B5 - Homeostasis & Response Flashcards
(32 cards)
What is the definition of homeostasis?
It is maintaining conditions within the body at the ideal level
The regulation of the conditions inside your body (and cells) to maintain a stable environment, in response to changes in both internal and external conditions
Maintaining a constant environment in the body
Give some examples of systems that help regulate the internal environment of an individual
The nervous system The hormonal (endocrine) system
What are the 3 main components that all automatic control systems are made from?
Receptor cells
Coordination centres (including bran, spine and pancreas)
Effectors
What does a negative feedback system do?
It counteracts changes - for example, if the body gets too hot, it will do something to counteract that, making the body go colder until it is at normal temperature again
Give some examples of things in the body that need to be kept at an ideal level through homeostasis and often negative feedback loops
Temperature Water levels Some other stuff Glucose levels in the blood Ion levels
Give an example of something that does NOT work in a negative feedback loop, and why
Adrenaline - because this is only used in fight or flight situations, so constantly running on adrenaline would cause the body to die from exhaustion
Also, pretty sure that adrenaline takes away energy from digestive system, so food is not digested efficiently whilst adrenaline is present
What happens through the negative feedback loop when levels are too low?
Receptors detects a stimulus or change in environment - the level is too low
The coordination centre receives and processes this information, then organises a response
The effector produces a response, which counteracts the change and restores the optimum level (the level is increased to this optimum level)
Homeostasis cannot be controlled, therefore it is automatic. True or false?
True
Talk about what happens through the negative feedback loop when levels are too high
Receptors detects a stimulus or a change in the environment - the level is too high
The coordination centre receives and processes the information, then organises a response
The effector produces a response which counteracts the change and restores the optimum level - the level decreases back to the ideal level
How long will effectors work for?
They will carry on producing their responses for as long as they’re stimulated by the coordination centre. This might cause the opposite problem - the level may change too much from the optimum level in the opposite way. Luckily, the receptors detect if the level becomes too different again, and negative feedback starts again
What does CNS stand for?
Central Nervous System - Brain, spine and nerves
Give the flow diagram to show a reflex arc
Receptor Sensory neurons Relay neuron (in CNS) Motor neurons (Effector) Response
What are 2 ways that a reflex action is different from an action controlled by hormones?
1) Reflexes act much quicker, (and are almost immediate
whereas hormones travel in the blood until they are detected, which takes longer)
2) Hormones have to be released into the bloodstream to travel, whereas reflexes travel through neurons
What are the following hormones that these glands produce, and what do they do?
a) Pituitary gland in the brain
b) Thyroid
c) Pancreas
d) Testes
e) Ovaries
f) Adrenal
a) Produces lots of hormones (LH, FSH being some), all about the growth of the body into adulthood
b) Thyroxine. Helps with metabolism
c) Insulin and glucagon. Controls the blood glucose
d) Testosterone. Puberty stuff
e) Oestrogen and progesterone. Menstrual cycle stuff
f) Adrenaline. For fight or flight responses & dangerous situations
What does CNS stand for? What does it do?
Central Nervous System. Refers to the brain and spine chord
It coordinated the response - it receives information from the receptors and then coordinates a response, which is carried out by effectors
What is the nervous system made from?
The CNS - central nervous system, meaning brain & spinal chord
Sensory neurons - Neurons that carry information as electrical impulses from receptors to the CNS (relay neurons between sensory neurons and motor neurons in the CNS)
Motor neurons - The neurons that carry electrical impulses from the CNS to effectors
Effectors - All muscles and glands which respond to nervous impulses
What are the differences between receptors and effectors?
Receptors are the cells that detect stimuli. There are many different types of receptors, such as taste receptors on the tongue, sound receptors in the ear. Receptors can form part of larger, complex organs (e.g. the retina of the eye is covered in light receptor cells)
Effectors respond to nervous impulses and bring about a change. Muscles and glands are known as effectors - as they respond in different ways. Muscles contract in response to a nervous impulse, whereas glands secrete hormones
In short - receptors detect, effectors act on that detection (once it has gone through neurons and the CNS)
Muscles and glands are types of what?
Effectors
What is the nervous system’s function?
Means that humans can react to their surroundings and coordinate their behaviour
How are reflexes even faster than normal responses to stimuli?
Because usually the neurons transmit the new information to the brain so it can decide what to do. Whilst this is extremely fast, it may not be fast enough to get you out of harms way. |So a reflex goes to the spinal cord instead, which is a shorter journey. Also, it’s why you have a reflex without thinking, as it isn’t something your brain is aware of until after it happened
Rearrange these stages of the reflex arc:
1) When the impulses reach a synapse between the relay neuron and the motor neuron, the same thing happens - chemicals are released and cause electrical impulses to be sent along the motor neuron
2) Because you don’t have to think about the response (which takes time), it’s quicker than normal responses
3) When a stimulus is detected by receptors, impulses are sent along a sensory neurone to a relay neurone in the CNS
4) The neuron in the reflex arcs go through the cord or through an unconscious part of the brain
5) The effector then takes action, usually a muscle contracts to move a body part away from danger, but it depends on the context
6) When the impulses reach a synapse between the sensory neurone and the relay neurone, they trigger chemicals to be released. These chemicals cause impulses to be sent along the relay neurone on the other side of the synapse
7) The impulses then travel along the motor neurone to the effector (usually a muscle)
4) The neuron in the reflex arcs go through the cord or through an unconscious part of the brain
3) When a stimulus is detected by receptors, impulses are sent along a sensory neurone to a relay neurone in the CNS
6) When the impulses reach a synapse between the sensory neurone and the relay neurone, they trigger chemicals to be released. These chemicals cause impulses to be sent along the relay neurone on the other side of the synapse
1) When the impulses reach a synapse between the relay neuron and the motor neuron, the same thing happens - chemicals are released and cause electrical impulses to be sent along the motor neuron
7) The impulses then travel along the motor neurone to the effector (usually a muscle)
5) The effector then takes action, usually a muscle contracts to move a body part away from danger, but it depends on the context
2) Because you don’t have to think about the response (which takes time), it’s quicker than normal responses
Where are synapses and what do they do?
They’re at the end of neurones, and they connect 2 neurones.
How do synapses work?
AT the end of one neuron, a nerve impulse arrives. his causes chemicals to be released into the gap known as the synapse. They diffuse across to the other side (the start of the next neurone). These chemicals - once found by the receptors on the opposite side - then cause a new electrical impulse in the next neurone. SO, the electircal impulse travels
What are reflexes?
Fast, automatic responses to certain stimuli that don’t involve the conscious part of the brain - they can reduce the chance of being injured, as it happens faster to get you out of harm’s way sooner
