Nervous System Flashcards
what does our nervous system do
tells us we exist and is our basis of reality
coordination, movement, emotion, responds to stimuli, learning
what makes up our nervous system
nerve cells called neurons, which transmit signals and impulses
What are dendrites
parts of nerve cells that conduct messages towards the cell body
what are axons
the part of nerve cells that conduct messages away from the cell body
what are synapses
the point where a message jumps from one neuron to another
what is the synaptic cleft / space
the gab in a synapse between two neurons
what are myelin sheaths
cells that insulate the nerve fibre electrically
what are the nodes of ranvier
gabs between the myelin sheaths that speed up nerve impulses
what is the cell body
the part that conducts normal cell functions and reactions
what are motor neurons
sends a signal away from the brain and CNS to an effector (muscle, fibre or gland) causing it to react
Cell body is inside the CNS
Short dendrite, Long axon
what are sensory neurons
start with a sensory receptor (pressure, heat, light)
sends a message to the CNS
Cell body outside the CNS (in ganglia)
Long dendrite, short axon
what are association (inter) neurons
relay neurons that are smaller than both sensory and motor neurons
entirely within CNS
both long and short axons and dendrites
convey messages between system parts in CNS
what are ganglia
nerve cell clusters or cluster of cell bodies
what are action potentials
nerve impulses that move along the length of an axon as a wave of depolarization
how does depolarization occur
when ion channels for K+ and Na+ open and cause a change in membrane potential
what are voltage gated channels
ion channels occupying the length of an axon that open in response to a change in potential
what domino affect allows nerve impulses
when depolarization occurs at one point on a neuron, it trigger the opening of ion channels in the next segment, this causes the depolarization to spread along the length of the axon as a unidirectional wave
What is the All or None response
If a minimum electrical stimulus is generated, then an action potential of the same magnitude will always occur, but if the stimulus is below the minimum no response will occur
what is the threshold potential
the minimum electric stimulus needed to open voltage gated channels ( around 55 mV )
What happens if the threshold potential is generated
an impulses is generated which travels down the axon towards the synapse
what do myelinated axons have that increase impulse speed
nodes of ranvier
in saltary conduction
increase to 200 m/s
what is the resting potential
the point where the axon is not conducting an impulse
more ATP is needed for the Na+/K+ pumps
what is the first stage of the action potential
depolarization
Na+ gated channels open, Na+ rushes in depolarizing the axon
what is the second stage of the action potential
repolarisation
K+ channels open, K+ rushes out re-polarizing the axon
what is the refractory / recovery period
axon restores the ion concentration as the Na+/K+ pump take the Na+ out of the cell, and K+ into the cell so its ready for the next impulse
what is the membrane on the neuron 1 side of the synapse called
the presynaptic membrane
what is the membrane on the dendrite of neuron 2 called
the post synaptic membrane
what is between the presynaptic and post synaptic membrane
the synaptic cleft or gap
what is contained within vesicles of neuron 1
neurotransmitters are contained within these vesicle and are pulled forward by the microtubules
what is on the post synaptic membrane
receptors that neurotransmitters bind to
what happens when an impulse moves into a synaptic ending
it stimulates vesicles to move to the pre synaptic membrane of the axon
what ions are necessary in the axon bulb in regards to vesicles
Ca 2+, which move into the bulb causing microtubules to contract
what happens when Ca2+ molecules cause microtubules to contract
the vesicles fuse to the membrane which then empty their contents (neurotransmitter substances) into the synaptic cleft
what happens to neurotransmitters in the synaptic cleft
they diffuse towards the receptor sites on the post synaptic membrane of the dendrite which can do one of three responses
what are the three possible responses triggered by neurotransmitters
1) increase the action potential of the dendrite
2) decrease the action potential of the dendrite
3) initiate an action potential in the dendrite (open Na+ gates)
why can the impulse only go one way across the synaptic gap
because the axon only has vesicles and the dendrite receptors
what does Acetylcholine do
controls, blood pressure, peristalsis
what does Noradrenalin do
raises Heart rate, Blood pressure, and dialation of pupils and bronchioles
what does serotonin do
controls mood, works with melatonin to help control sleep, wake up, and well being
what does dopamine do
deals with control of pleasure and motivation
what do enzymes do in the synaptic cleft
they break apart the neurotransmitters. this cleans out the gap so that a new impulse can be rapidly transmitted.
