The BRAIN - BEHS Science

The BRAIN - BEHS Science

The NERVOUS System Functions of the Nervous System Sensory senses stimuli from both within the body and

from the external environment Integrative analyzes, interprets, and stores information about the stimuli it has receives from the sensory portion of the nervous system

Motor responds to stimuli by some type of action muscular contraction glandular secretion Divisions of the Nervous System Central Nervous System (CNS) Peripheral Nervous System (PNS)

Somatic Nervous System (SNS) Voluntary Autonomic Nervous System (ANS) Involuntary Sympathetic Division Parasympathetic Division

Nervous System Schematic The Central Nervous System Consists of the brain and the spinal cord Sorts incoming sensory information

Generates thoughts and emotions Forms and stores memories Stimulates muscle contractions Stimulates glandular secretions The Peripheral Nervous System Connects sensory receptors, muscles, and glands in the peripheral parts of the

body to the central nervous system Consists of cranial and spinal nerves Afferent Neurons (Sensory) conduct nerve impulses from sensory receptors toward the CNS Efferent Neurons (Motor)

conduct nerve impulses from the CNS to muscles and glands The Somatic Nervous System Made up of sensory neurons that convey information from the cutaneous and special sense receptors in the head, body wall, and extremities to the CNS

Also contains the motor neurons from the CNS that conduct impulses to the skeletal muscles The Autonomic Nervous System Contains sensory neurons mainly from the viscera that convey information to

the CNS Contains the efferent neurons that conduct impulses to smooth muscle, cardiac muscle, and glands Unconscious control Two divisions of the ANS Sympathetic Division - stimulatory effect Parasympathetic Division - inhibitory effect

Neurons The nerve cells responsible for the special functions of the nervous system

sensing - remembering - thinking controlling muscle activity controlling glandular secretions Synapse - the functional relay points between two neurons or between a neuron and an effector organ Neuromuscular Junction

Neuroglandular Junction Parts of A Neuron Cell Body (Soma or Perikaryon) nucleus, cytoplasm, organelles of a neuron

Dendrites - tapered, highly branched processes protruding from the cell body usually very short AFFERENT FUNCTION Axons - long, thin, cylindrical process usually myelinated EFFERENT FUNCTION

Neuron Neurons Neuroglia Nervous system cells that support, nurture and protect the neurons Types of Neuroglia found in the CNS

Astrocytes Oligodendrocytes Microglia

Ependymal Cells Types of Neuroglia found in the PNS Neurolemmocytes (Schwann Cells) Astrocytes Star-shaped cells with many processes Participate in metabolism of neurotransmitters Maintain K+ balance for generation of

nervous impulses Participate in brain development Help form the blood brain barrier Provide a link between neurons and blood vessels Astrocyte Oligodendrocytes

Small cells with few processes Form a supporting network around the neurons by twining around neurons and producing a lipid and protein wrapping around the neurons (myelin sheath) Oligodendrocyte

Microglia Small phagocytic cells that protect the central nervous system by engulfing and invading microbes Clears away debris from dead cells Microglia

Ependymal Cells Neuroglia cells that line the brain ventricles Line the central canal of the spinal cord Helps form and circulate cerebral spinal fluid Ependymal Cells

Neuroglia of the PNS Schwann Cells - Neurolemmocytes Cells responsible for producing the myelin sheaths around the PNS neurons Schwann Cell

Myelination Schwann Cell (Neurolemmocyte) Myelination The process of developing or producing a Myelin Sheath Insulates the axon of a neuron Increases the speed of nerve impulse

conduction CNS - oligodendrocytes PNS - neurolemmocytes (Schwann Cells) Diseases such as Tay-Sachs disease and Multiple Sclerosis involve destruction of the myelin sheaths around the nerve

Myelination Myelinated Axon Unmyelinated Axon Neurophysiology The transmission of nerve (electrical) impulses from

nervous tissue to other nervous tissue, organs, glands, and muscles. Neuron Membrane Potential Neuron Action Potential Transmission of Nerve

Impulses An electrical event due to movement of ions across a membrane Also called an action potential Lasts about 1 msec (1/1000 of a second) Dependent upon diameter of the axon

larger diameter axons - 0.4 msec (1/2500 sec) 2500 impulses per second smaller diameter axons - 4 msec (1/250 sec) 250 impulses per second All or None Principle Ff depolarization reaches a

threshold, an action potential (impulse) is conducted Each action potential (impulse) is conducted at maximum strength unless there are toxic materials within the cell or the membrane has been disrupted Neuron Impulse

