Scientific Method
Experiment

Implementation of specific materials and methods designed to test a hypothesis
(should include a control group and experimental group)

Scientific Method
Data

Results generated by conducting experimental tests

Scientific Method
Conclusion

Statements based on analysis of test results that discusss evidence to support or reject the hypothesis

Scientific Theory

Widely accepted concepts based on extensive experimental evidence

Scientific laws

Also based on the extensive experimental evidence, but arise from numerous studies that have been shown to produce exactly the same results every time under the same circumstances

Homeostasis

Condition of equilibrium in the body's internal environment due to the constant interplay of all the body's regulatory processes

Metabolism

Sum of all chemical processes that occur in the human body

Catabolism

Phase of metabolism that invovles breaking down complex chemical substances into simpler ones;= decompostion reactions

Anabolism

Phase of metabolism that involves building complex chemical substances from smaller, simpler ones; = synthesis reactions

Disorder

Any abnormality of function

Disease

Illness characterized by a recognizable set of signs and symptoms

Symptoms

Subjective changes in body functions not apparent to ovbserver
Ex. Headache, Nausea

Signs

Objective Changes a clinician can observe and measure
Ex. Swelling, rash, fever, high blood pressure

Element

Substance that cannot be split into a simpler substance by ordinary chemical means

Atoms

Smallest units of matter that retain the properites and characteristics of an element

Atomic Number

Number of protons in nucleus of an atom of an element since number of elcetrons equals the number of protons, atomic number reveals number of electrons

Mass number

Sum of protons and neutrons in an atom

Atomic mass (weight)

Average of all naturally occurring stable isotopes of a given element in AMU (daltons)

Isotope

Atoms of element that have different numbers of neutrons and thus different mass numbers, but have same number of protons and electrons, so same chemical properties

Ion

Atom that has a positive or negative charge due to giving up or gaining electrons(ionization). which results in unequal number of protons and electrons

Molecule

Two or more atons (same or different) joined together by sharing of electrons

Compound

Substance that contains two or more different elements

Ionic bond

Force of attratcion tha holds ions having opposite charges together

Nonpolar covalent bond

Two or more atoms (same or different) share one or more pairs of their valence electrons equally

Polar Covalent bond

Two or more atoms (same or different) share one or more pairs of their valence electrons unequally equally and results in partial negative charge near atom with greater electronegativity and partial postive charge near other atoms

Hydrogen (H) bonds

Occur between polar molecules that contain polar covalent bonds betweeen H and very electonegative atons, such as O-H, N-H, or F-H bonds

Exergonic reaction

Release more energy than it absorbs

Endergonic Reaction

Absorbs more energy than it releases

Oxidation-Reduction redox reactions

Special type of exchange reaction that involves trnsger of electrons between atoms or molecules

Use of periodic table

Determine atomic number, mass number, atomic mass, number of protons, electrons, and neutrons, filling of electron shells, ionization

Inorganic Compounds

In general, lack carbon and are stucturally simple include water, many salts, acids, and bases

organic compounds

Contain carbon and many are relatively large and have unique characteristics that allow them to carry out complex functions include carbohydrates, lipids, proteins, nucleic acids and ATP

Adenosine triphosphate (ATP)

Major source of energy used to power reactions in body that require energy
-Most ATP in the cell is produced in mitochondtria
-Most ATP in th cell is produced by aerobic cellular respiration

6 Major Nutrients

WATER,VITAMINS, MINERALS, CARBOHYDRATES, LIPIDS, PROTEINS

Water - most important and abundant inorganic compound in all living systems
Glycogen - Storage form of carghydrates
Triglycerides - Storage form of lipids
Proteins - are not sroted for future use

Level 1 of protein structural organization
Primary

Unique aa sequence joined by covalent peptide bonds

Level 2 of protein sturctural organization
Secondary

Repeated twisting or folding of neighboring amino acids in polypeptide chain
(alpha helixes and pleated sheets)

Level 3 of protein structural organization
Tertiary

3-D folding pattern formed by various bonds; determines shape and how a protein will function

