Lecture 2 Flashcards
What is the importance of the nervous system?
- master control/communicator in the body
- every thought, action, emotion reflects its activity
- all body systems (both voluntary/involuntary) are controlled by it
What are the three functional classifications of the nervous system?
- input: through millions of sensory receptors tha tmonitor changes/stimuli inside/outside the body
- integration: processes and interprets the sensory input and decides what to do at each moment
- output: effects or causes a response by activating muscles or glands (effectors) via motor output
What are the two structural classifications of the nervous system?
Central NS and Peripheral NS
What are the functional classifications of the PNS?
Sensory/afferent:
- somatic fibers
- visceral fibers
Motor/efferent:
- somatic NS (voluntary)
- autonomic NS (involuntary): sympathetic NS, parasympathetic NS
What are the organs involved in the CNS and PNS?
CNS: brain, spinal cord, encased in bone
PNS: cranial nerves, spinal nerves, peripheral ganglia
What is the cortex?
outer layer of the brain
What are some anatomical directions?
Anterior: toward head
Posterior: toward tail
Rostral/cranial: toward the front of the face
caudal: away from front of the face
dorsal: top and back of head
ventral: bottom of skull or front of body
lateral: toward the side
medial: toward the middle
ipsilateral: structures on the same side of the body
contralateral: structures on opposite sides of the body
What are the two types of cells of the nervous system?
- supporting cells/neurogli/glia
- nerve cell/neurons
What are all the types of glial cells?
CNS glia:
- astrocytes
- microglia
- ependymal cells
- oligodendrocytes
PNS glia:
- schwann cells
- satellite cells
What do astrocytes do?
provide chemical and nourishment to neurons, regulate chemical composition of fluid surrounding neurons
Where are astrocytes located?
Processes of astrocytes surround capillaries and neurons of CNS
What are the function of oligodendrocytes?
form the myelin that surrounds many axons in CNS, each cell forms segments of myelin for several adhacent axons
What do nerve cells do?
transmit messages
What is the structure of a nerve cell?
- cell body (soma): metabolic center with nucleus surrounded by cytoplasm
- fibers (processes):
electrical signals towards cell body = dendrites; can be hundreds of dendrites
electrical signals travel away from the cell body = axons; each neuron only has one axon
What is ganglia?
collection of cell bodies in PNS
What are each axon terminal separated by?
synpatic cleft
What is a nuclei?
cluster of neuron cell bodies in CNS
What is a tract?
bundle of nerve fibers running through CNS
What is a nerve?
bundle of nerve fibers running through PNS
What is white matter?
dense collections of myelinated fibres
What is grey matter?
mostly unmyelinated fibres and cell bodies
What do sensory neurons receive?
impulses from sensory receptors to CNS, cell bodies are outside of CNS
- skin
- muscles/tendons
What is the sensory neuron for muscles and tendons?
proprioceptor
What is the sensory neuron for skin?
cutaneous sense organs
Where are motor neuron bodies located?
in CNS
What are association neurons (interneurons)?
connect motor and sensory neurons
What is somatosensory information?
Vision, hearing, balance, taste, smell, touch
What are the four somatosenses?
Cutaneous senses
proprioception
kinesthesia
organic senses
What is the function of cutaneous senses?
provide info from surface of the body
What is the function of proprioception?
provide info about location of the body in space
What is the function of kinesthesia?
provide information about movement of the body through space
What is the function of organic senses?
provide info from in and around the internal organs
What are the four categories of cutaneous receptors?
Merkels disks
ruffini corpuscles
meissners corpuscles
pacinian corpuscles
Draw the table with the characteristics of all the cutaneous receptors
slide 30
What are the two major functional properties of nerve impulses?
ability to respond to a stimulus and convert in into a nerve impulse
ability to transmit the impulse to other neurons, muscles or glands
What is the state of the PM of an inactive neuron?
polarized, fewer positive ions sitting on inner face than inner face
major positive ions outside cell are Na+
major positive ions inside cell are K+
as long as inside stays more -ve than outside, the neuron will stay inactive
What happens when pressure stimuli excites a cutaneus receptor of the skin?
Depolarization
permeability of the cell PM changes
Na+ is in much higher concentration outside the cell, it diffuses quickly into neuron
What happens after depolarization?
if stimulus is strong enough
the local depolarization initiates and transmits a long distance signal called action potential
What occurs after depolarization?
repolarization
- immediately after Na+ rush into neuron, membrane becomes impermeable to Na+ and permeable to K+
- K+ diffuse out of neuron
- this outflow restores electrical conditions to rest
What occurs after repolarization?
Initial ionic conditions are restored
- after repolarization the initial concentrations of Na+ and K+ ions inside and outside neuron are restored by activation of the Na+/K+ pump
- pump uses ATP to pump excess Na+ out and bring K+ in
- process spread across entire neuron