Neuron Action Potential Types of Impulse Conduction

Continuous Conduction - step by step depolarization of each sequential, adjacent area of of the nerve cell membrane typical of unmyelinated nerve fibers type of action potential in muscle fibers Saltatory Conduction - the jumping of an

action potential across specialized neurofibril nodes along the axon Nodes of Ranvier Nerve Conduction Gray and White Matter White Matter - the aggregation of

myelinated processes from many neurons Visible upon freshly dissected brain or spinal tissue White color is due to myelination Gray Matter - unmyelinated nerve cell bodies, axons, dendrites, ganglia, and

axon terminals Appears gray because of lack of myelin Gray and White Matter Protection and Coverings of the Protected by the Brain

cranial bones and the cranial meninges Dura Mater - outer layer Arachnoid - middle layer Pia Mater - inner layer

Also protected by cerebrospinal fluid fluid that nourishes and protects the brain and spinal cord continuously circulates through the subarachnoid space around the brain and throughout the cavities within the brain Meninges of the Brain

Cerebrospinal Fluid Mechanical Protection Serves as a shock absorbing medium Buoys the brain so it literally floats within the cranial cavity

Chemical Protection Provides an optimal chemical environment for neural signaling Circulation Acts as a medium for exchange of nutrients and waste products between the blood and nervous tissue

Transmission of Nerve Impulses at Synapses Most nervous conduction is from neuron to neuron (interneurons - 90%) Types of Synapses

Axon to dendrite Axon to soma Axon to axon Two ways to transmit impulses across a synapse Electrical Synapses

Chemical Synapses Meninges Connective tissue covering found around the brain and spinal cord Three layered membrane Dura Mater - outer most layer

dense irregular connective tissue Arachnoid - middle layer spider web arrangement of collagen fibers Pia Mater - inner most meninges

very delicate layer of thin tissue Spinal Cord Protective Coverings Dura Mater

Arachnoid Pia Mater Reflexes Fast, predictable, automatic responses

to changes in the environment that help maintain homeostasis Somatic Reflexes - involve skeletal muscles Visceral (Autonomic) Reflexes - involve responses of smooth muscles, the heart, and glands Involve the spinal nerves

The Reflex Arc A response by the body involving only the body segment being affected and the spinal cord Brain does not have to be involved

Receptor - the distal end of a sensory neuron (dendrite) Responds to a specific stimulus a change in internal or external environment Triggers a nerve impulse

Sensory Neuron - the neuron located in the gray matter of the spinal cord conducts impulses from the receptor to the spinal cord Integrating Center - a region within the CNS (spinal cord or brain) that interprets the information from the sensory neuron and initiates an appropriate response

Motor Neurons - the neurons arising from the integrating center that relay a nerve impulse to the part of the body that will respond to the stimulus Effector - the part of the body that responds to the motor nerve

impulse (usually a muscle or a gland) Effector - skeletal muscle - somatic reflex Effector - cardiac, smooth muscle, or gland -visceral reflex The Reflex Arc Reflex Arc Examples

Stretch Reflex - results in the contraction of a muscle if it has been stretched suddenly Tendon Reflex - results in the contraction of a muscle when a tendon is stretched suddenly Flexor (Withdrawal) Reflex sudden contraction and removal of a body segment as a result of a pain stimulus

Tendon Reflex Withdrawal Reflex also called Flexor/Withdrawal

Reflex The BRAIN The BRAIN One of the largest organs in the body Controls all mental functions Component of the CNS Composed of over 100 billion neurons

Comprises 2-3% of body weight Utilizes over 20% of bodys energy Major Divisions of the BRAIN CEREBRUM - occupies most of the cranium and is divided into right and left halves called hemispheres

CEREBELLUM - the posterior-inferior portion of the brain BRAIN STEM - consists of the medulla oblongata, the pons, and the midbrain it is continuous with the spinal cord DIENCEPHALON - located above the brainstem, composed primarily of the: Thalamus - Hypothalamus

