Physiology

Question 1

Sweat glands. Innervated by? Thermal/emotional sweating controlled by? Receptors?

Answer 1

Innervated by SNS.

Thermal sweating controlled by hypothalamus.

Emotional sweating is controlled by cerebral cortex.

Utilises acetylcholine recepetors

Question 2

What will shift the oxygen Hb curve to the left?

Answer 2

Decreased temp

decreased 2-3 DPG

Decreased H+ i.e. increased pH

Decreased CO

Fetal Hb

Question 3

In a 70 kg man there is a total of 45L of H2O. What does the total body water consist of?

Answer 3

Intracellular = 2/3
Extracellular (plasma (3.5L), interstitial fluids (8.5L), lymph and transcellular fluid) = 1/3
Transcellular is pleural, pericardial, synovial, luminal fluids, bowel)

Question 4

What is the intracellular component of cations?

Answer 4

K = 145 mmol/L (cells have a high take of K)
Na = 10 mmol/L
Ca = .001 mmol/L
Mg = 40 mmol/L

Question 5

How do you calculate plasma osmolalarity?

Answer 5

(Na + K) x 2 + glucose + urea

Question 6

What is the difference between osmolality and osmolarity?

Answer 6

Osmolality = solutes in 1 kg of solution (osmos/kg). Calculate in lab.

Osmolarity = solutes in 1L (osmo/L)

Question 7

What do is the normal plasma osmolality?

What is the urin osmol?

Answer 7

280-295 mosmol/L

300-1400 mosmol/L

Question 8

Anion gap?

Answer 8

(Na +K) - (HCO3 + Cl)
Normal AG 10-16

We have a positive anion gap as not all the anions are measured.

Question 9

Causes of a high anion gap?

Answer 9

Increases in unmeasured anions e.g. lactate, ketones, methanol, alcohol, urea (renal failure), salicylates

( as the cations will increase to compensate for increased anions)

MUDPILES

Question 10

Causes of low AG?

Answer 10

Decreased in unmeasured anions e.g. albumin, phosphate

Increased in unmeasured cations e.g. MM, IgG paraprotein

Bromide

Lab error

Question 11

In a normal AG aciodis, the urine anion gap is used to differentiate the causes. How do you calculate this and what are the causes?

Answer 11

(Na + K) - Cl.
Normal is 0 - 10 mmol/L

Increased = Renal (bicarb loss from kidney), Type I (distal, can’t secrete H+ therefore urine pH > 5.5 and low K) and
Type II RTA (Cannot absorb HCO3- therefore pH

Question 12

Causes of a normal AG? (CAGE) or ABCD

Answer 12

Due to loss of HCO3- from ECF:
Chloride excess
Acetazolamide/Addisons
GI causes – diarrhea/vomiting, fistulae (pancreatic, ureters, billary, small bowel, ileostomy)
Extra – RTA

ABCD:
Addisons (adrenal insufficiency)
Bicarbonate loss (GI or Renal)
Chloride excess
Diuretics (Acetazolamide)

Question 13

What does the Adrenal cortex consist of?

What does the Adrenal medulla consist of?

Answer 13

ZG = mineralcorticoids (aldosterone)

ZF = glucorticoids (cortisol, corticosterone)

ZR = androgens (testosterone and oestrogens)

Adrenal medulla
- catelcholamines (80% adrenaline, 20% noradrenaline)

Question 14

Thyroid binding globulin (TGB). What causes a high serum TBG?

Answer 14

Osetrogen
Tamoxifen
Raloxifen
Methadone

Question 15

Thyroid binding globulin (TGB). What causes a low serum TGB?

Answer 15

ANdrogens
Glucocortioids
Nicontinic acid
Danzol - synthetic steroid ethisterone that suppresses the production of gonadotropins and has some weak androgenic effects. Used in endometriosis.

Question 16

What is the function of Thyroid binding globulin (TGB)?

Answer 16

Synthesised in the liver.
Binds most of T4 and T3 in blood.
Higher affinity for T4 compared to T3. 
Only free hormone is active. 
Bound hormones represent a circulating storage pool. 
Decreased TGB in hepatic failure

Question 17

What are the T3 functions? 4Bs

Answer 17

Brain maturation
Bone growth
Beta adrenergic effects
Increased BMR

Question 18

Where is T4 converted to T3?

Answer 18

Peripheral tissues.

T3 binds receptors with greater affinity than T4.

Question 19

Which toxidromes is Nystagmus is a unique feature of?

Answer 19

ketamine and phencyclidine overdose.