Intro to nervous system (up to quiz 1) Flashcards
what is the central nervous system?
brain + spinal cord
what is the peripheral nervous system?
everything else - cranial nerves, spinal nerves, ganglia, enteric plexuses, receptors
what is neurology?
The branch of medical science that deals with the normal functioning and disorders of the nervous system
what are the three basic functions of the nervous system?
- Sensory Function - sensory receptors sense stimuli or changes inside and outside the body
- Integrative Function - analyzes the sensory information and determines an appropriate response
- Motor Function - respond to sensory information (after integration) by initiating glandular secretions or muscle contractions
what is neuroglia?
-nerve glue
-support cells
- 50:1 ratio to neurons
what are astrocytes?
Support and protect neurons, help to maintain a proper chemical environment for nervous impulses
Assist with the growth and migration of neurons during the development
Help form the blood-brain barrier
what are microglia?
Phagocytes, can engulf microbes or injured nerve tissue
what are oligodendrocytes (CNS) and Schwann cells (PNS)?
Lay down myelin around axons which act as a layer of insulation to speed up the conduction of the nerve impulse
what are the gaps in myelin called?
nodes of ranvier
what are ependymal cells?
Produce cerebrospinal fluid (CSF) which is found in brain ventricles, central canal of the spinal cord and the subarachnoid space within the meninges
what are neurons?
-the functional cell of nervous tissue, impulse-conducting cells
-the capability of becoming electrically excitable
- produce action potentials/electrical impulses in response to stimuli
what are dendrites?
short, branching, processes extending from the cell body which functions to receive impulses and conduct these impulses to the cell body
what are axons?
long cylindrical process extending from the cell body that conduct impulses away from the cell body to another neuron, muscle fibre or gland cell
what are axon side branches called?
axon collaterals
what do axon collaterals turn into?
divide into many axon terminals
what are at the end of axon terminals?
synaptic-end bulbs that possess synaptic vesicles that store neurotransmitters
what are neurotransmitters?
chemical substances released from axons that will affect the cell they communicate with (neuron, muscle cell or gland)
what is a synapse?
The “contact” between two neurons or between the neuron and the effector (muscle or gland)
the two cells don’t actually touch
what does a neuromuscular junction synapse with?
what about a neuroglandular junction?
with a muscle cell and a gland cell
what is an axoplasm?
cytoplasm of an axon
what is an axolemma?
plasma membrane of an axon
a nerve is comprised of what?
bundle of myelinated axons in the (PNS) covered with CT covering
what are tracts?
bundles of myelinated axons in the central nervous system which lack a protective connective tissue covering
what are multipolar neurons?
many dendrites, one axon
most common type in the central nervous system
somatic and autonomic motor neurons
what are bipolar neurons?
one dendrite and one axon
found in the retina of the eye, inner ear, and olfactory area of the brain
what are unipolar neurons?
one process emerging from the cell body
these are always somatic sensory neurons
what are afferent (sensory) neurons?
transmit sensory nerve impulses from receptors toward the central nervous system
what are interneurons or associated neurons?
transmit nerve impulses from one neuron to another neuron
-most common type (90%) and located exclusively in the CNS
what are efferent (motor) neurons?
transmit motor nerve impulses from the central nervous system to the effectors (muscles or glands)
how do neurons communicate?
through electrical signals called action potentials or nerve impulses
what is the resting potential of a neuron?
-70mv
- cytoplasm inside is negatively charged
-extracellular fluid outside is positively charged
why is the inside of the cell negative?
due to the accumulation of large negatively charged protein molecules (-potassium) on the inside than outside and more (+sodium) on outside
balanced maintained by sodium + potassium pumps
what is the threshold for an action potential?
-55mv
what makes an action potential travel more quickly?
if the axon insulated with myelin
_______________ are chemicals that bind receptors on other neurons (dendrites) or on effectors such as muscles (skeletal, cardiac, and smooth) or glands
neurotransmitters
what is a chemical synapse?
-When a neuron communicates with another neuron via neurotransmitters
-Some neurons within the central nervous system communicate directly via electrical synapses where the axons connect directly to dendrites via gap junctions
what is a sensation?
is the conscious or unconscious awareness of external or internal stimuli
what are exteroceptors?
Found on or near the body surface where they detect stimuli from the external environment; eg. visual, smell, taste, touch, pressure, vibration, temperature, and pain
examples relevant corpuscle of touch, Meisner corpuscle, hair root plexuses, Pacinian corpuscles, vibration, thermal, nociceptors- free nerve endings that detect pain
what are interceptors?
are located within the body and include baroreceptors which detect stretch in smooth muscle and chemoreceptors which detect chemical changes in body fluids
Detect stimuli associated with blood vessels / visceral organs
Impulses produced are only occasionally felt as pain or pressure; otherwise, we are not consciously aware of these sensations
what is the role of barorecptors?
detect stretch in smooth muscle
what is the role of chemoreceptors?
detect chemical changes in body fluids
what are proprioceptors?
located in muscles, tendons, and joints as well as the inner ear
Detect body position and movement through the detection of muscle length & tension and position & movement of joints
These receptors can protect muscles and joints from injury if a muscle is contracting too powerfully
what is the role of muscle spindles?
detect stretch of a muscle
what are Golgi tendons?
gives information to CNS regarding the force of contraction or tension in the muscle it is associated with
what are joint kinesthetic receptors?
acceleration/deceleration of joint, pain
what are mechanoreceptors?
stretching, touch, pressure, vibration, proprioception, hearing, equilibrium, blood pressure
what are thermoreceptors?
temperature
what are nociceptors?
pain receptors - physical or chemical damage to tissue
acute pain and chronic pain
what are photoreceptors?
light (retina of eye)
what are chemoreceptors?
detect chemicals in mouth, nose, and body fluids such as blood
eg. pH, oxygen and carbon dioxide levels, hormone levels, glucose levels, etc.