The Brain Ventricles Cavities within the brain Lateral ventricles (2) - located within each hemisphere in the cerebrum Third ventricle - a vertical slit between the lateral ventricles and inferior to the right and left halves of the thalamus

Fourth ventricle - space between the brainstem and the cerebellum Ventricles of the Brain Choroid Plexus Network of capillaries in the walls of the ventricles Covered with ependymal cells that form

the cerebrospinal fluid These ependymal cells are so close together they form the blood-brain barrier. Selectively permeable barrier Protects the brain and spinal cord from potentially harmful substances in the blood

Flow of CerebroSpinal Fluid Flow of CerebroSpinal Fluid Blood Supply to the Brain

One of the most metabolically active organs in the body Makes up only 2-3% of body weight but uses about 20% of available O2 at rest Well supplied with O2 and nutrients Only nutritional source for brain metabolic activity is glucose

Capillaries in the brain are much less leaky than other capillaries in the body and form a blood brain barrier The Brain Stem The most inferior portion of the brain Connects the brain to the spinal cord Composed of Three Areas

The Medulla Oblongata The Pons The Midbrain The Medulla Oblongata Most inferior portion of the brain stem Connects the brain stem to the spinal cord

Respiratory Center Adjusts rhythm and depth of breathing Cardiovascular Center Regulates heart rate and contraction force Influences vasoconstriction and vasodilation

Also controls coughing, vomiting, swallowing, and hiccupping The Medulla Oblongata The Medulla Oblongata The Pons

Lies superior to the medulla oblongata Together with the respiratory center in the medulla helps control respiration The Pons The Midbrain

Superior to the pons Connects the brain stem to the diencephalon The Midbrain Pons and Midbrain The Diencephalon

Area of the brain containing the: Thalamus Hypothalamus The Thalamus Oval structure that makes up 80% of the diencephalon Comprised of a pair of oval masses

(mostly gray matter) Principle relay station between the various sections of the brain The Thalamus The Hypothalamus A small portion of the diencephalon located below the

thalamus One of the main regulators of homeostasis in the body Lacks a blood brain barrier Partially protected by the sella turcica of the sphenoid bone Functions of the Hypothalamus

coordinates Nervous System and Endocrine System activities to maintain Homeostasis

Thirst, Hunger, Satiety Sleep Patterns and Waking States Sex Drive, Maturation, Aggression, and Rage influences movement of food through the Gastrointestinal Tract production and secretion of hormones That control other Endocrine Glands The Hypothalamus

Hypothalamus The Cerebrum Largest division of the brain Occupies most of the cranium Accounts for 85% of brain mass Divided into right and left hemispheres

Longitudinal Fissure Corpus Callosum Cerebral cortex - the outer surface area of the cerebrum Composed mainly of gray matter

Contains billions of neurons The Cerebrum Lobes of the Cerebrum Named after the bones that cover them

Frontal Lobe Parietal Lobe Temporal Lobe Occipital Lobe Frontal Lobe

Motor Areas Controls movement of voluntary skeletal muscles Association Areas Carry on high level intellectual processing

Problem Solving - Reasoning Planning Concentration - Memory - Behavior Emotions - Expressions Parietal Lobe

Sensory Areas Interprets sensations such as: touch - pressure - pain on the surface of the skin Association Areas Understanding of speech

Using words to express thoughts and feelings Temporal Lobe Sensory Areas Hearing and balance

Association Areas Interpret sensory experiences Memory of visual scenes - music smells and other complex sensory patterns Occipital Lobe

Sensory Areas Visual processing and interpretation Association Areas Combines visual images with sensory experience

The Cerebellum Cerebellum and Brainstem The Cerebellum Second largest portion of the brain Occupies the inferior and posterior aspects of the cranial cavity

Processes sensory information Balance - Coordination Maintains postural equilibrium Nervous System Disorders and Homeostatic

Imbalances Alzheimers Disease (AD) Disabling neurological disorder that effects about 11% of the population Fourth leading cause of brain death among the elderly A chronic, organic, mental disorder, a form of pre-senile dementia due to

atrophy of neurons of the frontal and occipital lobes AD patients usually die from complications due to being bedridden Amyotrophic Lateral Sclerosis (ALS)

