• body's ability to maintain relatively stable conditions
• function of most normal physiology

• if ability to maintain homeostasis is compromised, disorder and/or disease might result
• these are indicated by  
  • signs- measurable like a stop sign
  • symptoms- felt by patient

Which of the following is considered a symptom of disease?

1. fever
2. swelling
3. anxiety
4. 1 and 2
5. 2 and 3

• maintain homeostasis
• mediated by 
  • receptors- detect stimuli
  • control center- process input, generate output
  • effectors- respond by changing conditions

• reverses a stimulus condition
• regulates normal conditions
  • ex: blood pressure, body temperature

positive feedback systems

• positively enforces a stimulus condition
• regulates extraordinary conditions
  • ex: childbirth, urination, orgasm
• requires a shut-off mechanism

If the body's core temperature drops below a critical point, shivering is triggered tot generate heat and regain homeostatic temperature. What type of feedback system does this represent?

1. positive because it brings out a desired condition
2. negative because it requires energy
3. positive because body temperature is increasing
4. negative because it acts to reverse the stimulus condition

• covalent bonds
  • share electrons
  • polar covalent bonds
    • unequal sharing of electrons that characterize polar molecules
• hydrogen bonds
  • strong attraction between water molecules
• ionic bonds
  • hold molecules like salts together by charge

• polarity and hydrogen bonding give water properties of solvency and cohesion
• hydrogen bonding gives water high thermal stability

Which of the following describes the bonds that attach the hydrogen atoms to the oxygen atom in a water molecule?

1. they are polar bonds
2. they are covalent bonds
3. they are hydrogen bonds
4. a and b
5. b and c

1. they are polar bonds
2. they are covalent bonds
3. they are hydrogen bonds
4. a and b
5. b and c

• water self-ionizes 
  • H₂O <-> H⁺ + OH^-
• acids donate hydrogen cations in water
• bases accept hydrogen cations in water

• dehydration synthesis
  • monomer + monomer -> dimer ->->polymer +water
• hydrolysis
  • polymer + water -> monomer + monomer

• biological macromolecule
• sugars and starches
• functional groups: hydroxyl OH, carboxyl COOH
• monosaccharides
  • glucose
  • galactose
  • fructose
• disaccharides
  • sucrose= glucose + fructose
  • lactose= glucose + galactose
  • maltose= glucose dimer
• polysaccharides
  • glycogen= glucose polymer
    • good form of energy storage because the molecule is very stable

Glycogen, a polysaccharide contains many unstable hydrocarbon bonds and is readily oxidized. Glycogen is thus very effective as

1. a chemical messenger
2. a biological catalyst
3. a solvent
4. an energy storage molecule
5. genetic material

1. a chemical messenger
2. a biological catalyst
3. a solvent
4. an energy storage molecule
5. genetic material

The disaccharide sucrose can be broken down into monosaccharides glucose and fructose via the process:

1. hydrolysis
2. neutralization
3. dehydration synthesis
4. hydrogen bonding
5. ionization

1. hydrolysis
2. neutralization
3. dehydration synthesis- forms polymers
4. hydrogen bonding
5. ionization

• biological macromolecule
• fatty acids, triglycerides, phospholipids, steroids
• functional groups: methyl CH3
• non-polar- repels water
• fatty acids
  • carb acid with saturated or unsaturated hydrocarbon chain
• phospholipids
  • nitro group, phosphate group, glycerol, fatty acid tails
  • hydrophilic heads
  • hydrophobic tails

Lipid molecules typically have long hydrocarbon chains that make them

1. insoluble in water
2. hydrophobic
3. effective components of the plasma membrane
4. all of the above

1. insoluble in water
2. hydrophobic
3. effective components of the plasma membrane
4. all of the above

• amino acid polymer, formed by peptide bonds
• functional groups: methyl CH3, carboxyl COOH, amino NH₂  
• non-polar: methionine and tyrosine
• polar: cysteine and arginine
• primary structure
  • peptide-bonded sequence of amino acids
• secondary structure
  • hydrogen-bonded alpha or beta helix sheet
• tertiary structure
  • folding and coiling by R group interaction
• quaternary structure
  • association of multiple polypeptide chains

• proteins that act as catalysts in chemical rxns
• increase rate of rxn by lowering the activation energy required

peptide bonds

1. result in the formation of a carbon-nitrogen backbone in polypeptides
2. are formed by dehydration synthesis
3. from between the amino groups and carboxl groups of adjacent amino acids in a polypeptide
4. can be severed by hydrolysis
5. all of the above

1. result in the formation of a carbon-nitrogen backbone in polypeptides
2. are formed by dehydration synthesis
3. from between the amino groups and carboxyl groups of adjacent amino acids in a polypeptide
4. can be severed by hydrolysis
5. all of the above

