Nervous System Chapter 7

Four main parts of the Brain

1. Cerebral hemispheres 2. Diencephalon 3.Brain stem 4.Cerebellum

Discuss the formation and function of cerebrospinal fluid and the blood- brain barrier

1. Cerebrospinal fluid -Similar to blood plasma composition -Formed by choroid plexus -Forms a watery cushion to protect the brain - Circulated in the arachnoid space, ventricles, central canal of the spinal cord 2.Blood Brain Barrier -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

Types of Neuroglia

CNS Neuroglia Cells 1. Astrocytes -Abundant star-shaped cells -brace neurons from barrier b/t capillaries and neurons control chemical environment of brain 2.Microglia -spider-like phagocytes -Dispose of debris 3. Ependymal cells -Line cavities of the brain and spinal cord -Circulate cerebrospinal fluid 4. Oligodendrocytes -produce myelin sheath around nerve fiber in the CNS

Define CNS and PNS and list the major parts of each

CNS: Occupy the dorsal body cavity and act as the integrating and command centers of the NS. - Brain (cerebrum, cerebellum, and brainstem.) -The Midbrain(medulla and pons.) Diencephalon: (thalamus and hypothalamus) PNS: the part of the NS outside the CNS, consists mainly of the nerves that extend from the brain and spinal cord. -Afferent and Efferent: -Autonomic(Sympathetic NS and Parasympathetic NS ) -Somatic

Define reflex arc and list its elements.

Direct route from a sensory neuron, to an interneuron, to an effector. Elements 1. Receptor 2. Sensory neuron 3. Integration center 4. Motor neuron 5. Effector

Describe spinal cord structure

Exterior white matter- conduction tracts -Dorsal (posterior) horns -Anterior (ventral) horns Extends from 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

Protection of CNS including the 3 meninges

Protection: Cerebrospinal fluid and blood brain barrier. Meninges: 1. Dura mater: double-layered external covering, folds inward in several areas 2. Arachnoid Layer: middle layer and web-like 3. Pia mater: internal layer and clings to the surface of the brain

Reflex arc

Reflex: rapid, predictable, involuntary responses to stimuli Reflex arc: direct route from a sensory neuron to an interneuron to and effector. Types of Reflexes and Regulation 1. Automatic Reflexes -Smooth muscles regulation -Heart and blood pressure regulation -Regulation of glands 2. Somatic Reflexes -Activation of skeletal muscles

4 main parts of the brain

cerebral hemispheres diencephalon brain stem cerebellum

Reticular formation

controls alertness

3 connective tissues of a nerve

epimysium, perimysium, fascicles?

Basic Structure of a multipolar- neuron

many extensions from the cell body

Functional Classification of Neurons

Functional classification group neurons according to the direction the nerve impulse is traveling relative to the CNS 1. Sensory (afferent) neurons conduct impulses from sensory receptors to the CNS; most cell bodies are in the ganglia in the PNS. 2. Motor (efferent) neurons transmit impulses from the cNS to effectors in the body periphery. 3. Interneurons (association neurons) complete the communication pathway between sensory and motor neurons: their cell bodies reside in the CNS

Identify and Indicate the functions of the major regions of the cerebral hemispheres, diencephalon, brainstem, and cerebellum

Functions 1. Cerebral Hemispheres (Cerebrum) - paired (left and right), superior parts of the brain - include more than half of the brain mass - surface made of ridges (gyri) and grooves (sulci) 2. Diencephalon -Sits on top of brainstem -Enclosed by the cerebral hemisphere Made of 3 parts - Thalamus: transfers impulses to the correct part of the cortex for localization interpretation -Hypothalamus: helps regulate body temp, controls water balance, and regulates -Epithalamus: forms cerebrospinal fluid 3. Brain stem: Attaches to the spinal cord Parts of the brain stem -Midbrain: reflex centers for vision/hearing -Pons: has nuclei involved in control of breathing -Medulla Oblongata: controls heart rate, blood pressure, breathing, swallowing, vomiting 4. Cerebellum - Two hemispheres with convoluted surfaces -Provides involuntary coordination of body movements

