fundamental neurobiology Flashcards
what are the two original theories for the composition of the nervous system?
. reticular theory-composed of a network of structures- (continous tubes)
. cell theory- composed of discrete cells
what is the nervous system composed of?
the nervous system is made of individual cells called neurons
what is the function of the nervous system?
the nervous system send electrical signals very rapidly throughout the body
describe the path of the reflex arc?
stimulus receptor - convert stimulus to electrical signal-transduction sensory-PNS interneurons-CNS-brain and spinal cord motor-PNS effector-muscle response
what is an example of a simple behaviour controlled by REFLEX ARC?
myotatic reflex
what is a myotatic reflex?
muscle contraction in response to stretching within the muscle
what are the 3 different types of muscle?
skeletal- attached to skeleton -striated-forceful-voluntary
cardiac-found in heart-striated-forceful-involuntary
smooth- hollow organs/glands-unstriated-involuntary
what is the afferent sensory system?
afferent neurons carry sensory signals from the body to the brain
what is the efferent motor system?
efferent neurons carry signals away from the brain
what are the two types of efferent motor system?
somatic-innervates skeletal muscle
autonomic-innervates smooth and cardiac muscle and glands
what are the two types of autonomic efferent motor system?
. sympathetic - increase respiration and decrease digestion
.parasympathetic - slows heart rate and respiration
when is the sympathetic motor system used?
during flight , fright , fight
when is the parasympathetic motor system used?
resting and digestion
how many nerves connect the CNS to the rest of the body?
.43 pairs of nerves connect the CNS to the rest of the body
.12 pairs of cranial nerves exit the brain
.31 pairs exit at various levels of the spinal cord
what are the two types of cells of the nervous system?
- neurons or nerve cells
2. supporting cells
what are neurons or nerve cells?
. found in adult PNS and CNS
.generate and transmit electrical signals
.have similar structures to most cells only difference is it conducts electricity
.10^11
what are supporting cells?
.they have supporting roles in nerve cell functions
.10^12- several different types
what do most neurons have?
.several dendrites
. a cell body (soma) that contains the nucleus
. along axon
. synaptic region(axon terminals)
what structure do neurons have?
polar structure- information comes in one end+leaves in another
how does information flow?
. information flow is usually in one end (dendrites to synapses)
what is the function of dendrites?
.receive incoming electrical information
.each cell in the body is connected to dendrite to form electrical signal.
what is the structure of dendrites?
.their branching increases surface area
.spines on dendrites increase surface area
what is axonsomatic?
incoming neurons connect to the cell body
what is axoaxonic?
incoming neurons connect to axons
what is the function of cell body (soma)?
sums electrical signals coming from dendrites
what is the structure of cell body(soma)?
contains the usual organelles including prominent nucleus and nucleolus and rough ER(known as nissl substance)
what is the function of axon?
takes electrical signals away from the body
what is the structure of axon?
.varies in length from «1mm to>1m
.usually unbranched but may have collaterals
.the axoplasm is surrounded by a phospholipid bilayer membrane embedded with proteins
.possession of a myelin sheath
.contains actin , mircrotubles and intermediate filaments
where does axon join the soma?
join soma at axon hillock (where signal is generated)
where does axon end?
ends in synaptic terminals(where it contacts other neurons)
how do substances move within axon?
movement of substances via “axonal transport” and axoplasmic flow.
what is axoplasmic flow?
anterograde transport from cell body to synapse
transport protein to maintain+repair flow
.involves intermediate filaments and is slow(1-5 mm day)
one direction
Slow
involves intermediate filaments
what is axonal transport?
.anterograde and retrograde
. mediated via microtubules and neurofilaments which are faster(400-2000mm day)
.goes both ways
fast
e.g chemical towards synapse and waste products back from synapse to cell body