Lecture 1 - Homeostasis Flashcards
Define Homeostasis.
Process where cells, tissues, organisms etc. maintain sameness of their conditions
Examples of things to maintain?
Oxygen, CO2, nutrients, waste, salts, blood pH, blood volume and pressure, temperature etc.
Body responses to hot conditions?
Vasodilation
Pilorelaxation
Increased SA
Sweating
Body responses to cold conditions?
Vasoconstriction
Piloerection
Decreased SA
Shivering
Example of negative feedback loop?
Temperature OR Glucose levels
Example of positive feedback loop?
Platelets in blood OR Cervix and Oxytocin
Normal body temperature?
37 +- 0.5
Normal body pH?
7.35-7.45
What is Lactate Acidosis? And a solution?
Increased buildup of LA due to increased metabolism
Blow into a bag to blow off CO2
What can hyperventilation lead to?
Blood that is too alkaline
Hence reduce breathing rate to increase CO2 (risky bc little O2 = Hypoxia)
How do kidneys regulate body pH? And drawback?
Excrete H+ if blood is acidotic (retain HCO-)
Retain H+ if blood is alkylotic (excrete HCO-)
Drawback is it takes a few days to have an effect
Problem with gastric acid in oesophagus?
V acidic, can lead to Oesophagitis, stricture
If stomach loses mucus lining?
Can lead to gastric ulceration and perforation
Explain rough correlation between [H+] and pH?
What is a conc-pH relation to know?
Change in [H+] by factor of 2 (double or half) causes pH change of 0.3.
[H+] 40 = pH 7.4
[H+] 100 = pH 7.0
Describe/explain water ratio in body.
Total Body Water is 60%
Of that, 2/3 is intracellular fluid (inside cells)
1/3 is extracellular fluid (outside cells)
Of that, 80% is interstitial fluid (space outside cells) and 20% blood plasma.
