The Nervous System

Human Regulation

• In humans and animals regulation is done by the nervous and endocrine system – There are some

differences and some similarities between the two systems

Similarities between the Endocrine and Nervous system

• Both secret chemical messages – Nervous system

secretes – neurotransmitters

– Endocrine – secretes hormones

• BOTH PLAY A MAJOR ROLE IN HOMEOSTASIS

Differences between the Endocrine and Nervous system

• Nervous system response is much much faster

• Nerve response is shorter in duration than endocrine

Human Nervous system

• What is a neuron?– A neuron is the basic

cell of the nervous system

There are three types of neurons.

• Sensory Neurons – Transmit ( sends

messages) from receptors to the central nervous system ( fire is hot)

– They are located near the sensory organs such as

• Eyes

• Ears

• Nose

• Tongue

• Skin

Interneuron

• Another type of neurons

• Located mainly in the central nervous system – It’s job is to interpret

and relay the information from the sensory neurons to the motor neurons

Motor Neurons

• Transmit impulses from the central nervous system to the effectors – Effectors are glands

and muscles

• These messages cause the effectors to respond– ( fire is hot pull hand

back)

So what are nerves?

• Nerves are groups of neurons or parts of neurons specialized for high speed and long distances impulse transmission

• They can be – motor neurons – Sensory neurons – Or mixed

Nerves

• Most nerves have a fatty sheath– This is for

• Protection • Make sure not touching

other nerves or tissues

• A neuron is a long cell that consists of three regions: a cell body, dendrites, and an axon.

Nerves continued

• Dendrites- receive impulses and carry them toward the cell body

• Axon- carries impulses away from the cell body and toward other neurons, muscles, or glands.

• Cell body- contains the nucleus

How does it work

• Resting - no impulse, cell is polarized ( + on outside & - on inside)– Sodium/Potassium pump in axon using ATP

maintains this polarity

• 2.Impulse: stimulus excites neuron– Na+ gates open– Na+ goes inside, therefore inside becomes more +– Depolarization occurs ~ a nerve impulse– Impulse moves in one direction

Connection between Neurons

• Synapse: gap between neurons or neurons and effectors

• Neurotransmitter: chemical, such as acetylcholine, which, when secreted aid in the transmission of of an impulse across a synapse.

There are two parts to the Nervous System

-Central Nervous system

-Peripheral Nervous system

Central Nervous System (CNS)

• There are two main parts to the CNS – Brain – Spinal Cord

Brain

• Is a large mass of neurons located in the head – Responsible for controlling and coordinating most

activities of the body • Cerebrum:

– Conscious activities– Intelligence– Memory– Language– Voluntary activity

• Cerebellum:– Coordinates motor activity– Balance

• Medulla Oblongata:– involuntary activities such as breathing, & heart rate

Spinal Cord

• Lies within the vertebrae – Bones of the spinal column

• Spinal cord is connected to the Medulla

• It is the center for reflex activities – Does not require activity

from the brain to give off a response

• Reflex actions – are inborn reflexes – Ex blinking

Peripheral Nervous system

• Is located outside the CNS – It contains nerves that

extend throughout the body

– There are two parts to the PNS

• Somatic nervous system

• Autonomic nervous system

Somatic Nervous system

• These neurons deal with voluntary actions – Ex

• run • Play• Swing • Hit •

Autonomic nervous system

• Generally deal with involuntary acts – Breathing glands

Malfunctions of the nervous system

• Listed are some of the malfunctions of the nervous system – Cerebral Palsy – Meningitis – Stroke – Polio

Cerebral Palsy (CP)

• A group of diseases you are born with which disturb the motor functions

• Person still has normal mental capacity but – Speach and motor

function are distorted

Meningitis

• Inflammation of the membrane that surrounds the spinal cord and brain

Stroke

• Caused by a cerebral Hemorrhage ( burst of blood vessels) or a blood clot in the brain – May cause brain

damage or death

Polio

• Viral disease in the CNS may cause paralysis

• Can be prevented through immunization Shots