Nervous System

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Nervous System - Objectives

• Label and name the parts of the NS– the divisions of the NS

• Explain what a neuron looks like and the types you have in your body

• Describe the functions of the NS

Nervous System – Objectives 2

• Name the 4 major parts of the brain

• Describe the function of the 4 parts of the brain

• Explain how the major parts of the brain are broken into smaller parts and their functions

• Describe what happens as people age

Part 1 of the N.S.

• Central Nervous System (CNS)– Brain

• Located in the skull

– Spinal Cord• Located in the vertebral canal• Broken into 5 regions

– Cervical (Head, neck, shoulder, and upper limb movement)

– Thoracic (Rib and hip movement, Posture)

– Lumbar (Hip and lower limb movement)

– Sacral (Lower limb movement)

– Coccygeal (tailbone)

Part 2 of the N. S.

• Peripheral Nervous System (PNS)

– External to the CNS– Divided into 2 parts

• Sensory or Afferent division• Motor or Efferent division (divided into 2

parts)– Somatic motor nervous system– Autonomic Nervous System (ANS)

Cells of the Nervous System

• Neurons (primary cells)– Consist of a cell body and two types of

processes• Dendrites: Short, often highly branched

cytoplasmic extensions that are tapered from their bases at the neuron cell body to their tips

• Axons: long cell process extending from the neuron cell body

• Glial Cells or Neuroglia (secondary cells)

Structural Classifiaction of Neurons

• Multi-polar Neuron – many dendrites and an axon

• Bi-polar Neuron – a dendrite and

an axon

• Uni-polar Neuron – an axon and

no dendrites

Ways the Cells get information

• Cells either gain their information by:

– Secreting chemicals to the body and brain

– Create and send electrical impulses to get information to the body and the brain

The BrainAKA:

the control center

of the body

The Brain and It’s Parts…

• The control center for many of the body’s functions

• Parts– Brainstem– Cerebellum– Diencephalon– Cerebrum

• Connective tissue membranes

Brain Stem

• Consists of– Medulla oblongata– Pons– Midbrain

• Connects the spinal cord and cerebellum to the remainder of the brain

• 10-12 pairs of cranial nerves arise from it

Cerebellum and Diencephalon

• Attached to the posterior brainstem

• The word means “little brain”

• Divided into: – Anterior lobe– Posterior lobe

• Located between the brainstem and cerebrum

• Main components– Thalamus

• emotions

– Subthalamus• Motor functions

– Epithalamus• Sense of smell• Sleep-wake cycle

– Hypothalamus• ANS• Endocrine and Lymbic • Basic body functions

Cerebrum• What most people think

of when they think of the brain

• Accounts for the largest portion of total brain weight

• Divided into right and left hemispheres by a longitudinal fissure

• Each hemisphere is divided into lobes– Frontal lobe– Parietal lobe– Occipital lobe– Temporal lobe

Meninges, Ventricles, and Cerebrospinal Fluid

• Meninges are connective tissues that surround and protect things

• The ventricles hold the Cerebrospinal Fluid

• Cerebrospinal Fluid fills the ventricles, the space around the brain and is found in the spinal cord

Functions of the Nervous System

• Sensory Input– Sensory receptors monitor external and

internal stimuli

• Integration– The brain and spinal cord process input and

either respond, store, or ignore the input

Functions of the Nervous System

• Control of Muscles and Glands– Controls the major movements of the body

(skeletal muscle) as well as cardiac muscle, smooth muscle, and glands

• Homeostasis– Stimulates or inhibits the activities of other

systems to help maintain a constant internal environment

Functions of the Nervous System

• Mental Activity

– The brain is the center of this function

– It is the center of all activities• Consciousness• Thinking• Memory• Emotions

NS and the Skin

• Regulates body temperature by controlling sweat glands and blood vessels

• The skin hold receptors for heat, cold, temp, pain, pressure and vibration so that the NS can regulate what happens to the skin

NS and the:

• Bones– The NS makes one

aware of pain when a bone is broken making it less likely for us to move the part.

– The bones support and protect the NS

• Muscles– Stimulates muscle

contractions • Voluntary • Involuntary

– Maintains muscle tone– Sensory receptors in

the muscles tell the body where it is

NS and the:

• Endocrine System• Controls the release

of hormones– These hormones in

turn affect neuron growth and metabolism

• Lymphatic System• Stimulates and

Inhibits immunity in ways that are not well understood

NS and the:

• Cardiovascular System

• Regulates heart rate and force of contraction

• Changes blood vessel diameter

• Respiratory System• Regulates depth and

rate in which we breathe

NS and the Digestive System

• Regulates secretion from the digestive glands

• Regulates secretion from the digestive organs

• Controls the mixing and movement of the digestive tract

Aging and the Nervous System

• As people age:– The size and weight of the brain decreases– The senses gradually decline because the

number of neurons in this area declines– The functions of all other neurons decreases

because the number of neurons decline as well

– CNS processing decreases • https://www.youtube.com/watch?v=jJfESattZOY