Cell Physiology Flashcards Preview

Part 1 > Cell Physiology > Flashcards

Flashcards in Cell Physiology Deck (16)
Loading flashcards...
1
Q

Describe the 6 ways in which cells communicate with each other

A

1) Gap junctions (cell-cell)

Chemical messengers:

2) Neural synapses
3) Endocrine hormones in blood act on cells with specific receptors
4) Paracrine: cells release signals that diffuse to nearby neighbours
5) Autocrine: messengers released act on self
6) Juxtacrine: one cell has ligand on surface and one has receptor

2
Q

How do cells respond to excess messenger?

A

Decrease receptors through downregulation, internalisation or desensitisation

3
Q

How do cells respond to decreased messenger?

A

Upregulate receptors

4
Q

How do messengers cause changes?

A

1) Ion channels
2) Activation of cytoplasmic/nucleic receptors that increase mRNA transcription
3) Activation of Gq GPCRs which activate PLC leading to increased IP3 and DAG production
4) Activation of Gi or Gs GPCRs leading to a change in adenylate cyclase activity and therefore cAMP
5) Increased activate of tyrosine kinase receptors (insulin)
6) Increased activity of serine or threonine kinase

5
Q

What do IP3 and DAG do?

A

DAG leads to increased calcium release and IP3 activates PKC and increases protein phosphorylation

6
Q

How can substances be transported across cell membranes?

A

1) Exocytosis
2) Endocytosis (phagocytosis and pinocytosis)
3) Ion channels (open to both sides)
4) Carrier proteins (open to one side only)
5) Primary active transport (uses chemical energy e.g. ATP)
6) Secondary active transport (uses electrochemical gradient)

7
Q

What does Na+/K+ ATPase do?

A

Uses ATP to move 3Na+ out and 2 K+ in to maintain electrochemical gradient of ECF

8
Q

What percentage of energy does Na+/K+ ATPase use?

A

33% of basal energy, 70% of all energy from neurons

9
Q

What percent of the body is water?

A

60%

10
Q

What percent of total body water is ICF and what percent is ECF?

A

2/3 ICF (40% total body weight), 1/3 ECF, (20% total body weight)

11
Q

What percent of body weight is blood volume?

A

8%

12
Q

What percent of body weight is plasma volume?

A

5%

13
Q

How does body water distribution change in children vs adults?

A

ECF: ICF volume ratio is larger in children c.f. adults

14
Q

How does blood and it’s components change in pregnancy?

A

Total blood volume increases 40-45%, plasma volume increases by 50% (hemodilutes-physiological anaemia of pregnancy), Hct increases by 250ml w/o Fe and 450mL w Fe

15
Q

What is colloid osmotic pressure?

A

The component of total osmolality due to colloids (large MW particles) keeping fluid INTRAVASCULARLY

16
Q

How is what portion of ECF is interstitial fluid vs plasma?

A

75% interstitial fluid, 25% plasma