Homeostasis and response - The nervous system Flashcards
what are the names of the 2 parts of the nervous system
- Central nervous system (brain and spinal cord)
- the peripheral nervous system – nerve cells that carry information to or from the CNS
what is the role of the nervous system
enables humans to react to their surroundings and co - ordinate their behaviour
what is the CNS connected to the body by?
sensory 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
Nerve cell specializations
long axon insulated with a fatty sheath which are long so that they can carry messages up and down the body
- dendrons which branch further as dendrites which receive incoming impulses from other neurones
receptor to effector line
Stimulus → receptor → coordinator → effector → response
what is the CNS
A co- ordination centre, which recieves information from receptors then co-ordinates a response, carried out by effectors
what order does the reflex arc go in
Stimulus → receptor →sensory neurone→ relay neurone→ motor neurone→ coordinator → effector → response
what are relay neurones and what do they do
located in the spinal cord, these neurones connect sensory neurones to motor neurones.
what are synapses
the gap where two neurones meet
what is the cerebrum/ cerebral cortex responsible for
controls intelligence, personality, conscious thought and high-level functions, such as language and verbal memory.
what is the cerebellum/ responsible for
controls balance, co-ordination of movement and muscular activity.
what is the medulla responsible for
controls our heart and breathing rate
3 reasons why the brain is so hard to study
- it is protected by the skull, so it is difficult to access
- structures of the brain are complex, so it’s difficult to work out which parts of the brain carry out which function
- brain is delicate and easy to damage
how does electrical stimulation work
- by stimulating the brain with a current and monitoring the effects on the persons behaviour
what are nerve cells (neurones) adapted to do
to carry electrical impulses from one place to another
examples of effectors carrying out a response
- a muscle contracting
- a gland releasing a hormone
what is a reflex action
an automatic and rapid response to a stimuli
how does the reflex arc work
- the stimulus is detected by a receptor
- electrical impulses now pass from the receptor along a sensory neurone to the CNS
- at the end of the sensory neurone, there is a junction called a synapse
- at the synapse a chemical is released and these chemicals diffuse across to a relay neurone in the central nervous system where it triggers an electrical impulse - the electrical impulse now passes along the relay neurone and reaches another synapse
- chemical is released again and diffuses and the chemical triggers an electrical impulse in a motor neurone
- the electrical impulse now passes down the motor neurone to an effector
- effector carries out response
what happens at a synapse
- an electrical impulse travels through the first axon
- this triggers the nerve ending of a neurone to release chemicals called neurotransmitters
- these chemicals diffuse across the synapse and bind with receptor molecules on the membrane of the second neurone
- The receptor molecules on the second neurone bind only to the specific neurotransmitters released from the first neurone. This stimulates the second neurone to transmit the electrical impulse.
what is the hypothalamus responsible for
regulates temperature and water balance within the body
advantages of electrical stimulation
- they can observe the electrical activity in the brain
- allows us to narrow down specific regions to their functions
disadvantages of electrical stimulation
people can experience hunger, anger, fear or thirst whilst a relevant part of the brain is being stimulated, as they do the procedure whilst the patient is still conscious
what do MRI scans do
- use strong magnetic fields and radio waves to show details of brain structure and function
- they are able to show exactly which part of the brain is affected
- allow us to look at which parts of the brain are most active during different activities
Problems with brain surgery
-drugs do not always reach the brain through the membranes which surround it
- surgery is difficult because it is not fully understood what each part of the brain actually does, so may cause unintended damage
- surgery can cause unwanted side effects which may ruin a persons quality of life
what does the brain do
controls complex behaviour
what is the brain made out of
billions of interconnected neurones
features of the nervous system
- fast, rapid and precise
- effects are short lived
what does the brain do
controls complex behaviour such as language
3 ways scientists study the brain
- observing patients who have suffered brain damage
- electrically stimulate the brain
- use MRI scans
why do scientists observe patients with brain damage
- by looking to see where the damage has taken place, they can try to link that part of the brain to its function
