Physiology Flashcards by Abby Lang

Hypothalamic neurons secrete … or … hormones into the … … … to the … pituitary.

Stimulatory
Inhibitory
Hypophyseal portal system
Anterior

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Name the 6 hormones of the anterior pituitary.

GH
Prolactin
TSH
ACTH
LH
FSH

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Name the 2 hormones of the posterior pituitary.

Oxytocin

Vasopressin/ADH

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Explain the thyroid axis.

Hypothalamus releases TRH
Anterior pituitary releases TSH
Thyroid releases T3/4
T3/4 have a negative feedback on TRH and therefore TSH

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Test for the thyroid axis?

TSH assay

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Name the 3 secretions of the thyroid gland.

Triiodothyronine (T3)
Thyroxine (T4)
Calcitonin

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Which cells release calcitonin in the thyroid gland?

Parafollicular/ C cells

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Oxyphil cells are … and more …/… than chief cells.

Larger

Pink/lighter-staining

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What do follicular cells make + what amino acids forms this + where is it stored?

Thryroglobulin
Tyrosine
Colloid

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What do follicle cells do to iodide?

Take it up and oxidise it to iodine

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What happens to iodide once it has been oxidised to iodine in the follicular cells?

Moves into colloid
Combines with tyrosine residues in thyroglobulin 
Forms monoiodotyrosine (MIT) and diiodotyrosine (DIT)

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What components make up T3 and T4?

MIT + DIT = T3

DIT + DIT = T4

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Does the thyroid gland produce more T3 or T4 + which one is stronger/gets a greater response?

Produces more T4

T3 is stronger

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What 3 structures convert T4 to T3 + which one accounts for 80%?

Liver (80%)
Kidneys
Thyroid

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What 3 proteins bind to T3 and T4 bind to + which one most?

Thyroxine-binding globulin (TBG)
Pre-albumin
Albumin
Most bound to TBG

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Most T3/T4 is bound/unbound but only bound/unbound can enter cells?

Bound

Unbound

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Name 4 functions of thyroid hormones.

Increase BMR
Increase glucose uptake
Increase breathing/heart rate
Controls temperature

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Name the secretion of the parathyroid glands + what cell it comes from.

PTH

Chief cells

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Which hormone and its releasing hormone are dependent on thyroid hormone levels?

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What is the effect of hypocalcemia on voltage-gated Ca channels?

Opens them causing nerve conduction and tetany

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Name 3 ways PTH increases blood calcium?

Increased release from bone
Decreased release in urine
Increases vitamin D which increases intestinal absorption

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What cells secrete GH in the pituitary gland + what does GH stimulate release of and where?

Somatotroph

IGF-1 in the liver

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What pituitary cell releases prolactin + where does it act on + what inhibits secretion?

Lactroph cell
Breast tissue
Dopamine

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What are the 2 functions of ADH?

Promote water resorption in kidney

Vascontriction

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What does increased/ decreased ADH do to volume, concentration and osmolality of urine?

``` Increased = decreased volume, increased concentration, increased osmolality Decreased = increased volume, decreased concentration and decreased osmolality ```

What does osmolality and osmolarity mean?

Amount of solute dissolved in 1 kg | Amount of solute dissolved in 1 litre

Osmolality is calculated using the ... of a solution whereas osmolarity uses the ... of a solution. Osmolarity/osmolality is dependent on temperature and pressure.

Mass Volume Osmolarity

Describe the sex hormone/HPG axis.

Hypothalamus releases GnRH Anterior pituitary releases FSH and LH FSH and LH have a negative feedback on GnRH and therefore FSH and LH

How is GnRH released in males vs. females?

``` Males = constant Females = variably ```

What cells do FSH and LH act on in males + name of muscle cell of seminiferous tubules?

FSH = Sertoli LH = Leydig Myoid cells

High frequency pulses release ... and low frequency pulses release ...?

LH | FH

High oestrogen ... GnRH and high progesterone ... GnRH.

Increases | Decreases

What does FSH do in males vs. females?

``` Males = spermatogenesis Females = oogenesis and oestrogen secretion ```

What does LH do in males vs. females?

``` Males = testosterone secretion Females = formation of corpus luteum and progesterone secretion ```

What 2 structures does oxytocin affect + what female hormone increases its release?

Breasts and uterus | Oestrogen

What is the name of the first germ cell in females and when is it formed?

Primordial germ cell | 1st meiotic division

What is a polar body?

Haploid cell unable to be fertilised

Name the 2 stages of the menstrual cycle + how long does the cycle last?