ATP

1. an energy transfer molecule because it contains high-energy phosphate bonds
2. as a catalyst because it lowers the activation energy for a rxn
3. as an information storage molecule because it contains a sequence of nucleotides
4. as an energy storage molecule because it contains long hydrocarbon chains
5. none of the above

1. an energy transfer molecule because it contains high-energy phosphate bonds
2. as a catalyst because it lowers the activation energy for a rxn
3. as an information storage molecule because it contains a sequence of nucleotides
4. as an energy storage molecule because it contains long hydrocarbon chains
5. none of the above

1. all living things composed of cells
2. cells are the basic structural/functional units of life
   • structure and function of organism are due to cellular activity
3. all cells derived from preexisting cells
   • cells from all species are similar in composition/function

• cytoplasm 
  • internal cellular fluid containing organelles and cytoskeleton
• cytoskeleton 
  • collection of protein filaments 
    • structural framework within the cytoplasm- gives shape and support
    • mobilizes cell and cellular contents
    • microfilaments
    • intermediate filaments
    • microtubules

• made of actin
• form plasma membrane skeleton
• located on cytoplasmic side of membrane

• made of tough proteins like keratin
• give structural support
• may attach cells to other cells

• made of tubulin
• structure of cilia, flagella and mitotic spindle
• serve as tracks for organelle movement

• forms boundary between interior of cell and external environment
• primarily composed of phospholipids
  • hydrophilic heads on exterior
  • hydrophobic tails on interior
• other membrane lipids
  • cholesterol- modulates membrane fluidity
  • glycolipids- phospholipids with short hydrocarbon chain
• membrane proteins
  • location
    • transmembrane- extend the entire width of membrane
    • peripheral- on either side of membrane
  • examples
    • receptors- bind to chem messengers
    • enzymes- break down chem messenger
    • ion channels- gated or always open, allow ions to pass into and out of cell
    • cell id markers- glycoprotein that distinguishes host cell from foreign
    • cell adhesion molecules- bind one cell to another

The plasma membrane includes proteins with short carbohydrate chains. These are called

1. glycoproteins
2. lipoproteins
3. peptidoglycans
4. glycolipids
5. carbolipids

1. glycoproteins
2. lipoproteins
3. peptidoglycans
4. glycolipids
5. carbolipids

• small extensions of plasma membrane
• increase surface area of cells to increase sensory/absorption
• well developed in 
  • kidney and intestine for absorption
  • taste buds and inner ear for sensory

• hair-like surface extensions
• non-motile cilia 
  • thought to be for sensory functions
  • one found in most cells
• motile cilia 
  • propel material in a particular direction using power and recovery strokes
  • well developed in the respiratory tract and fallopian tubes

• whiplike surface extensions/appendages that are identical to cilia structure, but longer
• propel cell in a particular direction in response to stimulus
• only located on sperm cells in humans

• movement of particles through a membrane via hydrostatic pressure
  • weight of water provides force, no energy required
• transfers water, salts and nutrients from bloodstream to tissue fluid

• simple diffusion
  • movement of solute down a concentration gradient from regions of high to low solute concentrations
  • passive transport- no energy required
• osmosis
  • special case of diffusion where a concentration gradient is present, but the solute is unable to pass through the membrane
  • movement of water down a concentration gradient from regions of low to high solute concentrations
  • passive transport- no energy required

• ability of a solution to affect fluid volume and pressure inside a cell
• hypotonic 
  • higher solute concentration inside cell than in solution
  • cell expansion
• isotonic
  • equal solute concentration inside cell and solution
  • cell remains stable
• hypertonic
  • higher solute concentration in solution than inside cell
  • cell implodes

• require transmembrane carrier proteins embedded in plasma membrane for transport
• facilitated diffusion
  • passive transport- no ATP required in addition to carrier
• active transport
  • requires ATP in addition to carrier

• facilitates bulk movement of materials in or out of a cell
• endocytosis
  • phagocytosis- cell engulfs particles such as dust, debris, bacteria
  • pinocytosis- cell takes in droplets of extracellular fluid
  • receptor-mediated- involves binding to selective receptor proteins.  
• exocytosis
  • secretory vesicles containing outgoing materials form fusion pores with plasma membrane to release contents

• nuclear envelope
  • a double membrane surrounding the nucleus
  • perforated by nuclear pores that allow material transport
• chromatin
  • substance inside nucleus consisting of DNA and protein
• nucleoli
  • sites of ribosome production that may occur singly or in multiples inside the nucleus

• consists of interconnected, membrane-bound cisternae, or channels 
• RER
  • continuous with nuclear envelope
  • contain ribosomes 
  • synthesizes
    • phospholipids and proteins of the plasma membrane
    • proteins to be packaged and modified by other organelles
• SER
  • continuous with RER
  • synthesizes fatty acids and steroids
  • detoxifies alcohol and other drugs
  • stores calcium

• stack of cisternae
• modifies and packages proteins
• synthesizes carbohydrates

• membrane-bound vesicles containing digestive enzymes to break down material brought in via endocytosis
• can perform
  • autophagy- break down of worn-out organelles
  • autolysis- digestion of entire cell

Lysosomes and peroxisomes, which are membrane-bound sacs filled with enzymes, are usually produced and release by which of the following organelles?

