Homeostasis Flashcards
How do cells work best?
If they have correct:
Temperature
Water level
Glucose concentration
What is homeostasis?
Ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes.
Maintaining balance!
What do we need to keep balanced inside the body?
Conc O2 and CO2 pH Conc nutrients, waste, salt and other electrolytes Water content Body temp
What organs are involved in homeostasis?
Hypothalamus- control centre Pituitary gland (ADH) Lungs Liver Pancreas, kidney, muscles and skin
What are needed for homeostasis?
Receptors ,communication system and effectors.
What do receptors do?
Detect if a level is too high or too low- info communicated via nervous or hormonal system to effectors.
What do effectors do?
Respond to counteract change- bring level back to normal.
What mechanism restores level to normal?
Negative feedback.
What happens if the change is too big?
Effectors may not be able to counteract it, eg. A huge drop in temp.
What is a homoiotherm?
Organism that can regulate their own body temp internally independent of external temp ( warm blooded)
What is a poikilotherm?
Organisms which can’t regulate their own temp. Cold blooded
Do animals with a large surface area compared to volume lose heat faster or slower?
Will lose heat faster eg. Mouse or bird
Do animals with a small surface area compared to volume lose heat fast or slow?
Slower- larger interior volume. Skin on outside smaller area than internal volume. Maintain their temp better.
How do we reduce body temp through thermoregulation?
Sweating heat evaporates.
Hairs lie flat less air trapped
Vasodilation - Arterioles dilate, heat lost by radiation and convection.
How does the body increase body temp?
Shivering- muscle contraction
Hormones released thyroxine to increase metabolism
Hair stand up piloerection
Vasoconstriction keeping blood near core
Where is the thermoregulatlory centre?
Hypothalamus.
What hormone reduces blood suger?
Insulin
What hormone raises blood sugar?
Glucagon
How is glucose stored in the liver?
As glycogen
Briefly describe the process of blood sugar regulation?
Receptors detect low/high blood sugar. Pancreas detects and releases insulin or glucagon depending. Blood sugar returns to normal.
What cells release glucagon?
Alpha cells
What cells release insulin?
Beta cells from islets of Langerhans.
What is diabetes?
Inability to regulate blood sugar
What is osmoregulataion?
Water control - controlled by hypothalamus
What organs are involved in negative feedback?
Pituitary gland and kidneys
Where are the osmoreceptors located?
Hypothalamus
What happens when there isn’t enough water?
Hypothalamus sends signal to pituitary gland. ADH released and enters kidney stimulating it to reabsorb H2O. Smaller amount of conc urine produced.
What happens when there is too much water?
Hypothal sends message to pituitary. Pituitary slows release of ADH. Less ADH enters kidney, more urine, less conc. is produced
What is the function of the kidneys?
Clean blood by filtering out unwanted material eg. Urea, salt, water.
Where is urea made?
Liver
What happens in the kidneys?
Filtration-blood from renal artery-enters tubule area of capillary-capillary bed formed- blood filtered so all small particles go into Bowmans capsule.
Sugar and water reabsorbed.
Urea and excess H2O excreted as urine
What is dialysis?
Failure of kidneys excrete urine.( uses a SPM surrounded by dialysis fluid.
