BISC-225 TEST 2 Flashcards by Renee Glaser

Enzyme - pace of each reaction is controlled by a special type of protein

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metabolism - sum total of all reactions occurring within a cell

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anabolism - Larger molecules are constructed from smaller ones, requiring an input of energy

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anabolism provides all the substances required for cellular growth and repair.

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Dehydration synthesis is within Anabolism

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dehydration synthesis joins many simple sugar molecules to form larger molecules of glycogen.

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dehydration synthesis - an –OH ( hydroxyl group ) from one monosaccharide molecule and an-H ( hydrogen atom ) from a hydroxyl group of another monosaccharide are removed, forming a water molecule

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dehydration synthesis allows fat molecules and proteins to form.

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Dehydration synthesis - three hydrogen atoms are removed from a glycerol molecule, and an –OH group is removed from three fatty acid molecules to form a fat molecule

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Peptide bond or Dehydration synthesis - an –OH from one amino acid and an –H from the –NH2 of another amino acid are removed, resulting in a bond forming between a carbon atom and a nitrogen atom – this is a Peptide bond and holds the two amino acids together

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Catabolism - Larger molecules are broken down into smaller ones, releasing energy

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Hydrolysis - an example of catabolism in which a water molecule is used to split the large substances into two parts

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hydrolysis - reverse of dehydration synthesis

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Hydrolysis -requires the help of specific enzymes to occur

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Hydrolysis - disaccharides  monosaccharides; lipids  glycerol and fatty acids;proteins  amino acids; nucleic acids  nucleotides

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Enzymes - the reactions within cells include hundreds of very specific chemical changes that occur in a particular sequence
- the rates of these reactions are controlled

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Enzymes - Reactions require energy ( activation energy ) before they can proceed. The temperature within the cell is usually too mild to start these reactions – Enzymes
make the reactions possible.

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enzymes - usually globular proteins which function by lowering the activation energy required to start the reactions.

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enzymes - can speed up reactions by a factor of a million or more

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enzymes - very small quantities are needed since they are not consumed in the reaction

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each enzyme has specificity

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subtrate - each enzyme acts only on a particular substance

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catalase - found in peroxisomes of kidney and liver – has hydrogen peroxide as its substrate – breaks down H2O2 into water and oxygen

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different chemical reactions make up Cellular Metabolism with each reaction controlled by a specific enzyme.

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Chemical reactions make up metabolic pathways

hundreds of enzymes in each cell and each enzyme must be able to recognize its specific substrate

Enzyme molecule shape - identifying a substrate

the Enzyme Shape fits the special shape of its substrate molecule

Active sites of the enzyme temporarily combine with portions of substrate

Active sites - Interaction strains chemical bonds in substrate so that a particular reaction is more likely to occur - active sites

Active sites - the enzyme is released to its original form – able to bind another substrate

enzymes and substrate molecules - the speed of the reaction depends on the number

enzyme names are often derived from the substrate by adding –ase

lipase is lipid splitting enzyme

A regulatory enzyme often determines the rate at which a metabolic pathway functions.

regulatory enzyme often present in limited quantity – can become saturated when the substrate concentration exceeds a certain level

This rate-limiting enzyme is often the first enzyme in a series.

rate-limiting enzyme - often the product of a metabolic pathway inhibits this enzyme-negative feedback

cofactors and coenzymes are nonprotein components that are often necessary for an enzyme to work. They may help the active site reach an appropriate shape or help bind the enzyme to the substrate.

Cofactors may be the ion of an element, such as copper, iron, or zinc.

Coenzymes are small organic molecules – often composed of vitamin molecules or incorporate altered forms of vitamin molecules into their structures.

vitamins are essential organic substances that human cells cannot synthesize( or may not synthesize in sufficient quantities ) and therefore must come from the diet

Since enzymes are usually proteins, they can be denatured by heat, radiation, electricity, certain chemicals, and extreme pH values

ATP Molecules ( adenosine triphosphate )

Each ATP molecule consists of an adenine, a ribose, and three phosphates in a chain – the last phosphate attached by a high-energy bond

ATP molecule the chemical energy can be quickly transferred to another molecule in a metabolic reaction

An ATP that loses its terminal phosphate becomes ADP ( adenosine diphosphate ).

