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436552273 anaphy

436552273 anaphy

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ANAPHY REVIEWER

NERVOUS SYSTEM

⎯ Master control and communication system of the body

⎯ Communicates with body cells using electrical impulses which

are rapid and specific and cause almost immediate responses

FUNCTION OF THE NERVOUS SYSTEM

1. Sensory Input

⎯ Gathering information

⎯ To monitor changes occurring inside and outside the body

⎯ Changes: stimuli

⎯ Sensory organs

2. Integration

⎯ To process and interpret sensory input and decide whether

action is needed

⎯ Occurs in the CNS (brain)

3. Motor Output

⎯ A response to integrated stimuli

⎯ Activates muscles or glands (effectors)

ORGANIZATION OF THE NERVOUS SYSTEM

NERVOUS SYSTEM BASED ON STRUCTURAL

CLASSIFICATION

1. Central Nervous System

a) Organs

⎯ Brain and spinal cord

b) Functions

⎯ Integration; command center

⎯ Interpret incoming sensory information

⎯ Issue instructions based on past experience and current

conditions

2. Peripheral Nervous System

a) Nerves extending from the brain and spinal cord

⎯ Spinal nerves: carry impulses to and from the spinal cord

⎯ Cranial nerves: carry impulses to and from the brain

b) Functions

⎯ These nerves serve as communication lines among sensory

organs, the brain and spinal cord, and glands/muscles

⎯ Link all parts of the body by carting impulses from the

sensory receptors to the CNS and from the CNS to the

appropriate glands or muscles

NERVOUS SYSTEM BASED ON FUNCTIONAL

CLASSIFICATION

1. Sensory (Afferent) Division

⎯ Afferent: towards the CNS

⎯ Consists of nerves (composed of many individual nerve fibers)

that convey impulses to the CNS from sensory receptors located

in various parts of the body

⎯ Keeps the body constantly informed of events going on both

inside and outside the body

⎯ Acts as spy that detects different changes happening in and out

the body

a) Somatic Sensory Fibers

✓ soma = body

✓ Sensory fibers delivering impulses from the skin,

skeletal muscles, and joints

b) Visceral Sensory Fibers

✓ Transmitting impulses from the visceral organs

2. Motor (Efferent) Division

⎯ Carries impulses from the CNS to effector organs, the muscles

and glands; that is, they effect (bring about or cause) a motor

response

⎯ Output to the integrated NS

⎯ Issue fibers that carry impulses away from the CNS organs

a) Somatic Nervous System

✓ Allows us to consciously, or voluntarily, control our

skeletal muscles

✓ Voluntary nervous system

✓ Not all skeletal muscle activity controlled by this

motor division is voluntary – stretch reflex

b) Autonomic Nervous System

✓ Regulates events that are automatic, or involuntary,

such as the activity of smooth muscle, cardiac muscle,

and glands

✓ Involuntary nervous system which has two parts –

what one stimulates, the other inhibits

o Sympathetic

⎯ vigorous and strenuous acts

o Parasympathetic

⎯ Inhibit certain stimulus

NERVE TISSUE: STRUCTURE AND FUNCTION

TWO PRINCIPAL TYPES OF CELLS

⎯ Supporting Cells: mainly for support

⎯ Neurons: send electrical impulses

SUPPORTING CELLS

⎯ Are lumped or grouped together in the CNS as neuroglia (nerve

glue, glial cells / glia)

