B5 homeostasis And Response Flashcards
What is homeostasis
Maintaining a stable internal environment
Conditions need to be right in your body and kept steady. Cells need the right conditions in order to function properly
Homeostasis is all about the regulation of conditions inside your body
What do you have in your body to regulate your internal environment
Automatic control system
Both nervous and hormonal communication
Three main components which make up your automatic control system
Cells called receptors, coordination centres (brain, spinal cord and pancreas) and effectors
How does your automatic control system keep your internal environment statement
Use a mechanism called negative feedback. For example, when water gets too high or too low your body uses negative feedback to bring it back to normal.
Negative feedback timeline if a level is too high
- Receptor detects a stimulus - level is too high
- Coordination centre receives and processes the information and organises a response
- Effector produces a response which counteracts the change and restores the optimum level.
The level decreases
Negative feedback timeline if a level is too low
- Receptor detects a stimulus - level is too high
- Coordination centre receives and processes the information and organises a response
- Effector produces a response which counteracts the change and restores the optimum level.
The level increases
The effectors will carry on producing the responses for as long as….
They’re stimulated by the coordination centre. However this might cause the opposite problem and make the level change too much. Receptors will detect if the level becomes too different and negative feedback starts again.
Organisms need to respond to…
Stimuli (changes in environment) in order to survive
What is the nervous system
The nervous system means that humans can react to their surroundings and coordinate their behaviour
Parts of the nervous system
Central nervous system (CNS) - in vertebrates(animals with backbones) this consists of the brain and spinal cord. In mammals the CNS is connected to the body by sensory neurones and motor neurones
Sensory Neurones - neurones that carry information as electrical impulses from the receptors to the CNS
Motor neurones - neurones that carry electrical impulses from the CNS To effectors
Effectors - all your muscles and glands, which respond to nervous impulses
What are receptors
Receptors are cell that detect stimuli.
Examples of receptors
Taste receptors on the tongue, sound receptors in the ears.
What can receptors form
Form part of larger, complex organs
E.g the retina of the eye is covered in light receptor cells
What do effectors respond to
Effectors respond to nervous impulses and bring change
Why are muscles and glands known as effectors
They respond in different ways. Muscles contract in response to nervous impulse, whereas glands secrete hormones.
The Central nervous system is a…. and why
Coordination centre. It receives information from the receptors and then coordinates a response. Response is carry out by effectors
Example of the CNS in action (cat and bird)
- Bird sees cat in the corner of its eye(stimulus)
- Receptors in the birds eye are stimulated. Sensory neurones carry information from the receptors to the CNS.
- CNS decides what to do
- CNS sends information to the muscles in the birds wing(effectors) along motor neurones. Muscles contract and bird flies to safety.
What do synapses do
Synapses connect neurones.
The nerve signal is transferred by chemicals which diffuse across the two.
These chemicals set off a new electrical signal in the next neurone.
What are reflexes
Reflexes are rapid, automatic responses to certain stimuli that don’t involve the conscious part of your brain. Reduce chance of injury
E.g bright light in your eye your pupils automatically shrink so less light gets into the eye
What is the information in a reflex called
Reflex arc
Order of reflex arc
Impulses travel along the Sensory neurone - synapse - relay neurone - synapse - motor neurone - effectors
What are hormones
Chemical messengers sent in the blood
Chemical molecules released directly into the blood. Carried to other parts of body, only affect particular organs(target organs)
What do hormones control
Control things in organs and cells that need constant adjust,net.
Where are hormones produced
Various glands, called endocrine glands. These make up your endocrine system.