Level 4 of protein structural organization
Quaternary

Arrangement fo two or more polypeptide chains relative to each other

Acid

Below pH 7 , proton (H+) donor, dissociates into H+ and anions

Base

Above pH7, proton (H+) acceptor, dissociates into cations and OH- or another proton acceptor, such as NH3

Salt

Dissociates into cations and anions, neither of which is H+ or OH-

Acid + base -> Salt + Water

Buffer

Substance that resists drastic changes in pH (maintains pH0 by convering strong acids or bases into weak ones

Plasma membrane

Encloses and protects cell and contains functional proteins such as enzymes that catalyze chemical ractions, receptors that bind ligands and regulate cellular activity, transporters that regulate qwhat enters and exits cell, and cell identity markers

Cytoplasm

Cellular contents between the plasma membrane and the nucleus includes cytosol and organelles

Cytosol

Fluid that surrounds organelles

Organelles

Specialized structures with characteristic shapes and specific functions in cell growth, maintenance, and reproduction: include nucleus, nucleoli, ribosomes, rough ER, smooth ER, Golgi apparatus, mitochondria, centrioles, lysosomes, peroxisomes, and other structures

Nucleus

Spherical or oval-shaped sturcute where most of cell's DNA and nucleoli are located
"control cneter fo the cell"

Nucleoli

One or more spherical bodies in nucleus that are sites of rRNA synthesis and assembly of rRNA and proteins into ribosomal subunits

Ribosomes

Site of protein synthesis attached to nuclear envelope and rough ER, free in cytosol, and in mitochondria

Rough endoplasmic reticulum (RER)

Network of folded membranes with attached ribosomes that synthesize proteins, which then enter RER for processing and sorting synthesizes glycoproteins and phospolipids

Smooth endoplasmic reticulum (RER)

Network of folded membranes (with no ribosomes) that synthesizes fatty acids and steroids and may have other functions, such as detoxification of harmful substances, depending on cell type

Golgi apparatus

Modifies and packages proteins syntheseized in rough ER for tansport

Mitochondria

Genreate most of cell's ATP for enery to drive cellular activities
"powerhouse of the cell"

Centrioles

form mitotic spindle during cell division and involved in construction of structures such as flagella and cilia

Lysosomes

membrane-enclosed vesicles that contain digestive and hydrolytic encymes that breakdown foreign cells, worn out organelles, and a wide cariety of molecueles

Peroxisomes

Contain oxidative enzymes that can deactibate hrmful substances

Structural framework of cell's plasma membrane is a lipid bilayer

Two back to back layers made up of prmarily phospholipids plus cholesterol and glycolipids

"Fluid mosaic model"

Moving sea of fluid lipids with a mosaic of different functional proteins

Selectively permeable

Allows free passage of many lipid-soluble molecules but selectibely controls crossing of ions or polar substances through transporter proteins

Mitosis

Consists of nuclear division during cell division that produces two identical daughter cells with diploid number of chromosomes; mainly in somatic cell division

4 phases
Prophase
anaphase
metaphase
telophase

Cytokinesis

Cytoplasmic division during cell division begins in late anaphase, completed in telophase

Interphase

Perios between cell divisions during which cell is functionally and metabolically active and also undergoes growth and duplicates its DNA, organelles, and cytosolic components in anticipation of cell division

Meiosis

Reproductive cell divbison that produces gametes (oocytes in females and sperm in males0 in which the number of chromosomes in the nucleus are reduced by half (haploid Number)

DNA Replicaton

Synthesis of DNA from DNA template

Transcription

Synthesis of mRNA from DNA template

Translation

Synthsis of amino acid sequence of protein from mRNA template

Structure of DNA

-Double strande and has double helix structure resembling spiral ladder
-sides of ladder are formed by alternation deoxyribose sugars and phosphate groups
-rungs are formed by nitrogenous base pairs joined to each other by hydrogen bonds
-4 nirogenous bases: Guanine (G), Cytosine (C), Adenine (A), and Thymine (T)

Thymine pairs with adenine
Guanine paris with Cytosine

Structure of RNA

-differs from DnA
-Single-stranded instead of double-stranded
-Contains ribos instead of deoxyribose
-contains uracil rather than thymine
Uracil pairs with adenine
Guanine pairs with Cytosine (same in DNA)

