Pituitary gland

Question 1

What is a hormone?

Answer 1

A messenger carried from organ from where it is produced to the affected organ through the bloodstream

Question 2

What are the two types of hormones?

Answer 2

Steroid and peptide

Question 3

How are peptides synthesised as first

Answer 3

prohormones (long polypeptide chain) then cleaved by regulatory enzymes

Question 4

how are peptide hormones stored and released?

Answer 4

stored in vesicles and released by regulatory (stimulatory secretion)

Question 5

describe the receptors that peptide hormones bind to and how signal reach target?

Answer 5

Bind to receptors on cell membrane and transduce signal using 2nd messenger model

Question 6

how are STEROID hormones synthesised to at first? I.e precursor to all steroid hormones

Answer 6

synthesised from CHOLESTEROL in a series of reaction

Question 7

how are steroid hormones secreted?

Answer 7

Constitutive secretion

Question 8

what type of receptor does steroid hormone bind to?

Answer 8

intracellular receptors- transcription factors

Question 9

what is the pituitary stalk called?

Answer 9

infundibulum

Question 10

what are the 2 parts of the pituitary gland?

Answer 10

anterior (adrenohypohysis) and posterior(neurohypophysis)

Question 11

what are the 3 sections of the anterior pituitary gland

Answer 11

pars tuberalis
pars intermedia
pars distalis

Question 12

where does the pituitary gland sit

Answer 12

sella turcica of the sphenoid bone

Question 13

what part of the brain is located anterio- superior to the pituitary gland

Answer 13

optic chiasm

Question 14

what neurons regulate the anterior pituitary function?

Answer 14

Hypothalamic parvocellular neurons

Question 15

where does the parvocellular neurons terminate

Answer 15

median eminence

Question 16

How does signals from parvocellular neurons reach anterior pituitary gland?

Answer 16

VIA hypothalamo-pituitary portal circulatory system

Question 17

how is the anterior pituitary anatomically distinct from the hypothalamus?

Answer 17

DOES NOT contain neural tissue but contains glandular tissue, that’s why parvocellular neurons terminate in median eminence

Question 18

what type of endocrine cells make up the anterior pituitary gland?

Answer 18

Somatotrophs
Lactotrophs
Gonadotrophs
Corticotrophs
Thyrotrophs

Question 19

Describe in detail how the hypothalamus causes thyrotrophs to release THYROTROPHIN

Answer 19

hypothalamus parvocellular cells terminate in median eminece
secrete Thyrotrophin releasing hormone into portal system
goes to anterior pituitary (thyrotrophs) and causes thyotrophin to be released.
thyrotrophin released into the blood to thyroid gland
thyroid gland release thyroxin

Question 20

list the endocrine cells of anterior pituitary and their respective hormones they produced

Answer 20

somatotrophs- Growth hormone
Lactotrophs- Prolactin
Gonadotrophs- FSH and LH
Thyrotrophs- thyrotrophin
corticotrophs- Adenocorticotrophic hormone(ACTH)

Question 21

Which hormone produced by the parvocellular cells stimulate or Inhibit production of growth hormone

Answer 21

Stimulate- Growth hormone releasing hormone.

Inhibit- Somatostatin

Question 22

What hormone controls release of prolactin from lactotrophs?

Answer 22

Dopamine- IT INHIBITS ONLY

Question 23

What hormone controls release of TSH (Thyrotrophin)

Answer 23

THYROTROPHIN releasing HORMONE. IT STIMULATES only.

Question 24

What hormone controls release of the following? LH/FSH and corticotrophin(ACTH)?

Answer 24

LH/FSH- gonadotropin elapsing hormone

ACTH- corticotrophin releasing hormones

Question 25

Where are the receptors of the hormones produced by the anterior pituitary gland?

Answer 25

``` Growth hormone- bone/muscle or liver Prolactin- lactating breast or uterus Thyrotrophin- thyroid gland LH/FSH- testes or ovaries Corticotrophin- adrenal cortex ```

Question 26

What type of scanning is used to locate the pituitary gland?

Answer 26

MRI

Question 27

What causes BITEMPORAL hemianopia

Answer 27

When optic chiasm is compressed; hence contraletral fibres frommedial retinae cant be passed down to the brain. Hence lose peripheral vision. Caused by pituitary tumour underneath the optic chiasm.

Question 28

Outline the neuroendocrine reflex arc for milk production?

Answer 28

Mechanical stimulation by bay on breast Ascending pathway to hypothalamus where dopamine is produced in lesser amount. Less dopamine flow through portal circulatory system. Less lactotophs inhibited Increased plasma prolactin More milk synthesised in mammary glands

Question 29

What hormone produced by liver stimulate growth of bone and muscle

Answer 29

IGF1- adult | IGF-2 FOETUS

Question 30

What’s the difference between acromegaly and gigantism

Answer 30

Acromegaly -too much growth hormone in adults | Gigantism- in children. There’s increase in height as epiphyseal growth plates haven’t fused yet

Question 31

What are the other symptoms of acromegaly

Answer 31

``` Macroglossus- enlarged tongue Increased size of feet and hand Large jaw prognathism Sweatiness Headaches Prominent nose Intradental space ```

Question 32

What tests could you use to confirm acromegaly

Answer 32

Test for growth hormone or IGF-1 Test for oral glucose tolerance; liver glucagon secretion is affected due to too much growth hormone. I.e. you’re given too much glucose (75g sugary drink) and your growth hormone should drop after 2 hrs with rise in glucose.

Question 33

What hormones are produced by the neurohypophysis?

Answer 33

``` Arginine vasopressin(ADH/AVP) Oxytocin ```

Question 34

What neurones cause release of hormones form the neurohypophysis? Describe the process

Answer 34

Magnocellular neurone. It goes directly to neurohypophysis from hypothalamus as the posterior pituitary gland is made out of neural tissue( anatomically continuous with brain).

Question 35

Describe length and origin of magnocellular neurone that causes release of AVP

Answer 35

Long; supraoptic nuclie

Question 36

Describe the length and origin of the magnocellular neurone that causes release of oxytocin?

Answer 36

Long; paraventricular nuclei

Question 37

What causes release of AVP or oxytocin

Answer 37

Excitation ONLY of magnocellular neurones

Question 38

Describe and explain the function of AVP (ADH)?

Answer 38

Stiumulate water reabsorption into renal collecting duct; hence concentrates urine

Question 39

What receptor does ADH bind to in the collecting duct

Answer 39

V2

Question 40

What is the other function of AVP

Answer 40

``` A vasoconstrictor (binds via V1 receptor.) Stimulate ACTH release from adrenohypophysis ```

Question 41

Describe the action of oxytocin in the uterus in parturition

Answer 41

Binds to receptors in myometrial cells and causes contraction Baby delivered

Question 42

Describe the action of oxytocin in breast during lactation?

Answer 42

Bind to receptors on myoepithelial cells and causes contractiion Milk ejection

Question 43

What hormone does the adrenal cortex release after being stimulated by ACTH

Answer 43

CORTISOL.

Question 44

What is the peptide precursor for ACTH?

Answer 44

PRO OPIOMELANOCORTIN