ANATOMY AND PHYSIOLOGY Chapter 8 The Nervous System

The Nervous System The Nervous System is the major controlling and communicating system in the body

The means of communication is The Nervous System The means of communication is Electrical impulses Which causes immediate responses

Monitor changes occurring inside and outside the body 3 major Functions of the Nervous System Monitor changes occurring inside and outside the body These changes are called stimuli and the gathered info is called sensory input

This is called integration 3 major Functions of the Nervous System Process and interpret sensory input and make decisions about what should be done. This is called integration

The response is called motor output 3 major Functions of the Nervous System Effect a response by activating muscles or glands. The response is called motor output

Works along with the endocrine system 3 major Functions of the Nervous System So…… sensory input integration motor output Works along with the endocrine system

The Nervous System 2 Classifications: CNS Central Nervous System Made of brain and spinal cord

The Nervous System 2 Classifications: PNS Peripheral Nervous System Made of nerves (spinal and cranial)

Nerve Tissue 2 kinds: 1. Supporting Cells

Nerve Tissue 2 kinds: 2. Neurons

Nerve Tissue Neuroglia Supporting cells in the CNS Support, insulate, and protect neurons Not able to transmit impulses Never lose ability to divide so most brain tumors are gliomas. Tumors are formed by neuroglia

Nerve Tissue Neuroglia 1. Astrocytes Star shaped Cling to neurons Form a barrier btw neurons and capillaries Protect neurons from harmful substances in the blood Pick up excess ions and neurotransmitters

Nerve Tissue Neuroglia 2. Microglia Phagocytes that dispose of dead brain cells and bacteria

Nerve Tissue Neuroglia 3. Oligodendrocytes Produce insulating covering called myelin sheath

Nerve Tissue Supporting cells in the PNS Schwann cells Form the myelin sheath around nerve fibers in the PNS

Nerve Tissue Supporting cells in the PNS 2. Satellite cells Protective, cushioning cells

NEURONS Nerve Cells Made of: Cell body Axon Dendrite Transmit nerve impulses (messages) Made of: Cell body Axon Dendrite

Cell body - Center of cell. Contains the nucleus NEURONS Nerve Cells Cell body - Center of cell. Contains the nucleus Process or fibers extend from the cell body

Axon - conducts impulse away from the cell body NEURONS Nerve Cells Axon - conducts impulse away from the cell body Only one per neuron

Dendrite - conducts impulse toward the cell body NEURONS Nerve Cells Dendrite - conducts impulse toward the cell body 100s per neuron

1. dendrites 2. nucleus 3. Cell body 4. Myelin sheath 5. axon

Synapse junction between 2 neurons. Nerve Cells Synapse junction between 2 neurons. The 2 neurons never actually touch

Myelin white fatty covering on the axon. NEURONS Nerve Cells Myelin white fatty covering on the axon. They protect and insulate Also increase the rate of nerve impulse transmission

NEURONS Nerve Cells Myelin if the myelin sheath is destroyed as in multiple sclerosis, the person loses the ability to control their muscles.

NEURONS Myelin of the CNS Nerve Cells myelinated fibers White matter Gray matter myelinated fibers unmyelinated fibers

Afferent or Efferent NEURONS Classification Functional classification groups are according to the direction the nerve impulse is traveling Afferent or Efferent

Afferent Efferent NEURONS Classification Sensory. Carries impulse from organs to CNS Afferent Efferent Motor. Carries impulse from CNS to muscles, glands.

Irritability Conductivity Properties of Nerve Impulses Ability to respond to a stimuli Ability to transmit impulses to other neurons, muscles, glands

NA K pump Properties of Nerve Impulses depolarization repolarization Electro-chemical event. Na ion enters cell K ion leaves the cell causing a resting state. depolarization repolarization NA K pump

NA K pump acetycholine Properties of Nerve Impulses Active transport Neurons release neurotransmitters to influence other neurons. This opens a specific ion channel Neurotransmitter? acetycholine

Reflex Autonomic Somatic A reflex is a rapid predictable response to a stimulus Autonomic Somatic Regulates activities of smooth muscles, the heart and glands. Stimulates skeletal muscles

Reflex Autonomic Somatic Salivary reflex Pupillary reflex Patellar reflex Sucking reflex

Reflex Normal reflexes indicate normal nervous system functions Plantar reflex (Babinski) The normal reflex is toe flexion. If the toes extend and separate, this is an abnormal finding called a positive Babinski's sign.

Neural Tube Ventricles Central Nervous System CNS How nervous system 1st appears in embryo Chambers. We have 4

Neural Tube Deficiency of Folic acid = neural tube birth defects

Also called B9 Folic Acid Leafy vegetables such as spinach and turnip greens dried beans and peas, fortified cereal products,sunflower seeds and certain other fruits and vegatables are rich sources of folate. Some breakfast cereals are fortified with 25% to 100% of the recommended dietary allowance (RDA) for folic acid.