3 kinds of RNA made from DNA template

Messenger RNA (mRNA)
Ribosomal RNA (rRNA)
Trnsger RNA (tRNA)

Messenger (mRNA)

Directs proten synthesis

Ribosomal RNA (rRNA)

Joins with ribosomal Proteins to make ribosomes

Transfer (tRNA)

One end binds specific amino acid and other end has anticodon that base pairs with complimentary codon on mRNA, to hold amino acid in place on ribosome until it is incorporated into protein during translation

Codon (in mRNA)

each sequence of 3 nucleotides in mRNA that base-pairs with a DNA base triplet

Anticodon

Nucleotide triplet on tRNA that base pairs with complimentary mRNA codon

Introns

Regions within gene that do not code for parts of protein

Exons

Regions within gene that do code for parts of protein

Passive transport

substance uses its own kinetic energy to move down it concentration or electrochemical gradient across membrane until it reaches equilibrium (equal on both sides); does not require energy

Simple diffusion through lipid bilayer

allows passage of nonpolar substances

Facilitated diffusion through channels

allows passage of larger and highly polar/charged substances via transporter protein

Active transport

Energy-requiring process in which transport proteins move solutes across membrane against (up) concetration gradient

Primary active transport

enery derived from hydrolysis of ATP to "Pump" substance across membrane against (Up) its concentration gradient

Secondary Active transport

Harnesses potential energy of steep NA+ or H+ concentration gradient (established by primary atibe transport of these ions) to transport substance up its concentration gradient as Na+ or H+ move down their concetration gradient

Symporters

Move two or more substances in same direction

Antiporters

Move two or more substances in oppostie directions

Vesicle transport

Vsicles, small sacs that bud off from an existing membrane, transport substances between structures within cell or in and out of cell

Endocytosis

materials move into a cell in a vesicle formed by plasma membrane

Exocytosis

Membrane enclose "secretory" vesicles form inside cell, fuse with plasma membrane, and release their contents into extracellular fluid

Osmosis

Net movement of water across membrane not permeable to solutes

Tonicity

Measure of solution's ability to change volume of cells by altering their water content

Isotonic solution

concentrations of solutes same on both sides of membrane, so water enters and exits at same rate and cells maintain normal shape and volume

Hypotonic solution

has lower concentration of solutes than cytosol, so water enters cells faster than it leaves casuing cells to swell and burst

Hypertonic solution

has higher concentration of solutes than cytosol, so water moves out of cells faster than it moves in causing cells to shrink

Cell junctions

Contact points between plasma membrane of tissue cells

tight junction

Transmembrane proteins fuse adjacent cells' plasma membranes togher to retard the passage of substances and rom water tight seal so common in urinary and digestive tracts

adherens junction

Cells are joined by cadherin proteins of adjacent cells that insert into protein plaques inside plasma membrane so help epithelial surgaces resist separation

Desmosomes

have plaques and cadherins that attach cells to one another, but also have intermediate filaments that extend from desmosomes on one side fo cell across cytosol to desmosomes on opposite side of cell to prevent cells from separation under tension so common in epidermis and cardiac muscle

Hemidesmosomes

similar to desmosomes but contain integrins, rather than cadherins and anchor cells to basement membrane between epithelium and connective tissue

Gap Junction

membrane proteins called connexins form tiny fluid-filled tunnels called connexons that connect neighboring cells and allow rapid communictaion and diffusion of substances between the cells so common in nervous tissue and cardiac muscle

body tissue
epithelial tissue

covers body surface

body tissue
Connective tissue

protcets and supports body and organs

body tissue
muscle tissue

generates physical force neeeded to make body structures move

body tissue
Nervous tissue

detects changes in conditions inside and outside of body and responds by generating nerve impulses that control other tissues help maintain homeostasis

exocrine Gland
Sudoriferous glands

exocrine glands that secrete sweat into hair follicles or onto the skin's surface to lower body temperature

exocrine gland
sebacous glands

Exocrine glands connected to hair follicles that secrete an oily substance to help prevent hair and skin from drying out

exocrine gland
Ceruminous glands

modified sweat glands in external auditory canal that secrete ear wax to impede entrance of foreign particles

exocrine glands
Goblet cells

Unicellular exocrine glands that secrete mucus to help lubricate and protect lining of GI tract and help trap foreign particles in respiratory tract so they can be moved back out by cilia