1. golgi apparatus
2. ribosome
3. mitochondrion
4. centrosome
5. nucleus

1. golgi apparatus
2. ribosome
3. mitochondrion
4. centrosome
5. nucleus

• similar to lysosomes, but contain different digestive enzymes
  • catalase breaks down H₂O₂ molecules produces by oxidation rxns occurring in peroxisomes

• doubly-bound by membrane
• produces ATP from oxidized organic molecules
• cristae= folds
• matrix= space

The cellular process of translation occurs

1. inside the nucleus of the cell
2. only during the S phase of the cell cycle
3. at the ribosomes of the cell
4. only during mitosis
5. only in cells that secrete protein hormones

1. inside the nucleus of the cell transcription
2. only during the S phase of the cell cycle DNA replication 
3. at the ribosomes of the cell
4. only during mitosis
5. only in cells that secrete protein hormones

1. Gap phase 1- growth and normal metabolic roles
2. Synthesis- DNA replication
3. Gap phase 2- growth in prep for mitosis
4. Mitotic phase- PMATC

mitosis is

1. the synthesis of a protein using RNA as a template
2. the replication of a cell's DNA in preparation for division
3. the division of one cell into four cells for the production of eggs and sperm
4. the division of the nucleus of a cell into two identical nuclei

1. the synthesis of a protein using RNA as a template translation
2. the replication of a cell's DNA in preparation for division synthesis
3. the division of one cell into four cells for the production of eggs and sperm
4. the division of the nucleus of a cell into two identical nuclei

Cell junctions that form fluid-tight seals between adjacent cells are called

1. desmosomes
2. gap junctions
3. tight junctions
4. seal junctions

1. desmosomes give cells and tissues stability
2. gap junctions allow transfer of cytoplasmic material, communication
3. tight junctions
4. seal junctions 

• short, cylindrical arrangement of nine triplet microtubule groups
• centrosomes
  • pair of centrioles opposite and adjacent to one another
  • migrate to opposite poles during mitosis to form ends of mitotic spindle

• forms the coverings/linings of body
• has its own nerve supply but is avascular, requiring adjacent CT to supply nutrients and remove waste
• epithelial cells are:
  • specialized for material exchange 
  • arranged in continuous sheets
  • have little intercellular space
  • that have a free surface and basement membrane
• functions
  • controls transfer of substances in and out of body
  • protective surfaces resist abrasion- but require high rate of cell division for constant repair
  • secretory surfaces release cell products

• rapid material exchange via diffusion
• absorption
• secretion 
  • serous fluid
  • + propulsion of mucus
  • glandular products

The aveoli of the lungs, where gas exchange occurs, are lined with with ________ tissue because

1. this tough tissue resists abrasion
2. several layers of cells are necessary for absorption of oxygen
3. a thin surface facilitates diffusion
4. it contains many goblet cells for mucus secretion
5. all of the above

simple squamous epithelium

1. this tough tissue resists abrasion
2. several layers of cells are necessary for absorption of oxygen
3. a thin surface facilitates diffusion
4. it contains many goblet cells for mucus secretion
5. all of the above

• formed by the inward folding of epithelial tissue during development
• exocrine glands
  • external secretions
  • maintain connection to surface epithelium
• endocrine glands
  • internal secretions

• most abundant, widely distributed tissue
• highly vascular tissue, except cartilage
• widely spaced cells with a lot of extracellular matrix
• functions
  • binds, supports and strengthens other tissues (areolar)
  • protects and insulates internal organs (adipose)
  • compartmentalizes structures (cartilage, bone)
  • transport system (blood)
  • location of stored energy reserves (adipose)
  • source of immune response
• fibers
  • collagenous- resist stretching
  • reticular- sponge-like framework of lymphatic organs made of glycoprotein-coated collagen fibers
  • elastic- give elasticity

Fibroblasts can be found in

1. the epidermis
2. most types of CT
3. nervous tissue
4. two of the above
5. all of the above

1. the epidermis
2. most types of CT
3. nervous tissue
4. two of the above
5. all of the above

Tendons, which resist tensile stress in a single direction, are composed of ______ tissue

1. skeletal
2. areolar CT
3. dense irregular CT
4. elastic
5. dense regular CT

1. skeletal
2. areolar CT
3. dense irregular CT resists stretching in all directions 
4. elastic
5. dense regular CT