Also known as Lou Gehrigs Disease A relatively rare neurological disorder A syndrome marked by muscular weakness and atrophy with spasticity and hyperflexion due to degeneration of the

motor neurons of the spinal cord, medulla, and cortex A degenerative disease No known cure Bacterial Meningitis Infection of the meninges by the bacterium Haemophilus Influenzae Usually affects children under age 5 Symptoms include severe

headaches and fever Can lead to brain damage and even death if not treated Cerebral Palsy (CP) A group of motor disorders due to loss of muscle control Caused by damage to the motor areas of the brain during fetal development,

birth, or infancy About 70% of CP individuals are somewhat mentally retarded due to the inability to hear well or speak fluently Not a progressive disease but the symptoms are irreversible Epilepsy Short, recurrent, periodic, attacks of

motor, sensory, or psychological malfunction Characterized by seizures which can result in involuntary skeletal muscle contraction, loss of muscle control, inability to sense light, noise, and smell, and loss of consciousness Most epileptic seizures are idiopathic

Multiple Sclerosis (MS) The progressive destruction of the myelin sheaths of neurons of the CNS The sheaths deteriorates to scleroses hardened scars or plaques short circuits nerve transmission Cause is unknown

May be a type of an autoimmune disease No known cure Progressive loss of function with intermittent periods of remission Parkinsons Disease

(PD) A progressive disorder of the CNS that usually affects individuals over 60 Cause is unknown but a toxic environmental factor is suspected Chemical basis of the disease appears to be to little dopamine and too much Ach Treatment includes increasing levels of dopamine and decreasing Ach

Difficult because dopamine does not cross the blood brain barrier A chronic nervous disease characterized by a fine, slowly spreading tremor, muscle weakness and rigidity, and a peculiar gait Other causes may include brain

damage at birth, metabolic disturbances, infections, toxins, vascular disturbances, head injuries, and tumors and abscesses of the brain Usually can be controlled with drug therapy GABA - gamma aminobutyric acid

Symptoms include muscle tremor, muscle rigidity, bradykinesia, hypokinesia or dyskinesia, speech and walking impairment Attempting to transplant fetal nervous tissue into the damaged area of the brain of some Parkinsons Disease patients

Cerebral Vascular Accident (CVA) Stroke The most common brain disorder The most common brain disorder Characterized by slurred speech, loss of or blurred vision, dizziness, weakness, paralysis of a limb or hemiplegia, coma,

and death Ischemic CVA - due to lack of blood supply to a particular area of the brain Hemorrhagic CVA - due to the rupture of a blood vessel in the brain Risk Factors for Stroke hypertension heart disease smoking

diabetes atherosclerosis hyperlipidemia obesity excessive alcohol intake Sensations and Special Senses

Senses Specialized structures of the nervous system which provide information about the environment in which we live to help maintain homeostasis Functions of

Special Senses Sensory - monitoring the body and the external environment for changing conditions Sensory Pathways All pathways begin with a receptor and the sensory information is

transmitted to the CNS Always begins with a stimulus change in the environment Receptors Structures which provide feedback about the environment Are impulse specific

Only respond to one type of stimulus Many have sensory function adaptations May end as bare dendrites or be a complex organ

Vision The most complex of the special senses Over 70% of the sensory receptors in the body are photoreceptors for sight

Visual organs, the eyes are supported by a number of accessory structures and internal organs Dependent upon photoreceptors in the eyes The Eye Accessory Structures of the Eye

Eyelids - protects the anterior surface Conjunctiva - the mucous membrane of the eyelid Helps moisten and lubricate the eyeball Lacrimal Apparatus - secretes tears

lacrimal gland - lacrimal sac lacrimal canals

- nasolacrimal duct moistens and lubricates the eyeball fights against infection (enzymes in tears) Extrinsic Muscles of the Eyeball (6) skeletal muscles that move the eyeball Accessory Structures of the

Eye Structure of the Eye The wall consists of three layers of tissue or tunics Fibrous Tunic - outer layer Vascular Tunic - middle layer Nervous Tunic - inner layer

Fibrous Tunic Thick, outermost layer of the eyeball Sclera - the posterior white portion Forms most of the fibrous tunic The whites of the eye Cornea - the anterior transparent

portion of the fibrous tunic Bulges outward slightly Fibrous Tunic Vascular Tunic Extremely vascular Supplies blood to numerous structures of the eye

Choroid Iris - Ciliary Body - Lens Vascular Tunic

Choroid - posterior, thin portion of the vascular tunic A thin, dark brown membrane that lines most of the internal surface of the sclera Ciliary Body - anterior, thick portion of the vascular tunic

Thickest part of the vascular tunic Consists of smooth muscle fibers Attaches to the lens by ligaments Changes the thickness and shape of the lens.

