B9.4 - Homeostasis Flashcards
what is homeostasis?
→ the process of maintaining a stable internal environment
what is a simple process of homeostasis?
→ example of this: cells in our body require certain conditions to function properly. It can’t be too hot or too cold or acidic or alkaline. Needs a good supply of glucose and water.
→ the definition means that we are able to maintain a stable internal environment despite changes outside of our cells
→ our body uses automatic control systems that can recognise when there is a change from optimal conditions.
→ then sends a signal to reverse that change so the levels go back to normal.
what is an automatic control system?
When there is a change from optimal condition → our body sends a signal → reverses the change and then goes back to normal, optimal conditions
what are components of an automatic control system?
- Receptors- detect the changes (such as rises in temperature)
- Coordination centres - interpret the change (brain and spinal cord) and decides what needs to be done
- Effectors - carry out the change (such as; muscles contract, glands secrete hormones etc)
These components take place in different parts of the body and signals are needed for them to communicate
what is the importance of homeostasis?
For our body to maintain a stable internal environment which keeps our body in the best conditions to operate
what is blood glucose concentration?
→ blood glucose concentration describes the amount of sugar in the bloodstream
→ cells need a constant supply of glucose for the process of respiration
what is the negative feedback for an increased concentration in blood glucose concentration?
→ big meal (consists of a lot of carbs)
→ the carbohydrates are broken down in the intestines to glucose molecules
→ the glucose molecules are then absorbed into our bloodstream
→ the blood glucose concentration increases.
→ this increase is detected in the pancreas
→ pancreas secretes a hormone known as insulin into the bloodstream
→ insulin travels around the bloodstream and binds to certain receptors on certain cells
→ it tells the cells to take in some of the glucose floating around in the blood
→ the liver and muscles take up a lot of the glucose molecules
→ all the glucose molecules combine to form glycogen which is a long term storage form of glucose
→ all the glucose is then removed from the bloodstream and the blood glucose concentration decreases.
what is the hormone secreted when blood glucose concentration increases?
insulin
what does insulin do?
→ insulin travels around the bloodstream and binds to certain receptors on certain cells
→ it tells the cells to take in some of the glucose floating around in the blood
→ the liver and muscles take up a lot of the glucose molecules
where is insulin secreted from?
→ pancreas secretes a hormone known as insulin into the bloodstream
what do glucose molecules combine to form?
glycogen which is a long term storage form of glucose
where is the high concentration of blood glucose detected?
→ this increase is detected in the pancreas
what is the negative feedback for a decreased concentration in blood glucose concentration?
→ when we skip a meal and blood glucose levels are low
→ the pancreas detects the low concentration of blood glucose
→ secretes glucagon into the bloodstream
→ glucagon travels around the body and binds to lots of different cells, mainly liver cells
→ liver cells take the glycogen and break it down into lots of glucose molecules
→ the liver release glucose molecules into the blood
→ brings blood glucose concentration back to normal
→ all cells have a good supply of glucose needed for respiration
what is the hormone secreted when blood glucose concentration decreases?
glucagon
what does glucagon do?
→ glucagon travels around the body and binds to lots of different cells, mainly liver cells
→ liver cells take the glycogen and break it down into lots of glucose molecules
→ the liver release glucose molecules into the blood
→ brings blood glucose concentration back to normal
where is glucagon secreted from?
the pancreas
what is thermoregulation?
is the control of our internal body temperature
what is the thermoregulation centre?
A part of the hypothalamus in the brain
Acts as a thermostat for our body
how is changes detected in our body temp?
To help it we have receptors around our body which detects changes in body temp. Most of the receptors are found in the skin or blood vessels.
what are mechanisms our body uses to warm up?
→ conserve heat and generate more
- -> To conserve heat
- Constrict our blood vessels that lie near the surface of our skin (vasoconstriction)- This means less blood flows near surface so less heat energy is lost to the cool environment
- Contract erector muscles which makes our hairs stand on end
- This traps a small layer of insulating air
- Harder to lose heat from skin and helps keep ups warm
- -> To generate more heat
- We shiver
- Muscles contract automatically
- Requires a lot of energy for respiration
- Results in a lot of heat energy being released as waste
- Warms the body up
what are mechanisms our body uses to cool down?
- Erector muscles relax and allow hairs to fall flat
- Blood vessels expand (vasodilate)
- More heat energy to be transferred to surroundings
- Warm blood is passing close to skin surface - Produce sweat
- Mixture of water and salt released to surface of skin
- As sweat evaporates, it takes heat energy from our body along with it
- Because it requires a lot of energy to evaporate water
- Heat is lost and leaves us cooler