Connective tissue (CT)

includes tissues such as adipose (loose CT), tendons and ligaments (dense CT), cartilage, bone, blood and lymph
-binds togeether, supports, and strengthens other tissues (loose and dense CT)
-Protects and insulates internal organs (adipose)
-Compartmentalizes structures such as skeletal muscles (loos and dense)
-Major transport system(blood)
-Stored energy reserves (adipose fat tissue)
-Main site of immune responses (lymph and white blood cells

Muscle tissue

Muscle fibers use ATP to generate force
-3 types: Skeletal, cardiac, and smooth

Muscle tissue
Skeletal

usually attached to bones of skeleton, boluntary and striated (alternating light/dark bands on stained fibers)

Muscle tissue
Cardiac

Forms most of wall of hear, involuntary, branched, striated and contains intercalated discs (with gap junctions and desmosomes)

Muscle tissue
Smooth

Located in walls of hollow organs (blood vessels, airways, digestive, urinary, reproductive), involuntary, and nonstriated

Nervous tissue

Controls and integrates all body activities within limits that maintain life

Basic functions of nervous tissue

sensing nternal and external changes with sensory receptors processing, interpreting, and remembering those changes with effectors (muscles and glands)

Neuron

functional unit of nervous system; has the capactiy to produce action potentials receive and conduct nerve impulses

neuroglia

nervous system cells that have supportive roles do not receive or conduct nerve impulses

integumentary system

Includes skin, hair, and nails

Skin

Covers body, protects underlying tissues, and contains accessory structures that function in protection from microbes and sun, thermoregulation, and tactile sensations

eccrine suderiferous (sweet) glands

exocrine glands found throughout most of body that secrete sweat into hair follicles or onto the skin's surgace to lower body temperature

sebaceous (oil) glands

exocrine glands connected to hair follicles that secrete an oily substance to help prevent hair and skin from drying out

arrector pili muscle

smooth muscle near hair that is stimulated by autonomic nervous system to contract under sonditions of stress (such as cold or fright)

Meissner's corpuscle

encapsulated nerve ending that senses light touch

Pacinian corpuscle

encapsulated nerve ending that detects deep pressure

functions of skeletal system
support

structural framework for body; supports soft tissues and provides attachment points for tendons of most skeletal muscles

functions of skeletal system
Protection

protects many internal organs from injury

functions of skeletal system
movement

bones and muscles work together to produce movement: muscles are attached to bones, so when they contract, they pull bones

function of bone tissue
Mineral homeostasis

Several minerals, mainly calcium and phosphorus, are stored in bone tissue and realeased on demand into blood to maintain critcial mineral balcnces and to distribute minerals to other parts of body

function of bone tissue
blood cell production (hemopoieis or hematopoiesis)

function of red bone marrow (in spongy bone) occurs in skull, ribs, sternum, vertebrae, pelvis, and ends of arm and thigh bones produces red blood cells, white blood cells, and platelets

function of bone tissue
Triglyceride storage

function of yellow bone marrow consists mainly of adipocytes, which store triglycerides serves as important eneregy resrve (triglycerides)

Flexion

decrease in angle

extension

increase in angle, usually restorying to anatomical position

abduction

movement of a bone away from the midline

adduction

movement of a bone toward the midline

circumduction

mocement at distal end of body part in a circle (continuous sequence of flexion, abduction, extension and adduction)

ratation

bone revolves around its own longitudinal axis

supination

movement of forearm to turn palm anteriorly or superiorly

pronation

movement of forearm to turn palm posteriorly or inferiorly

sarcomeres

basic functional units of a myofibril in muscle, separated by Z discs

myofibrils

composed of 3 types of proteins (name proteins included in these 3 groups and describe their functional roles in sliding filament model of muscle contraction)

