nervous system - minus feedback loops Flashcards
what is the nervous system made of
central nervous system (CNS) and peripheral nervous system (PNS)
what body parts make up the central nervous system?
Brain, Spinal cord
what neuron’s make up the peripheral nervous system?
motor neurons, sensory neurons
what is an automatic nervous system, what muscles are applied (?) and an example
involuntary, smooth and cardiac, eg. heart beating
what is somatic nervous system, what muscles are applied (?) and example
voluntary, skeletal muscle, walking
what is sympathetic?
stress reaction, “fight or flight” reaction
what is parasympathetic?
returning to relaxed state, “rest and digest” reaction
what are schwann cells
type of glial cell that supports the nervous system
what are nerves
hundreds if individual neurons grouped into bundles
what are neurons
the functional unit of the NS
what are the parts of a neuron
dendrites, cell body, axon, myelin sheath, Schwann cells, node of ranvier, nucleus, axon bulb
what is dendrites?
receives information
what is cell body?
contains nucleus
what is the axon?
extension of cytoplasm
what is myelin sheath
white protein covering axons, acting as an insulator
what are schwann cells
glial cell forming sheath
what is neurilemma?
outer layer of myelin sheath
what are effectors?
carries response, muscle/glands
what is electrical impulse?
impulse that only goes in one direction
what are the three types of neurons
sensory neuron, interneurons, motor neurons
what is the physique of a sensory neuron
cell body on the side, dendrites further from the cell body, has a myelin sheath
what is the physique of an interneuron?
shorter, no myelin sheath
what is the physique of a motor neuron
dendrites right off cell body, has myelin sheath
what are the eight steps in THE REFLEX ARC
- stimulus
- sensory receptors
- sensory neuron
- interneuron
- CNS (brain or spine) - differs on which is closer to stimulus
- motor neuron
- effectors (muscle/glands)
- response
what is action potential
signals conducted by axons, massive change in membrane voltage
what is membrane potential?
charge separation across the membrane, type of potential energy
what is resting membrane potential?
potential difference across membrane in resting neuron
what does the sodium-potassium pump DO?
pumps using ATP
3 sodiums (Na+) goes OUT
2 potassiums (K+) goes IN
how does action potential work?
all or nothing
where does action potential occur?
node of ranvier/axon
what happens at the POLARIZED STATE?
NOR is at rest, @ -70 mV, uses ATP for pump, 3Na+ out, 2K+ in
what happens at the DEPOLARIZED STATE?
at +40 mV, facilitated diffusion, Na+ enters
what happens at HYPERPOLARIZATION?
in the process of being polarized, @ -90 mV, facilitated diffusion, K+ leaves
what happens at REPOLARIZATION?
is at the repolarized state, @ -70 mV, uses active transport, 3Na+ out, 2K+ in to return to original state
what are the steps in action potential
- resting potential
- depolarization
- repolarization
- hyperpolarization
- repolarized
what is the threshold?
a specific membrane voltage that excites cell
what is salatory conduction?
action potential jumping from node to node, the speed of transmission is faster of a myelinated neuron
what is multiple sclerosis?
auto immune disorder, immune system attacks myelin sheath in PNS
what is a synapse?
small space/gap between neurons and effectors
what is chemical synapses?
involves the release of chemical messengers called neurotransmitters from pre-synaptic neuron
what is an excitatory NT
FIRES reaction (depolarization)
what are the five steps of excitatory neurotransmitter?
- action potential moves presynaptic neuron-axon
- vesicles moves towards presynaptic axon, fuse with membrane
- vesicles release neurotransmitters into synapse by exocytosis
- NT binds with receptor proteins, causing depolarization
- enzyme breaks down NT, chemicals taken back to presynaptic neuron
what is an inhibitory neurotransmitter?
STOPS reaction
what are the five steps of inhibitory NT?
