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Nervous System.

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Presentation on theme: "Nervous System."— Presentation transcript:

1 Nervous System

2 Cells of the Nervous System
Neurons Dendrites Axons Schwann cells Synapse Supporting cells Glial cells Astrocytes Oligodendrocytes. Neurons: Contain a relatively large cell body containing the nucleus, cytoplasm, and all the major organelles. Dendrites, a cell process that conducts impulse toward the cell body. Axons, a cell process that conducts impulses away from the cell body. Axons usually contain a series of enclosing cells called Schwann cells. Collectively these Schwann cells are called the myelin sheath. Axons may be branched and end up in structures called synaptic knobs. The gap between nerve cells is the synapse. The cells bodies are located in the central nervous system.( brain and spinal cord). The cell bodies of certain nerves cluster outside of the spinal cord in aggregates called ganglia. These and the axons make up the peripheral nervous system. The major types of neurons of this system are: sensory and motor. They are connected to the central nervous system by structures called interneurons. Supporting cells: these cells outnumber neurons to one. They do not conduct impulses but are needed for the physical integrity of the system. Glial cells, Astrocytes and oligodendrocytes.

3 Central vs. Peripheral Nervous System
Cell bodies = central nervous system (brain and spinal cord) Ganglia Ganglia + axons = peripheral nervous system

4 Interneurons – connect peripheral neurons with CNS neurons
Types of Neurons Sensory Motor Interneurons – connect peripheral neurons with CNS neurons

5 Transmission Along Neurons
The Resting Potential: Cell membrane is negative (polarized). Membrane stores energy by holding charges apart. Positive outside and negative inside. Resting potential of a cell = -70 millivolts

6 Transmission (cont.) Sodium-potassium pumps on membrane
ATP driven Change in resting potential = a stimulus If stimulus depolarizes cell = Action Potential The action potential is an all or none event A neuron has a threshold potential -50 millivolts

7 The Brain Contains cavities (ventricles) Cerebrospinal fluid (CSF)
Meninges – 3 tough layers that protect brain and spinal cord Dura mater Arachnoid mater Pia mater

8 Central Nervous System (CNS)
1. Medulla Oblongata - controls involuntary and visceral activities. 2. Cerebellum - controls body balance, muscular coordination and equilibrium. 3. Hypothalamus - maintains the internal environment. 4. Thalamus - Sorts out and relays the incoming and outgoing impulses. 5. Cerebral cortex - center of all voluntary muscular control and mental activity 1. Medulla Oblongata: through the autonomic nervous system, controls involuntary and visceral activities. 2. Cerebellum: controls body balance, muscular coordination and equilibrium. 3. Hypothalamus: regulates body temperature, thirst, hunger, metabolism, pleasure, pain, sex, and rage ( in general it maintains the internal environment). 4. Thalamus: The center that sorts out the thousands of incoming and outgoing impulses and relays them to the various brain centers. 5. Cerebral cortex: center of all voluntary muscular control and mental activity. centers of analysis, coding, storage of information, recognition, memory, understanding, intelligence and sense integration are located here. The brain is not a solid structure; it contains cavities called ventricles which contain a liquid called cerebrospinal fluid. The brain and spinal cord are covered by three layers of tough material called meninges.

9 Autonomic Nervous System
Control of the involuntary muscles 2 separate parts sympathetic parasympathetic

10 Sympathetic vs. Parasympathetic
Heart Slows down Speeds up Arteries Dilates (opens) Constricts Digestive Organs Speeds up peristalsis Slows down peristalsis Bronchial Muscles Dilates Sweat Glands Decreases action Increases action

11 The Eye

12 Parts of the Eye Cornea - protection
Aqueous Humor - helps focus light onto the retina Iris - regulates amount of light entering the eye Lens - focuses light onto the retina Vitreous Humor - helps focus light onto the retina

13 Parts of the Eye (cont.) Retina - transmit signals to the optic nerve
Rods and Cones - sense to light Fovea - contains the highest concentration of cones Optic nerve - connects the eye to the brain Blind spot – no receptors, the eye is attached to the optic nerve here

14 The Ear

15 Parts of the Ear Pinna – gathers sound
Outer ear - connects outer ear with ear drum (tympanic membrane) Tympanic membrane - transmits sound waves to three tiny bones Hammer, anvil, and stirrup (middle ear) - send impulses to the oval window of the cochlea. Semicircular canals (inner ear) – balance Cochlea - change sound waves into nerve impulses

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