Nervous system

Functions of the Nervous System Slide 7.1a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 1. Sensory input – gathering information To monitor changes occurring inside and outside the body (changes = stimuli) 2. Integration – to process and interpret sensory input and decide if action is needed. 3. Motor output A response to integrated stimuli The response activates muscles or glands

Structural Classification of the Nervous System Slide 7.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Central nervous system (CNS) Brain Spinal cord Peripheral nervous system (PNS) Nerve outside the brain and spinal cord

Functional Classification of the Peripheral Nervous System Slide 7.3a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sensory (afferent) division Nerve fibers that carry information to the central nervous system Figure 7.1

Functional Classification of the Peripheral Nervous System Slide 7.3b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Motor (efferent) division Nerve fibers that carry impulses away from the central nervous system Figure 7.1

Functional Classification of the Peripheral Nervous System Slide 7.3c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Motor (efferent) division Two subdivisions Somatic nervous system = voluntary Autonomic nervous system = involuntary Figure 7.1

Nervous Tissue: Support Cells (Neuroglia or Glia) Slide 7.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Astrocytes Abundant, star-shaped cells Brace neurons Form barrier between capillaries and neurons Control the chemical environment of the brain (CNS) Figure 7.3a

Nervous Tissue: Support Cells Slide 7.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Microglia (CNS) Spider-like phagocytes Dispose of debris Ependymal cells (CNS) Line cavities of the brain and spinal cord Circulate cerebrospinal fluid Figure 7.3b, c

Nervous Tissue: Support Cells Slide 7.7a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Oligodendrocytes(CNS) Produce myelin sheath around nerve fibers in the central nervous system Figure 7.3d

Neuroglia vs. Neurons Neuroglia divide. Neurons do not. Most brain tumors are “gliomas.” Most brain tumors involve the neuroglia cells, not the neurons. Consider the role of cell division in cancer!

Support Cells of the PNS Slide 7.7b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Satellite cells Protect neuron cell bodies Schwann cells Form myelin sheath in the peripheral nervous system Figure 7.3e

Nervous Tissue: Neurons Slide 7.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neurons = nerve cells Cells specialized to transmit messages Major regions of neurons Cell body – nucleus and metabolic center of the cell Processes – fibers that extend from the cell body (dendrites and axons)

Neuron Anatomy Slide 7.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Extensions outside the cell body Dendrites – conduct impulses toward the cell body Axons – conduct impulses away from the cell body (only 1!) Figure 7.4a

Axons and Nerve Impulses Slide 7.11 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Axons end in axonal terminals Axonal terminals contain vesicles with neurotransmitters Axonal terminals are separated from the next neuron by a gap Synaptic cleft – gap between adjacent neurons Synapse – junction between nerves

Nerve Fiber Coverings Slide 7.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Schwann cells – produce myelin sheaths in jelly-roll like fashion Nodes of Ranvier – gaps in myelin sheath along the axon Figure 7.5

Application In Multiple Scleroses the myelin sheath is destroyed. The myelin sheath hardens to a tissue called the scleroses. This is considered an autoimmune disease. Why does MS appear to affect the muscles?

Neuron Cell Body Location Slide 7.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Most are found in the central nervous system Gray matter – cell bodies and unmylenated fibers Nuclei – clusters of cell bodies within the white matter of the central nervous system Ganglia – collections of cell bodies outside the central nervous system

Functional Classification of Neurons Slide 7.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sensory (afferent) neurons Carry impulses from the sensory receptors Cutaneous sense organs Proprioceptors – detect stretch or tension Motor (efferent) neurons Carry impulses from the central nervous system

Functional Classification of Neurons Slide 7.14b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Interneurons (association neurons) Found in neural pathways in the central nervous system Connect sensory and motor neurons

Structural Classification of Neurons Slide 7.16c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Unipolar neurons – have a short single process leaving the cell body Figure 7.8c

How Neurons Function (Physiology) Slide 7.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Irritability – ability to respond to stimuli Conductivity – ability to transmit an impulse The plasma membrane at rest is polarized Fewer positive ions are inside the cell than outside the cell