- action potential moves presynaptic neuron-axon
- vesicles moves towards presynaptic axon, fuse with membrane
- vesicles release neurotransmitters into synapse by exocytosis
- NT binds with receptor protein, causing hyperpolarization of postsynaptic neuron
- enzyme breaks down NT, chemicals taken back to presynaptic neuron
what is acetylcholine and what does it do?
a neurotransmitter that helps with muscle contraction
what is cholinesterase?
an enzyme made to break down acetylcholine
what is the function of the CNS?
structural/functional centre of ENTIRE NERVOUS SYSTEM, receives incoming info, evaluates and initiates outgoing responses
why can an injury on the spinal cord cause paralysis?
it is the vital communicator between the brain and PNS, severely injuring spinal cord can cause loss of communication, cuts communication between sensory and motor neurons
what is the cerebellum?
involved with unconscious coordination of posture, reflexes and body movements
what is the medulla oblongata
automatic, involuntary responses
what is pons?
relay centre between cerebral of right and left halves of cerebrum, cerebellum and rest of brain
what is the midbrain?
relays visual/auditory info between areas of hindbrain and forebrain, controls eye movement and control of skeletal muscle
what is the thalamus
consists neurons providing connections between various parts of the brain
what is the hypothalamus?
contains neurons controlling blood pressure, heart rate, body temp, and basic drives. major link to nervous and endocrine system
what is the cerebrum
centers for intellect, memory, consciousness and language. interprets/controls response to sensory info
covered with a thin layer of grey matter called cerebral cortex
what is corpus callosum
nerves connecting left and right sides of brain
what are the three parts of the brain
hindbrain, midbrain, forebrain
what are the parts of the hindbrain
cerebellum, medulla oblongata, pons
what are the parts of the forebrain
thalamus, hypothalamus, cerebrum
what are the four lobes of the brain?
frontal lobe, parietal lobe, occipital lobe, temporal lobe
what is the frontal lobe responsible for?
motor movement, memory, personality, critical thinking
what is the parietal lobe responsible for?
sensory, perception (taste and touch)
what is the occipital lobe responsible for?
visual processing
what is the temporal lobe responsible for?
auditory processing
what are sympathetic responses?
pupils dialate
air passages dialate
liver is stimulated to release glucose
inhibits digestion/urination
constricts bronchioles
increases activity of stomach and pancreas
what are parasympathetic responses
pupils constrict
air passages constrict
stimulates gallbladder to release bile
digestion and urination stimulated
what are somatic nerves, and what is the role of sensory and motor neurons
voluntary control of head, torso, limbs
sensory: input on environment
motor: output on environment
what are automatic nerves and what does it do
involuntary control of body, controlled by hypothalamus and medulla oblongata
controls glands, smooth/cardiac muscle (effectors), maintains homeostasis
what is the sclera
thick white part of the eye, support and protection
what is a choroid
black middle layer under sclera, absorbs scattered light
what are sensory ligaments
strings connected to lens, pulls/relaxes lens
what is the iris
coloured part of the eye, controls size of pupils
what is a pupil
hole in the eye, lets light into eye
what is lens?
focuses light of fovea, allows accomodation
what is cornea?
clear part of sclera, protection, first structure to converge (bend) light rays
what is the aqueous humour
fluid filled space, maintains shape of the eye
what is ciliary muscle?
attaches to suspensory ligaments, contracts and relaxes to control shape of eye using suspensory ligaments
what is the vitreous humour
back fluid filled space, maintains shape of eye
what is retina
yellow inner layer, photo receptor (rods and cones)
what is the fovea centralis
dark spot/indent at the back of the retina, highest concentration of cones
what is the optic disk
blind spot in eye, optic leaves eye (no rods/cones)
what is the optic nerve
carries nerve impulses to occipital lobe (brain)
what does it mean when an eye adapts?
pupil changes shape (contradicts or dialate), responds to the amount of light entering the eye
what does it mean when the eye accomodates
lens changes shape (rounding of lens), how we focus
what are rods?
photo receptor that allows us to see in dark light (black and white)
what are cones?
photo receptors that allow us to see colour, most dense at fovea centralis
what is the outer ear?
collects soundwaves, channels them to ear cannal
what is the middle ear
transfer sound vibrations from eardrum to inner ear
what is the inner ear
contains cochlea/semicircular canals
what is the pinna
outside flap of ear, shaped to enhance sound vibration to focus into ear
what is the auditory canal
tube leading to eardrum in middle of ear
what is typanum
first structure to move (eardrum)
what are ossicles
sound is amplified and passed to oval window
what is eustachian tube
equalizes ear pressure
what is the cochlea
contains specialized haircells that respond to sound waves
what are semicircular canals
maintains balance
what is the oval window
concentrates vibrations into membrane
what is the auditory nerve
haircells bend, electrical impulses sent to brain (temporal lobe)
what is the order of sound waves as they pass through the ear?
pinna > auditory canal > tympanum (eardrum) > ossicles > oval window > cochlea
what are the four types of sensory receptors
chemoreceptors?
what is a negative feedback loop
when product of reaction leads to decrease of output, reestablish homeostasis in system
