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My Phase 1 > Endocrine and Skin > Flashcards

Endocrine and Skin Flashcards

1
Q

Pituitary gland - where is it located?

A

At the base of the brain, connected to the hypothalamus by the infundibulum/pituitary stalk.
Consists of 2 lobes- anterior and posterior pituitary

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2
Q

describe the blood supply of the anterior pituitary gland - why is this significant?

A

Has a portal venous blood supply, the hypothalamic-hypophyseal portal system -no arterial blood supply.
Receives portal venous circulation from the hypothalamus, allowing transport of hormones.

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3
Q

what are the different types of hormone structures?
derived from:
e.g.

A
  • steroids: derived from cholesterol, e.g. cortisol
  • peptides: proteins e.g. insulin
  • thyroid hormones: derived from 2 modified tyrosine - thyroxine
  • catecholamines: stress hormones synthesised from tyrosine, e.g. adrenaline and noradrenaline
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4
Q

2 different ways in which hormones communicate with other cells

A
  • cell surface receptors: G protein coupling

- intracellular receptors

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5
Q

what structure is located just anteriorly to the pituitary gland?

A

the optic chiasm

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6
Q

Which is the most stored thyroid hormone?

How is its active form forced?

A

T4 most stored.
Iodase is cleaved off by deiodinases to form active T3.
Action similar to steroid hormones.

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7
Q

6 Key hormones of the anterior pituitary

what type of hormones are they?

A

Growth hormone
Prolactin
ACTH
= polypeptides

FSH and LH
TSH
= glycoproteins

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8
Q 
Anterior pituitary
Growth hormone:
- regulatory hormone(s) from the hypothalamus:
- effect of regulatory hormone
- effect of hormone
A
  • regulatory hormone(s): GHRH and somatostatin
  • effect of regulatory hormone: GHRH increases levels, SST inhibits
  • effect of hormone: acts on liver to secrete IGF-1. Stimulates protein synthesis, carb and lipid metabolism
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9
Q 
Anterior pituitary
Thyroid Stimulating hormone (TSH)
- regulatory hormone(s) from the hypothalamus:
- effect of regulatory hormone
- effect of hormone
A
  • regulatory hormone(s):TRH
  • effect of regulatory hormone: increases TSH release
  • effect of hormone: stimulates the thyroid gland to release T3 and T4
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10
Q 
Anterior pituitary
Prolactin
- regulatory hormone(s) from the hypothalamus:
- effect of regulatory hormone
- effect of hormone
A
  • regulatory hormone(s): dopamine
  • effect of regulatory hormone: inhibits release
  • effect of hormone: breast development and milk production
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11
Q 
Anterior pituitary
Adrenocorticotropic hormone (ACTH)
- regulatory hormone(s) from the hypothalamus::
- effect of regulatory hormone
- effect of hormone
A
  • regulatory hormone(s): CRH
  • effect of regulatory hormone: increases release
  • effect of hormone: stimulates the adrenal cortex to secrete cortisol
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12
Q 
Anterior pituitary
FSH and LH
- regulatory hormone(s) from the hypothalamus:
- effect of regulatory hormone
- effect of hormone
A
  • regulatory hormone(s): GnRH
  • effect of regulatory hormone: increased release
  • effect of hormone: gonads: germ cell development and secretion of sex hormones (androgens)
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13
Q

How do regulatory hormones reach the anterior pituitary gland?

A
  • regulatory hormones secreted by the neuroendocrine cells in the hypothalamus.
  • axons project to the median eminence at the base of the brain
  • at this site the neuroendocrine cells can release substances (hormones) into the Hypothalamo-hypophyseal portal vessels that travel directly to the anterior pituitary gland
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14
Q

where do neuroendocrine cells have their cell bodies?

A

In supraoptic and paraventricular nuclei

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15
Q

Most releasing hormones (from the hypothalamus) increase production of their respective hormones from the anterior pituitary.
What are 2 releasing hormones that have an inhibitory affect?