• consists of elongated muscle fibers that use ATP to generate force
• skeletal
  • striated and voluntary
  • body movements
  • posture
  • heat generation
• cardiac
  • striated and involuntary
  • found in cardiac walls
  • pumps blood from heart to all parts of body
• smooth
  • nonstriated and involuntary
  • found in blood vessel walls, airways, stomach, intestines, gall bladder and urinary bladder
  • breaks down and moves food through digestive tract
  • constricts blood vessels
  • eliminates wastes

• consists of neurons and neuroglia
  • neuron components: body, dendrite, axon
• functions to
  • sense stimuli
  • convert stimuli into nerve impulses
  • conduct nerve impulses to other neurons. muscle fibers or glands

• parenchyma
  • functional cells of organs
  • regenerate tissue to near-perfect reconstruction
• stroma
  • connective tissue forming the structural framework of organs
  • repair by stroma results in fibrosis, impaired scar tissue

• cell types
  • stem cells- give rise to keratinocytes
  • keratinocytes- 90% of epidermis that produces a lipid-rich sealant to prevent water loss
  • melanocytes- produce pigments eumelanin and pheomelanin
  • dendritic (Langerhans)- macrophages originating from bone marrow that signal other immune cells of invader presence
  • tactile (Merkel)- each associated with a sensory neuron to detect touch
• strata
  • basale 
    • single layer on basement membrane
    • contains keratinocytes, melanocytes and Merkel cells
    • mitosis for continuous keratinocyte regeneration
  • spinosum
    • abundant in desmosomes, giving strength and flexibility
    • keratinocytes produce more keratin
  • granulosum
    • produce lipid-rich secretion to repel water
    • cells undergo apoptosis
  • lucidum
  • corneum

The stratum of the epidermis that contains stem cells undergoing mitosis is the

1. stratum corneum 
2. stratum lucidum
3. stratum granulosum
4. stratum spinosum
5. stratum basale

1. stratum corneum 
2. stratum lucidum
3. stratum granulosum
4. stratum spinosum
5. stratum basale

In what stratum of the epidermis are the keratinocytes undergoing apoptosis?

1. basale
2. spinosum
3. granulosum
4. lucidum
5. corneum

1. basale
2. spinosum
3. granulosum
4. lucidum
5. corneum

• single layer on basement membrane
• contains keratinocytes, melanocytes and Merkel cells
• mitosis for continuous keratinocyte regeneration

• abundant in desmosomes, giving strength and flexibility
• keratinocytes produce more keratin

• produce lipid-rich secretion to repel water
• cells undergo apoptosis

• only in thick skin
• a few layers of flattened, clear, dead keratinocytes
• contains a lot of keratin

• many layers of flattened, dead keratinocytes
• continuously shed and replaced
• serves as a water barrier and protectant of lower layers

• papillary layer
  • areolar CT
  • dermal papillae- projections into epidermis = ridges of fingerprints
  • contains 
    • Meissner's corpuscles that recept touch
    • free nerve endings that recepts warmth, coolness, pain ect. 
• reticular layer
  • dense irregular CT
    • collagen and elastic fibers give skin extensibility and elasticity
  • contains 
    • hair follicles
    • sebaceous and sudoriferous glands

• adipose and areolar CT
• anchors skin to underlying tissue
• thermal insulator
• fat storage

• contribute to the variety of skin colors
  • melanin
    • produced in epidermis
    • dark skin = more melanin, not melanocytes
  • hemoglobin
    • blood in dermal capillaries causes pink coloration in fair skin
  • carotene
    • vitamin A precursor
    • stored in superficial layer of epidermis, dermis and hypodermis
    • large amount may cause orange coloration to the skin

• albanism
  • inherited inability to produce melanin causes pail skin, white hair and pink eyes
• vitiligo
  • patches of skin lose melanocytes and turn white, possible due to an autoimmune disorder
• jaundice
  • buildup of bilirubin causes yellowing of the skin and whites of eyes
  • often indicative of liver disease

• column of dead keratinized epidermal cells
• pili that function in
  • protection from injury and UV
  • reduction of heat loss
  • protection from foreign particles 
  • light touch reception 

nails

• clear, hard plates of dead keratinized epidermal cells
• function to grasp and manipulate objects
• consists of nail body, free edge and nail root

skin glands

• sebaceous
  • connected to hair follicles
  • keep hair from drying out and becoming brittle
  • prevents excess water evaporation
  • keeps skin pliable
  • inhibits bacterial growth
• sudoriferous
  • merocrine/eccrine
    • found on most areas of body
    • release watery, salty sweat through pores 
      • to regulate body temperature
      • in response to emotional stress
  • apocrine
    • found in axillae, groin, areolae and bearded region in males
    • release a viscous, milky sweat that produces an odor upon bacterial metabolism
      • active under stress and during sexual activity
• ceruminous

• modified sweat glands of external ear
• produce waxy secretion that mixes with sebum to form cerumen
  • acts as a barrier to foreign particles, organisms and water