Follicular phase Luteal phase 28 days

How long does the follicular phase last?

14 days

Explain hormonal control of the menstrual cycle up to ovulation.

FSH causes oogenesis and increased oestrogen Increased oestrogen lowers FSH Oestrogen hits threshold to cause a surge in LH which causes ovulation

What is the positive feedback threshold for oestrogen?

200

Name 3 effects of oestrogen on the the uterus/vagina.

Increases endometrial thickness Reduces vaginal pH Makes mucous softer

What is a primary follicle + secondary?

Oocyte covered by granulosa and theca cells | Larger oocyte with follicular fluid

Explain hormonal control of the menstrual cycle after ovulation.

LH causes formation of the corpus luteum | Corpus luteum secretes progesterone which decreases LH

How long does the corpus luteum survive + how does it know to degenerate + what does it become?

Up to 14 days Lack of hCG production of embryo at 12 days Corpus albicans

Name 3 clinical signs to detect ovulation.

Rise in progesterone Peak of LH 1 degree rise in body temperature

How does LH increase progesterone levels?

Causes angiogenesis to allow more cholesterol to be delivered and form progesterone

What do alpha, beta, delta and PP cells make in the pancreas?

``` Alpha = glucagon Beta = insulin Delta = somatostatin PP = polypeptide ```

Which 2 words describe what hormone insulin is + what is its initial form?

Anabolic peptide | Preproinsulin

Which 3 tissues does insulin increase glucose uptake in?

Muscle Adipose Liver

What other 2 substances does insulin increase uptake of + what tissues?

Amino acids in muscle | Lipids in adipose

Which 3 processes does insulin stimulate and 2 processes it inhibits?

Stimulates DNA/protein synthesis, lipogenesis and glycogenesis Inhibits lipolysis and gluconeogenesis

What is the structure of insulin?

Alpha and beta polypeptide connected by C peptide and held by disulphide bonds

When is the C-peptide lost?

When preproinsulin is cleaved to insulin

Glucose enters beta cells of pancreas via ... ... and is ... by ... to ...?

GLUT2 transporters Phosphorylated Glucokinase Glucose-6-phosphate

Glucokinase Km depends on BG. True or False?

True

How does glycolysis of glucose in beta cells causes insulin release?

ATP from glycolysis closes KATP channels | Ca channels open and influx causes vesicles to secrete insulin

What BG level is insulin normally released from vesicles?

5 mM or above

The KATP channel is an octamer made from a 4 ... and 4 ... subunits?

Kir6.1 | SUR1

Name a molecule which opens and closes the KATP channel.

``` Closes = SUs Opens = diazoxide ```

Secretion has ... stages and the first load of insulin comes from the ... ... ... and accounts for ...%?

2 Readily reversible pool 5%

Which 4 hormones increase BG?

Cortisol T3/4 ACTH GH

Name 2 incretins which increase prandial insulin release + where they are released from.

GLP-1 GIP Duodenum

Explain the mechanism of action of insulin on tyrosine kinase receptors.

Binds to alpha subunit | Causes beta subunits to phosphorylate and dimerise

How are ketone bodies formed?

Beta oxidation of acetyl-CoA

What does the HPA axis control?

Cortisol levels

What pathway that insulin activates controls glycogen synthesis and gene expression?

``` GS = P13K/PKB GE = Ras/MAPK ```

Explain the HPA axis.

Hypothalamus releases CRH Anterior pituitary releases ACTH Adrenal cortex releases cortisol Cortisol has a negative feedback on CRH and therefore ACTH

Test for cortisol + why?

9 am cortisol | Circadian rhythm means random measurements useless

What is released from the zona glomerulosa + what controls it?

Aldosterone | RAAS

Explain the RAAS in 4 steps.

Renin from kidneys converts angiotensinogen to angiotensin I ACE from PVE converts angiotensin I to angiotensin II Angiotensin II causes vasoconstriction and aldosterone release Aldosterone causes salt/water resorption

What is released from the zona fasciculata + what controls is?

Cortisol | ACTH

What is the effects of aldosterone on water, Na, K and H?

Water release Na reabsorption K and H Loss

Name 4 functions of cortisol.

Increases gluconeogenesis Increases fat/protein metabolism Stress response Maintains BP

What is released from the zona reticularis + what controls it?

Androgens | ACTH

What is the effect of cortisol on bone?

Osteoporosis

What is released from the adrenal medulla + what controls it?

Catecholamines (adrenaline/noradrenaline) | Sympathetic nervous system