A
  • dopamine is released to inhibit prolactin release

- somatostatin is released as an inhibitor to growth hormone (GHRH increases release)

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16
Q

What does the posterior pituitary consist of?

A

Not glandular like the ant. pituitary.
Largely a collection of axonal projections from the hypothalamus that terminate behind the anterior pituitary, and serve as a site for the secretion of neurohypophysial hormones (oxytocin and ADH) directly into the blood.

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17
Q

What is the hypothalamic–neurohypophyseal system composed of?

A

the hypothalamus (the paraventricular nucleus and supraoptic nucleus), posterior pituitary, and the axonal projections extending from nuclei –> pituitary.

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18
Q

What are the neurohypophysial hormones?

A

ADH and oxytocin - secreted from the posterior pituitary

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19
Q

Which nuclei in the hypothalamus has neurosecretory cells which secrete oxytocin?

A

Paraventricular nucleus

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20
Q

Which nuclei in the hypothalamus has neurosecretory cells which secrete ADH?

A

Supraopticnucleus

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21
Q

Arterial supply of the thyroid gland

A
  • superior thyroid artery

- inferior thyroid artery from subclavian artery, ascending branch supplies parathyroid

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22
Q

3 main hormones produced by the thyroid gland

A
  1. Thyroxine (T4) – Reservoir for T3
  2. Tri-iodo-thyronine (T3) – Major thyroid hormone
  3. Calcitonin
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23
Q

Which cells of the thyroid secrete thyroid hormone?

A

Follicular epithelial cells

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24
Q

Which cells of the thyroid secrete calcitonin?

A

Parafollicular cells

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25
Q

How is thyroxine/triiodothyronine made?

enzyme?

A

Iodination of Thyroglobulin (in thyroid follicle lumen).
Iodinated Tyrosines on Thyroglobulin combine to make T3 and T4.
Enzyme – Thyroid Peroxidase.
Steps are stimulated by TSH.

26
Q

What does T3 do?

A
  • increases metabolic rate
  • growth and development
  • increased catecholamine effect (sympathetic NS)
27
Q

Structure of thyroid gland

A

2 lateral lobes connected by isthmus.

posteriorly, superior and inferior parathyroid glands

28
Q

Describe the feedback loop of PTH

A
  • low calcium level
  • Parathyroid glands stimulated
  • increased production of PTH
  • acts on bone to increase calcium resorption, acts on kidney to increase calcium reabsorption and phosphate excretion
  • indirectly acts on small intestine - calcitriol from kidney –> increased vitamin D –> increased calcium absorption in the small intestine
    OVERALL: increased calcium
29
Q

Effect of PTH on bone

A

increases calcium resorpton

30
Q

effect of PTH on kidney

A

increased calcium reabsorption and phosphate excretion, calcitriol produced

31
Q

effect of PTH on small intestine

A

indirect effect -

calcitriol from kidney –> increased vitamin D –> increased calcium absorption

32
Q

effect of increased plasma insulin from beta cells of pancreas on muscle

A
  • increased glucose uptake and utilisation
  • glycogen synthesis
  • amino acid uptake
  • protein synthesis
33
Q

effect of increased plasma insulin from beta cells of pancreas on adipocytes

A

increased glucose uptake and utilisation

triglyceride synthesis

34
Q

effect of increased plasma insulin from beta cells of pancreas on liver

A
  • decreased gluconeogenesis
  • glycogen and triglyceride synthesis
  • no ketone synthesis
35
Q

Shape of R vs L adrenal glands

A 
R = pyramid
L = semilunar
36
Q

Blood supply of adrenal glands

A
  1. Inferior phrenic arteries (abdo aorta)
  2. Middle suprarenal arteries (abdo aorta)
  3. Inferior suprarenal arteries (renal artery)
37
Q

Layers of the adrenal cortex from out –> medulla

A
  1. Zona Glomerulosa
  2. Zona Fasciculata
  3. Zona Reticularis
  4. Medulla
38
Q

What does the Zona Glomerulosa produce?