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⎯ General Functions of Neuroglia: support, insulate, and protect

delicate neurons

1. Astrocytes

2. Microglia

3. Ependymal

4. Oligodendrocytes

1. ASTROCYTES

⎯ Abundant star-shaped cells that account nearly half of neural

tissue

⎯ Their numerous projections have swollen ends that cling to

neurons, bracing them and anchoring them to their nutrient

supply lines – blood capillaries

⎯ Form a living barrier between capillaries and neurons, help

determine capillary permeability, and play a role in making

exchanges between the two

✓ Help protect the neurons from harmful substances that might

be in the blood

⎯ Help control the chemical environment in the brain by “mopping

up” leaked potassium ions, which are involved in generating a

nerve impulse, and recapturing chemicals released for

communication purposes

2. MICROGLIA

⎯ Spiderlike phagocytes that monitor the health of nearby neurons

and dispose debris, such as dead brain cells and bacteria

⎯ Immunity and self-defense

3. EPENDYMAL

⎯ Line the central cavities of the brain and the spinal cord

⎯ The beating of their cilia helps to circulate the cerebrospinal

fluid that fills those cavities and forms a protective watery

cushion around the CNS

4. OLIGODENDROCYTES

⎯ Wrap their flat extensions (processes) tightly around the nerve

fibers, producing fatty insulating coverings called myelin

sheaths

⎯ Exclusive to CNS only

The glial cells are said to be mitotic. They divide rapidly, while

neurons don’t divide.

Consequently, most brain tumors are gliomas – tumors formed by

neuroglia

PNS GLIAL CELLS

1. Satellite Cells

⎯ Protect neuron cell bodies

2. Schwann Cells

⎯ Form myelin sheaths in the PNS

NERVOUS TISSUE: NEURONS

⎯ Nerve cells

⎯ Highly specialized to transmit messages (nerve impulses) from

one part of the body to another

⎯ Neurons differ structurally from one another, but they have

many common features

⎯ Have a cell body that contains the nucleus and one or more

slender processes extending from the cell body

MAJOR REGIONS OF NEURONS

1. Cell Body

⎯ Is the metabolic center of the neuron

⎯ Its transparent nucleus contains a large nucleolus

⎯ The cytoplasm surrounding the nucleus contains the usual

organelles, except that it lacks centrioles – amitotic

⎯ Contains Rough ER or Nissl Bodies and neurofibrils

⎯ Neurofibirils: intermediate filaments that are important in

maintaining cell shape and are abundant in the cell body

2. Processes

⎯ Armlike processes or fibers, vary in length from microscopic to

about 7ft in the tallest humans

⎯ The longest ones reach from the lumbar region of the spine to

the great toe

a) Dendrites

✓ Neuron processes that convey incoming messages (electrical

signals) toward the cell body

✓ Neurons may have hundreds of branching dendrites (dendr

= tree), depending on the neuron type

b) Axons

✓ Generate nerve impulses and typically conduct them away

from the cell body

✓ Each neuron has only one axon, which arises from a

conelike region of the cell body called the axon hillock

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ANAPHY REVIEWER NERVOUS SYSTEM ⎯ Master control and communication system of the body ⎯ Communicates with body cells using electrical impulses which are rapid and specific and cause almost immediate responses FUNCTION OF THE NERVOUS SYSTEM 1. Sensory Input ⎯ Gathering information ⎯ To monitor changes occurring inside and outside the body ⎯ Changes: stimuli ⎯ Sensory organs 2. ⎯ ⎯ 3. ⎯ ⎯ Integration To process and interpret sensory input and decide whether action is needed Occurs in the CNS (brain) Motor Output A response to integrated stimuli Activates muscles or glands (effectors) b) Functions ⎯ These nerves serve as communication lines among sensory organs, the brain and spinal cord, and glands/muscles ⎯ Link all parts of the body by carting impulses from the sensory receptors to the CNS and from the CNS to the appropriate glands or muscles NERVOUS SYSTEM BASED ON FUNCTIONAL CLASSIFICATION 1. Sensory (Afferent) Division ⎯ Afferent: towards the CNS ⎯ Consists of nerves (composed of many individual nerve fibers) that convey impulses to the CNS from sensory receptors located in various parts of the body ⎯ Keeps the body constantly informed of events going on both inside and outside the body ⎯ Acts as spy that detects different changes happening in and out the body a) Somatic Sensory Fibers ✓ soma = body ✓ Sensory fibers delivering impulses from the skin, skeletal muscles, and joints b) Visceral Sensory Fibers ✓ Transmitting impulses fr ...
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