Starting a Nerve Impulse Slide 7.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Depolarization – a stimulus depolarizes the neuron’s membrane A deploarized membrane allows sodium (Na + ) to flow inside the membrane The exchange of ions initiates an action potential in the neuron Figure 7.9a–c

The Action Potential Slide 7.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings If the action potential (nerve impulse) starts, it is propagated over the entire axon Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane The sodium-potassium pump restores the original configuration This action requires ATP

Nerve Impulse Propagation Slide 7.20 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The impulse continues to move toward the cell body Impulses travel faster when fibers have a myelin sheath Figure 7.9c–e

Continuation of the Nerve Impulse between Neurons Slide 7.21 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Impulses are able to cross the synapse to another nerve Neurotransmitter is released from a nerve’s axon terminal The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter An action potential is started in the dendrite

The Reflex Arc Slide 7.23 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Reflex – rapid, predictable, and involuntary responses to stimuli Reflex arc – direct route from a sensory neuron, to an interneuron, to an effector Figure 7.11a

Types of Reflexes and Regulation Slide 7.25 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Autonomic reflexes Smooth muscle regulation Heart and blood pressure regulation Regulation of glands Digestive system regulation Somatic reflexes Activation of skeletal muscles

Central Nervous System (CNS) Slide 7.26 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings CNS develops from the embryonic neural tube The neural tube becomes the brain and spinal cord The opening of the neural tube becomes the ventricles Four chambers within the brain Filled with cerebrospinal fluid

Cerebral Hemispheres (Cerebrum) Slide 7.28a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Paired (left and right) superior parts of the brain Include more than half of the brain mass Figure 7.13a

Lobes of the Cerebrum Slide 7.29a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Fissures (deep grooves) divide the cerebrum into lobes Surface lobes of the cerebrum Frontal lobe Parietal lobe Occipital lobe Temporal lobe

Specialized Areas of the Cerebrum Slide 7.30 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Somatic sensory area – receives impulses from the body’s sensory receptors Primary motor area – sends impulses to skeletal muscles Broca’s area – involved in our ability to speak

Specialized Area of the Cerebrum Slide 7.32a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cerebral areas involved in special senses Gustatory area (taste) Visual area Auditory area Olfactory area

Specialized Area of the Cerebrum Slide 7.32b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Interpretation areas of the cerebrum Speech/language region Language comprehension region General interpretation area

Layers of the Cerebrum Slide 7.33b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings White matter Fiber tracts inside the gray matter Example: corpus callosum connects hemispheres Figure 7.13a

Layers of the Cerebrum Slide 7.33c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Basal nuclei – internal islands of gray matter Regulates voluntary motor activities by modifying info sent to the motor cortex Problems = ie unable to control muscles, spastic, jerky Involved in Huntington’s and Parkinson’s Disease Figure 7.13a

Diencephalon Slide 7.34a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sits on top of the brain stem Enclosed by the cerebral heispheres Made of three parts Thalamus Hypothalamus Epithalamus

Thalamus Slide 7.35 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Surrounds the third ventricle The relay station for sensory impulses Transfers impulses to the correct part of the cortex for localization and interpretation

Hypothalamus Slide 7.36a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Under the thalamus Important autonomic nervous system center Helps regulate body temperature Controls water balance Regulates metabolism

Epithalamus Slide 7.37 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Forms the roof of the third ventricle Houses the pineal body (an endocrine gland) Includes the choroid plexus – forms cerebrospinal fluid

Midbrain Slide 7.39 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Mostly composed of tracts of nerve fibers Reflex centers for vision and hearing Cerebral aquaduct – 3 rd -4 th ventricles

Pons Slide 7.40 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The bulging center part of the brain stem Mostly composed of fiber tracts Includes nuclei involved in the control of breathing

Medulla Oblongata Slide 7.41 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The lowest part of the brain stem Merges into the spinal cord Includes important fiber tracts Contains important control centers Heart rate control Blood pressure regulation Breathing Swallowing Vomiting