contractile Proteins

Actin and myosin

actin

in thin filaments

myosin

in thick filaments

regulatory proteins

troponin and tropomysosin in thin filaments

structural proteins

titin, M line, dystropin, nebulin muscle action potential is stimulated by acetylcholine (neurotransmitter) realeased from motor neuron at neuromuscular junction that binds receptors on muscle cell membrane and leads to depolarization of membrane to threshold potential via opening of Na+ channels: be familiar with steps in generation muscle action potentials and muscle contractions

resting membrane potential

-90 mV

threshold Potential

-55 mV

Depolarizarion (potential becomes more positivve, moves toward threshold potential

involves opening of Na+ ion channels and produces action potential if threshold is reache, which causes opening of more Na+ channels and leads to contraction due to opening fo voltage-gated Ca++ channels

Sliding filament mechanism of skeletal muscle contraction

heads of myosin bind and form crossbrides with actin and pull the thin filaments toward the M line (midline); requires energy from ATP hydrolysis
-in relaxed muscle (no Ca2+ present), tropomyosin, held in place by troponin, covers myosin binding sites on actin and prevents the formation of crossbridges
-when sufficient Ca 2+ is present, it binds to troponin, which changes shape and moves tropomyosin, therby expsoing binding sites to allow crossbridge formations

Resting membrane prential in a neuron

-70 mV

Resting membrane potential in a muscle cell

-90 mV

Grades potentials

small local changes from resting membrane potential

depolarization

membrane becomes more positive can build to threshold potential, so excitatory

Hyperpolarization

membrane becomes more negative makes it less likely to reaach threshold, so inhibitory

threshold potential

-55 mV
Depolarizing potential required to generate an action petential

Central nervous system (CNS)

Consists of brain and spinal cord

Peripheral nervous system (PNS)

consists of the cranial nerves and spinal nerves, which contain both sensory and motor fibers

Divisions of nervous system (PNS)
Somatic (voluntary) nervous system (SNS)

Sensory neurons from skin and special sensory receptors to the CNS motor neurons to skeletal muscle

Autonomic (involuntary) nervous systems (ANS)

sensory neurons from viscral organs to CNS motor neurons to cardiac muscle, smooth muscle, and glands

sympathetic division

"fight or flight" stress and emergency responses

Parasympathetic division

"rest and digest" maintenance of homeostasis usually dominates

enteric nervous system (ENS)

Involuntary sensory and motor neurons that control gastrointestinal tract

neuron

Functional unit of nervous system
-conducts (sends and receives) nerve impulses to communicate with and control actions of other cells

Dendrites

one to many short, branched processes that receive input and conduct graded porentials toward cell body

axons

one thin, typically long process that conducts nerve impulses away from cell body (sends output) and releases neurotransmitter from synaptic end bulbs at ends of axon terminals
only one present, but branches to make many contacts most are myelinated

neuroglia

nervous system cells that have supportive roles
-do not conduct nerve impulses

neuroglia in the CNS
Astrocytes

maintain chemical environment in CNS and help form the blood-brain barrier

Neuroglia in the CNS
microglia

phagocytic role

Neuroglia in the CNS
Oligodendrocytes

form myelin sheath around CNS axons

Neuroglia in the CNS
Ependymal cells

line the cerebral cavities and produce cerebrospinal (CSF) fluid

Neuroglia in PNS
Schwann cells

Form a myelin sheath around PNS axons

Neuroglia in PNS
Satellite cells

role not clear, but believed to maintain chemical environment in PNS

Axons of PNS neurons

most covered by myelin sheaths produced by schwann cells

nodes of ranvier

gaps between myelin sheaths where many voltage-gated channels are located

myelinated fibers

myelin acts as electrical insulator and speeds conduction of nerve impulses

unmyelinated fibers

slow because small diameter and no myelin insulation

saltatory conduction

rapid nerve conduction that occurs in myelinated fibers where signal jumps node to node of Ranvier

continuous conduction

slow nerve conduction that occurs in unmyelinated fibers where entire length of axon must be depolarized step by step

Neurotransmitters

Released from axon terminals,diffuse across synaptic cleft, and bind to receptors on target cell; may be excitatory or inhibittory

Acetylcholine (ACh)