• first degree
  • only epidermis
  • mild pain, redness
• second degree
  • epidermis and dermis
  • pain, redness, blistering, some loss of skin function
• third degree
  • epidermis, dermis and subcutaneous layer destroyed
  • most skin function lost
  • burn region numb due to destruction of sensory nerve endings
  • skin grafting may be required

• protection 
  • keratin protects against microbes, heat, abrasion and chemicals
  • lipids protect against dehydration
  • sebum is bactericidal
  • melanin protects against UV
  • Langerhans and macrophages provide immune response
• cutaneous sensations
  • receptors detect touch, pressure vibration, warmth, pain ect
• excretion and absorption
  • sweat allows excretion of salts, water, ammonia and urea
  • fat-soluble vitamins and many drugs can be absorbed
• vitamin D synthesis
  • UV rays activate vitamin D precursor, converted to calcitriol by liver and kidney enzymes

Which of the following are skin cells that have an immune function?

1. Merkel cells
2. dendritic cells
3. adipocytes
4. keratinocytes
5. melanocytes

1. Merkel cells detect touch sensations
2. dendritic cells = Langerhans yes!
3. adipocytes
4. keratinocytes
5. melanocytes

Which of the following skin cells act as sensory receptors, detecting touch sensations? 

1. fibroblasts
2. melanocytes
3. keratinocytes
4. Langerhans cells
5. Merkel cells

1. fibroblasts immuno role
2. melanocytes produce melanin
3. keratinocytes produce keratin
4. Langerhans cells immuno role
5. Merkel cells

Skin participates in the maintenance of homeostatic body temperature by

1. modulation of dermal blood flow
2. sweating
3. thickening in cold weather
4. 1 and 2
5. 2 and 3

1. modulation of dermal blood flow
2. sweating
3. thickening in cold weather
4. 1 and 2
5. 2 and 3

• support
• protection
• movement
• mineral homeostasis
• blood production
• triglyceride storage
• acid-base balance

• ECM of bone tissue is 25% water, 25% collagen fibers and 50% crystallized mineral salts
  • mineral salts Ca₃(PO₄)₂ and Ca(OH)₂ combine to form hydroxyapatite
  • calcification is the formation of crystals among collagen fibers i

• osteogenic cells
  • unspecialized stem cells
  • mitotic that give rise to other bone cells
  • found in endosteum, periosteum and central canals
• osteoblasts
  • synthesize organic portion of bone matrix (collagen fibers)
  • become osteocytes
• osteocytes
  • mature bone cells trapped in own matrix
  • reside in lacunae (cavities)
• osteoclasts
  • huge cells derived from WBCs
  • secrete lysosomal enzymes to break down bone matrix
  • found in endosteum

• embryonic and fetal
  • intramembranous ossification
    • mesenchyme (embryonic CT) arranges into membranous sheets in future bone location
    • mesenchymal cells differentiate into osteogenic cells then osteoblasts
    • osteoblasts secrete organic bone matrix, then become osteocytes 
    • calcium and other mineral deposits cause matrix to harden
  • endochondral ossification
    • mesenchymal cells cluster at site of future bone, then differentiate into chondroblasts
    • chondroblasts secrete produce a hylaline cartilage model
    • perichondrium develops and chondroblasts here lengthen and thicken the model 
    • nutrient artery stimulates differentiation of perichondrial cells to osteoblasts instead of chondroblasts
    • capillaries form primary ossification center that spreads towards ends of model
    • osteoclasts form medullary cavity
    • spongy bone forms from secondary ossification center in epiphyses
    • epiphyseal cartilage remains until adulthood
• infancy, childhood and adolescence
  • growth in length and thickness

Intramembranous ossification occurs in which of the following bones?

1. tibia
2. parietal bones of the skull
3. femur
4. 2 and 3
5. none of the above

1. tibia long= endochondral 
2. parietal bones of the skull
3. femur long= endochondral 
4. 2 and 3
5. none of the above

• bone constantly broken down by osteoclasts during the process resorption and reconstructed by osteoblasts during the process deposition
• factors influencing remodeling:
  • minerals calcium and phosphorus
  • vitamins A,C,D,K,B₁₂
  • hormones insulin, IGFS, hGH, sex hormones

• types of fractures:
  • open
  • closed
  • comminuted
  • greenstick
• for bone to heal properly, they must be in alignment via reduction
  • open reduction is by hand with skin intact
  • closed reduction is surgical, often with internal fixation devices
• stages of repair
  • hematoma formation
  • fibrocartilaginous callus formation
  • bony callus formation
  • bone remodeling

In a _______ fracture, the bone is broken into several small fragments.

