Original Physiology Flashcards
Where in the kidney is the main resorption site for all ions?
Proximal convoluted tubule
What activates the intrinsic pathway of the clotting cascade?
Damaged endothelium
What activates the extrinsic pathway of the clotting cascade?
Tissue factor
What is cleaved to form Thrombin (IIa)
What activates this process?
Prothrombin (II)
Xa (Activated factor X)
What is the action of thrombin (IIa)?
Fibrinogen —> fibrin
I –> Ia
What is the lifespan of a RBC?
120 days
What is the lifespan of a WBC?
2-5 days
What is the lifespan of platelets?
5-9 days
What LFT parameters are raised during pregnancy?
ALP; GGT
What LFT parameters are reduced during pregnancy?
AST; ALT; bilirubin; albumin
What is the trigger for ADH release?
High serum osmolality
What is the weight of the non-pregnant uterus?
40-50g
What is the weight of the pregnant uterus?
1200g
What holds platelets together in the 1st stage of wound healing?
Fibrin
By what proportion does oxygen consumption increase in pregnancy?
20%
OR
30 - 50 mls/min
By what proportion does tidal volume increase in pregnancy?
40%
By what proportion does minute ventilation increase in the first trimester of pregnancy?
50%
What are the cardiovascular changes that occur during pregnancy?
Plasma vol up 45-50%
Cardiac output up 40%
Stroke volume up 30%
HR up 10% (15 beats/min)
Systemic vascular resistance (SVR) down 25%
What causes the increase minute ventilation during pregnancy?
Progesterone - it is known to directly stimulate ventilation by sensitizing the CNS respiratory centres to CO2
By what proportion does eGFR increase in pregnancy?
40%
In what ways does vasopressin/ADH promote water retention?
1) Insertion of water channel proteins called aquaporins into the collecting duct and DCT
2) Increased activity of urea transport proteins in the collecting duct promoting urea flow out of the collecting duct and water via increased osmotic gradient
3) Increased sodium reabsorption across the ascending loop of Henle
What lung parameters are unchanged in pregnancy?
FEV1 and FVC
Vital capacity
At what point does fetal urine become a major contributor to amniotic fluid?
Week 16 - up until then the major contributors are placenta and fetal skin
What are the only vitamins whose daily requirements don’t increase in pregnancy?
Vitamin D and vitamin K
At what gestation do the definitive alveolar form?
Week 36
Which lung volumes decrease in pregnancy?
*Total lung capacity
Residual volume
Functional residual capacity
Expiratory reserve volume
Inspiratory reserve volume
Diaphragm takes up space
Tidal volume increases (ERV/IRV around it)
Vital capacity stays the same
How is haemolytic disease of the newborn tested for?
Direct Coombs test
How does gestational diabetes affect free fatty acids and plasma ketones bodies?
Increased FFA and ketones bodies
By how many x is ALP increased in pregnancy?
x3
Oxygen consumptions increases by 20% in pregnancy, how much is this in ml/min?
50ml/min
By how much is total lung capacity decreased in pregnancy?
200ml decrease
What proportion of body calcium is stored in the skeletal system?
99%
At what gestation is dilutional anaemia at its greatest?
32/40
What is anuria?
<100ml produced in 24 hours
What is oliguria?
100-400ml or urine produced in 24 hours
What is normal urine output?
0.5-1ml/kg/hour, in infants 2ml/kg/hour
What is polyuria?
> 3000ml produced in 24 hours
How do LFTs change in pregnancy?
Albumin falls
ALP can be x3 higher (because the placenta also produces it)
Which layer of the ovarian follicle is vascular?
Theca layer
For how long do follicles have to grow before they can be recruited into the menstrual cycle?
65 days
Once follicles have reached the antral phase (resting — preantral — antral —- ovulatory phase) what hormone are they dependant upon for growth?
FSH
What drives cholesterol conversion to androgens, and in what cells?
LH drives
In Theca cells
What drives androgen conversion to estradiol, and in what cells?
FSH drives
Catalysed by aromatase in the granulosa cells
What are the features of a dominant follicle?
More FSH receptors
More granulosa cells (producing estrogen)
Higher intracellular cyclic adenosine monophosphate lvels
Produces estrogen -> positive feedback causes LH surge.