ATP can be resynthesized from an ADP by using energy released from cellular respiration to reattach a phosphate, a process called phosphorylation

The energy used in metabolic reactions is chemical energy which is held in the bonds that link atoms into molecules – energy is released when the bonds are broken.

Burning releases the chemical energy in these bonds as heat and light.

Cells “burn” glucose molecules in a process called oxidation to release energy used to promote cellular metabolism.

Burning in nonliving systems requires a relatively large amount of energy to begin, and most of the energy released escapes as heat and light.

In cells, where oxidation occurs, enzymes lower the activation energy needed to start the reactions, and cells capture almost half of the energy released by transferring it to special energy-carrying molecules.

the rest of the energy escapes as heat which helps maintains body temperature

Cellular respiration is the process that releases energy from molecules such as glucose and transfers it to other molecules.

cellular respiration the chemical reactions occur in a particular sequence, each one controlled by a different enzyme

some enzymes are in the cytosol, and others in the mitochondria

cellular respiration occurs in three distinct, yet interconnected series of reactions whose products include CO2, water, and energy

cellular respiration includes aerobic reactions and anaerobic reactions

Glycolysis ( “breaking of sugar” ) is a series of 10 enzyme-catalyzed reactions that break the 6-carbon glucose into two 3-carbon pyruvic acid molecules.

Glycolysis occurs in the cytosol

Glycolysis does not require oxygen

Glycolysis is the anaerobic phase of cellular respiration

Three main events: In Glycolysis a. glucose is phosphorylated by the addition of two phosphate groups – requires ATP – it “primes” the molecule for the rest of the steps b. the 6-carbon glucose is split into two 3-carbon molecules c. NADH is produced, ATP is synthesized, and two 3-carbon pyruvic acid molecules result. 1) hydrogen atoms are released and their electrons contain much of the energy in the original glucose molecule 2) the electrons are passed in pairs to molecules of the hydrogen carrier NAD+( nicotinamide adenine dinucleotide ): NAD+ + 2H  NADH + H+ 3) NADH delivers these high-energy electrons to the electron transport chain in the mitochondria, where most of the ATP will be synthesized

glycolysis - ATP is synthesized directly – substrate level phosphorylation.

Anaerobic Reactions - In the absence of oxygen ( which acts as the final electron acceptor ), NADH + H+ can give its electrons and hydrogens back to pyruvic acid in a reaction that forms lactic acid. This regenerates the NAD+ but the buildup of lactic acid eventually inhibits glycolysis and ATP production declines.

Aerobic Reactions - Aerobic pathways include the synthesis of acetyl coenzyme A, the citric acid cycle, and the electron transport chain – yielding water, carbon dioxide, and up to 36 ATP molecules.

Aerobic Reactions have three main events: formation of acetyl CoA, citric acid cycle, electron transport chain

FIRST: Formation of acetyl CoA 1) pyruvic acid moves into the mitochondrion 2) enzymes remove two hydrogen atoms, a carbon atom, and two oxygen atoms generating NADH and CO2, and leaving a 2-carbon acetic acid 3) the acetic acid combines with a molecule of coenzyme A to form acetyl CoA which carries the acetic acid into the citric acid cycle

SECOND: .citric acid cycle 1) begins when a 2-carbon acetyl CoA molecule combines with a 4-carbon oxaloacetic acid molecule to form the 6-carbon citric acid molecule a) CoA is released and can be used again to form acetyl CoA from pyruvic acid 2) the citric acid is changed through a series of reactions back to oxaloacetic acid 3) three important consequences of this cycle: a) one ATP is produced for each citric acid molecule that goes through cycle b) eight hydrogen atoms with high-energy electrons are transferred to NAD+and FAD ( flavine adenine dinucleotide ) for each citric acid molecule NAD+ + 2H  NADH + H+ FAD + 2H  FADH2 c) two carbon dioxide molecules are produced for each citric acid molecule

