Nervous System Outline Health Occupations

Nervous System Functions Directs the functions of all human body systems 100 Billion Nerve cells Carry messages from brain to rest of body

Neurons The basic element of nervous system Highly specialized Vary in function, shape, and size Separated by synapses Gaps in between each neuron Neurotransmitters Stimulates impulse to jump to next nerve

Neurons 3 Parts Cell Body Dendrites Axon Have fibers to reach out to send or receive impulses Dendrites Thin branching extensions of cell body Conduct nerve impulses to cell body Axon Conducts nerve impulses away from cell body Covered by a myelin sheath Fatty tissue that makes impulse travel faster End of axon has fibers that let the impulse leave the nerve

Neurons 2 Basic Properties Excitability Conductivity Ability to respond to a stimulus Conductivity Ability to transmit a signal

Neurons 3 Types Efferent (motor) Afferent (sensory) Interneurons Carry information to muscles and glands from CNS Afferent (sensory) Carry information from sensory system to CNS Interneurons Carry and process sensory information

Neuron bundles = Nerves Stimulus Receptor Impulse Nerve Receptor

Neuroglias Support, connect, protect, and remove debris Do not transmit impulses Form blood-brain barrier Permits some chemical substances to reach the brain’s neurons but blocks most others

Central Nervous System (CNS) Consists of: Brain Spinal cord Center of Control

CNS Functions Receives and interprets all stimuli Sends nerve impulses to instruct muscles and glands to take over or respond to certain actions Causes Voluntary and Involuntary actions

Brain Divisions Brainstem Cerebellum Cerebrum Diencephalon

Brain Stem Midbrain Pons Medulla Oblongata Visual reflexes Controls certain respiratory functions Medulla Oblongata Regulates heart & lung functions Swallowing Vomiting Coughing sneezing

Cerebellum Coordinates musculoskeletal movement Maintains balance Posture Muscle tone

Cerebrum 2 hemispheres Cerebral Cortex Four Lobes Left and Right Conscious decision making Four Lobes Frontal Moral Behavior, voluntary motor movements Parietal Controls and interprets senses and taste Temporal Memory, equilibrium, emotion, hearing Occipital vision

Diencephalon Deep portion of brain Contains: Thalamus Hypothalamus Relay center for sensations Controls: Heart rate Blood pressure Temperature regulation Water and electrolyte balance Digestive functions Glandular activities

Cerebrospinal Fluid (CSF) Fills the area between the brain and cranium Watery fluid that contains various compound Cradles and cushions brain

Spinal Cord Extends from base of brain to first lumbar vertebrae in back Protected by: Cerebrospinal fluid Vertebral column Meninges 3 layers of membranes that cover brain and spinal cord

Meninges Dura Mater (outer layer) Arachnoid Mater (middle layer) Tough, fibrous Contains channels for blood to enter brain tissue Arachnoid Mater (middle layer) Web-like structure Pia Mater (innermost layer) Contains blood vessels that nourish spinal cord

Peripheral Nervous System 12 Cranial Nerves Carry impulses to and from the brain 31 pairs of spinal nerves Carry messages to and from the spinal cord and the torso and extremities of the body

Peripheral Nervous System 2 Subsystems according to function Somatic Nervous System Autonomic Nervous System

Somatic Nervous System Receive and process sensory input from the skin, muscles, tendons, joints, eyes, tongue, nose and ears Excite voluntary contraction of skeletal muscles

Autonomic Nervous System Carry impulses from the central nervous system to glands, various involuntary muscles, cardiac muscle, and membranes Stimulates organs, glands and senses by stimulating secretions of substances Divided into sympathetic and parasympathetic divisions

Autonomic Nervous System Sympathetic Operates when the body is under stress Activates responses necessary to react in dangerous or abnormal situations Fight or Flight response Parasympathetic Operates to keep the body in homeostasis under normal conditions

The End