Homeostasis chapter 1

first lecture of physiology

What is homeostasis?

The maintenance of stable internal environment despite external change; loss causes disease/death

What is intrinsic regulation?

Local, automatic adjustment by cells/tissues (e.g., vasodilation in hypoxia)

What is extrinsic regulation?

Adjustment involving multiple systems (e.g., nervous + endocrine during exercise)

What is osmolarity and its normal range?

solute concentration; normal - 270 mOsm (0.9% saline), varies <0.5% under homeostasis.

What is ADH and what does it do?

Antidiuretic hormone; secreted when osmolarity is increased by 0.5-1%; increases water reabsorption and stimulates thirst.

What is the normal blood pH range?

7.35-7.45; <6.8 = fatal CNS depression, >7.8 = fatal overexcitation.

What are buffers and what do they do?

Molecules that stabilize pH by binding/releasing H+; prevent drastic shifts.