Week 2 - Nervous System Structure Flashcards
Types of receptors
Thermoreceptors- change in temp
Mechanoreceptors- mechanical pressure or distortion
Chemoreceptors- chemical change
Photoreceptors- Light
2 parts of nervous system
- The central nervous system (CNS)
Includes the brain and spinal cord
Functions: integrates and coordinates the
processing of sensory data and the transmission
of motor commands. Coordinates higher functions. - The peripheral nervous system (PNS)
Includes all neural tissue outside the CNS
Functions: Deliver sensory information to the CNS.
Carry motor commands to peripheral tissues and
systems
Organisation of nervous system
Receptors - special sensory receptors monitor smell taste vision balance and hearing. Visceral sensory receptors monitor internal organs. Somatic Sensory receptors monitor skeletal muscles, joints, and skin surface.
CNS
PNS - Includes Somatic and Autonomic Nervous systems. ANS has sympathetic and parasympathetic divisions.
Effectors- Skeletal muscle (SNS), Smooth muscle,cardiac muscle, glands, adipose tissue(ANS)
4 Types of neurons
Axonic
Bipolar
Unipolar
Multipolar
Describe anaxonic neurons
Found in brain and special sense organs, very small. No anatomic features that distinguish dendrites from axon, functions not fully understood.
Describe Bipolar neurons
Have 2 processes, 1 dendrite and 1 axon with cell body between them.
Rare
Occur in special sense organs.
Describe Unipolar Neurons
Dendrites and axon are continuous, cell body lies off to one side.
Most sensory neurons of PNS are unipolar.
Describe Multipolar neurons
2 or more dendrites and one axon
Most common neurons in CNS
All motor neurons that control skeletal muscle are multipolar.
Describe the spinal chord.
Major Passageway of sensory and motor impulses to/from the brain.
Integrates information on its own and controls spinal reflexes and automatic motor responses.
Consists of 31 segments.
Each segment contains a pair of dorsal root ganglia, containing the cell bodies of sensory neurons.
Dorsal rootsbring sensory info to SC
A pair of ventral roots contain axons of motor neurons.
Sensory(dorsal) and motor(ventral) roots are bound together into a single spinal nerve.
Sectional anatomy of the spinal chord
Gray Matter - contains cell bodies and neuroglia(glial) cells.
White matter - contains myelinated and unmyelinated axons.
Horns - projections of grey matter.
Describe spinal nerves
31 pairs of SN are grouped according to the region of the vertebral column where they originated.
Each pair of SN monitors a specific region of the body surface known as a dermatome.
Damage of a spinal nerve or of dorsal root ganglia produces a characteristic loss of sensation in the corresponding region of the skin.
Describe a reflex arc
Stimulus
Sensory neurons activated
Relayed to motorneuron skipping cns
Activation of motor neuron
Effector responds
Describe muscle spindles
highly specialised encapsulated muscle fibres(intrafusal) positioned parallel to normal muscle fibres
(extrafusal).
Sensitive to changes in muscle length
Afferent neuron wraps around the muscle spindle
Efferent neuron (Gamma) cause muscle spindles to
contract to maintain tension in middle of the fibres
Hence if muscle is stretching rapidly, a vigorous
contraction is caused to prevent overstretching
Describe 3 parts of brain
Reptilian Brain - brain stem
Mammalian Brain - the limbic system
Higher Brain - neocortex (cerebral cortex), which sets us apart from
ALL other animals
What are the 6 regions of the brain
Cerebrum
Diancephalon (Thalamus and Hypothalamus)
Cerebellum
Midbrain(Mesencephalon)
Pons
Medulla oblongata
