Summary BSC 2085 Exam 3 Study Guide

Anatomy & Physiology 1 – Exam 3 Notes

Chapter 11: Fundamentals of the Nervous System and Nervous Tissue:

The Nervous System:
-Master controlling and communicating system of body
- Cells communicate via electrical and chemical signals
- Rapid and specific
- Usually cause almost immediate responses

Functions of the Nervous System:
1.Sensory input  information gathered by sensory receptors about internal and external
changes
2. Integration  processing and interpretation of sensory input
3. Motor output  activation of effector organs (muscles and glands) produces a response

Divisions of the Nervous System:
1.Central Nervous System (CNS)
- Brain and spinal cord of dorsal body cavity
- Integration and control center  interprets sensory input and dictates motor output
2. Peripheral Nervous System (PNS)
- The portion of the nervous system outside CNS
- Consists mainly of nerves that extend from brain and spinal cord
- Spinal nerves  to and from spinal cord
- Cranial nerves  to and from brain

Peripheral Nervous System (PNS):
-Two functional divisions:
1. Sensory (afferent) division
- Somatic sensory fibers  convey impulses form skin, skeletal muscles, and
joints to CNS
- Visceral sensory fibers  convey impulses from visceral organs to CNS
2. Motor (efferent) division
- Transmits impulses from CNS to effector organs (i.e. muscles and glands)
- Two divisions:
1. Somatic Nervous System
2. Autonomic Nervous System

Somatic Nervous System:
-Somatic motor nerve fibers
- Conducts impulses from CNS to skeletal muscle
- Voluntary nervous system  conscious control of skeletal muscle

Autonomic Nervous System:

,-Visceral motor nerve fibers
- Regulates smooth muscle, cardiac muscle, and glands
- Involuntary nervous system
- Two functional subdivisions:
1. Sympathetic
2. Parasympathetic
- Work in opposition of each other

Histology of Nervous Tissue:
-Highly cellular; little extracellular space
- Tightly packed
- Two principal cell types:
1. Neuroglia  small cells that surround and wrap delicate neurons
2. Neurons (nerve cells)  excitable cells that transmit electrical signals

Neuroglia:
-Astrocytes (CNS)
- Microglial cells (CNS)
- Ependymal cells (CNS)
- Oligodendrocytes (CNS)
- Satellite cells (PNS)
- Schwann cells (PNS)

Astrocytes:
-Found in CNS
- Function = “janitor”; shape = “sea anemone”
- Most abundant, versatile, and highly branched glial cells
- Cling to neurons, synaptic endings, and capillaries
- Functions include:
- Support and brace neurons
- Play role in exchanges between capillaries and neurons
- Guide migration of young neurons
- Control chemical environment around neurons
- Respond to nerve impulses and neurotransmitters
- Influence neuronal functioning  participate in information processing in brain

, Microglial Cells:
-Found in CNS
- “White blood cells” of CNS
- Small, oval-shaped cells with thorny processes that touch and monitor neurons
- Migrate toward injured neurons
- Can transform to phagocytize microorganisms and neuronal debris




Ependymal Cells:
-Found in CNS
- Range in shape from squamous to columnar
- May be ciliated  cilia beat to circulate cerebrospinal fluid
- Line the central cavities of the brain and spinal column
- Form permeable barrier between cerebrospinal fluid (CSF) in cavities and tissue fluid bathing
CNS cells
- Makes CSF




Oligodendrocytes:
-Found in CNS
- Branched cells
- Processes wrap CNS nerve fibers, forming insulating myelin sheaths in thicker nerve fibers