Meninges Slide 7.45a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Dura mater Double-layered external covering Periosteum – attached to surface of the skull Meningeal layer – outer covering of the brain Folds inward in several areas

Cerebrospinal Fluid Slide 7.46 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Similar to blood plasma composition Formed by the choroid plexus Forms a watery cushion to protect the brain Circulated in arachnoid space, ventricles, and central canal of the spinal cord

Blood Brain Barrier Slide 7.48 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Includes the least permeable capillaries of the body Excludes many potentially harmful substances Useless against some substances Fats and fat soluble molecules Respiratory gases Alcohol Nicotine Anesthesia

Traumatic Brain Injuries (TBI) Slide 7.49 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Concussion Slight or mild brain injury Bleeding & tearing of nerve fibers happened Recovery likely with some memory loss Contusion A more severe TBI Nervous tissue destruction occurs Nervous tissue does not regenerate Cerebral edema Swelling from the inflammatory response May compress and kill brain tissue

Cerebral edema Swelling from the inflammatory response May compress and kill brain tissue Subdural hematoma Collection of blood below the dura Standards for these conditions were revised in 2004. Please check out TBIs at Mayoclinic.com for more current information on diagnostic terminology.

Cerebrovascular Accident (CVA) Slide 7.50 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Commonly called a stroke The result of a ruptured blood vessel supplying a region of the brain Brain tissue supplied with oxygen from that blood source dies Loss of some functions or death may result

Alzheimer’s Disease Slide 7.51 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Progressive degenerative brain disease Mostly seen in the elderly, but may begin in middle age Structural changes in the brain include abnormal protein deposits and twisted fibers within neurons Victims experience memory loss, irritability, confusion and ultimately, hallucinations and death

Spinal Cord Slide 7.52 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Extends from the medulla oblongata to the region of T12 Below T12 is the cauda equina (a collection of spinal nerves) Enlargements occur in the cervical and lumbar regions Figure 7.18

Spinal Cord Anatomy Slide 7.53b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Internal gray matter - mostly cell bodies Dorsal (posterior) horns Anterior (ventral) horns Figure 7.19

Spinal Cord Anatomy Slide 7.54 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Meninges cover the spinal cord Nerves leave at the level of each vertebrae Dorsal root Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system Ventral root

Peripheral Nervous System Slide 7.55 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Nerves and ganglia outside the central nervous system Nerve = bundle of neuron fibers Neuron fibers are bundled by connective tissue

Structure of a Nerve Slide 7.56 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Endoneurium surrounds each fiber Groups of fibers are bound into fascicles by perineurium Fascicles are bound together by epineurium Figure 7.20

Classification of Nerves Slide 7.57 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Mixed nerves – both sensory and motor fibers Afferent (sensory) nerves – carry impulses toward the CNS Efferent (motor) nerves – carry impulses away from the CNS

Autonomic Nervous System Slide 7.67 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The involuntary branch of the nervous system Consists of only motor nerves Divided into two divisions Sympathetic division Parasympathetic division

Autonomic Functioning Slide 7.74a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sympathetic – “fight-or-flight” Response to unusual stimulus Takes over to increase activities Remember as the “E” division = exercise, excitement, emergency, and embarrassment

Autonomic Functioning Slide 7.74b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Parasympathetic – housekeeping activites Conserves energy Maintains daily necessary body functions Remember as the “D” division - digestion, defecation, and diuresis

Development Aspects of the Nervous System Slide 7.75a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The nervous system is formed during the first month of embryonic development Any maternal infection can have extremely harmful effects The hypothalamus is one of the last areas of the brain to develop

Development Aspects of the Nervous System Slide 7.75b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings No more neurons are formed after birth, but growth and maturation continues for several years (new evidence!) The brain reaches maximum weight as a young adult However, we can always grow dendrites!

Nervous system

More Related Content

What's hot

Similar to Nervous system

More from Lawrence James

Recently uploaded

In this document

Nervous system