Nervous System

6/3/2016Nervous System2 Functions Coordinates all of the activities of the body. Enables the body to respond and adapt to changes both inside and outside the body. Coordinates all of the activities of the body. Enables the body to respond and adapt to changes both inside and outside the body.

6/3/2016Nervous System3 Neuron Nerve cell. Consists of a cell body containing a nucleus, nerve fibers called dendrites, and a single nerve fiber called an axon. Nerve cell. Consists of a cell body containing a nucleus, nerve fibers called dendrites, and a single nerve fiber called an axon.

6/3/2016Nervous System4 Dendrites: Carry impulses toward the cell body. Axon: Carries impulses away from the cell body. Dendrites: Carry impulses toward the cell body. Axon: Carries impulses away from the cell body.

6/3/2016Nervous System5 Myelin Sheath Many axons have a lipid (fat) covering called a myelin sheath. Increases the rate of impulse transmission. Insulates and maintains the axon. Many axons have a lipid (fat) covering called a myelin sheath. Increases the rate of impulse transmission. Insulates and maintains the axon.

6/3/2016Nervous System6 Synapses Spaces between the axon of one neuron and the dendrites of another. Impulses come from the axon “jump” the synapse to get to the dendrite of another neuron. Spaces between the axon of one neuron and the dendrites of another. Impulses come from the axon “jump” the synapse to get to the dendrite of another neuron.

6/3/2016Nervous System7 Neurotransmitters Special chemicals located at the end of each axon. Allow the nerve impulses to pass from one neuron to another. Special chemicals located at the end of each axon. Allow the nerve impulses to pass from one neuron to another.

6/3/2016Nervous System8 Afferent Nerves Sensory nerves. Carry messages from all parts of the body to the brain and spinal cord. Sensory nerves. Carry messages from all parts of the body to the brain and spinal cord.

6/3/2016Nervous System9 Efferent Nerves Motor nerves. Carry messages from the brain and spinal cord to the muscles and glands. Motor nerves. Carry messages from the brain and spinal cord to the muscles and glands.

6/3/2016Nervous System10 Associative Nerves Internuncial nerves. Say what?? It means “ serving to announce or connect.” Carry both sensory and motor messages. Internuncial nerves. Say what?? It means “ serving to announce or connect.” Carry both sensory and motor messages.

6/3/2016Nervous System11 Divisions of the Nervous System Central: brain and spinal cord. Peripheral: nerves. –Autonomic: involuntary body functions. –Somatic: cranial and spinal nerves. Central: brain and spinal cord. Peripheral: nerves. –Autonomic: involuntary body functions. –Somatic: cranial and spinal nerves.

6/3/2016Nervous System12 Parts of the Brain

6/3/2016Nervous System13 Cerebrum Largest and Highest section of the brain. Outer part is arranged in folds, called convolutions. Largest and Highest section of the brain. Outer part is arranged in folds, called convolutions.

6/3/2016Nervous System14 Cerebrum Responsible for reasoning, thought, memory, speech, sensation, sight, smell, hearing, and voluntary body movement.

6/3/2016Nervous System15 Cerebellum

6/3/2016Nervous System16 Cerebellum Section below the back of the cerebrum. Responsible for muscle coordination, balance and posture, and muscle tone. Section below the back of the cerebrum. Responsible for muscle coordination, balance and posture, and muscle tone.

6/3/2016Nervous System17 Diencephalon Located between the cerebrum and midbrain. Contains: –Thalamus: acts as a relay center and directs sensory impulses to the cerebrum. –Hypothalamus (see next slide). Located between the cerebrum and midbrain. Contains: –Thalamus: acts as a relay center and directs sensory impulses to the cerebrum. –Hypothalamus (see next slide).

6/3/2016Nervous System18 Hypothalamus, ctd. Regulates and controls the autonomic nervous system, temperature, appetite, water balance, sleep, and blood vessel constriction and dilation.

6/3/2016Nervous System19 Hypothalamus, ctd. Also involved in emotions such as anger, fear, pleasure, pain, and affection.

6/3/2016Nervous System20 Midbrain Located below the cerebrum at the top of the brain stem. Responsible for conducting impulses between brain parts and for certain eye and auditory reflexes. Located below the cerebrum at the top of the brain stem. Responsible for conducting impulses between brain parts and for certain eye and auditory reflexes.

6/3/2016Nervous System21 Pons Section below the midbrain and in the brainstem. Responsible for conducting messages to other parts of the brain. Certain reflex actions: chewing, tasting, saliva production, assisting w/ respiration. Section below the midbrain and in the brainstem. Responsible for conducting messages to other parts of the brain. Certain reflex actions: chewing, tasting, saliva production, assisting w/ respiration.

6/3/2016Nervous System22 Medulla Oblongata

6/3/2016Nervous System23 Medulla Oblongata Lowest part of the brainstem. Connects with the spinal cord and is responsible for regulating heartbeat, respiration, swallowing, coughing, and blood pressure. Lowest part of the brainstem. Connects with the spinal cord and is responsible for regulating heartbeat, respiration, swallowing, coughing, and blood pressure.

6/3/2016Nervous System24 Spinal Cord Continues from medulla oblongata and continues to the first or second lumbar vertebrae. Surrounded and protected by the vertebrae. Responsible for many reflex actions. Continues from medulla oblongata and continues to the first or second lumbar vertebrae. Surrounded and protected by the vertebrae. Responsible for many reflex actions.

6/3/2016Nervous System25 Meninges Three membranes that cover and protect the brain and spinal cord. Dura Mater: thick, tough outer layer. Arachnoid Membrane: middle layer, delicate and weblike. Three membranes that cover and protect the brain and spinal cord. Dura Mater: thick, tough outer layer. Arachnoid Membrane: middle layer, delicate and weblike.

6/3/2016Nervous System26 Meninges Pia Mater: closely attached to the brain and spinal cord. Contains blood vessels that nourish the nerve tissue. Pia Mater: closely attached to the brain and spinal cord. Contains blood vessels that nourish the nerve tissue.

6/3/2016Nervous System27 Ventricles Hollow spaces that connect w/ each other and with the space under the arachnoid membrane (the subarachnoid space).

6/3/2016Nervous System28 Ventricles Filled with a fluid called cerebrospinal fluid (CSF). CSF serves as a shock absorber. Filled with a fluid called cerebrospinal fluid (CSF). CSF serves as a shock absorber.

6/3/2016Nervous System29 Also carries nutrients to some parts of the brain and spinal cord. Helps remove metabolic products and wastes. CSF is produced in the ventricles of the brain by structures called choroid plexuses. Also carries nutrients to some parts of the brain and spinal cord. Helps remove metabolic products and wastes. CSF is produced in the ventricles of the brain by structures called choroid plexuses.

6/3/2016Nervous System30 After circulating, CSF is absorbed into the blood vessels of the dura mater and returned to the bloodstream through special structures called arachnoid villi.

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6/3/2016Nervous System32 Peripheral Nervous System Somatic: –12 pairs of cranial nerves and their branches. –31 pairs of spinal nerves and their branches. Somatic: –12 pairs of cranial nerves and their branches. –31 pairs of spinal nerves and their branches.

6/3/2016Nervous System33 Peripheral Nervous System Autonomic: maintains balance in the involuntary functions. Allows body to react to emergency. Autonomic: maintains balance in the involuntary functions. Allows body to react to emergency.

6/3/2016Nervous System34 Autonomic Nervous System Sympathetic: fight or flight response. Parasympathetic: slows systems back down. Sympathetic: fight or flight response. Parasympathetic: slows systems back down.