Nervous System

Cerebral Palsy

• Neurological disorder caused by NON PROGRESSIVE brain injury or malformation while brain is under development (before birth, during birth, or immediately after birth)

  • Only about 10% during the birthing process

• Primarily affects body movement and muscle contractions

• Non life threatening; expected to live well into adulthood

• Cannot be fixed but treatment and therapy can help

Paralysis

• Inability to move (and sometimes feel) in part of most of the body; typically a result of poison, illness, or injury

• Interruption in messages between brain and muscles

• Spinal cord injuries

• Guillain-Barre syndrome

• Bell’s palsy

• ALS

Epilepsy/Seizure Disorder

• Seizure: single surge of electrical activity in the brain

• Seizure disorder: condition in which a person has multiple seizures

Seizure is an abnormal electrical discharge that occurs in the brain…usually neurons flow in an organized fashion along the surface of the brain, but seizure is when it is excessive or abnormal

Can cause muscle spasms, limb switches, loss of consciousness

Can lead to change in feeling and behavior

→ maybe be as a result a metabolic disorder or genetic factors

Who gets seizure and seizure disorders?

• A number of risk factors can increase one's chances of developing a seizure:

  • Previous brain injury or infection

  • Having a history of a stroke

  • History of complex febrile seizures

  • Using certain recreational drugs or medications

  • Overdosing on drugs

  • Exposure to toxic substances

• Once diagnosed with seizure disorder, more likely to have an episode if:

  • Feeling stressed

  • Not getting enough sleep

  • Drinking alcohol

  • Changes in hormones (like with a woman’s menses)

Multiple Sclerosis or MS

• Disabling disease of the the CNS that disrupts the flow of information with the brain and between the brain and the body

• “Immune” system attacks CNS and damages the myelin

• Thought to be triggered in genetically susceptible individual by a combination of one or more environmental factors

• Diagnosed by elimination of other diseases

Amyotrophic Lateral Sclerosis (ALS)

• ALS (Lou Gehrig’s Disease)

• Progressive neurodegenerative disease that affects

• As motor neurons die, the ability of the brain to initiate and control muscle movement is lost

• Two variations: sporadic (90-95%) and familial 

• 100% fatal (death usually results 3-5 years from diagnosis)

3 basic functions of the Nervous System

Sensory, Motor, Integrative

Sensory Function

Monitors changes inside and outside the body, think 5 basic senses.

Integrative Function

Processes and interprets sensory input to create sensations and thoughts, makes decisions, etc.

Motor Function

Effects a response by activating muscles or glands

2 types of cells that make up nervous tissue

Neurons and Neuroglia

Neuroglial cells

Cells that support, insulate, and protect nerve cells.

5 types - Astrocytes, Microglial, Ependymal, Oligodendrocytes, Schwann Cells

Astrocytes

Star-shaped cells that brace and anchor neurons to their capillaries

Microglial Cells

Spider-like cells that dispose of debris (dead brain cells and bacteria)

Ependymal Cells

Cells lining the brain and spinal cord cavities; have cilia that circulate cerebral spinal fluid; forms a cushion

Oligodendrocytes

Cells that wrap around nerve fibers forming insulating sheaths (up to 50 neurons)

Schwann Cells

Form myelin sheaths around nerve fibers in the peripheral nervous system. Myelin is an insulative fatty substance.

Neurons

Nerve cells highly specialized to transmit impulses from one part of the body to another (cannot divide = not able to produce cancer)

Cell Body

Contains the nucleus and is the metabolic center of the cell

Dendrites

Numerous, short fibers that transmit impulses TOWARDS the cell body

Axons

A simple, long fiber that conducts impulses AWAY from the cell body

Axonal Terminals

Branches at the ends of an axon that release neurotransmitters

Synapse (synaptic cleft)

A gap separating two communicating neurons

Myelin Sheath

A white fatty material covering most long nerve fibers. It protects, insulates, and increases the transmission rate of nerve impulses.

Nodes of Ranvier

Unmyelinated gaps between segments of the myelin sheath that facilitate rapid conduction of nerve impulses.

