Homeostasis and Response Flashcards
What is homeostasis?
The regulation of the conditions inside your body, to maintain a stable internal environment.
Why is homeostasis important?
It regulates the conditions in your body,
- This is necessary for making sure your body is at the right temperature so enzymes work effectively,
- Your body temperature will change depending on the external environment, if it is cold your body will heat up to keep you from being warm,
- Your nerve and hormonal systems are also used to regulate your bodies conditions, such as blood sugar levels and oestrogen during a woman’s period.
What are the three main components that work together to make up the automatic control systems?
- Receptors,
- Coordination centres (brain, spinal cord, pancreas),
- Effectors.
What method does your automatic control system use when trying to keep your internal environment stable?
Negative feedback:
This counters the changes that your body experiences.
How does negative feedback work?
- The receptor picks up a stimulus (levels of glucose in blood are too high),
- The coordination centre receives and processes the information than organises a response (knows that levels of glucose must decrease),
- The effectors produce a response, which counteracts the change and restores the optimum level (The level of sugar in the blood is reduced).
What is a possible issue with the effectors?
They keep changing the conditions in your body until told other wise by a different stimulus from the receptors.
For example, if the blood sugar levels are too high, the effectors lower the levels, but may lower the levels of glucose in the blood to be too low, which is dangerous. Luckily the receptors pick up on differences in your body quickly so the effectors can keep your body at optimum conditions.
What is the function of the nervous system?
To produce a reaction from your body after sensing a stimulus.
What are the different parts of the nervous system?
- CNS (central nervous system),
- Sensory neurones,
- Motor neurones,
- Effectors.
What is the CNS?
- Made up of the brain and spinal cord only, and is located mainly in the vertebrae of animals,
- The CNS is connected to the body by the sensory neurones and motor neurones.
What is the Sensory neurone?
The neurones that carry information as electrical impulses from the receptors to the CNS.
What is the motor neurones?
The neurones that carry electrical impulses from the CNS to effectors.
What are effectors?
- They respond to nervous impulses and and bring about a response,
- All muscles and glands are an example of effectors,
- They respond to nervous impulses, for example, may cause muscles to contract or glands to secrete hormones.
What are receptors?
- The cells that detect stimuli,
- There are loads of different receptors like taste and sound receptors on your tongue and in your ear respectively,
- Receptors can create large complex organs like the retina in the eye, the retina is covered in light receptors.
What are the stages of the nervous system?
- Stimulus,
- Receptor detects the stimulus,
- The sensory neurone sends information from the receptor to the CNS using an electrical pulse,
- The motor neurone sends information from the CNS (decision from the CNS) to the effector using an electrical impulse,
- The effector carries out the instruction from the CNS,
- Then the muscle responds based on the effector.
What is a synapse?
The connection between two neurones, it is a small gap where the two neurones connect.
How does an electrical pulse travel across the synapse?
A pulse reaches the synapse (gap in between two neurones),
A chemical is released from the neurone with the impulse and the chemical diffuses across the synapse to the other neurone.
These chemicals then set off a new electrical impulse in the next neurone, identical to the one before.
What are reflexes?
These are automatic reactions that your body does in response to a stimulus, this response and reaction does not happen within the conscious part of the brain.
What is the main advantage of reflexes?
They prevent injury.
What is a reflex arc?
The passage of information for a reflex to take place.
What is the pathway of information for a reflex arc?
- Your receptors sense a stimulus,
- Information is sent from the receptors to the CNS via the sensory neurone,
- The sensory neurones electrical impulse travels across the synapse onto the relay neurone in the CNS,
- The impulse is then transferred across a synapse onto the motor neurone,
- The impulse then goes to the effectors and the muscles contract.
Where is the relay neurone found?
CNS.
What is the method for the ruler drop test/ reaction time?
- The person being tested should not have taken any caffeine, or drugs that will enhance performance before the test,
- The person should have their arm resting on the edge of the table, their index finger and thumb should be open, leaving a gap for the ruler to be dropped,
- A separate person should align the 0cm mark of the ruler with the top of the fingers,
- This person should drop the ruler with no warning, the person catching should try and catch the ruler in between their two fingers,
- The length on the ruler at their fingers is their reaction time in cm,
- This test should be done 3 times to take an average (mean),
- Then do the same with the performer drinking a fizzy drink/ caffeine before so their reaction time should increase,
- See the difference in reaction time, the second round should be a smaller distance/ quicker reaction time.
What are other methods to test for reaction time?
computer tests:
- clicking a mouse when a stimulus appears,
- computers are more precise as software can be used to get the exact time in milliseconds,
- it is also completely random, the performer cannot predict when the dot will appear, unlike the ruler drop because body language can give it away.
What are the three parts of the brain in the GCSE spec and what is their function?
> medulla - controls unconscious activity (breathing),
Cerebellum - responsible for muscular contractions,
Cerebral cortex - responsible for conscious things (intelligence, memory and language)
Where is the medulla located?
Near the spinal cord.
Where is the cerebral cortex located?
The top of the brain, the wrinkly part.
Where is the cerebellum located?
