Name: Date: Class: Unit 4 Outline: The Nervous System, Special Senses, and the Endocrine System

Transcription

1 Name: Date: Class: Unit 4 Outline: The Nervous System, Special Senses, and the Endocrine System The Nervous System and Nervous Tissue Nervous System Functions - gathering information Monitor outside the body inside and Process and interpret sensory input and decide if Response to integrated stimuli Activates Nervous System Structural Classification is needed or glands nervous system (CNS) nervous system (PNS) Nerves and spinal cord Functional Classification of the PNS Sensory ( Nerve fibers that carry information to the the brain ) division (efferent) division Nerve fibers that carry impulses the CNS Two subdivisions * Somatic nervous system = voluntary * Autonomic nervous system = involuntary Nervous Tissue: Support Cells (Neuroglia) Abundant, -shaped cells neurons Form barrier between capillaries and neurons Control of the brain Spider-like Dispose of environment cells Line brain and spinal cord Circulate fluid Produce nerve fibers in the CNS of the sheath around Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 18

2 cells Protect neuron cell cells Form myelin sheath in the Nervous Tissue: Neurons = nerve cells Cells specialized to messages Major regions * Cell - nucleus and metabolic center of the cell * - fibers that extend from the cell body Neuron Anatomy Cell body rough ER substance- specialized - intermediate cytoskeleton that maintains cell shape Large toward the cell body away from the cell body Axons and Nerve Impulses - conduct impulses - conduct impulses end in axonal terminals Axonal : Contain neurotransmitters Axonal terminals are separated from the next neuron by a with * Synaptic - gap between adjacent neurons * - junction between nerves Nerve Fiber Coverings sheaths - jelly-roll like covering (Schwann cells) Nodes of in myelin sheath along the axon - gaps Extensions outside the cell body Neuron Cell Body Location Most are found in the unmylenated fibers matter- cell bodies and - clusters of cell bodies within the white matter of the CNS - collections of cell bodies outside the CNS Neuron Classification and Nerve Impulses Functional Classification of Neurons (afferent) neurons Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 19

3 Carry impulses from the sensory * sense organs * - detect stretch or tension Motor ( Carry impulses from the CNS ) neurons (association neurons) Found in neural the CNS Connect sensory and in neurons depolarizes the neuron s membrane Depolarized membranes allow (Na + ) to flow inside Exchange of ions initiates an in the neuron Structural Classification of Neurons neurons- many extensions from the cell body neurons- one axon and one dendrite neurons- have a short single process leaving the cell body The Action Potential If the action potential ( over the entire axon ) starts, it is propagated ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane pump restores the original configuration Requires Nerve Impulse Propagation Impulse continues to move toward the Impulses travel faster when fibers have a sheath Functional Properties of Neurons - ability to respond to stimuli - ability to transmit an impulse The plasma membrane at rest is Fewer inside the cell than outside the cell Starting a Nerve Impulse ions are - a stimulus Nerve Impulse Continuation between Neurons Impulses cross the synapse to another nerve from a nerve s axon terminal is released Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 20

4 Dendrite of the next neuron has that are stimulated by the neurotransmitter An action potential is started in the system regulation reflexes Activation of Regions of the Brain Central Nervous System (CNS) muscles and spinal cord Develops from the embryonic tube Neural tube opening becomes * chambers within the brain * Filled with fluid Regions of the Brain hemispheres Brain The Reflex Arc - rapid, predictable, and involuntary responses to stimuli - direct route from a sensory neuron, to an interneuron, to an effector Cerebral Hemispheres (Cerebrum) parts of the brain (left and right) More than Surface ridges ( grooves (sulci) of the brain mass ) and Types of Reflexes and Regulation reflexes muscle regulation and blood pressure regulation Regulation of Lobes of the Cerebrum divide the cerebrum into lobes Surface lobes of the cerebrum Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 21

5 Specialized Areas of the Cerebrum lobe lobe lobe lobe sensory area- receives impulses from the body s sensory receptors Primary impulses to skeletal muscles area- sends area- involved in speech Cerebral areas involved in special senses Interpretation areas of the cerebrum Language region General interpretation area Layers of the Cerebrum area (taste) area area Area (smell) /language region matter Mostly of cell bodies layer matter Fiber tracts gray matter Ex: corpus hemispheres the connects nuclei- internal islands of gray matter Sits on top of the brain Inside the hemispheres Three parts for sensory impulses Transfers impulses to the correct part of the Under the Important system center Regulates body Controls Regulates Important part of the system (emotions) Attached to Houses the Includes the cerebrospinal fluid Brain Attaches to the Parts of the brain stem Mostly for localization and interpretation nervous balance gland gland plexus- forms cord of nerve fibers Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 22

