Regulation: Nervous System

A World Without Pain Four-year-old Roberto Salazar does not feel pain because of a rare genetic disorder. Perry Goldberger, 15, can't distinguish between hot and cold and cannot feel pain

NERVOUS SYSTEM

Nerve Cells Nerve cells = neurons Receive impulses and send the messages to various parts of the body via Cellular Communication Nerve cells make up: Nerves Brain Spinal cord Receptors

???? You accidentally place your hand on a hot iron and quickly move it away. What is the stimulus? What is the impulse? What is the response? What is the difference between the CNS and PNS? What is the function of a neuron?

Neuron Structure 1. Cyton- cell body 2. Cell nucleus 3. Dendrites – receive impulses

Neuron Structure Cont… 7. Axon – carries impulses away from the dendrites 6. Myelin Sheath – fatty covering of the axon which speeds up impulses 5. Schwann Cells (make myelin)

Neuron Structure Cont… 9. Terminal Branches Synapse – gap where impulses travel from the axon of one neuron to the dendrites of another neuron. Neurotransmitters – chemical messengers that cross the synapse

Types of Neurons Sensory: carry impulses to the CNS Motor: carry impulses from the CNS to other parts of the body such as muscles Mixed: contain both

Receptors Receive messages Found on the cell membrane and are VERY SPECIFIC!!!

CNS

The Brain Cerebrum – thinking, memory, voluntary actions, emotions Cerebellum – coordination and balance Medulla (brain stem) – involuntary actions like breathing and heartbeat

Spinal Cord Mass of nerve cells Vertebrae – protect it Function – relays impulses to and from the brain center for some reflex actions

Autonomic Nervous System Part of the peripheral nervous system Controls involuntary behavior (automatic) Examples: Breathing Heart rate Blinking, dilation of pupil Production of saliva Increases and decreases the rate of these involuntary behaviors to help maintain homeostasis

Reflexes- Reflex arc Involuntary behavior Reflex: Receptor (nerve endings in the knee) receive a message Sensory neuron sends to message to the spinal cord (CNS) The interneuron connects the sensory neuron to the motor neurons The motor neuron sends the message to the muscle in the leg (EFFECTOR) Effector then reacts such as a knee jerk

Somatic Nervous System Part of the peripheral nervous system voluntary behavior Examples: movement of skeletal muscles

Disorders of the Nervous System

Cerebral Palsy Birth disorder that affects motor function.

Polio A viral pathogen that polio affects the nerves, resulting in paralysis of the arms, legs or the diaphragm (which controls breathing). Between two and five per cent of people who develop paralytic polio will die. Half of those who survive will have permanent paralysis.

Stroke When a free-floating blood clot reaches the brain Blood vessel ruptures in the head/neck

Meningitis Inflammation of the meninges (membrane surrounding the brain and spinal cord) Can be viral (not severe) or bacterial (VERY severe) Symptoms come quickly Fever and chills, nausea and vomiting, sensitivity to light, severe headaches

The meningococcal vaccination is recommended for: Adolescents ages 11 - 12 and adolescents entering high school (about age 15) who have not already received the vaccination. All college freshmen who have not been vaccinated and are living in dorms. Those traveling to countries where diseases caused by meningococcus are very common