Excitatory on neuromuscular junction but inhibitory at others

glutamate

Major excitatory on neurotransmitter in CNS and PNS

Aminobutyric acid (GABA)

major inhibitory neurotransmmitter in forebrain

norepinephrine

regurlates mood, dreaming, awakening from sleep

dopamine

regulates skeletal muscle tone

serotonin

regurlates mood, temperature, and induction of sleep

Neuropeptide
Substance P

enhances perception of pain

Neuropeptide
Enkephalins (opioids)

relieve pain by blocking the release of substance P

spinal cord nerve tracts

pathways for travel of sendory and motor information

ascending nerve tracts

carry sensory information from spinal cord to brain

descending nerve tracts

carry motor information from brain to spinal cord

diencephalon

extends from brain stem to cerebrum and surrounds third ventricle

thalamus

Relays almost all sensory input to the cerebral cortex

hypthalamus

controls and integrates activities of the autonomic nervous system and the pituitary gland

epithalamus

contains pineal gland, which secretes melatonin to promote sleepiness
-Subthalamus containing subthalamic nuclei that work with the basal ganglia to help control body movements

brain stem

portion of brain between spinal cord and diencephalon

Medulla Oblongata

-lower part of the brain stem
-relays motor and sensory impulses between other parts of the brain and spinal cord
-has a crdiovascular center that regulates the force and rate of heartbeat and diameter of blood vessels
-has a respiratory center that adjusts the rhythm of breathing

Pons

-middle part of the brain stem
-relays impulses from one side of the cerebelllum to other and between medula and midbrain
-has pnneumotaxic and apneustic area to help control breathing

Midbrain

-upper part of the brain stem
-relays motor impulses from cerebral cortex to pons and sensory impulses from spinal cord to thalumus
-includes the red nuclei, which function with the cerebellum to coordinate muscular movements
-includes substantia nigra that releases dopamine for regulating muscle tome

cerebellum

posterior to medull and pons and inferior to posterior cerebrum
Functions: Coordinate complex, skilled movements
Reulate posture and balance
May have role in cognition and language processing

cerebrum

Consists of cerbral corex (ouoter rim of gray matter), white matter (interior), and gray matter nuclei deep within white matter
-divided into right and left hemispheres
-each hemispher receives sensory input from and controls muscles on opposite side of body

hemispheric lateralization

functional symmetry between the two hemispheres

left hemisphere

in most people, more important for reasoning, numeric, and scientific skills, language

Right Hemisphere

more specialized for art and music, spacial and pattern perception, emotional content of language, and face recognition

5 lobes

Frontal
Parietal
Occipital
Temporal
Insula

Cerebral Cortex
Primary sensory areas

Receive nerve impulses for specific stimuli determines location and basic characteristics of stimuli

Cerebral Cortex
Primary motor area

controls voluntary contractions of specific muscles or muscle groups

Broca's speech area

brain region where planning and production of speech occurs

aphasia

inablitlity to use or comprhend words caused by injury to language areas

Sensory association (secondary sensory) areas

usuallly receive input from primary sensory areas and other brain regions, including thalamus integrate/interpret sensory info by comparing with past sensory (memory)

premotor area

motor association area that controls learned skiloled movements and stores memory for such movements

basal ganglia

3 nuclei deep within each cerebral hemisphere that help regulate intiation and termination of movements

limbic system

has primary role in emotions, olfaction, and memory

reticular activating system (RAS)

involved in stimulatin and maintaining arousal and consciousness

Learning

acquiring new knowledge

memory

process of retaining and retrieving information

brain waves

collection of action potentials and graded potentials generated by neurons in brain

Electoencephalogram (EEG)

record of brain wabes (electrical signals) used for studying normal brain activity and diagnosing disorders such as tumor, trauma, and epilepsy

sleep

state of latered or partial consciousness from which a person can be aroused

2 components

non-rapid eye movement (NREM) and rapid eye movement (REM) sleep
-REM and NREM alternate throughout sleep
-Most dreams occur during REM sleep
-sleep deprivation impairs attention, learning and performance

