the nervous system Flashcards
what is the nervous system and what are the two main parts
system where electrical and chemical communication occurs throughout the body
the two main parts are central and peripheral nervous system
central nervous system
brain and central cord
peripheral nervous system
afferent nerves: sensory neurons
-messages from the periphery to the spinal cord
efferent nerves: motor neurons
-messages from spinal cord to muscles/glands
function of the neurons and Schwann cells
*Responsible for communication (Action
potential / neurotransmission)
*Many have a lipid sheath called myelin
*Myelin sheath is the protective layer that
wraps around the axons of neurons to aid in
insulating the neurons
- Oligodendrocytes (CNS)/Schwann cells
(PNS)
o Produce myelin
o Facilitate transmission
astrocytes and microglia
.astrocytes
o Enable homeostasis
o Physical barrier/connector
o Reuptake of neurotransmitters
o Support neurons
- Microglia
o Immune cells of the brain
o Phagocytose dead cells and debris
function of soma
control centre
dendrite
short branched extension of a nerve cell, where impulses received from other cells at the synapsis and transmitted to the cell body
axons
originate at axonal hillock
allows materials to be transported from cell body to axon terminal (and back)
where axon terminal meets target cell termed synapse
what are the functional types of neurons
peripheral nervous system
1) afferent or sensory neurons (sense)
signals from periphery to CNS
2) efferent neurons
motor neurons (respond): signals from CNS to the muscle/skin etc
central nervous system
3) interneurons (integrate) connecting brain and spinal cord
what is a nerve
a bundle of fibers that conduct impulses between the brain or spinal cord and another part of the body. nerves include fragments of neurons (axons) and non neuronal cells
membrane potential and nerve impluses
difference in electrical charge between the inside and outside of the neuron
nerve impulses are changes in membrane potential that travels down nerves
-cell membrane is highly impermeable to ions
what direction do action potentials travel
from dendrites to axons
function of brainstem
involuntary functions, blood pressure, breathing, vomiting, sleep/arousal
midbrain
pons
medulla
function of cerebellum
coordinates balance and movement
diencephalon
between brain stem and cerebrum
thalamus
hypothalamus
pineal gland
cerebrum: cortex
2 hemispheres joined by corpus callosum
* Surface folded
* Frontal: reasoning, planning, speech, movement, problem solving
* Parietal: movement/orientation recognition, sensory information (pain)
* Occipital: visual processing
* Temporal: perceptions/recognition of auditory stimuli
what does the cerebrum: sub-cortical structures include
basal ganglia: motor control
limbic system: amygdala: emotion and memory
hippocampus: learning and memory (under temporal lobe)
pituitary gland: a small gland located located at the base of brain below the hypothalamus- growth hormone, TSH
what are the 4 regions of the spinal cord
cervical
thoracic
lumbar
sacral
spinal cord function
- Connects your brain to your lower back
- Carries nerve signals from your brain to your body and vice versa
- Spinal cord is where information comes into the CNS and directions are sent out
how do nerves enter the spinal cord
sensory nerves enter via dorsal root
motor nerves leave via ventral control
what is the spinal nerve
a mixed spinal nerve, which carries motor, sensory, between the spinal cord and the body
function of visceral sensory neurons
- Monitor temperature, pain, irritation, chemical changes and stretch in the visceral organs
– Brain interprets as hunger, fullness, pain, nausea, well-being - Receptors widely scattered
- Visceral sensory fibers conduct sensory impulses (usually pain or reflex sensations) from the internal organs, glands, and blood vessels to the central nervous system
what is visceral reflex
the reflex arc of the autonomic nervous system which provides glandular or non-skeletal muscular response in internal organs like the heart, blood vessels, organs in the GI tract
function of the autonomic nervous system
maintains internal environment
mostly involuntary
modulates endocrine function
controls visceral functions
-circulation
-digestion
-excretion
autonomic nervous system input
sensory neurons from peripheral organs to centre in hypothalamus, meddula
autonomic nervous system output
systematic and parasympathetic nervous neurons
what do ANS nerves control
*Smooth muscle
-Bronchioles
-Iris
-Digestive system
-Bladder
-Vascular system
*Secretory glands
-Adrenal medulla
-Pancreatic islets
-Salivary glands
-Sweat
*Cardiac Muscle
-Control heart rate
-Control contractile
-force
features of sympathetic nervous system
fight or flight
short term survival
generally increases energy availability/ capacity and usage
-increases heart rate
-increased lung capacity
-increased blood flow to muscles
-increased blood glucose
features of parasympathetic nervous system
rest and digest
long term survival
generally reduces energy availability/capacity and usage
-decreases heart rate
-decreased lung capacity
-increased blood flow to digestive system
-increased fat/glycogen stores
where is the adrenal gland located and what type of nervous system is it a part of
located on top of the kidneys
can cause body-wide release of adrenaline/ epinephrine
what are the two Ach receptors
nicotine and muscarinic
what occurs during rest and digest
constriction of pupils
bronchiolar constriction
increased GI mortility + secretion
inhibitory effects on heart
what occurs during fight or flight
- Pupil dilation
- Bronchiolar dilation
- Increased heart rate/force
- Vasoconstriction in skin
- Increased blood glucose
- GI tract relaxation
- Increase adrenaline secretion from
- adrenal medulla
what are androreceptors
g protein coupled (metabotropic)
respond to adrenaline and nor adrenaline
adrenaline: diverse actions depending on target
depending on the downstream molecules they activate
look at slide 23 on nervous system 2
okay
