Nervous system Flashcards
what does the central nervous system-CNS consist of
the brain and the spinal cord
what does the peripheral nervous system-PNS consist of
the nerves leading to and from the CNS
e.g. spinal nerves
what does a typical nerve contain
sensory and motor neurons and ganglia
define neurons
neurons are nerve cells which are specialised to carry impulses
what is the function of sensory neurons
sensory neurons transmit impulses from sense organs toward the central nervous system
what is the function of interneurons
interneurons transmit impulses within the CNS from sensory and motor neurons
what is the function of motor neurons
motor neurons transmit impulses away from the CNS to muscle fibres and glands =effectors
define receptors
receptors are sensory cells that detects stimulus or a change in environment and generate impulses
define effectors
effectors are muscles or glands which are capable of producing a response
description and function of cell body
- it contains nucleus surrounded by cytoplasm and organelles such as mitochondria
- function is it produces neurotransmitter chemicals such as dopamine
description and function of axon
- elongated nerve fibre
- its function is to carry impulses away from the cell body
description and function of dendrites
- branched nerve fibres generally
- its function is to receive and transmit impulses toward the cell body
description and function of myelinsheath
- fatty membrane around the nerves
- both insulates and speeds up impulse transmission
function of schwan cell
-produces the myelin sheath
function of axon terminals
- neurotransmitter swellings release chemicals called neurotransmitters e.g. dopamine
- dopamine is stored in vesicles within the neurotransmitter swelling before being released
what is an impulse
- an impulse is an electrical message
- flow of positive ions carried by a neuron
what does the transmission of a nerve impulse require
- ions
- energy in the form of ATP
what are the characteristics of nerve impulses
- THE THRESHOLD OF SIMULATION
- the threshold is the minimum level of stimulus needed for impulse transmission. below the threshold no impulse is generated.
e. g. lukewarm water is below the threshold so no impulse is generated - THE ALL OR NOTHING EFFECT
- the impulse will travel the entire length or not at all: once started it cannot be stopped - THE REFRACTORY PERIOD
- the timespan after impulse transmission when stimulus fails to cause a response - SPEED OF IMPULSE
- impulses are faster when myelin sheath is present and when the diameter of the nerve fibre is greater
define synapse
the synapse is a region where two neurons come into close contact allowing impulses to pass from one neuron to another
what is a reflex action
is an automatic involuntary response to a stimulus
give examples of reflex actions
- coughing
- sneezing
- blinking
suggest an advantage of reflex actions
- fast response
- protection
what is the function of meninges
protects the CNS
how many layers are present in meninges
3 layers
what is the synaptic cleft
-the synaptic cleft is a tiny gap between 2 neurons at the synapse
draw diagram of the synapse
see diagram in the manual
give an account on how neurotransmitters work
- impulse arrives at neurotransmitter swelling
- ions stimulate the vesicles to fuse with the cell membrane and release neurotransmitter
- neurotransmitter diffuses across the synaptic cleft chemically transmitting the impulse to the next neuron
- neurotransmitter reacts with receptors
- an impulse is therefore transmitted to the next neuron
- following impulse transmission the neurotransmitter is broken down by enzymes and reabsorbed by the presynaptic neuron (where it is used to make new neurotransmitter)
suggest a possible role of drugs in relation to the nervous system
a drug can inhibit or enhance the transmission of an impulse
what are the main functions of the synapse
- to transmit impulses from one neuron to another or to an effector
- to control the direction of the impulse
- to protect against over stimulation of effectors
- impulses are prone to chemical alteration
name a disorder of the nervous system and give a possible cause of the disorder and a means of treatment
cause: Parkinson’s disease
cause: lack of neurotransmitter chemical dopamine
treatment: drugs are given that mimic the action of dopamine
differentiate between the cerebrum and the cerebellum
- cerebrum is located in the forebrain
- cerebellum is located in the hindbrain
what does grey matter consist of
-mostly cell bodies
what does white matter consist of
mostly axons
what is the function of the cerebrum
- controls voluntary actions such as movement
- controls memory and learning
what is the structure or the cerebellum
-it is second largest part of the brain and is highly folded
what is the function of the cerebellum
-controls balance and coordination
what does the medulla oblongata do
-connects the brain to the spinal cord
what is the structure of the medulla oblongata
-has clusters of nerve cells
what is the function of the medulla oblongata
-controls involuntary actions such as breathing and heartbeat
where is the hypothalamus located
-below the thalamus and connected to the pituitary gland
what is the function of the hypothalamus
-regulates homeostasis by monitoring osmoregulation, thermoregulation and blood pressure
where is the pituitary gland located
- located below and attached to the hypothalamus
- not part of the brain itself
what is the function of the pituitary gland
secretes TSH
TRUE or FALSE the cerebrum is the largest part of the brain
-TRUE
what is the cerebrum composed of
> 2 hemispheres -right hemisphere and left hemisphere
- right hemisphere controls the right side of the body and specialises in art, music, and emotional response
- left hemisphere controls the left side of the body and specialises in hand use, analysis and logic
what is the outer part of the cerebrum
- the cerebral cortex
- is highly folded
draw a labelled diagram of the interneuron
see diagram in manual
draw a labelled diagram of a motor neuron
see diagram in manual
draw a labelled diagram of the sensory neuron
see diagram in manual
draw a labelled diagram of the brain
see diagram in manual