Ciliary Body Iris - anterior, colored portion of the Vascular Tunic contraction of its smooth muscle accounts for dilation or constriction of the Pupils (openings to the inner cavities of the eyes)

Lens - special tissue which focuses and directs light entering the eye suspended by the Ciliary Body

located behind the Iris alteration of the shape of the lens to accommodate for near or far vision focusing (Accommodation) The Lens Iris Pupil Diameter Nervous Tunic

The inner layer of the eye Retina - a thin fragile layer of neurons that forms the inner lining of the eyeballs posterior wall Lines the posterior cavity and contains the photoreceptor cells (rods and cones), bipolar neurons, and ganglion cells

Optic Nerve - axons and ganglion cells Transmits images to the occipital lobe of the brain for interpretation of what we see Nervous Tunic Rods and Cones

Rods - elongated cylindrical dendrites that are sensitive to varying light conditions Allows us to see under varying light intensities (night vision)

Cones - dendrites with tapered ends Color sensitive Determines the sharpness of vision Rods and Cones Rods and Cones

Other Structures of the Nervous Tunic Optic Disc - blind spot where the optic nerve exits the retina Fovea Centralis - an area of the retina containing many cone cells the area of sharpest vision

Retina Elements of Vision in the Eye Vision spectrum of the eye only detect three colors Red - Green - Blue

Aspects of vision of the eye color motion

form depth Refraction

the bending of light rays as it travels through the eye the pathway of light as it travels through the eye influenced by: shape of the lens shape and thickness of the cornea amount and consistency of the Aqueous and Vitreous Humor

Refraction Vision Abnormalities Physiology of Vision Rods and cones convert light waves into a series of signals that results

in the generation of an action potential in the ganglion cells Both rods and cones contain pigments that decompose when exposed to light The decomposition of the pigments is what generates the action potential Visual Pathways

From the rods and cones, the nervous impulse is passed on to bipolar neurons and then on to ganglion cells Axons from the ganglion cells extend out

of the eye and converge to from the optic nerve The optic nerves cross behind the eye at an area known as the optic chiasma The optic nerve terminates at the thalamus Visual impulses from the thalamus

are transmitted by other neurons to the occipital lobe of the cerebral cortex where the impulses are interpreted as the sense of sight. Visual Pathway Hearing Dependent upon special organs within the ear

The ears are also associated with maintaining equilibrium and balance Three Regions of the Ears Outer Ear Middle Ear Inner Ear The Ear

Outer Ear Direct sound waves toward the eardrum Auricle - the outer appendage Auditory Canal - a tube that extends into the temporal bone The Outer Ear

Middle Ear Middle Ear An air-filled space within the temporal bone Tympanic Cavity - contains the auditory ossicles

Smallest bones in the body Malleus (hammer) Incus (anvil) Stapes (stirrup) Auditory (Eustachian) Tube - a tube from the middle ear to the pharynx

Allows for pressure equalization between the middle ear and the atmosphere Tympanic Membrane (Eardrum) thin, semitransparent membrane separating the outer and the middle ear Vibrates in response to sound waves

striking it The vibrations are then transmitted to the auditory ossicles Middle Ear Structures The tympanic membrane and auditory ossicles convert sound waves into mechanical movement within the middle ear and then

transmit that motion to the oval window The oval window opens into the cochlea of the inner ear Within the inner ear the vibrations of the stapes causes the fluid within the inner ear to move stimulating the receptors for hearing

The Three Regions of the Inner Ear

Formed by the canals of the bony labyrinth and the series of sacs of the membranous labyrinth Involved in both the sense of hearing and the maintenance of balance and equilibrium Cochlea Vestibule Semicircular Canals

The Inner Ear Inner Ear Structures The Semicircular Canals - three loops that lie at right angles to each other

The Vestibule - the chamber between the cochlea and the semicircular canals Both the semicircular canals and the vestibule are involved with maintaining balance or equilibrium The Cochlea - shape resembles a snail shell