THIRD: electron transport chain 1) the high-energy electrons in NADH and FADH2 are handed off to the electron transport chain, which is a series of enzyme complexes that carry and pass electrons along from one to another a) on the folds of the inner mitochondrial membranes 2) the energy is transferred to ATP synthase, an enzyme complex that uses this energy to phosphorylate ADP to form ATP 3) these reactions are known as oxidation/reduction reactions 4) the final enzyme in the chain gives up a pair of electrons that combine with two hydrogen ions and an atom of oxygen to form a water molecule: 2 e- + 2 H+ + ½ O2  H2O a) thus oxygen is the final electron “carrier”

Carbohydrate Storage a. metabolic pathways are interconnected so that certain molecules are able to enter more than one pathway b. glucose molecules may enter catabolic pathways and used to supply energy or may enter anabolic pathways and be stored or be converted to nonessential amino acids c. excess glucose in cells can be linked together forming glycogen for storage – about 400 – 450 grams – ¼ in the liver, ¾ in skeletal muscles, small amount in cardiac muscle d. glucose can be converted to fat and stored in adipose tissue – if more carbohydrates are taken in than can be stored as glycogen or required for normal activities

Genetic Information passes to a child from its parents in the form of DNA.

Genetic Information DNA contains the information for construction of the proteins in the cells

gene ( about 20,325 of these ) -the portion of the DNA molecule containing the genetic information for making a particular protein

Genome - All of the DNA in a cell

exom is a small part of the genome encodes protein

nucleotides are the building blocks of nucleic acids (DNA, RNA)-a nucleotide consists of a 5-carbon sugar, phosphate group, and an organic, nitrogen-containing base. a. in DNA, the bases are adenine, thymine, guanine, and cytosine b. the DNA molecules form long strands (polynucleotide chains) by alternately joining their sugar and phosphate portions – providing a “backbone” to which the bases are attached c. DNA consists of 2 polynucleotide chains with the nitrogenous bases projecting from the backbone of one strand binding to the bases of the second strand 1) the two strands are antiparallel d. the bases pair in a particular manner, due to their shape – complementary base pairs 1) adenine pairs with thymine, guanine pairs with cytosine e. the sequence of bases in one of the strands encodes the information of a protein f. the double-stranded DNA molecule twists to form a double helix which may be several million base pairs long

DNA Replication 1. Each newly formed cell from mitosis must have an identical copy of DNA; therefore DNA must replicate, before mitosis can occur. This replication occurs during interphase. 2. Hydrogen bonds holding the two strands together break, the helix unwinds and pulls apart, exposing unpaired nucleotide bases. 3. DNA polymerase catalyzes the base pairing of new nucleotides to the exposed nucleotides of the strand. a. enzymes knit together the sugar-phosphate backbone 4. The resulting two DNA molecules are exactly like the original DNA molecule and during mitosis one DNA molecule goes to each new cell.

Genetic Code 1. Each of the twenty different amino acids in a polypeptide chain is represented in a DNA molecule by a triplet code, consisting of sequences of three nucleotides. a. e.g. CGA represents one kind of amino acid; GCA represents another amino acid 2. The sequence of nucleotides in a DNA molecule dictates the sequence of amino acids in a particular protein molecule. 3. DNA is in the nucleus and protein synthesis occurs in the cytoplasm – RNA is used to get the genetic information from the nucleus to the cytoplasm

RNA molecules have single stranded, have ribose sugar, and the bases are adenine, uracil, cytosine, and guanine.

Messenger RNA will carry the information from the nucleus to the cytoplasm and must be synthesized from the DNA strand.