1. compound
2. comminuted
3. Colles
4. greenstick
5. impacted

1. compound
2. comminuted
3. Colles
4. greenstick
5. impacted

• Calcitriol
  • a form of vitamin D that increases blood calcium by promoting
    • calcium absorption in the digestive tract
    • osteoclast activity
• parathyroid hormone 
• secreted by parathyroid gland and increases blood calcium by increasing
  • the number and activity of osteoclasts
  • calcium retention in kidneys
  • calcitriol production

• Calcitonin
  • secreted by thyroid gland and decreases blood calcium by
    • inhibiting osteoclast activity
    • accelerating bone deposition

Which of the following bone fractures carries an increased risk of infection?

1. impacted
2. greenstick
3. compound
4. comminuted
5. Pott

1. impacted
2. greenstick
3. compound
4. comminuted
5. Pott

_____ are bone cells that are not derived from osteogenic cells

1. osteoblasts
2. osteocytes
3. osteons
4. osteoclasts
5. lacunae

1. osteoblasts
2. osteocytes
3. osteons
4. osteoclasts
5. lacunae

What is the correct order of the organizing units of muscles from smallest to largest?

• produces body movements
• communication
• stabilizes body movements
• moves substances through the body

• produces body movements
• communication
• stabilizes body movements
• stores and moves substances through the body
• generates heat essential for enzyme function

• connective tissue organizes skeletal muscle and attaches it to other structures
  • each muscle fiber/cell is surrounded by areolar CT called the endomysium
  • muscle fibers are in groups called fascicles, which are surrounded by perimysium CT
  • entire muscle surrounded by epimysium CT
  • tendons are cords of dense regular CT continuous with epimysium
    • aponeuroses are broad sheet-like tendons

• responsiveness- voltage change in response to stimulus
• conductivity- spread of excitation across tissue
• contractility- shortening upon stimulation
• extensibility- cells stretchable
• elasticity- cells return to original length after stretching

bundles of protein filaments called myofilaments inside muscle fibers

• thick filaments
  • made of myosin
  • look like golf clubs
• thin filaments
  • made of actin
  • looks like beaded necklace
  • tropomyosin and troponin
• elastic filaments
• made of titin, a springy protein

• functional unit of muscle tissue
• arrangement of thick and thin filaments causing striations in skeletal muscle
• for muscle contraction, thin filaments attached to Z discs slide over thick filaments, shortening the sarcomere
• A bands are dark and contain thick filaments
• I bands are light and contain elastic filaments

• synapse- connection between nerve cell and target cell
  • neuromuscular junction- synapse between nerve cell and muscle fiber
• synaptic knob- swelling at ends of motor nerve branches
  • contain synaptic vesicles that store ACh
• motor end plate- depression in the sarcolemma where the synaptic knob rests
  • has junctional folds for increased surface area that and have ACh receptors
• synaptic cleft- space separating the nerve and muscle fibers
• Schwann cell- covers entire neuromuscular junction
• acetylcholine- neurotransmitter at neuromuscular junctions

1. ATP molecule attached to myosin head is hydrolyzed, releasing energy and extending the head
2. the extended myosin head binds to an actin filament, forming a crossbridge
3. the myosin head flexes, pulling the actin filament
4. another ATP binds, detaching the myosin from the actin filament

• when nerve signal stop, ACh is no longer released
• calsequestrin binds to calcium
• calcium dissociates from troponin
• tropopmyosin once again blocks actin binding sites
• calcium ions actively pumped into SR

• leakage channels- open and close randomly
• ligand-gated channels- open and close in response to a specific chemical stimulus
• mechanically-gated channels- open and close in response to mechanical stimulation (vibration, touch, pressure ect)
• voltage-gated channels- open and close in response to change in membrane potential

The thick filaments in a muscle fiber are made of a golf-club-shaped molecule called

1. myosin
2. actin
3. tropomyosin
4. troponin

before a muscle can contract, calcium must bind to

1. troponin
2. tropomyosin
3. casequestrin
4. actin
5. myosin head

1. troponin
2. tropomyosin
3. casequestrin
4. actin
5. myosin head

Smooth muscle cells

1. have sarcomeres like skeletal muscle
2. are under voluntary control
3. have thin filaments attached to protein masses called dense bodies
4. are found only in the heart

1. have sarcomeres like skeletal muscle
2. are under voluntary control
3. have thin filaments attached to protein masses called dense bodies
4. are found only in the heart

• processes incoming sensory information
• source of thought, emotions and memories
• origin of impulses that stimulate muscles to contract and glads to secrete

• somatic
  • sensory neurons that convey info from body to CNS
  • motor neurons conduct impulses to skeletal muscles
• autonomic
  • sympathetic and parasympathetic
• • sensory neurons that convey info from viscera to CNS
  • motor neurons that conduct impulses to smooth muscle, cardiac muscle and glands
• enteric
  • consists of enteric plexuses in GI tract
  • sensory neurons monitor chemical changes and stretching in walls of GI
  • motor neurons control contraction of GI smooth muscle and secretions

• produce decremental current as ions leak through leakage channels
• only spread over short distances
• spread rapidly
• may vary in strength
• can occur in dendrites of neurons