Define senility and list some possible causes

-gradual lack of oxygen due to the aging process leads to this -characterized by forgetfulness, irritability, difficulty in concentrating and thinking clearly, confusion-certain drugs - low blood pressure -constipation -poor nutrition -depression -dehydration -hormone imbalances

Name the 3 meningeal layers and state their functions

-Dura Mater: double layered external covering; periosteum is attached to surface of skull, meningeal layer is outer covering of brain -Arachnoid layer: middle layer, web-like -Pia Mater: internal layer that clings to surface of brain

Contrast the effect of the parasympathetic and sympathetic divisions on the following organs: heart, lungs, digestive system, blood vessels.

-Heart 1. Sympathetic: heart race increases 2. Parasympathetic: heart rate regulated at low normal levels -Lungs 1. Sympathetic: bronchioles of lungs dilated 2. Parasympathetic: respiratory rate is at low normal levels -Digestive System 1. Sympathetic: blood withdrawn from digestive organs so it goes to heart, brain, skeletal muscles 2. Parasympathetic: actively digesting food like normal -Blood Vessels: 1. Sympathetic: blood vessels dilated 2. Parasympathetic: blood vessels normal

Identify the site of origin and explain the function of the sympathetic and parasympathetic divisions of the autonomic nervous system

-Sympathetic: 1. preganglionic neurons in gray matter of spinal cord from T1-L2; axons leave cord through ventral root, enter spinal nerve and pass through communicating branch to enter sympathetic chain ganglion 2. Prepares body for fight or flight, mobilizes body during extreme situations; also activated during times of physical stress 3. E Division: exercise, excitement, emergency, embarrassment -Parasympathetic 1. preganglionic neurons located in brain nuclei of several cranial nerves (vagus), and in S2-S4 levels of spinal cord 2. Allow body to calm down and unwind to conserve energy; promotes normal digestion 3. D Division: Digestion, Defecation, Diuresis

List several factors that may have harmful effects on brain development

-maternal infection -lack of oxygen -smoking -radiation -drugs

Name the four major nerve plexuses give the major nerves of each, and describe their distribution.

1. Cervical Major nerve: phrenic Distribution: Diaphragm skin and muscles of shoulder and neck 2. Brachial Major nerves: Axillary, Radial, Median, Musculocutaneous, and Ulnar Distribution: a. Deltoid muscle and skin of shoulder, muscles, and skin or superior thorax b. Triceps and extensor muscles of the forearm; skin posterior upper limb c. Flexor muscles and skin of forearm and some muscles of hand d. Flexor muscles of arm; skin of lateral forearm e. Some flexor muscles of forearm; wrist and many hand muscles; skin of hand 3. Lumbar Major nerves: Femoral (lateral and anteirr cutaneosu

Functions of cerebral lobes

1. Frontal lobe - (left frontal lobe) speech. language region -Language comprehension region 2. Parietal lobe -Damage to this lobe of the cerebral cortex could cause inability to sense pain. 3. Occipital lobe -Visual area 4. Temporal lobe -Auditory area - olfactory area This lobe of the cerebral cortex controls hearing, smell, and taste.

List the two major functional properties of neurons

1. Irritability - Ability to respond to stimuli 2. Conductivity - Ability to transmit an impulse

Describe the general structure of a neuron, and name it's important anatomical regions.

1. Multipolar neurons: many extensions from the cell body -Dendrites: conduct impulses toward the cell body -Axons- conduct impulses away from the cell body 2. Bipolar neurons: one axon and one dendrite 3. Unipolar neurons: have a short single process leaving the cell body. Neuron Anatomy 1. Axons end in axonal terminals 2. Axonal terminals contain vesicles with neurotransmitters 3. Axonal terminals are separated from the net nerron by a gap Synaptic cleft- gap b/t adjacent neuron Synapse- junction between nerves

List the types of general sensory receptors and describe their functions

1. Naked nerve endings: pain and temp receptors 2. Meissner's corpuscle: tough receptors 3. Pacinian corpuscles: deep pressure receptor 4. Golgi tendon organ:proprioceptor(advise our brain of our own movements. 5. Muscle spindle: proprioceptor(advise our brain of our own movements.