Proprioceptors

sense joint postiiont and movement and muscle length and tension

nocioceptors

sense pain found in all tissues of the body except the brain

Thermoreceptors

sense warmth or cold

tactile receptors

sense tough, pressure, vibration, tickle, and itch

Special senses

olifaction, gestation, vision, hearing and equilibrium involve much more complex, specialized receptors that somatic sensations

gustation

sense of taste
-chemical sense in shich tastants are dissolves in saliva and detected by gustatory hairs in taste buds

taste buds

detect 5 gustatory stimuli (bitter, sour, sweet, salty, and umami-meaty/savory)
-taste on the anterior 2/3 of the tongue comes from sensory axons of the facial nerve
-taste on the posterior 1/3 of the tongue arises from sensory axons of the glosssopharyngeal nerve

Olfaction

Sense of smell
-Chemical sense in shich odorants are dissolved and detected by olfactory hairs of olfactory receptors

olfactory nerve (cranial nerve 1)

formed by bundles of olfactory receptor (1st order neurons)axons that terminate in olfactory bulb

olfactory tract

formed by axons of olfactory bulb neurons (2nd order neurons) that project to lateral olfactory are in temporal lobe

Cornea

transparent and vurved coat that covers iris that functions in refraction of litht:helps focus light onto retina

lens

refracts light: helps focus light on macula lutea of retina to provide clear images

Iris

Colored portion of eye that faces anteriorly

Pupil

hole in center that functions to regulate amount of light entering eye changing size of pupil is regulated by autonomic reflexis

parasympathetic reflex

circular muscles contract in bright light to constrict pupil

sympathetic reflex

radial muscles contract in dim light to dilate pupil

retina

serves as beginning of bisula pathway

optic disc

site where optic nerve exits back of eyeball
blined spot because contains no photoreceptors (rods and cones)

Retinas 2 layers

pigmented and neural

pigmented epithelium

nonvisual portion that has melanin
absorbs stray light and help keep image sharp and clear

nueral layer

multilayered outgrowth of brain that processes visual input then sends nerve impulses down axons that form optic nerves

Photoreceptors in retina

named for shape of their outer segment

rods

photoreceptors active in dim light that detect shades of gray contains photopigment called rhodopsin

Cones

photoreceptors active in bright light with photopigments to detect color each one caontains one of 3 different photopigments (opsins) for color produce sharper vision than rods

emmetropic eye

Normal eye that can sufficiently refract light rays from an object 20ft away so that a clear image is focused on the retina

Myopia

nearsightedness
occurs because eyeball is too long relative to focusing power of cornea and lens

hypermetropia (hyperopia)

Farsightedness
Occurs because eyball is too short relative to focusing power of cornea and lens

astigmatism

parts of image are out of focus, producing blurred or distorted vision occurs due to irregular curvature of cornea

Three major processes involved in image formation

-refraction (bending) of light by cornea and lens to focus light rays onto retina
-accommodation of lens: incresing curvature of lens so light is still focused as objects move closer to eye
-constriction of pupil to prevent light rays from entering through periphery of lens which minimizes blurriness

auricle

collects sound waves

external auditory canal (meatus)

directs sound waves to tympanic membrane

tympanic membrane (eardrum)

vibrated by sound waves, which vibrates ear ossicles in turn

auditory (ear) ossicles

transmit and amplify vibrations to oval window include: malleus, incus, and stapes

cochlea

contains series of fluids, channels, and membranes that transmit vibrations to organ of Corti for hearing

organ of corti

contains hair receptor cells that produce receptor potentials, which elicit nerve impulses in cochlear branch of vestibulocochlear nerve (cranial nerve VIII)
ventually nerve impulses reach primary and secondary auditory areas involved in awareness and interpretation of sound

vestibular apparatus

contains receptor organs for snse of equailibrium
includes: semicircular ducts, utricle, and saccule
Movement of sterocilia on hair cells of saccule and utricle leads to generation of nerve impulses in vestibular branch of vestibulocochlear nerve (cranial nerve VIII)

Static equilibrium

maintance of body position (mainly the head) relative to the force of gravity

Dynamic equilibrium

maintance of body position (mainly the head) during sudden mmovements such as rotation, acceleration, or deceleration

semicircular ducts

contains hair (receptor) Cells for dynamic equilibrium

Utricle and saccule

contain hair cells for dynamic and static equilibrium