Endrocrinology physiology Flashcards

1
Q

Pituitary gland position

A

Hanging off hypothalamus connected to the infundibulum

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2
Q

Nuclei found in the posterior pituitary gland

A

Supraoptic nucleus

Paraventricular nucleus

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3
Q

What does the supraoptic nucleus secrete?

A

ADH/ Vasopressin

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4
Q

What stimulates the supraoptic nucleus in the hypothalamus

A

low blood volume

low blood pressure

high plasma osmolality

pain

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5
Q

What effect does alcohol have on the supraoptic nucleus

A

Inhibitory

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6
Q

What does the paraventricular nucleus secrete in the posterior pituitary gland

A

Oxytocin

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7
Q

What stimulates the paraventricular nucleus in the posterior hypothalmus

A

Birthing process

Suckling

Ejaculation

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8
Q

What is the hypophyseal portal system

A

2 capillary beds (primary & secondary capillary plexuses)

Connected in series through an intermediate portal vein

this is the anterior pituitary connection

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9
Q

The paraventricular nucleus secretes what in the anterior compartment of the pituitary gland

A

CRH: Corticotropin-releasing hormone

TRH: Thyrotropin-releasing hormone

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10
Q

Action of CRH

A

Stimulates genes in corticotrope.

Proopiomelanocortin gets broken down into Alpha Milano stimulating hormone (alpha MSH) and adrenocorticotropic hormone (ACTH)

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11
Q

Action of TRH

A

Stimulates thyrotrope to release TSH

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12
Q

What does the arcuate nucleus secrete

A

Growth Hormone releasing hormone

PIH or dopamine

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13
Q

The action of Growth Hormone releasing hormone

A

Causes stimulation of somatotrope to secrete growth hormone

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14
Q

The action of PIH or dopamine

A

Stimulates lactotrope to secrete Prolactin

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15
Q

Ganado tropen releasing hormone action

A

Stimulates Gonadotrope to secrete FSH LH

Depending on the frequency of GnRH: High frequency is LH, lower frequency is FSH

Somatostatin inhibits this

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16
Q

Nucleus present in anterior pituitary gland

A

Paraventricular nucleus

Arcuate nucleus

Preoptic nucleus

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17
Q

What does oxytocin bind to in the uterus?

A

smooth muscle of the myometrium

causing it to contract and therefore help during birthing process

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18
Q

Oxytocins involvement in lactation

A

Binds to the mammillary bodies of breasts send signals to the hypothalamus

Results in milk ejection during lactation

Stimulated by suckling

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19
Q

Oxytocin has a ____ half life

A

short

so regulated frequnetly

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20
Q

What receptor does ADH bind to the principal cell of the collecting tube

What receptor does ADH bind to in blood vessels

A

Vasopressin type 2 receptor

Vasopressin type 1 receptor

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21
Q

Steps of ADH activation

A

Stimulus sends receptors to the hypothalamus

The supraoptic nucleus causes ADH to be secreted

Binds to V2 receptors

Stimulates Gs protein which binds to GTP and gets activated

This then binds to adenyl cyclase and converts ATP into cAMP activating pKa

pKa then goes and inserts into vesicles containing aquaporin 2 into the apical membrane

increases H20 Permeability of collecting duct

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22
Q

Effects of stimulation of ADH

A

Stimulated by low blood pressure or high plasma osmolality

In blood vessels: Increase vasoconstriction and therefore peripheral resistance and therefore increase blood pressure

In kidneys: Causes the increase of plasma volume and therefore BP

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23
Q

Hormones of the anterior pituitary gland

A

FLAT PIG

FSH

LH

ACTH

TSH

Prolactin

GH

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24
Q

What nucleus secrete growth hormone

A

Arcuate nucleus

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25
Q

What inhibits/ stimulates prolactin

A

inhibits PIH or dopamine (arcuate nucleus)

stimulates: thyrotropin-releasing hormone (paraventricular nucleus)

Stimulates: oestrogen + breastfeeding

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26
Q

How does iodide enter from the blood into follicles of the thyroid gland

A

secondary active transport

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27
Q

What does thyroid peroxidase do?

A

Iodide oxidation: turns iodide ions into iodine

Iodination: puts I2 onto amino acids on tyrosine amino acids

Fuses DIT + DIT = T4 (Throxine)

Fuses MIT + DIT = triodothyronin

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28
Q

What is it called when a tyrosine amino acid has:

one iodide group

two iodide group

A

Monoiodotyrosine

Diiodotyrosine

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29
Q

What makes up the thyroid hormone?