Contains the organs of hearing (Corti) Receptor cells that move in response to endolymph motion Releases neurotransmitters that stimulate nerve impulses

The Cochlea Organ of Corti Cross Section of Cochlea Inner Ear (Labyrinth)

Consists of a winding, complicated series of passageways or canals Bony Labyrinth - a series of canals within the temporal bone Contains perilymph

Membranous Labyrinth - an internal series of sacs and tubes Contains endolymph Conforms to the bony labyrinth shape Also helps form the shape of the three regions of the inner ear

Vestibulocochlear Nerve Nerve Pathways

Sound waves cause the tympanic membrane to vibrate The vibration of the tympanic membrane causes the stapes to move back and forth Movement of the stapes back and forth pushes the oval window in and out producing waves in the perilymph of the inner ear

Pressure waves in the perilymph push the vestibular membrane inward increasing the pressure of the endolymph within the cochlear duct The hair cells in the Organ of Corti convert the motion of the endolymph to the release of neurotransmitters These neurotransmitters stimulate a nerve impulse in a sensory branch of

the Vestibulocochlear Nerve (CN #VIII) The impulse is then transferred through the midbrain and the thalamus and finally terminates in the temporal lobe of the cerebral cortex where the sound is

interpreted Physiology of Hearing Nervous System Disorders and Homeostatic Imbalances Alzheimers Disease

(AD) Disabling neurological disorder that effects about 11% of the population Fourth leading cause of brain death among the elderly A chronic, organic, mental disorder, a form of pre-senile dementia due to atrophy of neurons of the frontal and occipital lobes AD patients usually die from

complications due to being bedridden Amyotrophic Lateral Sclerosis (ALS)

Also known as Lou Gehrigs Disease A relatively rare neurological disorder A syndrome marked by muscular weakness and atrophy with spasticity and hyperflexion due to degeneration of the motor neurons of the spinal cord, medulla, and cortex A degenerative disease

No known cure Bacterial Meningitis Infection of the meninges by the bacterium Haemophilus Influenzae Usually affects children under age 5 Symptoms include severe headaches and fever Can lead to brain damage and even death if not treated

Cerebral Palsy (CP) A group of motor disorders due to loss of muscle control Caused by damage to the motor areas of the brain during fetal development, birth, or infancy About 70% of CP individuals are somewhat mentally retarded due to the

inability to hear well or speak fluently Not a progressive disease but the symptoms are irreversible Epilepsy Short, recurrent, periodic, attacks of motor, sensory, or psychological malfunction Characterized by seizures which can

result in involuntary skeletal muscle contraction, loss of muscle control, inability to sense light, noise, and smell, and loss of consciousness Most epileptic seizures are idiopathic Multiple Sclerosis (MS) The progressive destruction of the myelin sheaths of neurons of the CNS

The sheaths deteriorates to scleroses hardened scars or plaques short circuits nerve transmission Cause is unknown May be a type of an autoimmune disease

No known cure Progressive loss of function with intermittent periods of remission Parkinsons Disease (PD) A progressive disorder of the CNS that

usually affects individuals over 60 Cause is unknown but a toxic environmental factor is suspected Chemical basis of the disease appears to be to little dopamine and too much Ach Treatment includes increasing levels of dopamine and decreasing Ach Difficult because dopamine does not cross

the blood brain barrier A chronic nervous disease characterized by a fine, slowly spreading tremor, muscle weakness and rigidity, and a peculiar gait Other causes may include brain damage at birth, metabolic disturbances, infections, toxins, vascular disturbances, head injuries,

and tumors and abscesses of the brain Usually can be controlled with drug therapy GABA - gamma aminobutyric acid Symptoms include muscle tremor, muscle rigidity, bradykinesia, hypokinesia or dyskinesia, speech

and walking impairment Attempting to transplant fetal nervous tissue into the damaged area of the brain of some Parkinsons Disease patients Cerebral Vascular Accident (CVA)

Stroke The most common brain disorder The most common brain disorder Characterized by slurred speech, loss of or blurred vision, dizziness, weakness, paralysis of a limb or hemiplegia, coma, and death Ischemic CVA - due to lack of blood supply to a particular area of the brain