FSH causes the dominant follicle to induce LH receptors, allowing it to survive, whilst the FSH levels falls and so the other small follicles die by atresia
Which hormone causes the completion of the first meiotic division of the oocyte after ovulation?
LH
What induces the 2nd meiotic division of the oocyte?
Fertilisation
What is the thickness of the endometrium during the luteal/secretory phase?
6mm
What is normal testicular volume?
15-30ml
How much cooler are the testes compared to core body temperature?
1.5-2 degrees
What cells line the tubules of the testes?
Sertoli
What are the cell stages of spermatozoa?
Spermatogonia — primary spermatocytes — secondary spermatocytes — spermatids — spermatazoon
How long is the epididymis?
5m (highly coiled)
How long does it take for the spermatozoa to pass through the epididymis?
8-14 days
What is the combined length of the male and female reproductive tract that a sperm must traverse in order to fertilise an oocyte?
30-40cm
To what pH does ejaculate raise the vagina to, and why?
Rises it from 3-4 to 7.2
This is because the motility of the sperm is inhibited by acidic pH
Where does capacitation occur, and what is its purpose?
Occurs in the presence of uterine or uterine tube fluid, usually in the ampulla of the tube.
It alters the surface of the sperm head to make it more responsive to signals in the immediate area of the oocyte
By how many litres does cardiac output increase in pregnancy?
30-50%, from 4.5L/min to 6L/min
When does the rise in cardiac output plateau during pregnancy?
24-30/40
By what proportion does heart rate increase in pregnancy?
10%
By how many mmHg does BP fall in pregnancy?
From 8-36/40:
Systolic falls by 5mmHg
Diastolic falls by 10mmHg
How does the axis of the heart change in pregnancy and why?
The axis is shifted anteriorly and to the left as a result of the upward displacement of the diaphragm by the enlarging uterus
What are the ECG changes in pregnancy?
L axis deviation: 15 degrees
Lead III - twi and Q wave
AVF - Q wave
How does the increase in ventilation in pregnancy affect blood gases?
pCO2 falls to 4.1 (normal 4.7-6.0)
How does the slightly lower pCO2 effect bicarbonate?
PCO2 fall causes the blood to becomes slightly alkaline, in response the bicarbonate levels fall to 19-20 (normal 22-26)
How does residual volume change in pregnancy?
From 1500ml (non-pregnant) to 1300ml
How does total lung capacity change in pregnancy?
From 5L (non-pregnant) to 4.8L
By how many ml/minute does oxygen consumption increase in pregnancy? And how is that distributed?
Increased by 50ml/min
—> 20ml/min to fetus
—> 6ml/min to increased cardiac output
—> 6ml/min to increased renal work
—> 18ml/min to increase in metabolic rate
By how much do the kidneys increase in size in pregnancy?
1cm
What is the glomerular filtration rate during pregnancy?
140-170ml/minute
How does U&Es change during pregnancy?
Urea falls to 3.1
Creatinine falls to 47
Why does sickness occur in pregnancy?
Gastrointestinal tone and motility are reduced by progesterone, resulting in delayed gastric emptying
This reduced motility also increases stool transit time, allowing more time for colon reabsorption of water, making constipation more common
Why are pregnant women more prone to gallstone formation?
Due to reduced gallbladder contractility
By what proportion does plasma volume increase in pregnancy?
At what gestation does it reach its peak?
45% (2600ml —> 3800ml)
Expansion reaches its peak at 32/40
Which coagulation factors increase in concentration in pregnancy?
VII
VIII
X
Which coagulation factors are unchanged in pregnancy?
XI
XIII
What is the average milk production per day?
500-1000ml/day
Equilibrium in breastfeeding mothers is reached at approx. 3/52 whereby milk production is tailored to requirement
What is the energy content of 100ml breast milk?
75 kcal
Why is breast milk advantageous in babies with diarrhoea?
Because breastmilk has approx. 1/3rd to conc of sodium and chloride concentration compared to cows milk, and high solute load (as in cows milk) can exacerbate diarrhoea
What are the different types of lochia?
Lochia rubra - red
Lochia serosa - pink
Lochia alba - white
What promotes the formation of more myometrial gap junctions as labour approaches?
Oestrogen
increased myometrial gap junctions allow the transmission of chemical and electrical signal and so promote coordinated contraction