A

T4 thyroxine +

T3 triiodothyronine

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30
Q

How is T3 + T4 made from tyrosine molecule

A

Tyrosine is broken down into T3 + T4 components via lysozyme enzymes

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31
Q

Thyroid synthesis steps

A
  1. TRH release from paraventricular nucleus from hypothalamus
  2. Anterior pituitary to release from TSH
  3. TSH stimulates follicle cells of the thyroid to synthesise thyroglobulin
  4. Iodide trapping
  5. Oxidation of iodide via thyroid peroxidase
  6. Iodination of tyrosine amino acids
  7. Couple of the DIT + MIT
  8. Endocytosis of thyroglobulin with T3 + T4
  9. Lysosomal enzymes cleave T3 + T4 out of thyroglobulin
  10. Exocytosis of T3 + T4 into blood plasma
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32
Q

How does T3 act

A

Inducing gene transcription and protein synthesis

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33
Q

What does the Thyroid hormone do?

A

Promotes normal bone growth + maturation

Promotes muscular function and development

Increase basal metabolic rate/ O2 usage

Promotes normal C.O

Promotes an increase in synapses/myelinations/dendrites

Promotes G.I motility + secretions

Promotes normal hydration of skin

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34
Q

What cell is stimulated by low calcium levels

A

Chief cells

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35
Q

What does it mean when there is low blood calcium

A

Stimulates the parathyroid to secrete parathyroid hormone

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36
Q

How does the Parathyroid hormone affect kidneys

A

Increases calcium reabsorption decreasing Ca2+ excretion

Excreting phosphates as well

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37
Q

The indirect effect of the parathyroid hormone

A
  1. When exposed to sunlight 7 dehydrocholesterol gets drawn into the blood and broken down into Cholecalciferol
  2. Goes into the liver to become 25-OH Cholecalciferol
  3. Parathyroid hormone stimulates an enzyme in the kidney which together with 25OH cholecalciferol becomes 1,25 diOH Cholecalciferol (calcitriol)
    1. Calcitriol is the active form of vitamin D
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38
Q

What makes up the adrenal cortex

A

Zona glomerulosa

Zona Fasiculata

Zona Reticularis

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39
Q

What stimulates the adrenal cortex

A

Angiotensin 2 (1st)

low Na+ or high K+ (2nd)

ACTH (3rd)

Both undergo GS protein mechanism e.t.c to produce pKa which phosphorylates cholesterol conversion of ….

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40
Q

What is aldosterone derived from and what type of hormone is it?

A

Cholesterol

Steroid hormone

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41
Q

What inhibits Zona glomerulosa

A

Atrial natriuretic peptide

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42
Q

What hormones are corticosteroids

A

steroid hormones produced in the adrenal cortex

Cholesterol is the Precursor

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43
Q

What does aldosterone do?

A

Increase Na+ absorption

Decrease K+

Increase H2O absorption

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44
Q

Where is aldosterone produced

A

Zona glomerulosa

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45
Q

Where is cortisol secreted

A

Zona fasciculata

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46
Q

What stimulates Cortisol secretion

A

ACTH

undergoes same action as with aldosterone

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47
Q

What is cortisol derived from?

A

cholesterol

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48
Q

Steroid hormones transported around blood

A

Steroid hormones need carrier proteins to travel within the blood

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49
Q

What does zona glomerulosa secrete

A

Mineral corticoids (Aldosterone)

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50
Q

What does zona fasiculata secrete

A

Glucocorticoids (Cortisol)

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51
Q

What does zona reticulosa secrete

A

Gonadocorticoids (Androgens)

52
Q

What stimulates zona fasiculata

A
53
Q

What does cortisol do

A

Protein catabolism

Suppresses immune system

Lipolysis

54
Q

Gonadocorticoids are …

A

weak

55
Q

Adrenogens act on

A

Weak and therefore act as precursor

Fmelaes to release oestrogen

Males release testosterone

Libido effect

56
Q

What feedback system does cortisol induce

A

Negative feedback system

57
Q

Primary stimulant for sympathetic nervous system

A

Short term acute stress

Fight or flight

58
Q

What contains sympathetic nerve fibers

A

Ventral grey horn of the spinal cord

59
Q

What do chromaffin cells of the adrenal cortex convert tyrosine into

A

Epinephrine (80%)

Norepinephrine (20%)

60
Q

What does epinephrine do once secreted by the adrenal cortex

A

Binds to the liver and through Gs protein… results in glycogenolysis and gluconeogenesis increasing glucose in blood

Increases BP and lypolysis

61
Q

What is a heterocrine gland and given example

A

Has both endocrine and exocrine function

Pancreas

62
Q

What cells do the endocrine portion of the pancreas have (Islets of Langerhans)