The bottom right of the brain, opposite the medulla.
What are the three methods used to study the brain?
- Studying patients with brain damage
- Electrically stimulating the brain,
- MRI scans
How does studying patients with brain damage help scientist to learn about the brain?
If there is a part of the brain which is damaged the body will be effected, you can then determine the role of this part of the brain by looking at the damage and change the person undergoes
How does electrically stimulating a part of the brain help scientists to learn about the brain?
When the brain is stimulated by an electrode placed on the tissue, something will happen, depending on what happened you can find out the function of the part of the brain that was stimulated.
For example, we now know that Parkinson’s can be treated using electrical stimulation of the brain to prevent muscle tremors.
How does an MRI scan help scientists to learn about the brain?
An MRI scan makes a very detailed image and shows the activity of the brain, it can show what parts of the brain are active when doing certain tasks. For example, what part of the brain is used when trying to recall a memory or listening to music.
What are the risks of experimenting on brains?
- physical damage to the brain,
- increased problems with a disorder (speech issues)
What is the scelra?
A tough supporting wall of the eye.
What is the cornea and its’ purpose?
A transparent outer layer in front of the eye that refracts light onto the retina.
What is the iris and its’ purpose?
The coloured part of your eye, it has muscles that control the diameter of the pupil, this controls the amount of light that can enter the eye at once.
What is the lens and its’ purpose?
A convex tissue that is transparent, it focuses light onto the retina’s light receptors.
What are the ciliary muscles and the suspensory ligaments and what do they do?
An antagonistic pair that controls the shape of the lens to bend light effectively.
What is the retina and its’ purpose?
A group of light receptors at the back of the eye that receive light and turn the image into an electrical impulse.
What is the optic nerve and its’ purpose?
A nerve at the back of the eye that carries impulses from the retina to the brain.
Why does the amount of light entering the eye have to be controlled?
Too much light onto the retina will damage it.
How does the iris control the shape of the lens?
Circular muscles contract and radial muscles relax when there is too much light, this constricts the pupil,
Circular muscles relax and radial muscles contract when here is too little light, this dilate the pupil.
Why does the pupil need to dilate and constrict?
> Dilate - to allow more light to enter the eye when there is little light,
Constrict - to stop very bright/ a lot of light entering the eye and damaging the retina.
How do we focus on objects that are further away or closer?
The lens either becomes slimmer and taller, to focus the light a little (focus on far away object),
or gets fatter and shorter to focus the light a lot (focus on closer object).
How does the ciliary muscles and suspensory ligaments work together to help focus light?
When focusing on a close object: - Ciliary muscle contracts, - Suspensory ligament relaxes. When focusing on a distant object: - Ciliary muscles relax, - suspensory ligaments contract.
Why are some people long sighted?
When someone is long sighted, their lens does not refract the light enough, therefore the light actually focuses behind the retina.
Why are some people short sighted?
When someone is short sighted, refracts the light too much, therefore the light actually focuses in front the retina.
How do you treat long sightedness?
You wear glasses with a convex lens.
How do you treat short sightedness?
You wear glasses with a concave lens.
How do you treat vision defects?
- Glasses
- Contact lens,
- Laser eye surgery,
- Replacement lens surgery
How do contact lens’ work?
They are tiny lenses that sits on the surface of your eye to help bend the light correctly, They are very convenient for sports because they do not get in the way like glasses, they are also invisible and do not effect appearance.
what are the two types of contact lenses?
Hard lenses and soft lenses, soft lenses are mores comfortable but carry more risk of infection.
How does laser eye surgery work?
The tissue in the cornea is vaporised by a laser, making the cornea thinner, will help with short sightedness, changing the shape of the cornea will help with long sightedness.
However, there is a chance (like will all surgeries) the the eye could become infected during the procedure.
How does replacement lens surgery work?
The lens of the patient is removed and replaced by a transparent plastic lens, this will fix the vision of the patient.
However, since the surgery operate within the eye, there is a higher risk and chance of infection compared to laser eye surgery or contact lenses. The retina could also be damaged because the surgery operates inside the eye.
What part of our body is responsible for the regulation of temperature?
- There is a thermoregulatory centre in the brain which contains receptors that are sensitive to the blood temperature in the brain,
- Receptors in the skin also send signals to this part of the brain so that the thermoregulatory centre can act depending on the information it gets form the skin/ blood temp.
How does the thermoregulatory centre in the brain change the temperature in your body?
Using negative feedback.
Explain what happens when humans core temperature is too high?
- Temperature receptors pick up a high temperature,
- The thermoregulatory centre receives impulses from the receptors and instantly sends an impulse to the effectors to act on the increase in core heat,
- The effectors produce a response, e.g. sweat glands release sweat to cool down the body.
Explain what happens when humans core temperature is too low?
- Temperature receptors pick up a low temperature,
- The thermoregulatory centre receives impulses from the receptors and instantly sends an impulse to the effectors to act on the decrease in core heat,
- The effectors produce a response, e.g. muscles produce a response,
Some effectors work antagonistically, one muscle will heat up, while the other cools down in order to create an average temperature.