8A. Adaptations Flashcards
What is homeostasis? (3)
- Homeostasis is the physiological regulatory mechanisms that maintain a constant ‘internal environment’ for the organism in the face of changing conditions.
- Enables animals to adjust to summer heat and winter cold
- Farm animals are endotherms - the body temp of livestock maintained outdoors are the same in winter or summer
Explain this graph
If theres a marked disturbance the value leaves the comfort zone and compensatory reactions need to take place to restore the value to its comfort zone
What are biochemical reactions used for? Where do they take place?
- facilitate maintenance
- growth
- production/reproduction
Constant internal environment
What is the general mechanism for homeostasis?
What are the advantages of having multiple sensors and effectors for each function in homeostasis?
- Fail safe - if one fails, the others can carry out the process
- Fine tune - adjustments can be made for a more specific response
- Faster and stronger responses are possible
What type of feedback is usually seen in homeostasis?
The output from effectors feeds back to the sensors, and usually the feedback is negative. This means the output from the effectors will reduce further output by the effector.
What is glucose?
Glucose is the main energy source for the body, particularly the brain.
A single substance who’s homeostasis is maintained by a multitude of means
Which species has the highest and lowest blood glucose levels?
H: Pig
L: Sheep
What happens if blood glucose gets too low?
Brain function is impaired as the brain requires glucose as an energy source.
What happens if blood glucose gets too high?
It can dehydrate cells as water enters blood vessels via osmosis to attempt to dilute the blood glucose.
What are the sensors/control centers/effectors involved in blood glucose homeostasis?
Sensors: pancreas and hypothalamus
Control centers: pancreas and hypothalamus
Effectors: liver, muscle and fat
Explain the importance of this diagram
- BLOOD: Glucose absorbed by small intestine and is in blood stream but has to be excreted
- CELL MEMBRANE: the membrane is not permeable so glucose has to be actively transported
- CYTOPLASM: one its in the cytoplasm, converts to glycogen otherwise more glucose can’t come in
- GLUCOSE - GLUCOSE 6 PHOSPHATE: enzyme
- GLYCOGEN SYNTHESIS: enzymes cause linkage units
- RIGHT SIDE OF GLYCOGEN: in muscles and liver (glycolysis)
- BOTTOM: enzymes play a role in regeneration of glucose, muscle cells only use energy portion but liver does both
Without the uptake of glucose, bgl rise rapidly after a meal and does not come down for many hours
What roles does the pancreas play in glucose homeostasis?
- The pancreas is both a sensor and a control center in glucose homeostasis.
- It contains alpha and beta cells that can detect blood glucose levels.
Explain this graph
- Blood glucose increases
- Pancreatic cells release b cells
- B cells secrete insulin
- Insulin activates enzymes in liver and muscle that convert glucose to glycogen
AND - Insulin increases the carriers that move glucose into cells
- Blood glucose decreases
Describe the process that takes place when blood glucose decreases.
- Decreased glucose
- Pancreatic cells release a cells
- A cells secrete glucagon
- Glucagon activates phosphorylase, which in the liver converts glycogen to glucose; this glucose enters the blood
- Blood glucose increases.
