Week Twelve & Fourteen Lecture Study Guide Flashcards
Structure of a nerve
a. axon wrapped in endoneurium
b. several fascicle of axons wrapped in perineurium
c. several fascicles wrapped in epineurium to form a nerve.
12 Cranial Nerves
I. Olfactory-sensory only-for smell only
II. Optic nerve-sensory only-sight
III. Oculomotor-motor nerve only-eye muscle movement
IV. Trochlear-motor nerve only-eye muscle movement
V. Trigeminal-largest cranial nerve:
sensory-from face to mouth(oral cavity)
motor-to muscle of mastication
VI. Abducens-Motor only-Eye muscle movement
VII. Facial-
Sensory-From face
Motor-to muscles of facial expression
VIII. Vestibulocohlear-sensory only-sensory from ear for hearing and balance.
IX. Glossopharyngeal-
sensory-from taste buds on posterior tongue
X. Vagus-
sensory-to the viscera (from abdomen)
motor-to the smooth muscle and diaphragm
XI. Accessory-motor nerve only-motor to neck muscles that move head and neck
XII. Hypoglossal-motor only-motor to the muscles of the swallowing and the tongue
Difference between sensory and motor nerves
- Sensory
a. Afferent neurons
b. Receives incoming stimuli from the body or outside the environment
c. nerve impulses carried to the central nervous system. - Motor neurons
a. also called efferent neurons
b. transmits a nerve impulse to an effecter site
c. nerve impulses are carried away from the central nervous system.
What is the difference between the somatic nervous system and autonomic nervous system.
- Somatic-
a. innervates skeletal muscles and sensory receptors
b. Effectors are skeletal muscles
c. Major neurotransmitter-acetycholine - Autonomic-
a) innervates smooth muscles, cardiac muscles, organs, and glands
b)Effector sites-smooth muscles, cardiac muscles, organs, and glands
-Parasympathetic-regulates everyday neural activities
-Sympathetic-control during times of stress
Definition of the somatic sensations: Perception & Sensation
Sensation-conscious and unconscious awareness of external or internal stimulus
perception-conscious awareness and interpretation of sensation
Definition of potential difference
The difference in electrical charge between 2 points (outside and inside of the cell) separated by the nerve cell membrane.
What is the resting membrane potential?
What the electrical make up is of a neuron at rest.
In a nerve cell, the RMP is measured at -70mV.
What is the resting membrane potential?
What the electrical make up is of a neuron at rest.
In a nerve cell, the RMP is measured at -70mV.
What is threshold potential?
When the RMP is depolarized to -55mV.
If the nerve itself is stimulated enough to cause depolarization, the RMP goes to -55mV or below and that si how an action potential is created. the action potential must be generated before the nerve will work. The action potential will not be generated if the RMP is above -55mV.
What is action potential?
It is rapid depolarization after the threshold potential is reached. This will result in the membrane potential reaching a positive 30 mV.
What is hyperpolarization?
More negative
What is depolarization?
Less negative.
When we began to stimulate the nerve, we will cause it to depolarize. When it depolarizes it becomes less negative. ex) -75mv to -55mV
What is repolarization?
resetting a nerve cell back to normal(back to negative 70mV)
What events occur during nerve stimulation (generation of an action potential)?
RMP is -70mV
Step 1: Depolarization to the threshold (nerve cell)potential of -55mV.
Step 2: Activation of sodium channels (ions) and rapid depolarization begins. The sodium pours into the nerve until it causes the rapid depolarization of a nerve cell at the RMP state from -70mV to +30mV. This causes an action potential to occur and go down the entire length of the nerve cell membrane.
Step 3: The sodium channel inactivates and the potassium channels activate.
Step4: The RMP of the nerve cell begins to repolarize and return to normal permeability. the sodium channels regain their resting condition, and the potassium channels begin closing. The transmembrane potential drops until the potassium channels have closed. the RMP will go from +30mV back to -70mV. The transmembrane potentials returns to resting levels.
Which cell produce myelin in the CNS?
oligodendrocyte
Which cell produces myelin in the PNS?
Schwann cell
Large PNS axons are large axons covered in myelin produced by Schwann cells.
a) nodes of Ranvier-are gaps or breaks
between the myelinated covering in
Schwann cells.
Myelinated neurons can carry nerve impulses quicker than unmyelinated neurons.
White matter in brain is the myelinated fibers.
Gray matter in the brain is the unmyelinated fibers or cell bodies only.
neurons
brain nerve fibers(neurons with axons extending out of it) or brain nerve cells
neuron structure
-Cell body
-Organelles
-Nissi Bodies
Neuron processes\Nerve fibers
-Axons
-Dendrites
What is innervation?
Innervation occurs when a nerve innovates a muscle. its when a nerve stay plugged into a muscle or gland where the action occurs.
Diagram of a neuron nerve cell body
one axon from a neuron
several dendrites in a neuron
characteristics of a dendrite
-Many per neuron
-Short and branched
-Receptors portion of a neuron
-carry impulses toward the cell body
characteristics of an axon
-one per neuron
-a long thin process or stem
-carry impulses away from the cell body
-End in synaptic knobs 9a junction between either two neurons or a nerve and neuron at an effector site.
