Nervous System and Senses Flashcards
Define the central nervous system
consists of the brain and spinal cord
Define the peripheral nervous system
consists of cranial and spinal nerves; voluntary; relays information to the CNS
Define autonomic nervous system
part of the peripheral nervous system; consists of the sympathetic and parasympathetic divisions; involuntary nervous system
Describe the sympathetic division of the ANS
dominant in stress situations; fight or flight response; increased heart rate, vasodialation in muscles, bronchioles dilate, liver supplies body with more energy, digestion slows, vasoconstriction in the skin and viscera
Describe the parasympathetic division of the ANS
dominates in non-stressful situations; normal functioning of organs; digestion will be efficient, defecation and urination may occur
Define neuron
cells comprising the nervous system
Define dendrite
extensions of a neuron that transmit impulses toward the cell body
Define axon
single extension of a neuron that transmits impulses away from the cell body
Describe Schwann cells
schwann cells wrap axons and dendrites in the PNS; layers called myelin sheath; insulates cell from other neurons; stimulate regeneration
Define nodes of Ranvier
the part of the neuron cell membrane that carry the electrical impulse
Define neurolemma
the nuclei and cytoplasm of the schwann cells located outside the myelin sheath
Define neuroglia
provide supporting framework for neural tissue, regulate the environment around neurons, and act as phagocytes
Define synapse
small gap between an axon and a dendrite
Define neurotransmitter
in response to the arrival of an electrical signal, neurotransmitters are released and diffuse accross the synapse to chemical receptors
Define acetylcholine
neurotransmitter found at neuromuscular joints, in the CNS and PNS
What is a neuron not carrying an electrical impulse considered to be?
polarized
Describe the charges of a polarized neuron
positive on the outside of the cell and negative on the inside
What happens to a neuron once it receives stimulus from a neurotransmitter and Na+ ions rush into the cell?
depolarization
What happens to a neuron once K+ rushes out of the cell?
repolarization
Describe the late stage of the repolarization of a neuron
sodium/potassium pumps return Na+ ions outside and K+ inside
Define sensory neurons
carry impulses from receptors to the CNS
Define motor neurons
carry impulses from the CNS to effectors
Define interneurons
only found in the CNS; carry motor or sensory impulses
Define nerve
group of axons and/or dendrites of many neurons with blood vessels and connective tissue
Define nerve tract
groups of neurons within the CNS; also called white matter
State the function and cranial nerve number of the Oculomotor nerve
3; movement of the eyeball, constriction of the pupil
State the function and cranial nerve number of the Vagus nerve
10; sensory for cardiac, respiratory, and blood pressure relexes; decreases heart rate; increases digestive secretions
State the purpose of stretch reflexes
keep us upright without having to think about doing so; spinal cord relex, the brain is not involved
State the purpose of flexor reflexes
stimuli detects danger or hazard and responds by pulling away from it; spinal cord reflex, the brain is not involved
Describe the reflex arc
- receptors detect a change and generate a response2. sensory neurons transmit impulse to the CNS3. synapse occurs between stimulated sensory neuron and a interneron4. interneuron synapses with a motor neuron5. effector receives the impulse and performs its action
State the function of the ventricles of the brain
four cavities; formation of CSF
State the function of the medulla in the brain
regulates heart rate, diameter of blood vessels, blood pressure, and respirations
State the function of the pons in the brain
works with the medulla to produce normal breathing rhythm
State the function of the midbrain in the brain
control visual and auditory reflexes; control equilibrium
State the function of the cerebellum in the brain
control involuntary movement; controls equilibrium
State the function of the cerebrum in the brain
largest part of the human brain; surface is called the cerebral cortex; contains lobes that control different functions
Describe the function of the frontal lobes of the cerebral cortex
motor areas that generate impulses for voluntary movement; Broca’s motor speech area
Describe the function of the parietal lobes of the cerebral cortex
interpret the cutaneous sensations; receives impulses from stretch receptors for conscious muscle sense; taste buds
Describe the function of the temporal lobes of the cerebral cortex
auditory areas; olfactory areas; speech areas concerned with the thought that precedes speech
Describe the function of the occipital lobes of the cerebral cortex
visual areas; judging distance; seeing in 3D
Name the outermost meninge made of fibrous connective tissue that lines the skull and vertebral canal
dura mater
Name the middle meninge made of web like strands of connective tissue
arachnoid membrane
Name the innermost meninge that covers the surface of the spinal cord and brain
pia mater
Where is cerebrospinal fluid found?
between the arachnoid and the pia mater, the subarachnoid space
Describe the functions of cerebrospinal fluid
brings nutrients to the CNS and removes waste products; acts as a cushion for the CNS
Define sensations
enables the body to respond appropriately to ever changing situations to help maintain homeostasis
Define receptors
detect stimuli and generate a response
Define projection
sensation that seems to come from the area where the receptors were stimulated
Define intensity
sensation felt more distinctly and to a greater degree
Define contrast
effect of a previous sensation on a current sensation
Define adaptation
becoming unaware of a continuing stimulus
Define after-image
sensation remains in the consciousness even after the stimulus has stopped
Name the cutaneous senses and their purpose
touch, pressure, heat, cold, and pain; provide us with information about the external environment
Define referred pain
pain felt in a cutaneous area that originates in an internal organ
Define proprioception
muscle sense; ability of the brain to know where the muscles are and how they are positioned
Define chemoreceptors
receptors that detect chemicals in solutions as taste and vaporized chemicals that have been sniffed as smell
Define conjunctiva
thin membrane lining the inside of the eyelids and covering the whites of the eye
Where are tears produced?
lacrimal glands
Define sclera
thickest layer of the eyeball; visible as the whites of the eye
Define cornea
transparent and has no capillaries; the first part of the eye that refracts light
Define choroid layer
contains blood vessels; dark blue pigment that absorbs light to prevent glare
Define lens
made of transparent, elastic protein; has no capillaries; shape changed by ciliary muscle to allow focus
Define iris
colored part of the eye
Define retina
contains rods and cones; lines the posterior two thirds of the eyeball
Define rods
detect the presence of light
Define cones
detect colors
Define fovea
small depression directly behind the center of the lens that contain cones
Neurons carrying impulses from the cones and rods travel down what path?
converge at the optic disc and pass through the wall of the eyeball as the optic nerve
Define the function of vitreous humor
semi solid fluid that keeps the retina in place
Define aqueous humor
tissue fluid between the lens and the cornea that nourish each
What is another name for the ear drum?
tympanic membrane
Name the three bone in the middle ear
malleus, incus, and stapes
Define eustachian tube
extends from the middle ear to the nasopharynx and permits air to enter or leave
Define cochlea
in the inner ear; comprised of three fluid canals
Explain the function of the utricle and saccule in the inner ear
membranous sacs with hair cells that are moved by gravity as the position of the head changes that is interpreted by the brain to maintain equilibrium subconsciously
