The Nervous System Flashcards
Central nervous system
Brain and spinal cord
Site of information processing
The nervous system
2 parts:
Central nervous system
Peripheral nervous system
Peripheral nervous system
All nerves outside of the brain and spinal cord
2 parts:
-Sensory
-Motor
Sensory
Afferent
Carries impulses to the CNS
Motor
Efferent
Carries impulses from CNS to muscles
3 parts:
Voluntary, autonomic, neuroendocrind
Voluntary
Relays commands to skeletal muscles
Autonomic
Stimulates glands, respiratory, and digestive muscles
Neurocrind
Controls glands and hormone production
Bundles of axons
CNS – tracts
PNS – nerves
Clusters of cell bodies
CNS – nuclei
PNS – ganglia
The Brain
- Cerebellum
Little cerebrum.
Extension of the hindbrain.
Controls coordination.
The Brain
- Cerebrum
Largest part. Correlation, Association, and Learning.
Receives sensory data from the thalamus.
Motor fibers extend to the spinal cord.
2 halves/hemispheres connected by a nerve tract or Corpus Callosum.
Each hemisphere divided into 4: frontal, parietal, temporal, and occipital lobes
The Brain
- Cerebral cortex
Thin layer, only a few mm on surface of cerebrum.
Densely packed nerve cells.
~ 10 million cells.
10% of all brain neurons
The Brain
- Corpus striatum
Interior of cerebrum. Gray matter
Motor control.
Large groups of nuclei or cell bodies called basal ganglia.
Coordinates complex muscular activities – I.e. Play a piano
The Brain
- Corpus Callosum
Bundles of thin fibers that connect the 2 hemispheres.
Also called White Matter.
Damage leads to speech and perception difficulties.
The Brain
- The Thalamus
Site of sensory integration in the brain.
Auditory, optical impulses go to thalamus and then brain surface.
The Brain
- Hypothalamus
Integrates visceral responses.
I.e. Temp., heart beat, respiration
The Brain
- Limbic system
Hippocampus and amygdale are the two parts of it.
Ancient area in brain.
Controls emotional responses.
Hippocampus
Formation and recall of memories
3 classes of nervous receptors:
- Mechanoreceptors -
- Chemoreceptors -
- Photoreceptors -
- Mechanoreceptors -
Hearing, touch, pain
- Chemoreceptors -
Taste, smell
- Photoreceptors -
Vision
Types of senses:
Temp.
Free nerve ending of skin and hypothalamus are used.
Cold receptors - triggered by a lowering of temp.
Heat receptors - triggered by a raising of temp.
Types of senses:
Pain
Stimulus that is about to cause tissue damage
Causes increase in heart beat and blood pressure
Nociceptors -
Nociceptors -
Free nerve ending on body surface that sense:
Extreme temp.
Intense mechanical stimulation
Chemicals released from damaged cells.
Types of senses:
Force
Touch and pressure
Phasic receptors
Intermittently activated.
I.e. Hair follicle receptors - use touch and mechanical motion.
I.e. Meissner’s corpuscles - sense touch in areas without hair.
I.e. Fingers, palms, nipples
Tonic receptors
Constantly activated.
Tonic receptors:
Ruffini endings -
In dermis
Tonic receptors:
Merkel cells -
on skin surface, measures duration and extent of touch
Pacinian corpuscles
Afferent axon and a capsule of connective tissue filled with fluid. Senses vibration.
Muscle spindles
Deep in skeletal muscle.
In all vertebrae except bony fish.
Measure muscle stretch
Golgi tendon organ
Monitor tendon stretch
Angular motion:
Semicircular canals
In the ear, sense up/down…front/back…right/left movements.
Consists of the ampulla and capula.
Ampulla
A swollen chamber at the end of a canal
Capula
Wedge of gelatinous material connected to the vestibular nerve.
Lateral line organs
In fish.
Allows fish to orient itself as it moves upstream
Sensing chemicals:
Taste
Fish
On body surface, used by bottoms feeders to find food.
Sensing chemicals:
Taste
Terrestrial vertebrates
Buds on tongue.
4 types: sweet, salty, sour, bitter
Sensing chemicals:
Smell
Or olfaction.
Chemoreceptors in the nasal passages.
Sensing chemicals:
Hearing
Tympanic membrane
Or eardrum.
Large membrane.
Separates outer and middle ear
Sensing chemicals:
Hearing
Ossicles
Bones.
Malleus - hammer, incus - anvil, stapes - stirrup.
Transmit vibration to the oval window and increase the force of the vibration.
Sensing chemicals:
Hearing
Oval window
Membrane which leads to the cochlea
Sensing chemicals:
Hearing
Cochlea
(Latin - snail)
Coiled, fluid filled chamber in the inner ear
Sensing chemicals:
Hearing
Eustachian tube
Connects middle ear with the throat.
Equalizes air pressure on the middle and outer ear.
Sensing chemicals:
Hearing
Organ of corti
Tectorial nerve, hair cells, auditory nerve, and basilar membrane.
Sensing chemicals:
Hearing
Sonar
In whales and dolphins.
Emit a sound wave and determines the amount of time needed for it to return.
Greater time = greater distance away.
Refractory period
In nerves, when sodium is pumped out and potassium is pumped back in. The membrane is unable to react to stimulus at this time.
Resting membrane potential
An all or none reversal of the electric potential of a muscle cell membrane. The reversal moves along the nerve cell because voltage sensitive ion channels are activated and allow the ions to move across the membrane.
Chemically gated ion channel
A channel that is used for only one type of ion and a neurotransmitter opens this type of channel
Hyperpolarization
More than 70 millivolts of difference are created between the inside and outside of the membrane by pumping more potassium inside the membrane. Usually a membrane has 70 millivolts or less. The extra potassium must be removed first before a potential can occur. This is a method of controlling or turning off the nerve.
Depolarization
When sodium flows into a nerve and potassium flows out.
Cornea
The transparent membrane which begins to focus light in the eye.
Iris
The muscles between the cornea and the lens of the eye can change the size of the pupil. This opening is called the iris.
Ampullae of Lorenzini
A receptor that monitors current flow in the water and can help fish find prey.
Electroplates
An organ in electric catfish and eels that can produce up to 500 volts of electricity. It helps them find and kill prey.
The steps in nerve transmission:
- Synaptic vesicles filled with acetylcholine fuse with the membrane of the presynaptic neuron.
- Acetylcholine diffuses across the synaptic cleft and binds to the post synaptic ion channel receptor.
- Na+ rushes into the ion channel.
- Acetylcholinesterase degrades acetylcholine and closes the ion channels.
- An action potential occur in the post synaptic neuron.
The process of hearing
- The tympanic membrane vibrates.
- 3 ossicles move and start a fluid wave
- Fluid wave moves the basilar membrane
- Bend cillia on hair cells.
- Stimulate tectoral and auditory nerves.
- You hear.
Blood pressure
Monitored at 2 sites: Carotid sinus and aortic with baroreceptors.
They sense the tension in artery walls.
Gravity:
Statocysts -
The sensory structure. Determines orientation of body to force of gravity.
The statocysts contain a saccule and utricle, or cell lined with hair cells. Small calcium carbonate crystals called otoliths fall on the hair cells and this tells your brain which way is up.