A

Alpha cell-glucagon

Beta cells-Insulin

63
Q

What is beta pancreatic cells stimulus

A

Hyperglycaemia

64
Q

What stimulates alpha pancreatic cells

A

Hypoglycaemia

Sympathetic nervous system

65
Q

What does the exocrine portion of the pancreas have

A

Acini 99%

66
Q

Where are insulin contained in the beta cell of the pancreas

A

Vesicles

C peptide is also within the vesicles

67
Q

How is insulin produced

A

You have proinsulin undergoes cleaving processes in the RER modifications resulting in them being packaged in vesicles

Hyperglycaemia means that glucose enters through beta cells and gets broken down into ATP

Causes Vesicles to exocytose

68
Q

What is C peptide

A

A good way to monitor insulin levels

69
Q

What does insulin do?

A

The liver:

Promotes glycogenesis (Decrease glucose) and minor effect on protein synthesis

Increase amino acid uptake

Adipose tissue:

Stimulated lipogenesis

Increase glucose uptake via GLUT 4 = decrease blood glucose

Muscle:

Increase glucose uptake via Glut 4. A minor effect is glycogenesis

Increase amino acid uptake + protein synthesis

70
Q

What does the endocrine portion of the pancreas have

A

Islets of Langerhans 1%

71
Q

What does pancreatic alpha cell secrete

A

Glucagon

72
Q

What does glucagon do?

A

In liver:

gluconeogenesis & glycogenolysis + to increase blood glucose levels

In adipose tissue:

Lipolysis

73
Q

What is oogonium

A

Stem cells (dipolid)

74
Q

What happens prepuberty

A

oogonium ⇢ primordial follicle (2n) stuck in prophase 1

75
Q

Primary oocyte is…

A

Primordial follicle → Late secondary oocyte

76
Q

What phase is graffian cells stuck in

A

Metaphase 2

77
Q

What cells is primordial follicle stuck in

A

Prophase 1

78
Q

Follicular phase

A

Primordial follicle → graffian cell

79
Q

Follicular phase products

A

Mitosis

Oestrogen is produced

Follicular fluid

primary oocyte → secondary oocyte

80
Q

What days does the follicular phase take place

A

1-14 days

81
Q

What day of ovulation is peak oestrogen levels

A

day 14 (end of the follicular phase)

There is also a high amount of oestrogen in the mid follicular phase. This inhibits FSH and stimulates LH.

82
Q

What happens at end of the follicular phase

A

Oestrogen stimulates GnRH to secrete LH and inhibits FSH (LH surge)

83
Q

What does LH surge do?

A

increase follicular fluid (blood flow to antrum)

Stimulates graffian cells to release secondary oocyte- ovulation day 14-15

The secondary oocyte is caught by fimbriae and stays in the ampulla

84
Q

What is the ovulatory phase

A

LH surge

85
Q

How is the corpus luteum formed?

A

LH stimulates Remaining granulosa cells from ovulation to specialise

LH stimulates the corpus luteum to produce progesterone

86
Q

What arteries are there within endometrium

A

Stratum functionalis: Spiral and Coil arteries

Stratum Basalis : Striaght arteries

87
Q

Why is there blood during the menstruation phase

A

As the stratum Functionalis is being shed the spiral and straight arteries are also being shed.

88
Q

Proliferation phase of menstrual cycle

A

regenration of stratum functionalis

regenerate spiral and coiled arteries

makes uterine glands

thin cervical mucous production

oestrogen is the primary hormone

Days 6-14

89
Q

Secretory phase

A

The main hormone is progesterone

Angiogenesis

Secretion of uterine glands

Thickening cervical plug

Day 15-28

90
Q

Where is spermatogenisis occuring

A

Seminiferous tubu`les

91
Q

Where is spermatogenisis occuring

A

Seminiferous tubu`les

92
Q

What cells make up seminiferous tubes

A

Sertoli cells

they are connected to one another via tight junctions/adherens junctions

93
Q

What is the importance of tight junctions within seminiferous tubules

A

Splits into two compartments the basal compartment and the ad lumen compartment

Creates a barrier from preventing sperm antigens from entering bloodstream and therefore immune response- called the blood testes barrier

94
Q

What does a spermatogonium split into? (2n)

A

Undergoes mitosis to become type A cell and type B cell

They type A cell continues to become reused is the next spermatogonium

Type B cell goes to ad luminal compartment (tight junctions open up)

95
Q

When does a type B cell become a spermatocyte

A

When it gets past tight junctions and goes from basal lumen to ad luminal compartment

96
Q

How are secondary spermatocyte made?