Organs in the CNS
Brain
Spinal cord
Organs in the PNS
Cranial nerves-12
Spinal nerves-31
What is the refractory period?
All or nothing response-we we either hit nerve threshold potential or we don’t
What is saltatory propagation along a myelinated axon?
A myelinated axon can carry a nerve impulse much faster than a myelinated axon.
What is the difference between Meissner’s corpuscles and Pacinian corpuscles?
Meissner’s-
-Encapsulated nerve endings
-Mechanoreceptors
-detect light touch
-Abundant in hairless portions of the skin
Pacinian-
-Encapsulated nerve endings
-Mechanoreceptors
-detect pressure
-Abundant in deep subcutaneous tissues.
The organs of the special senses?
-sight-organ is the retina
-hearing-the organ is the organ of Corti located in the cochlea
-Olfaction(smell)-organ is the olfactory epithelium located in the upper nasal cavity.
-taste(Gustation)-organ is the taste buds
-static equilibrium-organ is the macula
-dynamic equilibrium-organ is the crista ampullaris
What is the difference between acute pain and chronic pain?
Acute Pain
-occurs rapidly
-Not felt in deep tissues
-Sharp and fast
-Myelinated fibers
-Stops when stimulus
-Stops when stimulus is removed
Chronic pain-
-Begins slowly and increases intensity over time
-Dull aching and throbbing
-Can occur anywhere
-Unmyelinated fibers
-Continues after stimulus is removed
How are spinal nerves formed?
They are formed when the fusion of the dorsal and ventral root from the spinal cord emerge from the vertebrae of the vertebral column.
What is a nerve plexus?
A branching network of anterior branches of the spinal cord.
What does the sensory receptor mechanoreceptors do?
Pick up light touch like a pin stick.
Chemoreceptors?
picks up and measure chemical sensations in our body like electrolytes, calcium, etc.
Thermoreceptors?
Pick up hot and cold.
Thermoreceptors?
Pick up hot and cold.
Nocioreceptors?
Pain receptors. Protect from further injury.
Photoreceptors?
How much light is in retina and picks up light rays.
Types of Somatic Senses (ex: exteroceptive, proprioceptive)
Exteroceptive-Changes at the body surface.
Proprioceptive-Changes muscles, tendons, and body position
visceroceptive-Changes in the viscera
Temperature senses
Heat receptors-pick up heat
cold receptors-pick up cold
Difference between muscle spindles and Golgi Tendon organs
Muscle spindles-
-Locate din skeletal muscle near tendon junction
-Helps maintain position of limbs
Golgi tendon organs-
-Helps maintain posture and prevent tearing of tendons
Prioprioceptors?
Stretch receptors that send info regarding length and tension of the muscles to the brain and spinal cord.
2 types-
Muscle spindles
Golgi tendon organs
Sound Wave pathway
Step 1 Auricle-collects sound waves
Step 2 External auditory meatus-Starts vibrations of sound waves and directs waves to ear drum and the middle and inner ear.
Step 3: Tympanic membrane
Step 4: Auditory Ossicles(Medulla, Incus, Stapes)
Step 5: Perilymph of scala vestibuli
Step 6: Endolymph of cochlear duct
Step 7: Hair cells in organ of Corti in Cochlea
What does the autonomic nervous system control? Include the differences between the sympathetic & parasympathetic nervous systems?
it regulates smooth muscle, cardiac muscle, and glands.(Involuntary actions).
Sympathetic:
-pre-ganglionic neurons in lateral gray horns in spinal cord
-Ganglia near spinal cord
-Post ganglionic fibers release NE at neurotransmitter junction
Parasympathetic:
-pre-ganglionic neurons in brain stem and in lateral gray horns of sacral spinal segments
-Ganglia in or near target organs
-Post ganglionic fibers release ACh acetylcholine)
what is the pons?
-The bridge to the higher brain.
-Its the bulging portion of the brain stem.
-main functions are as part of the regulation of the rate and depth of respiration.
-it relays sensory information to the cerebellum and thalamus.
Thalamus?
Central relay station for incoming conscious sensory information except smell.
Name the sensory and motor areas in the lobe sin the cerebrum.
Primary motor cortex-located in pre-central gyrus. responsible for motor movement
motor speech cortex(Broca’s area)-motor speech area-Located in left frontal lobe above temporal lobe.
Primary somatosensory cortex-receives information from skin receptors. In post central gyrus.
Visual cortex-receives information from sight receptors.-in occipital cortex.
auditory cortex-receives information from sound receptors (in temporal cortex)
gustation cortex-receive information form taste receptors
Regions(Structures) of the Brain
Cerebrum-largest portion of brain, divided into two hemispheres separated by the corpus collosum
-Cerebellum-bottom back of brain-responsible for voluntary muscle movement
-Diencephalon
Brain Stem-pons & medulla oblongata-controls breathing & heartbeat
Corpus Collosum?
A bunch of fiber tracts that between the right and left hemispheres of the brain. it helps the hemispheres communicate with each other.
