Cell Biology

Question 1

Homeostasis is…

Answer 1

Involuntary neuronal and hormonal control of the body environment to keep all physical parameters within normal limits

Question 2

Total body water =

Answer 2

0.6 x body weight

Question 3

Extracellular water is … of total body water

Answer 3

1/3

3/4 interstial and 1/4 plasma

Question 4

Which ion is higher in intracellular fluid?

Answer 4

Potassium

Question 5

Diffusion

Answer 5

Solute movement from a higher concentration to a lower concentration

Question 6

Osmotic pressure

Answer 6

Concentration gradient caused by unequal distribution of ions across a semi-permeable membrane causing water to move towards the high electrolyte concentration
Keeps water in the blood vessel

Question 7

Oncotic pressure

Answer 7

Concentration gradient caused by unequal distribution of macro-molecules across a membrane
Keeps water in the blood vessel

Question 8

Which pressure is greater? Why?

Answer 8

Oncotic pressure is greater than osmotic pressure as proteins are much larger than water and have a greater water pull than ions

Question 9

Why is water attracted to ions?

Answer 9

When water is formed, oxygen pulls electrons from hydrogen ions, creating a positive pole and a negative pole.
1 molecule of water will bind 1 sodium or potassium ion.
= dissolving.

Question 10

Hydrostatic pressure

Answer 10

Pushes water out of the blood vessel

Question 11

Blood pressure in the capillary

Answer 11

1. Hydrostatic pressure from arties is high - forces fluid out
2. Hydrostatic pressure drops over length of capillary
3. By the time blood reaches veins, hydrostatic pressure is lower than oncotic pressure, so fluid is reabsorbed into blood

Question 12

Factors causing extravasation (fluid movement out of blood vessel) (4)

Answer 12

Increased BP
Blocked Lymph drainage
Inflammation
Liver failure

Question 13

Factors causing fluid retention (2)

Answer 13

Hypernatremia (too much sodium)

Renal failure

Question 14

Chemical communication in the body

Answer 14

1. Stimulus
2. First messenger (hormone or neurotransmitter)
3. Receptor
4. Secondary messenger (change how cell responds)
5. Inhibitory or excitatory action
6. Cellular response

Question 15

Negative feedback

Answer 15

Most common form of feedback
Normally, neurotransmitter is released from nerve ending and binds to target
Negative feedback is when neurotransmitter binds to pre-synaptic nerve, inhibiting more neurotransmitter release

Question 16

Positive feedback

Answer 16

Found when the body wants to liberate something, e.g. giving birth, defecation

Question 17

Giving birth - positive feedback loop

Answer 17

1. Cervix dilation
2. Stretch receptors in cervix fire
3. Hypothalamus
4. Posterior pituitary releases oxytocin
5. Acts on uterine muscle causing contractions
6. Forces baby through cervix - greater stretch