Hemorrhagic CVA - due to the rupture of a blood vessel in the brain Risk Factors for Stroke hypertension heart disease smoking diabetes atherosclerosis hyperlipidemia

obesity excessive alcohol intake Clinical Terms Diseases and Disorders Ametropia

Myopia - nearsightedness Imaged focused in front of the retina Presbyopia - a defect in vision in advancing age involving loss of accommodation or recession of near point (results in farsightedness) Hyperopia - farsightedness

Image focused in back of the retina Cataracts Abnormal loss of transparency of the lens Vision becomes blurry or cloudy Can be removed and have an artificial lens inserted Most often occurs to individuals over the age of 50. Exposure to sunlight

and smoking increases the risk. Conjunctivitis - inflammation of the conjunctiva, the mucous membrane that lines the eyelid and is reflected to the eyeball. Also known as Pink Eye

Strabismus cross-eyed Glaucoma

A group of eye diseases characterized by elevated intraocular pressure in the eye resulting in atrophy of the optic nerve which may lead to blindness Caused by an obstruction of the outflow of the aqueous and vitreous humor

Minor cases can be treated with eye drops More severe cases may require a surgical incision into the iris of the eye Macular Degeneration

The destruction or tearing away of the retina from the back of the eye Commonly occurs in the region of the retina known as the macula lutea Can be caused by: Vascular diseases (diabetes) Chronic increased pressure (glaucoma) Sudden blow or impact to the head or eye

(Detached Retina) Vertigo A condition of dizziness and spatial disorientation In some individuals it is due to heights or fear of high places A spinning sensation that may result in loss of balance and equilibrium

Tinnitus Ringing or tinkling sounds or sensations in the ear Middle Ear Infection

Infection of the tympanic membrane or other structures associated with the middle ear (Otitis Media) Deafness Loss of the ability to hear Conductive Deafness: deafness resulting from any condition that

prevents sound waves from being transmitted to the auditory receptors Sensorineural Deafness: deafness due to defective function of the cochlea, organ of Corti, or the auditory nerve

Recently Viewed Presentations

  • The Hotel Business - Valencia

    The Hotel Business - Valencia

    Cooperating with the banquet chef to check menus and service arrangements. Checking that the client is satisfied. Checking last-minute details. Making out client bills immediately after the function. Adhering to all hotel policies and procedures. Calculating and distributing the gratuity...
  • Business Model Generation

    Business Model Generation

    Four action framework (ERRC Grid) Which of the factors that the industry takes for granted should be eliminated? Which factors should be reduced well below the industry standards? Which factors should be raised well above the industry standards? Which factors...
  • Supplement E Simulation Copyright 2013 Pearson Education, Inc.

    Supplement E Simulation Copyright 2013 Pearson Education, Inc.

    Example E.2 : Specialty Steel Products. Formulate a simulation model for Specialty Steel Products that will estimate idle-time hours, overtime hours, and subcontracting hours for a specified number of lathes. Design the simulation model to terminate after 20 weeks of...
  • The FRAME Routine Key Topic Roman Geography is

    The FRAME Routine Key Topic Roman Geography is

    Rome was centrally located in the Mediterranean Basin and distant from eastern powers. Located on the Italian Peninsula . Created a crossroads for trade along the Mediterranean Sea—known as sea-borne commerce. Rome was protected by: 1) The Alps. 2) Seas...
  • Your Health Triangle - Montgomery Township School District

    Your Health Triangle - Montgomery Township School District

    Choose a symbol to represent all of your "yes" answers. Graphing Your Results For example, if you like softball/baseball, you can use: Graphing Your Results Use your symbols to form a Health Triangle to represent your scores. Label each side....
  • Chapter 9 slides, 3rdedition

    Chapter 9 slides, 3rdedition

    Cryptography and Network Security © by Xiang-Yang Li Department of Computer Science, IIT
  • Formation of the Universe

    Formation of the Universe

    Such fact-supported theories are not "guesses" but reliable descriptions of the real world. Formation of the Universe The Big Bang Theory (BBT) Red Shift Shift of wavelengths of light towards the red end of the spectrum; happens as a light...
  • Foundations of Planning - Pearson Education

    Foundations of Planning - Pearson Education

    Chapter 5 Foundations of Planning Robbins et al., Fundamentals of Management, 4th Canadian Edition ©2005 Pearson Education Canada, Inc. 1 Planning Defining the organization's goals, establishing an overall strategy, and developing a hierarchy of plans to achieve goals Common Elements...