Messenger RNA nucleotides form complementary base pairs with a section of the strand of DNA that encodes a particular protein – the strand of DNA must be “read” in the correct direction; and only one of the antiparallel strands contains the genetic information

an enzyme called RNA polymerase determines the correct DNA strand and the correct direction for RNA synthesis

the RNA polymerase binds to a promoter ( a region of DNA that begins a gene ) - this causes the DNA molecule to unwind at this region, exposing the gene

RNA polymerase moves along the strand, exposing more of the gene, while RNA nucleotides are binding complementarily to the DNA nucleotides forming a mRNA strand ( messenger RNA )

when the RNA polymerase reaches a termination signal ( a specific DNA base sequence ), the newly formed mRNA is released from the RNA polymerase and it leaves the DNA 1) the DNA rewinds

Transcription is process of copying DNA information into the structure of an mRNA molecule

translation is protein synthesis: the mRNA molecule leaves the nucleus through pores and enters the cytosol where it becomes associated with ribosomes and act as templates, or patterns, for synthesizing proteins

Codon is the complementary set of three nucleotides in the RNA molecule 1) there are 64 possible RNA base triplets encoding for twenty different amino acids more than one codon can specify the same amino acid

In Protein Synthesis the correct amino acids must be present in the cytoplasm and they must align in the proper sequence along a strand of mRNA in order to synthesize

transfer RNA is a type of RNA that aligns the amino acids along the mRNA

Transfer RNA consists of 70-80 nucleotides and has a complex 3-D shape – its two ends have unique shapes important for its “connector” function

One end of transfer RNA has a specific binding site for a particular amino acid – at least one tRNA molecule for each of the twenty amino acids – ATP provides the energy to form the bond between amino acid and tRNA

the other end of transfer RNA includes a region, called the anticodon

Anticodon contains three nucleotides in a particular sequence unique to that tRNA – the anticodon bonds only to a specific complementary codon of the mRNA

There are 64 different codons but 3 of these do not code for an amino acid, they are “stop” signals; signaling the end of protein synthesis. a. there are 61 different tRNAs, specific for the 61 codons – more than one type of tRNA can correspond to the same amino acid ( there are only 20 amino acids)

Binding of tRNA and mRNA occurs in close association with a ribosome.

ribosomes are small particles consisting of two subunits – composed of proteins and ribosomal RNA b. the smaller subunit binds to mRNA near a beginning codon and then tRNA brings its amino acid into position and temporarily joins to the ribosome 1) a second tRNA brings its amino acid and binds to mRNA – the first tRNA releases its amino acid, providing energy for a peptide bond to form between the two amino acids c. this process continues as the ribosome moves along the mRNA 1) a mRNA strand is usually associated with several ribosomes at the same time

Proteins called chaperones fold the developing protein into its unique shape – and when the process is completed, the protein is released from the mRNA into the cytoplasm as a functional molecule

ATP provides the energy for protein synthesis – 3 ATP molecules are required to link each amino acid to the growing chain.-

Proteins called transcription factors activate certain genes, thereby controlling which proteins a cell produces and how many copies form. a. extracellular signals such as hormones and growth factors activate transcription factors

Mutations are changes in the DNA – due to an error during replication or to some sort of damage.

Some mutations cause devastating medical conditions; others can be beneficial. a. up to 1% of individuals in some populations have mutations that render their cells unable to become infected with HIV

During mutation replication, a base may pair incorrectly with the newly forming strand, extra bases may be added, bases may be deleted, bases may move another region of the strand, or even move to another chromosome. a. all of these result in a changed DNA strand – the genetic information is changed 1) if a protein is constructed from this information, its molecular structure may be faulty and the function altered or absent b. e.g. sickle cell anemia 1) the change of one base leads to this disorder

cells detect the damage in their DNA molecules and use repair enzymes to clip out the defective nucleotides and fill the resulting gap with complementary bases – thus restoring the original structure of the DNA.