Cerebral cortex?
Outer layer of the cerebrum (gray matter). it controls conscious behavior like ideas, thoughts, and emotions.
Cerebellum?
Coordinates subconscious voluntary skeletal muscle movement, skilled movements, posture, , and balance. -Located inferior to the occipital lobe
Where is the Pneumotaxic area of the respiratory center and what does it do?
Its located in the pons and it helps control our respiratory rate.
Where is the autonomic reflex center and what does it do?
Its located in the medulla oblongata and it maintains the visceral organ homeostasis.
Where is the cardiac center and what does it do?
Its located in the medulla oblongata and it controls the cardiac contraction force and rate.
Where is the vasomotor center and what does it do?
Its located in the medulla oblongata and it regulates blood pressure.
Where is the involuntary activity center and what does it do?
Its located in the medulla oblongata. It controls coughing and sneezing.
The anatomy of the ear
- External ear
a. Lobe
b. pinna (auricle)
c. external auditory meatus
d. tympanic membrane - Middle ear
a. auditory ossicles
-malleus
-incus
-stapes
b. oval window
c. pharyngotympanic (Eustachian) tube - Inner Ear
a. cochlea
b. cochlea duct
c. organ of Corti-organ of hearing
d. round window
e. semicircular canals
Brain Ventricles
a. Lateral ventricles (right & left ventricle)in each cerebral hemisphere
b. Third ventricle between hemispheres
c. Fourth ventricle beside the cerebellum and connects to the central canal of the spinal cord
Meningeal layers of the CNS?
a. Dura Mater
1. outer most layer of touch connective tissue
2. Attached to bones of skull, but not to the vertebrae
b. Arachnoid Mater
1. middle layer
2. net like tissue surrounding brain and spinal cord
c. Pia Mater
1. innermost layer
2. intimately covers the brain, including fissures and grooves
Meningeal layers of the CNS?
a. Dura Mater
1. outer most layer of touch connective tissue
2. Attached to bones of skull, but not to the vertebrae
b. Arachnoid Mater
1. middle layer
2. net like tissue surrounding brain and spinal cord
c. Pia Mater
1. innermost layer
2. intimately covers the brain, including fissures and grooves
Cerebrospinal fluid-
-in between meninges layers.
-Fluid found in the areas of the brain and spinal cord.
Spinal cord
- Origination point for spinal nerves
- Dorsal and ventral roots from the spinal cord merge to form spinal nerves
- Ascending tracts (sensory) located in posterior spinal cord
- Descending tracts (motor) located in anterior spinal cord.
Spinal Cord Characteristics
-called brain stem until it passes downward to the foramen magnum (then it is called the spinal cord) and into the vertebral canal.
-The spinal cord terminates in the conus medullaris
-31 segments with the cervical and lumbar enlargements present
-Cauda Equina
-Filum Terminale
Cross Sectional Anatomy of the Spinal Cord
-Gray matter surrounded by white matter
-Gray matter contains cell bodies of interneurons (unmyelinated)
-White matter contains myelinated axons of interneurons
Sectional organization of the Spinal cord
-The somatic and viceral sensory is located in the dorsal root portion of the spinal cord
-The visceral motor and somatic motor is located in the ventral roof of the spinal cord
Anatomic Features of Spinal Cord
-Ventral Root
-Dorsal Root
-Dorsal Root ganglion
-Ganglion is a bundle of
cell bodies outside the
CNS.
Dorsal root ganglion contains cell bodies of sensory neurons.
Ascending Nerve Tracts?
-Located in Dorsal column
-Carries Sensory impulses
Descending Tracts?
-Located in anterior column
-Carries motor impulses
Reflex Arc?
-Simplest form of nerve pathway
-In our bodies to keep us from damaging ourselves
-Does not involve the brain for interpretation
Examples: knee jerk reflex, sneezing, blinking, withdrawal, jaw jerk reflex
Reflex Arc components
Receptor
Sensory neuron
interneuron
motor neuron
effector site
Anatomy of the eye
- lacrimal apparatus
- cornea
- pupil
- iris
- sclera
- retina-organ of vision
- lens
- ciliary body
- choroid coat
- suspensory ligament
- optic nerve
- optic disc
- extrinsic eye muscles
a. lateral rectus-moves eye laterally
b. medial rectus-move eye medially
c. superior rectus-moves eye up
d. inferior rectus-moves eye down
e. superior oblique-moves eye down and laterally
f. inferior oblique-moves eye up and laterally
Saltatory Propagation Along a Myelinated Axon
a) An action potential develops in the initial segment
b) Local current depolarizes the next node to threshold
c) An action potential develops in the node
d) A local current depolarizes the membrane at the next mode. This process will continue along the length of the axon.
Synaptic Transmission
Step 1- Arrival of Action potential at synaptic knob. Nerve impulse in pre-synaptic neuron depolarizes the synaptic knob
-Calcium channels open
Neurotransmitter ACh) released from synaptic vesicles
-Neurotransmitter diffuses (ACh is removed from the synaptic cleft) across synaptic cleft causing depolarization of post-synaptic neuron