Topic 5- Homeostasis and Response Flashcards
What is homeostasis?
It is all about the regulation of the conditions inside your body (and cells) to maintain a stable internal environment, in response to changes in both internal and external conditions.
Give 2 automatic control systems that regulate your internal environment.
Nervous and hormonal communication systems.
Give 3 examples of what automatic control systems control.
- Body temperature
- Blood glucose
- Water content
Give 3 examples of what automatic control systems control.
- Body temperature
- Blood glucose
- Water content
Give 3 main components your automatic control systems are made up of.
- Receptors
- Coordination centres
- Effectors
Give 3 examples of coordination centres.
- Brain
- Spinal cord
- Pancreas
`
Name the mechanism used by automatic control systems to keep your internal environment stable.
Negative feedback
Give 2 examples when your body uses negative feedback.
When the level of water or temperature gets too high or too low.
What is a stimulus?
A change in the environment.
What does your body do if the level of something is too high? (1)
Receptor detects a stimulus- level is too high.
What does your body do if the level of something is too low? (2)
The coordination centre receives and processes the information, then organises a response.
What does your body do if the level of something is too high? (2)
The coordination centre receives and processes the information, then organises a response.
What does your body do if the level of something is too high? (3)
Effector produces a response, which counteracts the change and restores the optimum level- the level decreases.
What does your body do if the level of something is too low? (1)
Receptor detects a stimulus- level is too low.
Why do the internal conditions of your body need to be regulated?
Your cells need the right conditions in order to function properly, including the right conditions for enzyme action.
What does your body do if the level of something is too low? (3)
Effector produces a response, which counteracts the change and restores the optimum level- the level increases.
Why do the effectors carry on producing the responses?
They’re stimulated by the coordination centres.
What is the problem with effectors producing the responses for too long?
It changes the level too much (away from the ideal).
What does the CNS consist of in vertebrates?
The brain and spinal cord only.
What happens if the effectors change the level too much?
The receptor detects if the level becomes too different and negative feedback starts again.
What are the 4 main parts of the nervous system?
- Central Nervous System (CNS)
- Sensory neurones
- Motor neurones
- Effectors
What does the nervous system allow?
It allows humans to react to their surroundings and coordinate their behaviour.
What are vertebrates?
Animals with backbones.
What is the CNS connected to in mammals?
It is connected to the body by sensory neurones and motor neurones.
What are sensory neurones?
The neurones that carry information as electrical impulses from the receptors to the CNS.
What are motor neurones?
The neurones that carry electrical impulses from the CNS to effectors.
What are effectors?
They are all your muscles and glands, which respond to nervous impulses.
What are receptors?
They are cells that detect stimuli.
Give 2 examples of receptors.
- Taste receptors on the tongue
2. Sound receptors in the ears
What can receptors form?
Part of larger, complex organs
What do effectors respond to?
To nervous impulses and bring about a change.
How do muscles respond to a nervous impulse?
Muscles contract
How do glands respond to a nervous impulse?
Glands secrete hormones.
What is the CNS?
It is a coordination centre- it receives information from the receptors and then coordinates a response.
What is the response carried out by?
Effectors
Describe the transmission of information to and from the CNS.
Stimulus→ Receptors→ CNS (coordinator)→ Motor neurone→ Effector→ Response
How is information carried from the receptors to the CNS?
By sensory neurones
How are electrical impulses carried from sensory neurones to motor neurones?
By relay neurones
How are electrical impulses carried from the CNS to effectors?
By motor neurones
Where are relay neurones found?
In the central nervous system.
What are relay neurones?
The neurones that carry electrical impulses from sensory neurones to motor neurones.
What is a synapse?
It is the connection between two neurones.
What is the nerve signal transferred by?
By chemicals which diffuse across the gap.
What do the chemicals transferred do in synapse?
These chemicals then set off a new electrical signal in the next neurone.
What are reflexes?
They are rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain.
What do reflexes reduce?
The chances of being injured.
