

A

. contain cells that secrete PTH

. levels of PTH is regulated by free calcium in the blood stream

42
Q

what is the function of PTH ?

A

retains Ca

  1. increases renal tube absorption of calcium in the kidney - decrease loss of Ca in urine
  2. augments gastrointestinal absorption of Calcium
43
Q

what type of stimuli occurs in the parathyroid glands?

A

. humoral stimulus

this is because levels of PTH regulated by free calcium in the bloodstream

44
Q

where are adrenal glands located?

A

they sit on top of the kidney

45
Q

what are the three regions in the adrenal glands?

A 
. capsule - holds everything together
. medulla - in the centre , which are large blood vessel
respond to neural stimulus
. cortex - ACTH from pituitary acts here
respond to hormonal stimulus
46
Q

what hormones does cortex release in respond to ACTH ?

A

. corticosteroids
1. mineral corticosteroids
2. glucocorticoids
. androgens

47
Q

what is the function of mineral corticoids? ie. aldosterone

A

. retains water and maintains BP and blood volume , it does this by increasing Na+ retention by the kidney and water.- increases water and na absorption
. electrolyte balance and blood pressure

48
Q

what is the function of glucocorticoids? ie. cortisol

A

. increases metabolism of fats/glucose
. increases blood glucose levels through gluconeogensis
. suppresses immune system
. linked to stress

49
Q

what is the function of androgens?

A

. precursors to testosterone

. estrogen has effect maintaining male/female characteristics

50
Q

where are the hormones that the adrenal cortex derive from ?

A

. the adrenal cortex produces hormones derived from cholesterol as they are steroid based hormones

51
Q

what is the function of the medulla?

A

. secretes hormones that help cope with emotional or physical stress
. produces two hormones
1. adrenaline ( epinephrine )
2. noradrenaline ( norepinephrine )
medulla hormones are released by sympathetic innervation

52
Q

how is the endocrine system regulated by negative feedback?

A

. corticosteroids are regulated by ACTH from the anterior pituitary gland
. ACTH secretion is regulated by CRH secretion from the hypothalamus
. if levels of glucocorticoids increase it has a negative effect in pituitary gland and thus negative effect on hypothalamus

53
Q

what are the two glands that make up the pancreas ?

A

. exocrine gland - releases pancreatic enzymes into the duodenum to aid digestion
. endocrine gland - secretes insulin and glucagon to regulate blood glucose levels

54
Q

what are the endocrine cells that make up the pancreas?

A

the islet of langerhans

55
Q

what is the structure of islet of langerhans ?

A

. uniformly distributed along fenestrated capillaries with pores to allow easy transfer of hormones in/out the blood
. there is no specific cellular pattern or lamination
. the pancreas contains many islets which are linked by bridges/linkages of these cells

56
Q

what are the 5 cell types that make up the islet of langerhans?

A
  1. alpha cells 30-40%
  2. beta cells 50%
  3. delta cells 10-20%
  4. F cells
  5. epsilon cells
57
Q

what is the function of the function of the 5 types of cells that make up the islet of langerhans?

A

they secrete hormones
1. alpha cells - secrete glucagon - increase blood sugar level
2. beta cell - secrete insulin - decrease blood sugar level
3. delta cells - somatostatin and gastrin -
gastrin - regulates the exocrine function of pancreas
somatostatin- inhibits gastrin
4. F cells - pancreatic polypeptide - regulate digestive enzyme
5. Epsilon cells - ghrelin- controls hunger
tells you when to eat

58
Q

function of alpha cells in the pancreas ?

A

. secrete glucagon
. liver breaks down glycogen to glucose
. glucagon increase blood glucose levels

59
Q

what is the function of beta cells in the pancreas ?

A

. secrete insulin
. increase glucose uptake
. insulin decreases blood glucose levels

60
Q

what is the main metabolic effect of insulin ?

A

. facilitates uptake of glucose into muscle and adipocytes
. stimulate liver to store glucose as glycogen
. stimulates liver to convert excess glycogen to fatty acids

61
Q

what happens when insulin secretion goes wrong ?

A

type 1 diabetes

62
Q

what is type 1 diabetes ?

A

is an autoimmune disease that kills off the pancreatic beta cells

63
Q

what happens when you have type 1 diabetes ?

A

. less insulin production and secretion

. this leads to a loss of control of blood glucose levels - they increase

64
Q

what is the function of insulin ?

A

suppresses glucagon secretion.

when there is no insulin glucagon is secreted in excess which increases blood glucose further

Neural Biology 1 (58 decks)

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