Nervous System Flashcards
What are the stimuli and receptors for sight?
Light
Photoreceptors
What are the stimuli and receptors for hearing?
Sound
Auditory receptors
What are the stimuli and receptors for smell?
Chemicals in air/odour
Olfactory receptors or chemoreceptors
What are the stimuli and receptors for taste?
Chemicals
Chemoreceptors
What are the stimuli and receptors for touch?
Mechanical forces, pressure
Mechanoreceptors
What are the ‘other senses’ and their receptors?
Changes in temp - thermoreceptors
Blood pressure - baroreceptors
Body positioning - proprioreceptors
What does the human nervous system consist of?
Stimulus
Receptor
Coordination centre (CNS)
Effector (muscle/gland)
Response
What does CNS stand for, and what is it?
Central nervous system, consists of spinal cord and brain. It processes signals and coordinates how body should respond
What must you say when talking about an effector muscle in a nervous system question?
(And glands)
That the muscle contracts to bring about the response
(Glands secrete/release hormones/chemicals)
What is the PNS?
The peripheral nervous system
Consists of motor and sensory neurones that carry information between receptors, CNS and effectors
How is information carried in the nervous system?
By electrical impulses in neurones (nerve cells)
When does information go via the brain, and when via your spinal cord?
If you are in pain, or an unexpected situation eg. a ball is thrown at your face, it goes via spinal cord, otherwise via your brain (for conscious thought)
Structure of a sensory neurone?
Spindly dendrites at receptors, connected to axon terminals at end by the axon. Axon is coated in a myelin sheath made of fatty schwann cells. Cell body sticks out of axon.
Structure of a motor neurone?
Dandelion-clock-like structure of dendrites with cell body in middle connect to axon terminals at emd via axon. Axon is the same as in a sensory neurone, just without the cell body
Please look at your book for neurone structures
Please diva 😛
How is the nerve cell adapted for its function?
- long axon to carry messages over long distances
- axon insulated by fatty myelin sheath to increase speed of electrical impulses along neurone
- tiny branches (dendrites) at each end recieve incoming nerve impulses from other neurones
What is multiple sclerosis?
- myelin sheath is attacked by immune system, leaving axon fibre exposed
- either electronic impulse travels slower due to lack of myelin sheath, so by time it reaches CNS, it decided to not bother sending an impulse
- or axon fibre is damaged too, so no signal sent to CNS
What is a reflex action?
A way for the body to automatically and rapidly respond to a stimulus to reduce any further damage to the body. Doee not involve any conscious part of the brain
What is the pathway of a reflex action, and what is it called?
Stimulus
Receptor
Sensory neurone
Relay neurone in spinal cord
Motor neurone
Effector
Response
It is called a reflex arc
Why does a reflex arc go through spinal cord rather than the brain?
It is a faster route for a more rapid response
A message is still sent to the brain, but only after the response had been enacted
What is a synapse?
The gap between neurones (neurones don’t link together physically)
Electrical impulses pass across synapse using chemical transmitters
Describe the process of an impulse passing across a synapse
- electrical impulse arrives at pre-synaptic terminal
- causes vesicles (containing a chemical called a neurotransmitter) to be released into synaptic cleft
- neurotransmitters diffuse across synaptic cleft and bind to receptors on post-synaptic on dendrite of other neurone.
- second neurone is stimulated to transmit the electrical impulse
- takes about 0.5ms in total
What is the synaptic cleft?
The actual gap between two neurones
What is a reaction time?
The time it takes your body to react to a stimulus
