Nueroanatomy Flashcards
Central Nervous System (CNS)
Consists of the brain and the spinal cord. Integrating and command center of the nervous system: receives incoming sensory signals, interprets the signals, and dictates motor responses.
Peripheral Nervous System (PNS)
Part of nervous system outside of CNS:
- Cranial nerves
- Spinal nerves
- Ganglia
Ganglia
PNS
collection of cell bodies
Sensory input
Afferent
Receive signals and gather information
Integration
Integrate incoming signals (to determine whether or not the information should be passed along)
Motor output
Efferent
Communicate signals to target cells (other neurons or muscles or glands)
Dendrite
Receiving and processing end of neuron
Cell body
Synthesizes information and proteins. Decides whether or not to send information down the line.
Axon
Sending end of neuron.
Arises from the cell body at a specialized area called the axon hillock. Axons are covered with myelin, which helps them convey the nerve impulse rapidly.
Somatic sensory
General: touch, pain, pressure, vibration, from skin, body wall and limbs.
Special: hearing, equilibrium, vision
Visceral sensory
General: stretch, pain, temperature, chemical changes, nausea, hunger.
Special: taste and smell
Somatic motor
Motor innervation to skeletal muscles
Visceral motor
Motor innervation to smooth muscle, cardiac muscle and glands
Multipolar neuron
many processes extend from the cell body; all are dendrites except for a single axon
Bipolar neuron
two processes extend from the cell body: one is a fused dendrite; the other is an axon
Unipolar (psuedounipolar)
one process extends from the cell body and forms central and peripheral processes, which together comprise an axon.
Where are bipolar neurons found?
rare, sensory neurons found in some special sensory organs (olfactory, eye, ear). Visual input from eye to brain.
Where are multipolar neurons found?
most abundant in body, major neuron type in the CNS. Most are interneurons that conduct impulses within the CNS, some are motor that conduct impulses from CNS to effector ( muscle/gland).
Where are unipolar (psuedounipolar) neurons found?
mainly in the PNS. Common only in the dorsal root ganglia of the spinal cord and sensory ganglia of cranial nerves.
What is it called when one neuron connects up to another neuron?
a chemical event
What is a reflex arc?
simple chains of neurons that cause our simplest, reflexive behaviors and reflect the basic structural plan of the nervous system.
What is a neuron?
a nerve cell
What is a nerve fiber?
a long axon
What is a nerve?
a collection of axons in the PNS
What is a monosynaptic reflex?
one reflex. example: knee jerk
What is a polysynaptic reflex?
more common than monosynaptic, one or more interneurons are part of the reflex pathway between sensory and motor. Example: pricking a finger with a tack.
What is a sensory neuron?
afferent neuron, transmit impulses toward the CNS from sensory receptors in the PNS.
What is a motor neuron?
efferent neuron, make up the motor division of the PNS. carry impulses away from the CNS to effector organs (muscles and glands).
What is an interneuron?
lie between sensory and motor neurons. confined entirely to CNS. make up 99.98% of neurons in the body.
What is the function of glial cells?
Aka neuroglial. Provide support in the CNS and PNS (hold the brain together), insulate the neurons and keep electrical activities of adjacent neurons from interfering with each other.
What is an astrocyte cell?
(star cell) most abundant glial cell. Provides physical support (clasp and hold parts of neurons, wrap capillaries and hold them). can also signal increased blood flow through capillaries in active regions of the brain.
What is a microglial cell?
Immune defense
Tiny cell; scavenger of the brain: migrate to and then engulf invading microorganisms and injured or dead neurons.
What is a oligodendrocyte cell?
produces myelin sheath
“few branch cells”: line up in small groups and wrap their cell processes around thicker axons in the CNS, producing insulating coverings called myelin sheath.
What is a ranvier?
myelin sheath gap on a myelinated axon.
What is an ependymal cell?
“wrapping garment”: bear cilia that helps circulate the fluid. Form a simple epithelium that lines the central cavity of the spinal cord and brain.
What are the support cells of the CNS?
1) Astrocyte
2) Microglial
3) Ependymal
4) Oligodendrocyte
What is a satellite cell?
surround neuron cell bodies within ganglia.
resemblance to moons or satellites around a planet.
What is a schwann cell?
surround all axons in the PNS and form myelin sheaths around many of these axons. Monogamous.
What are myelin sheaths?
produced by oligodendrocytes in the CNS and Schwann cells in the PNS.
What is a peripheral nerve?
cable-like collection of axons
What is the endonerium?
myelinated axons covered by a thin layer of CT
What is a perinerium?
groups of axons, fascicles covered by CT
What is epinerium?
tough fibrous sheath covering the whole nerve.
What are the 4 regions of the brain?
1) cerebrum
2) diencephalon
3) brainstem
4) cerebellum
What is the cerebrum and its function?
- 2 hemispheres that account for 83% brain mass
- highest level of analysis of sensory input
- highest level of somatic motor control (i.e. plan responses)
- speech, articulation of thought, memory
- association of memory, emotion, reasoning, motivation, personality, judgement, intelligence, etc.
What is sulci?
grooves of the brain