Introduction to homeostasis Flashcards
(12 cards)
What is homeostasis?
-Steady internal physical and chemical conditions maintained by living systems
- Condition of optimal functioning (includes many variables including temp, O2 saturation, pH, BMs, hormone levels, electrolyte levels & fluid balance)
What is a negative feedback loop?
- reduces the effect of change and helps maintain balance in the system
- occurs when the output of a system is used to reduce or regulate its own activity
3 components of a negative feedback loop
- Receptors, the cell tissue or organ that detects the change
- Control, the cell tissue or organ that compares the change to normal and initiates a response= often the hypothalamus
- Effectors, the cell, tissue or organ that’s acts to revert the change back to normal
Negative feedback loop of body temperature
- body temperature exceeds 37 degrees
- Nerve cells in skin and brain
- Temperature regulatory center in brain
- Sweat glands throughout body
- Increased heat loss
Blood sugar too high
-Blood sugar too high
- beta cells in pancreas release more insulin
- glucose is taken up by cells and the liver reduces gluconeogenesis
- blood sugar levels fall
Blood sugar too low
- Blood sugar too low
- alpha cells in pancreas release glucagon
- liver increases production of glucose
- blood sugar levels rise
Temperature too high
- Body temperature too high
- Hypothalamus detects a raise in temperature
- Signals to skin to vasodilate and sweat so heat is lost
- body temperature falls
Temperature too low
- Body temp too low
- hypothalamus detects a fall in temp
- signals to skeletal muscle to shiver to generate heat and the skin to vasoconstrict to reduce heat loss
- temp rises
What does CO2 level affect?
Affects pH
CO2 too high
-Hypercapnia (high CO2)
- detected by central (brain) & peripheral (carotid body) chemoreceptors
- brain stem sends signals to diaphragm and intercostal muscles
- person breathes deeper and more rapidly
- more CO2 is blown off
- CO2 levels fall
O2 too low
- Hypoxia (low oxygen)
- detected by central (brain) and peripheral (carotid body) chemoreceptors
- brain stem sends signals to diaphragm and intercostal muscles
- person breathes deeper and more rapidly
- more oxygen is breathed in and absorbed into blood stream
- O2 levels rise
If Chronic O2 levels low
-Kidneys also make more erythropoietin
- signals to bone marrow to make more RBC
- oxygen carrying capacity of blood is increased
