topic 9.4. Flashcards
what is the mammalian nervous system composed of
- central nervous system
- peripheral nervous system
what are the three common neurons
- sensory
- relay
- motor
sensory neuron
- connects sensory receptors to the CNS through long dendrons
- short axons
- sends electrical impulse from the receptor within the organ/coordination centre
relay neuron
- carry action potentials between the sensory and motor neurons
- found within the CNS
- short axons and dendrites
motor neuron
- communicates from the CNS to effectors via long axons
- short dendrites
- myelin sheath
spinal cord
- cylindrical bundle of nerve fibres runs from brain stem to lower back
- surrounded by spinal vertebrae (protection)
- consists of nerve tissue (neurons, glia, blood vessels).
- 31 pairs of spinal nerves branching out between vertebrae to the body
- made of grey matter surrounded by white matter
- important coordination centre
- actions take place without conscious thought - reflex responses
what are reflex responses controlled by
- reflex arc
what is the function of the reflex arc
- to bring about appropriate responses to a particular stimulus as quickly as possible without time delay
what are two main type of reflexes
- spinal reflexes (hand moves from hot object)
- cranial reflexes (blinking)
grey matter
made up of motor nerve cell bodies and relay neurons
H-shaped region
white matter
made up of long nerve fibres running the length of the spinal cord
myelinated axons
relay neuron
relays impulses from sensory neurons to motor neuron
ventral root
carries only motor nerve fibres from spinal cord into spinal nerve
motor neuron
carries impulse from spinal cord to effector
effector
muscle fibres which contract to move hand away
motor end plate in muscle
transfers impulse to effector organ
sensory neuron
carries impulse from stimulated sensory recepetor
sensory receptor
picks up stimulus
spinal nerve
mixed nerves carrying both motor and sensory fibres
dorsal root ganglion
contains all the cell bodies of the sensory nerve fibres
dorsal root
carries only sensory nerve fibres from the spinal nerve into the spinal cord
the brain
- made up of white and grey matter
- grey matter - made of neuron cell bodies
- white matter - consists of nerve fibres
medulla oblongata
controls breathing and heart rate
cerebellum
controls balance and coordination of movement
cerebrum
initiates movement
hypothalamus
thermoregulation and osmoregulation
peripheral nervous system
divided into two systems; voluntary and autonomic nervous system
voluntary nervous system
- motor neurons that are under conscious control involving the cerebrum
sympathetic - structure
- myelinated preganglionic fibres leave the CNS & synapse in a ganglion
- the ganglia are very close to the CNS - preganglionic fibres are short & postganglionic fibres are long
autonomic nervous system
- motor neurons aren’t in control of conscious areas of the brain
- control bodily functions that are normally involuntary
what is the autonomic nervous system divided into
sympathetic and parasympathetic systems
During the First World War, some soldiers received head wounds that damaged one side of
the cerebellum.
Explain why this soldier had problems moving his right arm.
- damage is done to the left side of cerebellum
- movement of the right arm is no longer automatic
- hence the soldier has to think before moving it
parasympathetic - structure
- myelinated preganglionic fibres leave the CNS & synapse in a ganglion
- ganglia are near to effector organ - preganglionic fibres are long & postganglionic fibres are short
sympathetic - function
- produces noradrenaline at the synapses
- main function is to stimulate the bodies fight-or-flight response
- rapid response
parasympathetic
- produces acetylcholine at the synapses
- stimulates bodies “rest and digest” or “feed and breed” response
- slower, inhibitory effect
compare and contrast the central nervous system and the peripheral nervous system
- both contain nerve cells
- both contain synapses
- PNS contains sympathetic & parasympathetic system but CNS does not
- only the PNS has sensory input and motor output
- only the CNS carries out processing of information
sympathetic and parasympathetic nervous system act…
…antagonistically
state the part of the brain used to think about moving your arm
cerebrum
state one function of the cerebellum
- balance
- coordination
- posture
what would lead to an increase in heart rate
- release of noradrenaline by the sympathetic nervous system
state the part of the brain responsible for osmoregulation
hypothalamus
explain how on a very hot day, the brain ensures that the water potential of the blood remains constant
- sweating occurs causing loss of water from the blood
- water potential in the blood falls
- osmoreceptors are stimulated
- pituitary gland secretes ADH into the blood
- causing the kidney tubules to reabsorb more water into the blood