61 codons specify the 20 amino acids – therefore some amino acids are represented by more than one codon – usually the codons for the same amino acid differ only in the 3rd base of the codon

a mutation in the 3rd base, may result in a codon for the same amino acid 1) e.g. GGA and GGG each specify proline

if a mutation occurs in the 2nd base, the substituted amino acid is often very similar in structure as the normal one, and the protein may not be changed enough to affect its function

people have two copies of every chromosome, and therefore each gene. a. if one is mutated, the other may provide enough of the gene’s normal function so that this is not a harmful mutation

A mutation occurring in an adult cell may not be noticed because of all the normal cells surrounding it – in a developing embryo, the abnormal cell will give rise to many more abnormal cells and this can be very destructive

Mutations may occur spontaneously if a chemical quirk causes a base in an original DNA molecule to be in an unstable form just as replication occurs there.

mutagens are substances that cause mutations

ultraviolet radiation in sunlight can cause an extra chemical bond to form between thymines that are adjacent on a DNA strand – this bond causes a kink that can cause incorrect base insertions during replication 1) repair enzymes may fix the damage if its not too severe – but in cases of a sunburn, the cell dies because of too much damage, and skin peeling results

Inborn errors of metabolism are disorders resulting from inheriting a mutation that alters an enzyme.

the Metabolism enzyme blocks a biochemical pathway and has two general effects: 1) the substance the enzyme acts upon builds up 2) the substance resulting from the enzyme’s normal action becomes scarce b. these can drastically affect health 1) e.g. PKU

Degenerate is a genetic code that amino acids can be specified by more than one codon

ATP provides the energy to form the bond between amino acid and tRNA

DNA is in the nucleus and protein synthesis occurs in the cytoplasm

RNA is used to get the genetic information from the nucleus to the cytoplasm

The sequence of nucleotides in a DNA molecule dictates the sequence of amino acids in a particular protein molecule.

tissues are layers or groups of similar cells with a common function

intercellular Junctions – connect cell membranes to each other

tight junction – membranes of adjacent cells converge and fuse with the area of fusion surrounding the cells like a belt 1) e.g. lining the inside of digestive tract, linings of tiny blood vessels in brain

desmosomes – rivets or “spot welds” adjacent skin cells, forming a reinforced structural unit

gap junctions – these are tubular channels that allow ions, nutrients, and other small molecules to move between the cells 1) e.g. heart muscle and muscles of the digestive tract connected by these

EPITHELIAL TISSUES 1. Widespread throughout body. 2. Lines body cavities, covers organs. 3. Always have a free surface. The underside is anchored to connective tissue by a thin, nonliving layer called the basement membrane. 4. Generally lack blood vessels – nutrients diffuse from connective tissue. 5. Reproduce rapidly, so injuries heal quickly. 6. Tightly packed, with little intercellular material – form effective barriers. 7. Classified according to shape of cells and number of layers of cells: a. simple – one layer b. stratified – more than one layer c. squamous – thin, flattened cells. d. cuboidal – cells are cubelike e. columnar – cells are elongated – taller than wide 8. The free surface of epithelial cell are modified to reflect their specialized functions

EPITHELIAL TISSUES - Widespread throughout body.

EPITHELIAL TISSUES - Lines body cavities, covers organs.

EPITHELIAL TISSUES- Always have a free surface.

basement membrane - The underside of epithelial tissues is anchored to connective tissue by a thin, nonliving layer

EPITHELIAL TISSUES - Generally lack blood vessels – nutrients diffuse from connective tissue.

EPITHELIAL TISSUES - Reproduce rapidly, so injuries heal quickly.

EPITHELIAL TISSUES - Tightly packed, with little intercellular material – form effective barriers.

