Chapter 11 - Functional Organization of Nervous Tissue

Detect/receive stimuli from receptors; process and respond to sensory info; initiate response based on sensory info; primary center for mental activities

Functions of the nervous system

Sensation

Process of nervous system receiving information about internal or external environment; helps maintain homeostasis

Stimulus

A change in environment; detected by major senses

Integration

Process of stimuli being received and

processed by the CNS; compares current stimuli to other stimuli, memories, etc.; generates a specific response

Response

Process in which the nervous system answers a stimulus in a voluntary or autonomic way

Voluntary response

Process in which the somatic nervous system responds to a stimulus by contracting skeletal muscle

Involuntary response

Process in which the autonomic nervous system responds to a stimulus by stimulating smooth muscles or glands, regulating cardiac muscle, and maintaining homeostasis

Neurons

Main cell type in nervous system; send signals along an axon

Nerves

Collections of axons located outside the CNS

Cranial nerves

12 pairs of nerves that originate in the brain

Peripheral (spinal) nerves

31 pairs of nerves that originate from the spinal cord

Glial cells

Support cells of the nervous system that don’t send signals

Central and peripheral nervous systems

Major anatomical divisions of the nervous system

Central nervous system

Division of the nervous system made of the brain and spinal cord; is encased in bone

Peripheral nervous system

Division of the nervous system made of spinal nerves, cranial nerves, sensory receptor, ganglia, and plexuses; located outside the brain and spinal cord

peripheral nervous system

Division of the nervous system that detects stimuli, transmits it to the spinal cord, and receives signals from the CNS

Central nervous system

Division of the nervous system that processes, integrates, stores, and responds to information from PNS

Skeletal muscle

Effectors of somatic nervous system

Cardiac and smooth muscle and glands

Effectors of autonomic nervous system

Sensory (afferent) and motor (efferent)

Divisions of the peripheral nervous system

Sensory (afferent) division

Division of the peripheral nervous system that detects stimuli sends action potential toward the central nervous system through nerves

Motor (efferent) division

Division of the PNS that sends action potentials away from the CNS toward effectors via cranial or spinal nerves

Somatic and autonomic

Motor divisions of the peripheral nervous system

Somatic nervous system

Part of PNS that sends signal from CNS toward effectors; stimulates VOLUNTARY motor response in skeletal muscle contraction and learned motor skills

Autonomic nervous system

Part of the PNS that sends signals from the CNS toward effectors; stimulates INVOLUNTARY actions like smooth muscle contractions and maintaining homeostasis

Sympathetic and parasympathetic

Divisions of the autonomic nervous system

Sympathetic nervous system

Part of ANS that triggers physical activity and the flight or fight response due to immediate threats; uses norepinephrine as a neurotransmitter

Parasympathetic nervous system

Part of ANS that triggers rest and digestion in the body; uses ACh as a neurotransmitter

neurons and glial cells

Main types of cells in nervous system

Dendrites

Branch like arms on cell body of neuron that receive stimuli from other neurons; conduct signals toward cell body and axon

Cell body

Primary site of protein synthesis in neurons; contains neurotransmitters and organelles

Axon

Part of neuron covered by myelin that transmits actions potential from one side of neuron to another; conducts action potential away from cell body (anterograde); ends at presynaptic terminals

Myelin sheath

Part of neuron that covers axon and increases speed of action potential

Presynaptic terminals

Part of the neuron that holds neurotransmitters in vesicles and transmits them to the dendrites of another neuron

Node of ranvier

Gap between myelin sheath on the axon; helps with transmission of signal down the axon

Shape/structure (number of dendrites) and function (direction of signal)

Classifications of neurons

Multipolar neuron

Most common shape of neuron in CNS

Multipolar neurons

Neurons that have many dendrites and an axon; most common in CNS

Astrocyte, ependymal, oligodendrocyte, and microglial

Types of glial cells in CNS

Astrocytes

The largest and most numerous type of glial cell in CNS; looks like a star; provide structural support for neurons and blood vessels; form the blood brain barrier

Blood brain barrier

A barrier formed around blood vessels in the brain that keeps toxins out of brain fluid; controls what substances can enter the brain fluid through tight junctions

Ependymal cells

Type of glial cell that filters blood to create cerebrospinal fluid; found lining the ventricles of brain to move CSF

Microglia

Type of glial cell that is very small and phagocytic; plays a role in immune function and responds to inflammation

Oligodendrocytes

Type of glial cell that holds nerve fibers together and forms myelin sheath around axons of CNS neurons