6 Reflex centers for hearing Bulging center part of the brain Mostly Includes nuclei involved in the control of Medulla and tracts part of the brain stem Merges into the Important control centers Blood Diffuse mass of the brain stem control regulation Formation matter along control of visceral organs Reticular activating system plays a role in cycles and consciousness hemispheres with convoluted surfaces coordination of body movements The Spinal Cord and CNS Protection Spinal Cord Extends from the medulla oblongata to the region of (collection of spinal nerves) and lumbar region enlargements Spinal Cord Anatomy white mater- conduction tracts Internal bodies Anterior ( Central cerebrospinal fluid matter- mostly cell (posterior) horns ) horns filled with cover the spinal cord Nerves leave at the level of each root root Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 23

7 Protection of the CNS and skin Skull and vertebral column fluid barrier Meninges Double-layered covering * - attached to skull * layer- outer covering of the brain layer Clings to the the brain Cerebrospinal Fluid Similar to blood composition Formed by the Watery cushion to protect the brain layer -like layer Circulated in space, ventricles, and central canal of the spinal cord of Blood Least permeable of the body Excludes Useless against: Respiratory Traumatic Brain Injuries No Nervous tissue Tissue does not Cerebral inflammatory response May kill brain tissue Cerebrovascular Accident (CVA) Ruptured supplying a brain region Brain tissue supplied with from that blood source dies Possible loss of some functions or Progressive brain disease Barrier substances /fat soluble molecules injury damage from and vessel Disease Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 24

8 Mostly the, but may begin in middle age Structural brain changes include abnormal fibers within neurons deposits and twisted loss, irritability, confusion and ultimately, hallucinations and death The Peripheral Nervous System (PNS) Peripheral Nervous System Nerves and ganglia outside the = neuron fibers bundled by Structure of a Nerve tissue surrounds each fiber - group of fibers by perineurium binds fascicles together Classification of Nerves nerves- sensory and motor fibers (sensory) nerves- carry impulses toward the CNS Efferent ( impulses away from the CNS Cranial Nerves 12 pairs of nerves that serve the and neck Numbered in order, Nine mixed nerves; ) nerves- carry to back sensory only Distribution of Cranial Nerves I II III IV Olfactory nerve- sensory for nerve- sensory for vision Oculomotor nerve- motor for eye muscles muscles - motor for V Trigeminal nerve- sensory for ; motor for chewing muscles VI VII for eye muscles nerve- motor nerve- sensory for taste; motor for the face VIII Vestibulocochlear nerve- sensory for and hearing IX Glossopharyngeal nerve- sensory for X ; motor for the pharynx nerves- sensory and motor for pharynx, larynx, and viscera XI Accessory nerve- motor for and upper back XII Hypoglossal nerve- motor for Spinal Nerves pairs of spinal nerves at the level of each vertebrae Spinal nerves formed by combination of spinal cord Named for the and dorsal roots where they arise Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 25

9 organs Somatic- Autonomiccardiac muscle, and glands Somatic- muscle muscle, Autominic- acetylcholine,, or norepinephrine Sympathetic Division Originates from Norepinephrine and are neurotransmitters through Response to unusual stimulus Takes over to activities - exercise, excitement, emergency, and embarrassment Autonomic Nervous System branch of the nervous system Only Two divisions Somatic and Autonomic Nervous Systems Differences nerves division division - one motor neuron Autonomic- - and ganglionic nerves Parasympathetic Division Originates from the brain stem and through is the neurotransmitter activities Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 26

10 Conserves Maintains daily necessary functions and diuresis - digestion, defecation, Development Aspects of the Nervous System Formed during the embryonic development month of infections can have harmful effects Hypothalamus- one of the to develop areas of No formed after birth; growth and maturation continues for several years Brain reaches maximum as a young adult Special Senses: The Eye The Senses General senses of touch Special senses Smell Taste Sight Hearing The Eye and Vision of all sensory receptors are in the eyes Each eye has over a million Protection for the eye Mostly enclosed in a bony orbit Surrounded by cushion of Accessory Structures of the Eye glands- modified sebacious glands lubricate the eye glands- modified sweat glands between the eyelashes Membrane that lines the Connects to the surface of the eye Secretes Lacrimal lacrimal fluid Lacrimal lacrimal fluid from eyes Lacrimal lacrimal fluid toward to lubricate the eye - produces - drains - provides passage of duct- empties lacrimal fluid into nasal cavity Function of the Lacrimal Apparatus Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 27