EPITHELIAL TISSUES - Classified according to shape of cells and number of layers of cells

epithelial tissues - simple – one layer

epithelial tissues - stratified – more than one layer

epithelial tissues - squamous – thin, flattened cells.

epithelial tissues - cuboidal – cells are cubelike

epithelial tissues - columnar – cells are elongated – taller than wide

EPITHELIAL TISSUES - The free surface of epithelial cell are modified to reflect their specialized functions

Simple Squamous Epithelium 1. Single layer of thin, flattened cells – fit tightly together like floor tiles; nuclei broad and thin. 2. Common at sites of diffusion and filtration – air sacs ( alveoli ) of the lungs, walls of capillaries, covers membranes that line body cavities. 3. Easily damaged because they are so thin.

Simple Cuboidal Epithelium 1. Single layer of cube-shaped cells with centrally located spherical nucleus. 2. Covers the ovaries, lines kidney tubules and ducts of certain glands ( pancreas, salivary glands, and liver ) – functions in secretion and absorption.

Simple Columnar Epithelium 1. Single layer of elongated cells with nuclei usually near the basement membrane. 2. Cells may be ciliated or nonciliated. a. cilia, which are 7-10 um in length, extend from the free surface of cells and move constantly 1) e.g. move egg cells through the oviducts to the uterus 3. Nonciliated epithelium lines the uterus and portions of the digestive tract. a. this tissue is thick, enabling it to protect underlying tissues b. cells of digestive tract secrete digestive fluids and absorb nutrients from digested food 4. Cells that are specialized for absorption often have many tiny, cylindrical processes extending from their surfaces. a. these processes are called microvilli and are from 0.5 to 1.0 um long – they increase the surface area of the cell membrane 5. Goblet cells are typically scattered among the cells of this tissue. They secrete a protective fluid called mucus onto the free surface of the tissue.

Simple Columnar Epithelium - Single layer of elongated cells with nuclei usually near the basement membrane.

Simple Columnar Epithelium - Cells may be ciliated or nonciliated.

Simple Columnar Epithelium - cilia, which are 7-10 um in length, extend from the free surface of cells and move constantly 1) e.g. move egg cells through the oviducts to the uterus

Simple Columnar Epithelium - Nonciliated epithelium lines the uterus and portions of the digestive tract.

Nonciliated epithelium - this tissue is thick, enabling it to protect underlying tissues

Nonciliated epithelium - cells of digestive tract secrete digestive fluids and absorb nutrients from digested food

Simple Columnar Epithelium Cells that are specialized for absorption often have many tiny, cylindrical processes extending from their surfaces.

microvilli - many tiny, cylindrical processes

microvilli are from 0.5 to 1.0 um long – they increase the surface area of the cell membrane

Goblet cells are typically scattered among the cells of Simple Columnar Epithelium tissue.

Goblet Cells secrete a protective fluid called mucus onto the free surface of the tissue.

Pseudostratified Columnar Epithelium - The cells appear stratified due to the nuclei being at different levels and the cells vary in shape – but it is only one layer.

Pseudostratified Columnar Epithelium - Often fringed with cilia. Goblet cells secrete mucus, which the cilia sweep away.

Pseudostratified Columnar Epithelium - lines passages of respiratory system – mucus traps dust and microorganisms that enter with air, cilia moves mucus and trapped particles upward and out of the airways

Stratified Squamous Epithelium - Several layers of cells – the outermost layers have flattened cells while the deeper layers, where cell division occurs

Stratified Squamous Epithelium - consist of cuboidal or columnar cells

The epidermis consists of Stratified Squamous Epithelium tissue

as the older Stratified Squamous Epithelium cells are pushed outward, they accumulate a protein called keratin, then harden and die

Stratified Squamous Epithelium produces a dry, tough, protective material that prevents water from escaping and blocks chemicals and microorganisms entering.

Stratified Squamous Epithelium lines oral cavity, throat, esophagus, vagina and anal canal. The tissue is not keratinized in these regions and the cells remain alive.

Stratified Cuboidal Epithelium - Consists of two or three layers of cuboidal cells that form the lining of a lumen.

