Homeostasis and the nervous system Flashcards
What does Homeostasis mean ?
Homeostasis is all about the regulation of the conditions inside your body ( and cells) to maintain a stable interal environment, including response to changes in both internal and external conditions.
Why do we need to maintain a stable internal environment?
The conditions in your body need to be kept steady, even when external environment changes. This is really important because your cells need the right conditions in order to function properly, including the right conditions for enzyme action.
How does our bodies regulate our internal environment?
You have loads of automatic control systems in your body, including both nervous and hormonal communication systems. For example, there are systems that maintain your body temperature, your glucose level and your water content.
What are all the automatic control systems made up of ?
They are made up of three main components which work together to maintain a steady condition - cells called receptors, coordination centres (including the brain, spinal cord and pancreas) and effectors.
How does your automatic control systems keep your internal environment stable by using a mechanism called negative feedback ?
When the level of something ( e.g water or temperature) gets too high or too low, your body uses negative feedback to bring it back to normal.
What is a stimulus?
A change in the environment.
What happens when a receptor detects a stimulus - level is too high ?
The coordination centre receives and processes the information, then organises a response.Effectors produce a response, which counteracts the change and restores the optimum level - the level decreases.
What happens when a receptor detects a stimulus - level is too low ?
The coordination centre receives and processes the information, then organises a response. Effectors produce produces a response which counteracts the change and restores the optimum level - the level increases.
What could go wrong with negative feedback ?
The effectors will just carry on producing the responses for as long as they’re stimulated by the coordination centre. This might cause the opposite problem - making the level change too much . Luckily the receptors decrease if the level becomes too different and negative feedback back starts again.
Why do we have a nervous system?
A nervous system means that humans can react to their surroundings and coordinate their behaviour.
What are the 5 parts of the nervous system?
Central nervous system
Sensory Neurones
Motor Neurones
Effectors
Receptors
What is the Central Nervous System ?
In mammals, the CNS is connected to the body by sensory neurones and motor neurones. It is a coordination centre - it receives information from the receptors and then coordinates a response. The response is carried out by effectors.
What are sensory Nuerons?
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 ?
All your muscle and glands, which responds to the nervous impulses.
What are Receptors and Efforts form?
Part of complex organ
What are receptors?
They are cells that detect stimuli, there are many different types of receptors such as taste and sound receptors, receptors can form part of larger, complex organs. E.g. the retina of the eye is covered in light receptor cells.
What do effectors do ?
They respond to nervous impulses and bring about change. E.g. Muscles contract in response to a nervous impulses, whereas glands secrete hormones.
Example:
When a bird spits a cat skulling towards it (this is the stimulus) The receptors in the bird’s eye are stimulated. Sensory neurones carry the information from the receptors to the CNS. The CNS decides what do to about it. The CNS sends information to the muscles in the bird’s wings (the effectors) along motor neurones. The muscles contract and the bird flies away to safety.