What is a reflex arc?
It is the passage of information in a reflex (from receptor to effector).
What do the neurones in reflex arcs go through?
The spinal cord or through an unconscious part of the brain.
Why are reflexes quicker than normal responses?
You don’t have to think about the response (which takes time).
Why does the body have to balance the amount of energy gained and lost?
To keep the core body temperature constant.
What does the thermoregulatory centre in the brain contain?
Receptors that are sensitive to the temperature of the blood flowing through the brain.
How does the thermoregulatory centre receive information about skin temp.?
It receives impulses from temperature receptors in the skin giving information about skin temperature.
What does the thermoregulatory centre do if the temperature is too hot? (1)
Temperature receptors detect that core body temperature is too high.
What does the thermoregulatory centre do if the temperature is too hot? (2)
The thermoregulatory centre acts as a coordination centre- it receives information from the temperature receptors and triggers the effectors automatically.
What does the thermoregulatory centre do if the temperature is too hot? (3)
Effectors, e.g. sweat glands, produce a response and counteract the change.
What does the thermoregulatory centre do if the temperature is too cold? (1)
Temperature receptors detect that core body temperature is too low.
What does the thermoregulatory centre do if the temperature is too cold? (2)
The thermoregulatory centre acts as a coordination centre- it receives information from the temperature receptors and triggers the effectors automatically.
What does the thermoregulatory centre do if the temperature is too cold? (3)
Effectors, e.g. muscles, produce a response and counteract the change.
What does the thermoregulatory centre do if the temperature is too cold? (4)
Body warms up.
What does the thermoregulatory centre do if the temperature is too hot? (4)
Body cools down.
How do some effectors work?
Antagonistically- they’ll work at the same time to achieve a very precise temperature.
What does working antagonistically allow?
This mechanism allows a more sensitive response.
What does the body do if the temperature is too hot?
- Hair erector muscle relaxed
- Blood supply to surface of skin
- Sweat gland produces sweat
How does producing sweat help with cooling down body temperature?
It evaporates from the skin. This transfers energy to the environment.
How does blood supply to surface of skin help reduce the body temperature?
The blood vessels supplying the skin dilate so more blood flows close to the surface of the skin. This is called vasodilation. This helps transfer energy from the skin to the environment.
What does the body do if the temperature is too cold?
- Hairs erect
- No sweat
- Blood supply shut off
How does the hairs standing up help cool the body temperature?
Hairs stand up to trap an insulating layer of air.
What is vasoconstriction?
It is when blood vessels supplying skin capillaries constrict to close off the skin’s blood supply.
Why does the body shiver when it’s cold?
This needs respiration, which transfers some energy to warm the body.
Give the optimum temperature for enzymes in the body.
Around 37°C
What hormone does your body produce if it is in shock?
Adrenaline
What are hormones?
They are chemical molecules released directly into the blood. They are carried in the blood to other parts of the body, but only affect particular cells in particular organs (called target organs).
When do hormones need to control things in organs and cells?
Hormones control things in organs and cells that need constant adjustment.
What do hormones tend to do?
Relatively long-lasting effects.
What are endocrine glands?
Hormones are produced in (and secreted by) various glands, called endocrine glands.
What makes up your endocrine system?
Endocrine glands
Give 6 examples of glands.
- Pituitary glands
- Ovaries
- Testes
- Thyroid
- Adrenal gland
- Pancreas
What does the pituitary gland produce?
Many hormones that regulate body conditions.
Why is the pituitary gland sometimes called the master gland?
These hormones act on other glands, directing them to release hormones that bring about change.
What are ovaries- females only?
They produce oestrogen, which is involved in the menstrual cycle.
What are testes- males only?
They produce testosterone, which controls puberty and sperm production in males.
What is a thyroid gland?
These produce thyroxine, which is involved in regulating things like the rate of metabolism, heart rate and temperature.
What is the adrenal gland?
These produce adrenaline, which is used to prepare the body for a ‘fight or flight’ response.