List two important functions of the spinal cord

1. Provides a two way conduction pathway to and from the brain 2. Is the major reflex center

List the general functions of the nervous system

1. Sensory input: gathering information. Monitors changes occurring inside and outside the body. Homeostasis-balanced internal environment (controlled by NS and Endocrine system). 2. Integration: process and interpret the sensory input and decide if action is needed. 3. Motor output: a response to integrated stimuli and the response activates muscles or glands.

Afferent, efferent, and interneurons

Afferent: carry impulses toward the CNS Efferent: carry impulses away from the CNS Interneurons (association neurons): found in neural pathways in the CNS and connect sensory and motor neuron

Describe the composition of gray matter and white matter

Gray matter: contains mostly unmyelinated fibers and cell bodies. White Matter: Consists of dense collections of myelinated fibers(tracts)

Describe the events that lead to the gernation of a nerve impulse and its conduction from one neron to another

Impulses are able to cross the synapse to another nerve 1. Neurotransmitters is released from a nerve's axon terminal 2. The dendrite of the next neuron has receptors that are stimulated by the neurotransmitters 3. An action potential is started in the dendrite. -start with an inactive neuron that is polarized, meaning more positive ions (Na+) on the outside and more negative ions on the inside even though some K+ exist on the inside -enough neurotransmitters released to cause change in membrane's permeability -gates of sodium channels open and sodium flows into cell b/c it is in a high concentration outside the cell -this depolarizes the neuron because now there is more positive inside and more negative outside (graded potential) -if enough sodium comes into neuron, it starts an action potential which is an all or nothing response - it either happens to the entire axon or doesn't happen at all -after sodium rushes in, membrane changes permeability again and potassium is able to diffuse out of cell -This repolarizes cell because there is now more positive on the outside and less on the inside so polarization is back to normal except now Na is inside cell and K is out -a neuron can't conduct another impulse until repolarization occurs -Concentrations of Na and K restored by a sodium potassium pump which uses ATP to pump out 3 Na and pump in 2 K

Describe the General structure of a nerve

Nerve is a bundle of neuron processes wrapped in connective tissue coverings (endoneurium, perineurium, and epineurium) Nerves and ganglia outside the CNS

State the functions of neurons and neuroglia

Neurons=nerve cells/ cells specialized to transmit messages Neuroglia: includes many types of cells that generally support, insulate, and protect the delicate neurons. Also have special functions - Astrocytes: form barrier b/t capillaries and neurons and control chemical environment of brain. -Microglia: spider-like phagocytes and dispose of debris -Ependymal cells: line cavities of the brain and spinal cord and circulates cerebrospinal fluid. -Oligodendrocytes: produce myelin sheath around nerve fibers in the CNS.

Discuss the distribution of the dorsal and ventral rami of spinal nerves

Spinal nerves: 31 pairs of nerves are formed by the union of the dorsal and ventral roots of the spinal cord on each side. The spinal nerve proper is very short and splits into dorsal and ventral rami. Dorsal rami serve the posterior body trunk; ventral rami (except T1 through T12) from plexuses (cervical, brachial, lumbar, sacral) that serve the limbs)

Explain the structural and functional classifications of the NS.

Structural Classification 1. All nervous system structures are classified as part of the CNS (brain and spinal cord) or PNS (nerves and ganglia) Functional 2. Motor nerves of the PNS are classified on the basis of whether they stimulate skeletal muscles (somatic division) or smooth/cardiac muscle and glands (autonomic division)

Classify neurons according to structure

Structural classification: based on the number of processes extending from the cell body. -Multipolar neurons: if there are several it is this. All motor and association neurons are multipolar which makes it the most common structural type. -Bipolar: neurons with two processes- an axon and a dendrite. They are rare in adults found only in some special organs(eyes, nose) where they act in sensory processing as receptor cells. - Unipolar neurons: have a single process emerging from the cell body, but it is very short and divides into central and peripheral processes. Only the small branches at the end of the peripheral process are dendrites.

5 ways of protection of the CNS

scalp and skin -skull and vertebral column -meninges -cerebrospinal fluid -blood-brain barrier