11 Properties of lacrimal fluid Dilute salt solution ( ) Contains and lysozyme Protects, moistens, and lubricates the eye Extrinsic Eye Muscles Muscles attach to the outer surface of the eye Produce eye Structure of the Eye Wall is composed of three tunics - outside layer - middle layer - inside layer Choroid Layer -rich nutritive tunic Pigment prevents light from scattering Modified interiorly into two structures * Pigmented layer that gives eye body- smooth muscle * - rounded opening in the iris Sensory Tunic ( ) Contains receptor cells (photoreceptors) Signals pass from photoreceptors via a two-neuron chain neurons cells Signals leave the retina toward the brain through the The Fibrous Tunic White tissue layer Seen anteriorly as the anterior portion Allows Only human tissue that can be without fear of rejection, central to pass through itself easily Neurons of the Retina and Vision Found mostly toward retinal Dim light vision and vision Perception is all in Detailed Densest in the o of the retina with only cones No photoreceptor cells are at the optic disk Cone ( ) tones vision of the retina - area Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 28

12 types of cones Each sensitive to different light - result of lack of one cone type Lens crystal-like structure Held in place by a ligament attached to the ciliary body Internal Eye Chamber Fluids humor Watery fluid found between the and Similar to Maintains intraocular Provides for the lens and cornea Reabsorbed into venous blood through the canal of Schlemm humor behind the lens Keeps the eye from Lasts a not replaced substance Lens Light must be focused on the retina for optimal vision Eye is set for distance vision (over Lens must change shape to focus for and is ft away) objects Visual Pathway of the retina Optic nerve Optic nerve crosses at the optic Optic t (axons form optic radiation) Visual occipital lobe Eye Reflexes Internal muscles controlled by nervous system of the and muscles constrict pupils in bright light Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 29

13 Viewing close objects causes External muscles control eye movement to follow objects Viewing close objects causes (medial movement) Special Senses: The Ear The Ear senses (balance) Different organs house receptors for each sense Anatomy of the Ear Divided into External Ear areas (external) ear ear ear only Structures (auricle) External External Auditory Canal Narrow chamber in the bone Lined with canal (wax) glands Ends at the Middle Ear ( Cavity) -filled cavity within the temporal bone Only involved in Two tubes are associated with the inner ear The opening from the auditory canal is covered by the membrane The auditory tube connecting the middle ear with the * Equalizing pressure during yawning or * Otherwise it is Bones of the Tympanic Cavity bones Vibrations from eardrum move the Bones transfer sound to the (hammer) (anvil) (stirrip) ear Inner Ear (Bony ) Sense organs for hearing and balance Filled with Maze of bony chambers within the temporal bone Organs of Hearing Organ of Located within the = hair cells on the basilar membrane Gel-like tectorial membrane is capable of bending hair cells Cochlear nerve attached to hair cells transmits nerve impulses to the brain Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 30

14 Mechanisms of Hearing Vibrations from sound waves move membrane cells are bent by the membrane Action potential starts in the nerve Continued stimulation can lead to Organs of Equilibrium Receptor cells are in two structures Two functional parts of equilibrium canals equilibrium equilibrium Equilibrium - receptors in the vestibule Report on the of the head Anatomy of the Hair cells are embedded in the float in a gel around the hair cells Movements cause to bend the hair cells membrane (tiny stones) Head Upright Head Tilted Equilibrium - receptors in the semicircular canals the hair cells Action of head movements hair cells Special Senses: Smell and Taste of hair cells (gelatinous cap) covers stimulates the Senses- Taste and Smell Both senses use chemoreceptors Stimulated by in solution Taste has types of receptors Smell differentiates a large range of chemicals Both each other and respond to many of the same stimuli - Sense of Smell Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 31

