CH. 11- Fundamentals of Nervous System and Nervous Tissue

Nervous system is the master controlling and communicating system of the body

1. Sensory Output-- to sense changes in the internal and external environment and conducts signals from sensory receptors (ex. light detecting cells of the eye)

2. Integration- the analysis/interpretation of the sensory signals and the formulation of appropriate responses
3. Motor Output- conduction of signals from the integration centers to effector cells, such as muscle or gland cells, which perform the body's responses is to respond to stimuli by initiating action

1. Central Nervous System (CNS)- consists of the brain and the spinal cord (dorsal body cavity). Integration and command center (interprets sensory input and dictates motor responses)

B. Peripheral Nervous System (PNS)- consists of nerves that carry signals into and out of the CNS.
Spinal nerves carry impulses to and from the spinal cord.
Cranial nerves carry impulses to and from the brain

Sensory (Afferent) Division- nerve fibers (axons) convey impulses TO the CNS from sensory receptors located throughout the body.
i.) Somatic adifferent fibers- carry impulses from the skin, skeletal muscles and joints to the brain.
ii.) Visceral adifferent fibers- transmit impulses from visceral organs to the brain.
II.) Motor (Efferent) Division- transmits impulses from the CNS to the effector.

i) Somatic Nervous System- Voluntary nervous system--conscious control of skeletal muscles (contraction)
ii) Autonomic nervous System (ANS)- Involuntary nervous system--regulates smooth muscle, cardiac muscle (contraction) and glands (secretion)
Two divisions:
Sympathetic- (stimulates-getting excited)
Parasympathetic (inhibits-calming down)

Neuroglia (glial/supporting cells)- provide a supportive scaffold for neurons.

Neurons- excitable cells that transmit electrical signals

Neuroglia
Astrocytes (CNS)- most abundant. Star-shaped cells, radiating processes support, brase and anchor neurons to blood capillaries (nutrient supply). Help form blood-brain barrier. Maintain appropriate ion and neurotransmitter concentrations.

Ii) Microglial Cells (CNS)- defensive cells in the CNS, transform into phagocytic cells-clear away microbes and dead cells

Iii) Ependymal Cells (CNS)- form epithelial membrane lining ventricles of brain and central cavities of brain. Produce cerebrospinal fluid (CSF), Cilia aid in circulation of CSF

Iv) Oligodendrocytes (CNS)- cell processes wrap around CNS axons and form insulating myelin sheath.
v.) Schwann Cells (PNS)- Produce myelin sheaths and wrap around axons in PNS

Vi.) Satellite Cells (PNS)- flat cells that surround and support neuronal cell bodies (ganglia) in PNS. Has many of the same functions as astrocytes for the CNS.

Neurons are structural units of the nervous system. They conduct messages in the form of nerve impulses from one part of the body to the other. Long-lived, amitotic, and have a high metabolic rate.

Neroun cell body:
Also called perikaryon of soma.
Neuron organelles are located here
contains the nucleus and nucleolus
Has well-developed Nissl bodies (through endo retic)
In CNS referred to as nuclei
In PNS referred to as ganglia