L5 Nervous System Structure and Function Flashcards
what are the 6 main regions of the brain?
Medulla Oblongata Pons Midbrain Cerebellum Diencephalon Telencephalon
How does the medulla oblongata contribute to voluntary control of movement?
control of automatic function relaying signals between the brain and spinal cord
coordination of body movement
How does the Pons contribute to voluntary control of movement?
- Sleep and control of autonomic
- Relays sensory info between cerebellum and cerebrum
How does the Midbrain contribute to voluntary control of movement?
connects pons and cerebral hemispheres.
Controls responses to sight, eye movement, body movement and hearing
How does the Cerebellum contribute to voluntary control of movement?
Comparing, evaluating and integrating centre for postural adjustments and reflex-related movement
How does the Diencephalon contribute to voluntary control of movement?
thalamus, hypothalamus, epithalamus and subthalamus
Hypothalamus - regulates body temperature and metabolic rate
How does the Telencephalon contribute to voluntary control of movement?
Has 2 hemispheres of cerebral cortex including the corpus striatum and medulla
what is the hierarchy of motor control
- Motor cortex - direct motor control. major output pathway to spinal motor neurons
- Cerebellum - Modulates movement accuracy
- Basal Ganglia - strategic aspects of movement
what is the spinal cord protected by? What does it attach to ?
protects by the vertebral column
attaches to the brainstem
what are the 3 types of neurons the spinal cord contains?
motor neurons
sensory neurons
interneurons
what are the 2 main tracts in the spinal cord?
Pyramidal (lateral) tract
Extrapyramidal (ventromedial) tract
what are the 4 things that a motor neuron consists of
- cell body - contains nucleus
- Dendrites - conduct impulses toward cell body
- Axon - carries impulse AWAY from the cell body
- Can be covered in Schwann cells - that form the myelin sheath - Synapse - contact points between axon and dendrite of another neuron
Resting membrane potential of a nerve cell:
Negative charge inside cells at rest (polarised) -40 to -75
What is this determined by?
What is this maintained by?
Determined:
- permeability of plasma membrane to ions
- Difference in ion concentrations across membrane - Na+ K+ Cl- and Ca+2
Maintained:
- Potassium tends to diffuse out of the cell
- Na+/K+ pump moves 2K+ in and 3Na+ out
Action potentials occur when….
What does this then cause?
occurs when a stimulus of sufficient strength depolarises the cell.
this causes the opening of Sodium channels and the sodium floods into the cell. The inside therefore becomes more positive
What is repolarization and what happens here?
the return to resting membrane potential
Potassium leaves the cell and the sodium channels close
what is the neuromuscular junction?
interface between the end of a myelinated motor neuron and a muscle fibre; transmits nerve impulse to initiate muscle action
what do excitatory postsynaptic potentials do? what 2 summations can these be?
cause depolarization
Temporal summation - sum of several different EPSPs from one presynaptic neuron
Spatial Summation - sum of several different presynaptic neurons
What is the structure, function and action of the muscle spindles
Structure –> Intrafusal fibres that are parallel to normal muscle fibres. Gamma motor neurons that stimulate the Intrafusal fibres to contract with the extrafusal fibres
Function = responds to changes in length of the muscle
Action = Stretch reflex = stretch of muscle causes reflex contraction eg knee-jerk reflex
What is the structure, function and action of the Golgi Tendon Organ
Function = monitors tension developed in the muscle to ensure the muscle isn't damaged during excessive force Action = stimulation results in reflex relaxation of muscle. Ability to voluntarily oppose GTO inhibition may be related to gains in strength
Structure - capsule of extrafusal fibres within the musculotendinous junction. One end connects to the muscle fibres. The other connects to the tendon
what are the muscle chemoreceptors and the mechanoreceptors sensitive to?
Chemo = sensitive to changes in the chemical environment around the muscle Mechano = sensitive to muscle contraction and stretch
Describe the Structure and function of the autonomic nervous system
Function = maintains internal environment, organs not under voluntary control Structure = Has sympathetic and parasympathetic divisions
What to the sympathetic and parasympathetic divisions do?
Sympathetic = noradrenaline. Excites effector organ . Fight or flight Para = acetylcholine. Inhibits effector organ. Rest and digest