15 Olfactory receptors are in the roof of the Neurons with long Chemicals must be dissolved in for detection are transmitted via the olfactory nerve Interpretation of smells is made in the Sense of Taste receptor organs Location Most are on the Soft The Tongue and Taste tongue is covered with projections called with no taste buds with taste buds papillae with taste buds Taste buds are found on the of papillae house the papillae- sharp papillae- rounded papillae- large Structure of Taste Buds cells are the receptors Have gustatory hairs (long Hairs are stimulated by chemicals dissolved in Impulses are carried to the gustatory complex by several nerves because taste buds are found in different areas Taste Sensations ) nerve nerve nerve receptors Some acids receptors receptors receptors Developmental Aspects of the Special Senses Formed early in development Eyes are the brain All special senses are at birth The Endocrine System The Endocrine System Uses (hormones) released into the blood ions of messages control several major processes Mobilize of body Maintain Regulate Hormone Overview and development Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 32

16 Produced by specialized Secreted by cells into fluids Transferred to target sites by the activity of other cells Chemistry of Hormones -based hormones - made from cholesterol - made from highly active lipids Mechanisms of Hormone Action Hormones affect only target or organs Target cells have specific Hormone work of the cells Effects Caused by Hormones Changes in permeability or electrical state influences the of proteins, such as enzymes Activation or inactivation of Stimulation of Enters Bind to a specific the nucleus Bind to specific sites on the cell s DNA Activate synthesis of new proteins Hormone Action in that result in Sets off a series of reactions that an enzyme a reaction that produces a second messenger molecule Control of Hormone Release Levels in the blood maintained by feedback (low hormone levels) in the blood triggers the release of more hormone Stops once an appropriate level in the Hormonal Stimuli of Endocrine Glands is reached glands are activated by other hormones Humoral Stimuli of Endocrine Glands Changing blood levels of certain stimulate hormone release Neural Stimuli of Endocrine Glands impulses stimulate hormone release Binds to membrane Does Hormone Action enter the cell Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 33

17 Size of a Hangs below Gland bone protects it Two functional lobes tissue Posterior pituitarytissue Hormones of the Anterior Pituitary pituitary- glandular hormones affect non-endocrine targets Four stimulate other glands (tropic hormones) Characteristics of all anterior pituitary hormones Act through systems Regulated by stimuli, mostly negative feedback General (or peptides) -messenger Hormone (GH) hormone Growth of skeletal and long bones synthesized into proteins broken down for energy Other Anterior Pituitary Hormones (PRL) Stimulates and maintains production after childbirth Function in hormone (ACTH) Regulates activity of is unknown cortex -stimulating hormone (TSH) Influences growth and activity of Other Anterior Pituitary Hormones hormones Regulate hormonal activity of the * -stimulating hormone (FSH) o Stimulates development in ovaries o Stimulates sperm development in testes * hormone (LH) o Triggers o Causes ruptured follicle to become the corpus luteum o Stimulates production in males Pituitary - Hypothalamus Relationship Hypothalamus produces releasing and affect the pituitary gland The 2 hormones are transported the Hormones of the Posterior Pituitary Stimulates during labor Causes hormones that pituitary contractions ejection hormone (ADH) Inhibits Large amounts cause production Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 34

18 Endocrine Glands and Hormones At base of the (increased blood pressure) Gland lobes and connecting isthmus Produces two hormones hormone * hormone * Decreases blood levels (deposited in bone) Two glands region (3 layers) tissue region Sits on top of the Hormones of the Adrenal Cortex Glands - outer glandular - inner neural (outer layer of AC) Regulates content in blood, water, and electrolyte balance Target organ- and cortisol (middle layer of AC) Promote Help resist long-term metabolism hormones (inner layer of AC) Some Hormones of the Adrenal Medulla Prepare body to deal with stress Mixed gland Produces to cross cell membrane to enter the blood Both maintain blood (male) (female) - allows glucose - allows glucose homeostasis Glands Tiny masses on thyroid Secrete hormone Stimulate calcium from bone) (remove Stimulates Intestine (absorb calcium) Raise the blood and levels in Found on the third ventricle of the Secretes Gland Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 35

19 Establishes body s sleep cycles Posterior to the Largest in Produces Matures some types of blood cells Important in system development Hormones of the Ovaries Produced by or placenta Development of secondary female characteristics Matures organs Prepares receive a fertilized egg Maintains Produced by the Implantation of in the uterus Hormones of the Testes Produced in cells of testes Produce several androgens * Male characteristics * Growth and maturation of reproductive system and and children follicles reproductive to production cycle - most important * cell production Endocrine System Development Most endocrine organs operate smoothly until caused by ovaries inefficiency Reduced estrogen problems are common production declines with age Many glands output with age Endocrine Regulation of Homeostasis and Glucagon Roles of the Hypothalamus and Adrenal Glands in Stress Response Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 36