Functional classification of Neurons

Sensory (afferent)

Motor (efferent)

Interneurons

Sensory (afferent) neurons

Neurons that carry impulses from the sensory receptors to the CNS

Motor (efferent) neurons

Neurons carrying impulses from the CNS to the muscles and glands

Interneurons

The “middle-man,” contains both sensory and motor neurons

Structural classification of neurons

Multipolar

Bipolar

Unipolar

Multipolar

has multiple processes

Bipolar

2 processes (axon and dendrite)

Unipolar

has a single process that branches immediately into 2 fibers

CNS (central nervous system)

Brain and spinal cord

PNS (peripheral nervous system)

peripheral nerves (31 pair spinal nerves, 12 pair cranial nerves)

the PNS separates further into the:

Somatic (voluntary) Nervous System

and

Autonomic (involuntary) Nervous System

Somatic Nervous System

Allows us to voluntarily/consciously control our skeletal muscles

Autonomic Nervous System

Regulates automatic involuntary events like the activity of smooth and cardiac muscle

The Autonomic Nervous System is divided further into the:

Parasympathetic Nervous System

and

Sympathetic Nervous System

Parasympathetic Nervous System

“Resting and Digesting” branch of the autonomic nervous system that conserves energy and promotes relaxation and digestion. The 3 D’s: Digesting, Defecation, and Diuresis

Sympathetic Nervous System

“Fight or Flight” system, functions to provide best response to a threat (Excitement, Emergency, Exercise)

Brain

Consists of 4 areas

• Cerebrum

• Diencephalon

• Cerebellum

• Brain Stem

Cerebrum

Largest, convoluted, superior portion of the brain (mushroom cap)

Separated by a deep longitudinal fissure that divides it into 2 halves called cerebral hemispheres

4 lobes of the cerebrum

Frontal

Parietal

Temporal

Occipital

Frontal Lobe

Responsible for thinking and creativity; primary motor area (skeletal muscle movement)

Parietal Lobe

Regulates memory of objects and their uses; sensory area (pain, temp, and pressure)

Temporal Lobe

Regulates speech, hearing, and memory

Occipital Lobe

Visual area

Insular Lobe

Located behind the temporal and frontal lobes; may be associated with controlling behavior related to feelings of pleasure and happiness

Corpus Callosum

A network of nerve tissue that connects the right and left brain hemispheres

Cerebral Cortex

Outermost 2-4 mm of the cerebrum that contains gray matter

Most information processing in the brain happens here

White matter

Made of myelinated neurons; found to the interior of the brain

Gray Matter

Un-myelinated neurons; found in the cerebral cortex

Sulci vs Gyri

Gyri - Peaks

Sulci - Valleys

Ventricles

Cavities in the brain that aid in the circulation of cerebral spinal fluid

Diencephalon

Sits directly on top of the brain stem; sometimes called the innerbrain

Diencephalon parts

Thalamus

Hypothalamus

Epithalamus

Thalamus

Relay station for sensory impulses

Hypothalamus

Regulates body temp, water balance, metabolism, and sleep

Epithalamus

Cerebral Spinal Fluid is formed here

Cerebellum

“Sara Bellum the ballerina.” Cauliflower-like structure at the back of the brain responsible for coordination, balance, and posture.

Brain stem

The brain-spinal cord connector. Located below the diencephalon

Brain Stem Parts

Midbrain

Pons

Medulla Oblongata

Midbrain

Forms the upper part of the brain stem. Involved in vision and hearing.

Pons

Located below the midbrain; involved in the control of breathing

Medulla Oblongata

Located below the pons; directly connects to the spinal cord; Controls breathing, heart rate, and blood pressure; nerves cross here

Spinal Cord

~17 inches long and extends to L1 or L2. Contains 31 pair of spinal nerves

Protection of the CNS

Meninges:

• Dura Mater - Outermost layer; leather and tough

• Arachnoid Mater - Middle, weblike layer

• Pia Mater - innermost layer; clings tightly to the brain and spinal cord

Cerebral Spinal Fluid

Water fluid similar to blood that protects nervous tissue; surrounds the brain and spinal cord. Think of a pillow for the brain. If your head hits a hard surface, it cushions the blow.