A

The primary spermatocyte undergoes meiosis 1 to become 2 secondary spermatocyte

This further undergoes meiosis 2 to become spermatids

97
Q

Spermatids become _____ via _____

A

Spermatozoa via spermiogenesis

98
Q

Spermatogenesis

A
99
Q

What cell do LH act on for spermatogenesis on the actions does it do

A

Leydig cells they convert cholesterol into testosterone

100
Q

What cell do FSH act on for spermatogenesis on the actions does it do

A

Acts on Sertoli cells to produce Androgen Bonding protein (ABG)

101
Q

What two molecules are needed for spermatogenesis

A

testosterone and Androgen Bonding protein (ABG)

102
Q

What is the role of androgen bonding protein

A

Helps keep testosterone very soluble and highly concentrated

103
Q

What process do Sertoli cells primarily help with

A

Spermiogenesis

104
Q

What kind of feedback system does a high testosterone levels initiate

A

Negative feedback system

105
Q

What hormone is secreted by Sertoli cells when sperm levels are too high

A

Inhibin causes a negative feedback system with hypothalamus and anterior pituitary

106
Q

Summary of the path of sperm to outside

A

S-Seminiferous tubules

R- Rete testis

E- Efferent duct

E- Epipdyms

V- Vas deferens

E- Ejaculatory duct

N- Nothing

U-Urethra

P- Penile Urethra

SREEVEN UP

107
Q

Seminal vesicles

A

Accounts for 60-70% of seminal fluid

Fructose

Prostaglandin

Coagulase

108
Q

Prostate gland

A

Accounts for 30% of seminal fluid

Citrate

Fibrinolysis

PSA

109
Q

Role of prostaglandin in fertilisation

A

binds to the smooth muscle of the uterus and causes it to contract- retropulsion

110
Q

Role of coagulase in fertilisation

A

Allows for sperm to bind to vagina wall

111
Q

Stages of fertilisation

A
  1. Capacitation: cleaning of the sperm head. by the end it only has modified glycoproteins on its head. Increases mobility of sperm
  2. Acrosomal reaction: sperm binds with the ZP3 receptor. Calcium rushes in and activates the acrosome releasing its contents. Digests zona pellucida
  3. Fast block to polyspermy: sperm touches oocyte membrane beta unit of protein allows sodium in inhibiting other sperms from attaching
  4. Slow Block to Polyspermy: Alpha unit of protein causes the smooth endoplasmic reticulum releases Ca++ and activates lysozyme to fuse with the oocyte membrane. ZP3 degrades and hardens the zona pellucida. Sperm can no longer bind to the ZP3 receptor.
  5. Secondary oocyte undergoes meiosis Pronucleus of male and female fuse together
112
Q

How many phases can the menstrual cycle be subdivided into?

A

Follicular phase (0-14)

Luteal Phase (14-28)

113
Q

What happens in the follicular phase of the menstrual cycle

A

FSH will enter the ovaries and stimulate follicle maturation of primary follicles and mature follicles into a secondary follicle.

Oestrogen is produced during this phase

As oestrogen levels are rising to have positive feedback from LH. More LH is is secreted (LH surge= ovulation)

Oocyte is released

114
Q

What kind of feedback does oestrogen have on the pituitary gland 10 days before the menstrual cycle begins

A

Negative and therefore inhibiting LH

115
Q

In low concentration oestrogen inhibits …

A

LH secretion

116
Q

When is FSH released? What is it in response to?

A

Low oestrogen conc

117
Q

Roles of oestrogen

A

Stimulate bone and growth

Muscle growth

Stimulation of endometrial growth

Maintain female secondary characteristics

118
Q

In high concentrations oestrogen stimulates

A

LH

119
Q

Why is there an FSH surge alongside an LH surge

A

As a side effect of LH

120
Q

What hormones does the corpus luteum secrete

A

Oestrogen

Inhibin

Progesterone

121
Q

Luteal phase

A

Days 15-28

Progesterone is increasing

Oestrogen is still detectable, just in smaller amounts.

This suppresses GnRH release

Inhibin is increasing

Progesterone (+ oestrogen) stimulate endometrium growth

122
Q

What feedback system does inhibin have

A

As the corpus luteum develops inhibin suppresses GnRH secretion

123
Q

What happens to the corpus luteum during the luteal phase

A

The corpus luteum will degrade and therefore the hormones it secretes will decrease alongside it. It allows for other oocytes to mature.

124
Q

Ovulation graph

A
125
Q

Spermatogenesis vs spermiogenesis

A

Spermiogenesis: spermatid → spermatozoon. The maturation of a spermatid leads to the formation of a Sperm cell (spermatozoon). This takes place within Sertoli cells

Spermatogenis: Fomration of spermatozoa. Spermatogonium → 4 spermatozoa