what happens to the neurotransmitter parts broken apart in the synaptic cleft
the parts diffuse back into the axon to be rebuilt into new neurotransmitter substances
what is a reflex arc
a reflex action (eye blink, hand jerking away from hot objects) in which a stimulus causes a response, without the brain being involved in making a decision
what is the direction of a nerve impulse
receptor makes a message
sensory neuron takes to CNS (spine)
interneuron passes message to motor neuron
motor neuron takes away from CNS
Effector receives message and reacts
what are examples of internal reflexes
breathing rate, heart rate, blood pressure, blinking
what secondary path is followed after a reflex arc
another neuron goes to the brain, but by the time it has arrived the motor neuron has already activated an effector
what are the two parts of the Central Nervous System
The brain and Spinal cord
what protects the central nervous system
bone (skull + vertebrae), meninges (wrapping), Cerebral Spinal Fluid (cushion + protection)
what Is the primary function of the Central Nervous System
Information Processing
What makes up the Peripheral Nervous System
the nerves and ganglia that lie outside the central nervous system projecting towards and away from it
What does the Peripheral Nervous system do
carries impulses to and from the CNS
What are the two parts of the peripheral nervous system
Cranial Nerves (12 pairs)
Spinal Nerves (31 pairs)
What nerves are in the Somatic Nervous System
nerves that serve the musculoskeletal system and nerves that serves the exterior sense organs
What does the somatic nervous system do
gives you information about the external environment and allows you to respond to it
What does the Autonomic Nervous System do
controls the internal organs automatically and without “awareness”, maintains homeostasis and regulates activity of cardiac + smooth muscle reflexes + glands
what is the sympathetic system responsible for
Fight or Flight
what does the sympathetic system do
dilates pupils, accelerates heartbeat and breathing, inhibits digestive tract
what are the neurotransmitters for the sympathetic system
Noradrenalin, Adrenalin, and Epinephrine
What is the structure of the Sympathetic system
Postganglionic is longer than preganglionic
Comes from middle of spinal cord (thoracic + a few lumbar)
2 motor nerves 1 ganglia
What is the Parasympathetic system responsible for
Normal activity, rest and digest
maintains a related body state
what is the neurotransmitter for the parasympathetic system
Acetylcholine
What is the structure of the Parasympathetic system
Preganglionic is longer than postganglionic
comes from brain, lower part of spinal cord
2 motor nerves 1 ganglia
what are the two parts of the autonomic nervous system
Sympathetic and Parasympathetic
What are the two parts of the Peripheral Nervous system
Somatic and Autonomic nervous system
What are the three functions of the spinal cord
- Communication between brain and body
- Centre for reflex action
- Role in internal organs (ex aortic and carotid bodies)
What are the parts of the spinal cord
Cervical (neck)
Thoracic
Lumbar (abdominal)
Sacral (tail bone)
What parts of the spinal cord have peripheral nerves
The thoracic, lumbar, and sacral
what happens when the spinal cord is severed
loss of sensation and voluntary movement
paraplegia if in thoracic region
Quadriplegia if in Cervical
What is adrenalin
a hormone produced by the medulla (inner layer) of the adrenal glands (one on top of each kidney)
What is adrenalin responsible for
the flight or fight response
What are the 6 things adrenaline does
1) Dilates pupils to raise visual alertness
2) Increases heart rate to supply more blood to body faster
3) Decreases blood flow and peristalsis of digestive tract
4) Increases blood flow to the CNS and skeletal muscles (contraction for action)
5) Widens air passage way
6) Contraction of diaphragm (gasp)
What effects does adrenaline continue
sympathetic nerve impulses as a neurotransmitter
what are the four lobes of the cerebrum
the Frontal
the parietal (back)
the occipital (dorsal + behind parietal)
the temporal (below frontal and parietal)
what does the medulla oblongata do
controls the unconscious aspects of the body like heartbeat, breathing, vomiting, coughing, sneezing, hiccoughing, swallowing, and controlling internal organs
Where is the Medulla Oblongata
Closest part to the spinal cord
What is the Cerebrum responsible for
consciousness (info processing, responding, Q’s, memory)
What are sulcus
groves that divide each hemisphere into the 4 lobes
what are parts of the cerebrum
outer layer: Cortex
Left + Right Hemisphere
4 lobes
What does the Thalamus do
it is the central real station for sensory impulses, where it sorted out messages, before sending them to the cerebrum or appropriate regions of the brain
“gatekeeper of the cerebrum
Where is the thalamus
below the corpus callous
last stop before the cerebrum
what does the cerebellum do
receives sensory info and motor output
lets the body have smooth and graceful motions (muscle coordination)
maintains body position in space (proprioception)
in charge of balance by receiving sensory info from the inner ear
describe the appearance of the cerebellum
2nd largest part of the brain
resembles a butterfly
what is the hypothalamus in charge of
homeostasis, hunger, sleep, thirst, body temp, blood pressure
links the nervous and endocrine system (controls the pituitary gland)
controls the internal organs
where is the hypothalamus
below the thalamus
what is the corpus callosum
the portion of the brain that connects the two cerebral hemispheres to share info
horizontal tract, first nerve connection between hemispheres
what do each cerebral hemispheres have
their own memory and style of thinking
what does the pituitary gland do
links the nervous and endocrine system
the master gland
what are the three parts of the brain stem
the mid brain
pons
medulla oblongata
what does the midbrain do
relay station for tracts between cerebrum and spinal cord/cerebellum
what does the Pons do
contains bundles of axons between body and rest of CNS, functions with medulla oblongata
what is the pituitary gland
a small gland (two parts, anterior and posterior lobes) that produces a large number of hormones, many of which control the release of hormones from other glands in the body. The “Master Gland”
what does the posterior pituitary gland do
releases hormones that are made in the hypothalamus and stored in the post pit gland
these hormones are transferred and stores in special hollow nerve ribres that run from the hypothalamus to the post pit gland
ex ADH and Oxytocin
what does the anterior pituitary gland do
makes and releases its own hormones. stimulated to release its hormones by releasing hormones from the hypothalamus. blood connection between the hypothalamus and the ant. pit
what hormones are made in the Ant. Pit gland
growth hormones
prolactin
FSH and LH
Thyroid stimulating hormones (TSH)
Adrenal Cortex Stimulating Hormone (ACTH)
Melatonin
what monitors the levels of pituitary hormones in the blood and how are they controlled
the hypothalamus monitors the levels and they are controlled by a negative feedback system (except oxytocin) so the levels remain relatively constant. Sex hormones FSH and LH vary in the female