• sensory input from skin carried to CNS by spinal nerves
• dermatome
  •  region of skin providing input by a single pair of spinal nerves
  • dermatome locations can be useful in diagnostics and therapy

• fast, autonomic, unplanned sequence of actions that occurs in response to particular stimulus
• can be inborn or learned
• considered spinal or cranial, depending on location of integration

• pathway followed by nerve impulces that produce a reflex
  • sensory receptor- may be neuron or other sensory receptor
  • afferent neuron- carries the signal to CNS
  • integrating center- in the gray matter of the CNS
  • efferent neuron- carries the signal away from the CNS
  • effector- skeletal muscle in a somatic reflex

Which of the following are neuroglia that form myelin sheaths in the PNS

1. Schwann cells
2. oligodendrocytes
3. astrocytes
4. microglia
5. satellite cells

1. Schwann cells
2. oligodendrocytes
3. astrocytes
4. microglia
5. satellite cells

• is maintained by sodium potassium pumps
• is around -70 mV
• is maintained by the negatively charged species that cannot diffuse out of the cell
• results in the membrane being polarized at rest

• sensation is the conscious or subconscious awareness of changes in the internal or external environment
• impulses reaching spinal cord may be part of reflex arc
• impulses reaching brain stem may cause change in heart or respiratory rate
• impulses reaching cerebral cortex are consciously perceived
  • perception is the constant awareness and interpretation of sensations mainly controlled by cerebral cortex

• stimulation of receptor
• transduction of stimulus
• generation of nerve impulses
• integration of sensory output

• free nerve endings- bare dendrites of sensory neurons
• encapsulated nerve endings- dendrites enclose in a capsule of CT 
• separate cells- specialized cells that synapse with sensory neurons

• exteroreceptors
  •  located at or near body surface
  • detect stimuli from external environment
• interoreceptors
  • located in muscles, blood vessels, viscera, nervous system
  • detect stimuli from internal environment
• proprioceptors
  • located in muscles, tendons, joints, inner ear
  • provide information about body position and movement

• mechanoreceptors- sensitive to mechanical stimuli
• thermoreceptors- 
  • free nerve endings sensitive to temperature changes
  • cold receptors mostly in stratum basale
  • warm receptors mostly in dermis
• nociceptors 
  • sensitive to painful stimuli (intense thermal, mechanical or chemical stimuli)
  • found everywhere except brain
  • tissue injury or irritation releases chemicals like prostaglandins, kinins and potassium ions that stimulate nociceptors
• photoreceptos- sensitive to light
• chemoreceptors- sensitive to chemicals

• cutaneous sensations include tactile, thermal and pain sensations
• propioceptive sensations 
  • allow us to know where our head and limbs are
    • kinesthesia- the perception of body movement
    • weight discrimination- the ability to assess the weight of an object
  • propriceptors
    • muscle spindles
    • golgi endon organs
    • joint kinesthetic receptors

• touch
  • detected by meissner corpuscles, hair root plexuses, merkel discs, and ruffini corpuscles
• pressure
  • detected by meissner corpuscles, merkel discs and pacinian corpuscles. 
• vibration
  • detected by meissner (lower frequency) and pacinian (higher frequency)
• itch
  • stimulation of free nerve endings by certain chemicals
• tickle
  • stimulation of free nerve endings by someone other than yourself

• fast pain
  • perception very rapid
  • sharp or acute pain felt by needle puncture or knife cut to the skin, for example
• slow pain
  • perception may begin a second of more after stimulus
  • chronic, burning, aching or throbbing pain like toothache

• pathway from sensory receptor to primary somatosensory area of cerebral cortex consist of three neurons
  • first order neurons
    • conduct impulses from receptor to spinal cord or brain stem
  • second-order neurons
    • conduct impulses from spinal cord/brain stem to thalamus
  • third-order neurons
    • conduct impulses from thalamus to primary somatosensory area of cerebral cortex

• chemical sense, detected by chemoreceptors
• five tastes: salty, sweet, sour, bitter, umami
• olfaction influences gustation

• small protrusions on the tongue
  • vallate papillae
    • 100-300 taste buds
    • V-shaped row
    • back of tongue
  • fungiform papillae
    • ~5 taste buds
    • mushroom-shaped
    • scattered all over tongue
  • foliate papillae
    • along sides of tongue
    • only in early childhood
  • filiform papillae
    • no taste buds
    • have tactile receptors
    • all over tongue

• gustatory receptor cells
  • have microvilli called gustatory hairs, which are sites of taste transduction
• supporting cells
  • surround receptor cells
• basal cells
  • stem cells that give rise to supporting cells via mitosis

• tastant is dissolved in saliva to be detected
• stimulation of gustatory receptor produces receptor potential 
• this causes the release of a neurotransmitter at a synapse with a first-order sensory neuron. 
• induces an action potential in the sensory neuron

