Nervous System Flashcards
Neuron general function and structure
Function:
- Basic functional units of nervous system.
- Depolarization and repolarization (K+/Na+ pump).
- Requires high amounts of O2.
Structure:
- Dendrites and axons
White matter
- Fibers beneath the cortex and corpus callosum.
- Connect two halves of the cerebral cortex.
Myelin
Myelin axons conduct impulses faster
Dendrites function and structure
Function:
- Receive stimuli from other neurons & conduct the stimuli to the cell body.
- Can serve as sensory receptors for inside/outside body (heat, cold, touch, pressure, physical changes).
Structure:
- Short, numerous, multibranched.
Axon function and structure
Function:
- Conduct nerve pulses away from cell toward another neuron or effector cell.
Structure:
- Single, long process; may be covered with myelin.
Gray matter
Cerebral cortex; outer layer of the brain
Efferent nerves
“Motor Nerves”
- Conduct impulses away from CNS.
- Motor Nerves: cause skeletal muscle contraction and movement.
Afferent nerves
“Sensory Nerves”
- Conduct impulses towards CNS.
- Sensory Nerves: conduct sensations from sensory receptors in the skin & other locations in the body to the CNS.
Somatic nervous system
Actions under conscious/voluntary control
Automatic nervous system
- Controls and coordinates automatic functions.
Ex: slowing HR in response to low blood pressure.
Central nervous system (CNS)
- Brain: Cerebrum, cerebellum, diencephalon, & brainstem.
- Spinal cord
Peripheral nervous system (PNS)
- All the nerves that reach every part of the body.
- Somatic & Autonomic nervous system.
Sympathetic nervous system
- “Fight or flight” response.
- Epinephrine
Parasympathetic nervous sytem
- “Rest & digest” system.
- Acetylcholine
Somatic reflexes
Involve contraction of skeletal muscles
Autonomic reflexes
Regulate smooth muscle, cardiac muscle, and endocrine glands
Withdrawal reflex
Results in contraction or flexing of muscles.
Ex: stepping on lego, so you move your foot off the ground.
Palpebral reflex arc
Light tap on the medial canthus of the eye produces a blink of the eyelids
Pupillary light reflex (PLR)
Normal response to shining light in the eye of an animal for the iris in both eyes to constrict
Cerebrospinal fluid (CSF)
- Fluid between layers of the meninges & in canals & ventricles inside the brain and central canal of spinal cord.
- Provides cushioning function.
- May play role in regulation of autonomic functions such as respiration & vomiting.
Cerebrum function & structure
Hint: this is the brainy part of the brain
Function:
- Area of the brain responsible for higher-order behaviors (learning, awareness, etc).
Structure:
- Gray matter: cerebral cortex; outer layer of brain.
- White matter: fibers (connect halves of cerebral cortex) beneath cortex & corpus callosum.
- Gyri: folds in cerebral
- Fissures: deep groves separating gyri
Cerebellum function and structure
“Butt of the brain”
Function:
- Responsible for coordinated movement, balance, posture, & complex reflexes.
Structure:
- Caudal to cerebrum
Diencephalon (midbrain) function/structure & associated structures
Function/structure:
- Passageway/connection between brain stem & cerebrum.
Associated structures:
- Thalamus: relay station for reg sensory inputs to cerebrum.
- Hypothalamus: interface between nerv. & endocrine system.
- Pituitary: endocrine “master gland”
Brain stem function and structure
“Primitive brain”
Function:
- Responsible for basic support functions of the body.
- Connection between brain & the spinal cord.
Structure:
- Composed of the midbrain, pons, & medulla oblongata.
- Many cranial nerves originate from here.
Cross extender reflex
“contralateral reflex”
- Prevents individual from falling when withdrawal reflex is stimulated.
- Afferent sensory impulse crosses to other side of spinal cord & stim muscles to extend the opposite limb.
Stretch reflex
“ipsilateral reflex”
- Contraction of a muscle in response to its own stretching
- Ex: Patellar ligament (below kneecap) getting tapped. Force causes lig to stretch stimulating contraction of quads. This makes the leg stretch (kick).
Sodium (Na+) Potassium (K+) pump
Specialized molecule that pumps Na+ from inside the neuron to outside. They also pump K+ from outside to inside.
Depolarization & Repolarization of the Na+/K+ pump
1. Resting state
2. Depolarization
3. Beginning of repolarization
4. Repolarization
- Resting: Na+ has been pumped in and K+ pumped out the cell, producing a neg charge.
- Depol: Na+ channel is open, sodium flow into the cell. Produces neg charge OUTside the cell.
- Beg of repol. Na+ gate is closing whole the K+ gate is open.
- Repol: K+ gate closes after sufficient amount of potassium has restored neg charge INside the cell.
