Anatomy & Physiology: Unit 3 Concept 1

Sensory Input

receives stimulus via millions of sensory receptors throughout the body

Integration

processes the input stimuli and decides what should be done

Motor Output

activates effector organs to cause a response

Neurons

nerve cells

excitable cells that respond to stimuli by conducting impulses to transmit signals

Neuroglia

glial cells

supportive cells that provide nutrition, insulation, and help with signal transmission

Soma (Cell Body)

the life support containing the nucleus and most organelles (such as tons of mitochondria)

Processes

extensions from the cell body

Dendrites

the main receptors of signals, input region

Axon

generates and transmits nerve impulses, the conducting region, also known as a nerve fiber

Nerves

bundles of axons that extend from the brain and spinal cord to the rest of the body

Ganglion

collection of nerve cell bodies located in the body (just not the brain or spinal cord)

Axon Terminals

the end of the axon that releases neurotransmitters at a synapse when a nerve impulse is received, the secretory region

Myelin Sheath

covers long axons (nerve fibers) to protect and electrically insulate them to increase the speed of nerve impulse transmission

Nodes of Ranvier

unmyelinated gaps in the myelin sheath that aid in increasing the velocity of nerve signal conduction

Multipolar

meaning greater than three processes (1 axon and two or more dendrites)

99% of neurons

Bipolar

2 processes (1 axon and 1 dendrite)

rare, found in a few special sense organs

Unipolar

1 process, dividing from the cell body like a T

in the ganglia (group of sensory neurons) in the PNS

Sensory Neurons

afferent neurons

transmit information from sensory receptors to CNS

most are structurally unipolar

Motor Neurons

efferent neurons

transport information from the CNS to the rest of the body

most are structurally multipolar to send impulse to multiple places

Interneurons

association neurons

housed in the CNS and transport information between the sensory and motor neurons

therefore are the most structurally multipolar

Somatic Nervous System

nerve impulses are sent down the neuron’s axon to the neuromuscular junction

aCh is released into the synaptic cleft for stimulation

binds to receptors on the skeletal muscle cell which transmits the AP to initiate muscle contraction

Autonomic Nervous System

muscle fibers innervate cardiac and smooth muscles as well as glands to control involuntary movements

a 2 neuron chain is used to connect the CNS to effector organs

the 1st neurons cell body starts in the CNS and synapses with a second neuron that extends to the effector organ

norepinephrine is released in the sympathetic nervous system while aCh is released into the parasympathetic, both can be stimulatory or inhibitory

Parasympathetic

rest and digest

set up to communicate with one effector organ at a time

uses neurotransmitter NE and hormones for stimulation and inhibition

Hormones

released from glands to bloodstream

Sympathetic

fight or flight

multiple effector organs at once

uses NE and hormones for stimulation and inhibition

is antagonistic to the parasympathetic division, but they can work together cooperatively

Mechanoreceptors

mechanical force, like vibration, pressure, stretch, and touch

Thermoreceptors

change in temperature

Photoreceptors

light

Chemoreceptors

chemicals

Nociceptors

pain

Reflexes

an automatic reaction to a stimuli

Innate Reflex

a rapid, predictable motor response to a startling stimulus

Learned Reflex

a response resulting from practice, repetition, or experience