• salty 
  • sodium enters receptor cells through sodium channels,  depolarizing the membrane and releasing neurotransmitter
• sour
  • usually acidic, where the hydrogen ion enters hydrogen channels, depolarizing the membrane and releasing neurotransmitter
• other tastants
  • do not enter receptor cells
  • activate second-messenger systems causing release of neurotransmitter

• cranial nerves contain axons of neurons that innervate taste buds
  • facial nerve
    • serves anterior 2/3 of tongue
  • glossopharyngeal nerve
    • serves posterior 2/3 of tongue
  • vagus nerve
    • serves taste buds in throat and epiglottis
• impulses from cranial nerves sent to gustatory nucleus of the medulla
• from the medulla, impulses sent to limbic system, hypothalamus and thalamus
  • impulses that reach the thalamus are relayed to the primary gustatory area of the cerebral cortex and give rise to perception of taste

• threshold is the lowest concentration at which a chemical can be detected
• threshold from lowest to highest
  • bitter  
    • most poisons activate bitter receptors, likely an evolutionary adaptation
  • sour
  • salty 
  • sweet

• adaptation is a decreased sensitivity to a stimulus in the presence of continued exposure
  • can occur for a specific taste in 1-5 minutes
  • thought to be due to changes in taste receptors- processes in CNS also likely play a role

• olfaction is a chemical sense detected by chemoreceptors
• odorants are chemicals that stimulate olfactory receptors
• olfactory sensations propagate to limbic system like gustatory- can evoke strong emotional response

• olfactory epithelium is located in superior part of nasal cavity
• cell types:
  • olfactory receptors
    • firs-order neurons
    • have olfactory hairs that are sites of olfactory transduction
  • supporting cells
    • columnar epithelial cells
    • provide support and nourishment
  • basal cells
    • stem cells
    • give rise to new olfactory receptors

• odorant molecules bind to olfactory receptor proteins in receptor cell membranes
• binding initiates a second-messenger pathway
• leads to opening of sodium channels, depolarizing the membrane and producing a generator potential

• olfactory receptor axons extend through foramina in the cribiform plate of the ethmoid bone
  • form olfactory nerves that terminate in olfactory bulbs in brain
  • axons of olfactory bulb neurons form olfactory tract, some extend to primary olfactory area of cerebral cortex
  • from primary olfactory area, impulses are routed to other regions of brain
    • orbitofrontal- identify and discrimiate among odors and smell and taste are combined to give overall flavor
    • hippocampus and amygdala- memory and emotion
    • hypothalamus- major endocrine control center

• olfactory threshold is very low, meaning only a few molecules need to be present to be perceived
• adaptation begins rapidly in the first second, then progresses slowly
• complete adaptation to some odors can occur after a minute

• fibrous tunic
  • mostly sclera (white of eye)
  • cornea on the anterior aspect (covering the iris)
• vascular tunic
  • choroi
  • ciliary body
  • iris
• retina
  • pigmented layer
  • neural layer (beginning of visual pathway)

• pupil constriction
  • circular muscles of iris contract
  • bright light
  • parasympathetic
• pupil dilation
  • radial muscles of iris contract
  • dim light
  • sympathetic

• lens divides eyeball into two cavities
  • anterior cavity
    • anterior and posterior chambers divided by iris
    • filled with aqueous humor
  • vitreous chamber
    • lies between lens and retina
    • filled with jelly-like mass called vitreous body

• brian stem
• cerebellum
• diencephalon
• cerebrum

• medulla oblongata
  • heartbeat regulated by cardiovascular center
  • breathing rhythm adjusted in medullary rhythmicity area
  • reflexes such as vomiting, deglutition, sneezing, coughing and hiccuping
  • learning of new motor skills
  • sensory functions from gustatory nuclei, cochlear nuclei and vestibular nuclei
• pons
  • connect different parts of brain by conducting signals for voluntary movement from cerebrum to cerebellum
  • vestibular nuclei
  • pneumotaxic and apneustic areas control breathing
• midbrain
  • superior colliculi involved in eye movements for scanning and tracking
  • inferior colliculi involved in auditory pathway and startle reflex

• net-like arrangement of grey and white matter extending from brain stem
• sensory neurons in reticular activating system is involve in awaking from sleep
• motor neurons involved in regulation of posture and muscle tone

• relays sensory impulses bound for primary sensory areas of cortex
• transmits motor impulses from cerebellum to motor areas of cortex
• maintenance of consciousness

• control center of autonomic nervous system and endocrine system
• receives sensory impulses related to somatic and visceral senses and from vision, taste and smell receptors
• ANS control
• hormone production
• emotional and behavioral regulation
• eating and drinking
• body temperature
• circadian rhythms and sleep-wake cycle

• some are sensory, motor or mixed
• part of the PNS
• carry out sensory and motor impulses between brain and body