Week 8 Flashcards
What are the functions of the Nervous System?
- Sensory, integrative, motor
- response to stimuli
- integration of body processes
- control of voluntary effectors (skeletal muscles), and mediation of voluntary reflexes
- control of involuntary effectors (smooth muscle, cardiac muscle, gland) and mediation of autonomic reflexes (heart rate, blood pressure, glandular secretion etc)
- responsible for conscious thought and perception, emotions, personality, the mind
What are the functional classes of neuron? Explain in detail the 3 different classes. What way do they transmit impulses. What are their structure?
- Sensory (afferent):
- transmit impulses towards the CNS
- cell body devoid of dendrites and presynaptic inputs and is located adjacent of the spinal cord
- peripheral ending of axon is modified as sensory receptor
Motor (efferent):
- carry impulses away from the CNS
- cell bodies situated in the CNS
- Receive many inputs from other neurons which influences their output to effector organs
Interneurons (association neurons):
- connect between neurons in CNS pathways
- entirely within CNS (99% of neurons - 100billion)
- the more complex the required action the greater the number of interneurons interposed between afferent and efferent neurons
This is just for your information :)
Most nerves are mixture of afferent and efferent fibres and somatic and autonomic fibefibres
- Classified according to direction transmit impulses.
Mixed - both sensory and motor fibres; impulses both to and from CNS
- Sensory nerves - impulses only towards CNS
- Motor nerves - impulses only away from CNS
Pure sensory or motor nerves are rare.
Please explain what Group A fibres are. Cheers cobber.
- Large diameter, myelinated somatic sensory and motor fibres of skin, skeletal muscles, joints
- Transmit at up to 150m/s
Please explain what Group B fibres are.
- Intermediate diameter, lightly myelinated fibres
- Transmit at up to 15m/s
Please explain what Group C fibres are.
- Smallest diameter, unmyelinated fibres
- Transmit at up to 1m/s
It would be wonderful if you could plz explain a nerve reflex (an example of a nerve pathway). Just for context, nerve reflexes are a fast sequence of responses to a stimulus.
- Sensory receptor - at site of stimulus action
- Sensory neuron - transmits afferent impulses to CNS
- Integrating centre - either monosynaptic or poly synaptic region within CNS
- Motor neuron - conducts efferent impulses from integration to effector organ
- Effector - muscle fibre or gland cell that responds to efferent impulses by contracting or secreting
Define Central Nervous system (CNS)
- Brain and spinal cord
- integrative and control centres
Define Peripheral nervous system (PNS)
- cranial nerves and spinal nerves
- communication lines between the CNS and rest of the body
Define sensory (afferent) division
- somatic and visceral sensory nerve fibres
- conducts impulses from receptors to CNS
Define motor division
- motor nerve fibres
- conduct impulses from CNS to effectors (muscles and glands)
Define somatic nervous system
- Somatic motor (voluntary)
- Conducts impulse from CNS to skeletal muscles
- axons of somatic motor neurons extend from CNS to effector
- all somatic motor neurons release acetylcholine (ACh) to activate nicotinic receptors on skeletal muscle
Define the Autonomic nervous system (ANS)
- Visceral motor (involuntary)
- conducts impulses from the CNS to cardiac muscles, smooth muscles and glands
- regulates internal environment
- operates without conscious control
- divided into sympathetic and parasympathetic nervous systems
Define sympathetic division.
- mobilises body systems during activity (fight or flight)
- associated with fear and stress
Define parasympathetic division
- conserves energy
- promotes house-keeping functions during rest
- rest and digest