A

Aldosterone

In response to decreased blood volume

39
Q

What does the Zona Fasciculata produce?

A

Glucocorticoids (cortisol)

40
Q

What does the Zona Reticularis produce?

A

sex hormones e.g. androgens

41
Q

What does the medulla produce?

A

adrenaline/noradrenaline

42
Q

What is the RAAS

A

the renin–angiotensin–aldosterone system (RAAS) is a hormone system that regulates blood pressure and fluid balance.

43
Q

Effects of cortisol from the zona fasciculata

4

A

Produced during stress

  1. Metabolism: protein to aas, triglyceride to FFAs and glycerol, gluconeogenesis
  2. Circulation: increased vasoconstriction
  3. Decreased inflammation and specific immune response
  4. Decreased nonessential functions, e.g. reproduction and growth
44
Q

WHat are the 3 main catecholamines secreted from the adrenal medulla?

A

80% adrenaline
20% noradrenaline
small amounts of dopamine

45
Q

Actions of catecholamines secreted by the adrenal medulla (sympathetic nervous system)

A
  • increased glycogenolysis
  • increased breakdown of adipose tissue triglyceride
  • increased cardiac function
  • diversion of blood from viscera to skeletal muscles by vasocontriction (in viscera) and vasodilation (in muscles)
  • increased lung ventilation - stimulates brain breathing centres, dilates airways
46
Q

Endocrine roles of the kidney

A
  • produces erythropoietin: stimulates RBC production
  • converts 25-OH vit D to active 1,25-OH vit D
  • calcium metabolism
47
Q

Where does normal proliferation of the skin occur?

A

In the basal layer

48
Q

Functions of the skin

A
  • barrier to infection
  • thermoregulation
  • protection against UV
  • vitamin D synthesis
  • regulate H2O loss
49
Q

3 basic layers of the skin

A

Epidermis, dermis, subcutaneous tissue

50
Q

What are the layers of the epidermis?

A 
Outer
Stratum corneum
stratum granulosum
stratum spinosum
stratum basale
51
Q

What is the stratum corneum of the epidermis made up of? why is this important?

A

Made up of corneodesmosomes and desmosomes.
Corneodesmosomes are adhesion molecules which keep the corneocytes together.
no.s increase in psoriasis, decrease in atopic excema

52
Q

In a healthy skin barrier, what does filaggrin produce?

A

natural moisturising factor (NMF)

53
Q

what is the importance of NMF?

A

Fills corneocytes, helping to maintain the skins hydration

Also helps to maintain an acidic environment at the outer surface of the stratum corneum

54
Q

What is desquamanation?

A

In order to balance the introduction of new cells in the basal layer of the epidermis, mature corneocytes are shed from the surface.
Involves degradation of the extracellular corneo-desmosomes by protease enzymes.

55
Q

What is the role of the lipid lamellae of the skin?

A

Keeps water inside the skin cells, protects against irritants and allergens.

56
Q

What are all skin flare ups caused by?

A

allergens which are able to penetrate into the skin, where they are met with lymphocytes which release chemicals that induce inflammation.

57
Q

endocrine roles of the kidney?

A
  1. Produces erythropoeitin which stimulates bone marrow maturation of red blood cells.
    Levels increase in response to anaemia, decrease in polycthaemia
  2. Vitamin D activation - calcitriol formed, increasing calcium reabsorption
58
Q

What does ADH secreted by the posterior pituitary do?

A
  • aquaporins –> collecting duct, retaining fluid in the body
  • acts as a vasoconstrictor to increase blood pressure
59
Q

where is ADH primarily synthesised?

A

in the supraoptic nuclei of the hypothalamus

60
Q

what does oxytocin secreted by the posterior pituitary do?

A

Stimulates the contraction of the smooth muscles of the breasts for milk ejection during lactation in response to suckling.
Stimulates the contraction of uterine smooth muscles until the baby is born
Promotes the onset of labour

61
Q

what receptor type do all pituitary and hypothalamic hormones act on?

A

G-protein coupled receptors

My Phase 1 (14 decks)

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