Stratified Cuboidal Epithelium - Lines the ducts of mammary glands, sweat glands, salivary glands, and pancreas; also lining of developing ovarian follicles and seminiferous tubules.

Stratified Columnar Epithelium - Several layers of cells with the surface cells being elongated and the basal layers consisting of cube-shaped cells.

Stratified Columnar Epithelium - Found in the vas deferens, part of the male urethra, and in parts of pharynx

Transitional Epithelium - Specialized to change in response to increased tension.

Transitional Epithelium - Inner linings of urinary bladder, ureters, and part of urethra.

Transitional Epithelium - forms an expandable lining as these structures fill with urine – forms barriers so that the contents can’t diffuse back into internal environment

Glandular Epithelium - Cells specialized to produce or secrete substances

Glandular Epithelium - these cells usually found in cuboidal or columnar epithelium

Glandular Epithelium - one or more of these cells make up a gland

Endocrine glands - secrete their products into tissue fluid or blood.

Exocrine glands - secrete their products into ducts that open onto some internal or external surface.

Exocrine glands are unicellular glands and multicellular glands

unicellular gland – consists of a single epithelial cell – e.g. goblet cell

multicellular gland – consists of many cells

multicellular glands are simple glands and compound glands

simple gland – communicates with the surface by an unbranched duct

compound gland – has a branched duct

these simple gland and compound gland types may also be further classified as to the shapes of their secretory portions

simple and compound gland shapes of their secretory portions are tubular glands and tubular glands

tubular glands have epithelial-lined tubes

alveolar glands have saclike dilations at their terminal portion

coiling and branching of the tubular and alveolar glands

The Three step method of secretion are merocrine glands, apocrine glands, and holocrine glands in exocrine glands

merocrine glands – release fluid products by exocytosis 1) salivary glands, pancreatic glands, sweat glands 2) serous cells secrete watery fluids, usually has high concentration of enzymes-called serous fluid 3) mucous cells secrete a thicker fluid called mucus, a substance rich in the glycoprotein mucin

serous cells - secrete watery fluids, usually has high concentration of enzymes-called serous fluid

mucous cells - secrete a thicker fluid called mucus, a substance rich in the glycoprotein mucin

apocrine glands - lose small portions of their glandular cell bodies during secretion 1) mammary glands, ceruminous glands

holocrine glands - release entire cells during secretion – the cells then disintegrate, releasing their secretions 1) sebaceous glands of the skin

CONNECTIVE TISSUES - Most abundant tissue type by weight.

CONNECTIVE TISSUES - Bind structures, provide support and protection, serve as frameworks, fill spaces, store fat, produce blood cells, protect against infections, and help repair tissue damage.

CONNECTIVE TISSUES - Cells are further apart than epithelial tissue cells

CONNECTIVE TISSUES - have an abundance of intercellular material, or matrix, between them.

CONNECTIVE TISSUES - consists of proteins fibers and a ground substance whose consistency varies from fluid to semisolid to solid

CONNECTIVE TISSUES cells usually divide and most have a good blood supply and are well nourished

Fixed Cells - Fibroblasts and mast cells

Wandering Cells - macrophages

Fixed cells – usually present in stable numbers.

fibroblast - the most common – large, star-shaped cell; produces fibers by secreting protein into the matrix

mast cells - large and widely distributed, located near blood vessels

mast cells - release heparin, a compound that prevents blood clotting

mast cells - release histamine, a substance that is a vasodilator

Wandering cells – appear temporarily in tissues, usually in response to an injury or infection

macrophages = histiocytes – originate as white blood cells and are very numerous – usually attached to fibers but can detach and actively move about 1) specialized to carry on phagocytosis – function as scavenger cells that can remove foreign particles from tissues – important defense against infection

Collagenous fibers - thick threads of collagen ( the major structural protein of the body

Collagenous fibers - grouped in long, parallel bundles

Collagenous fibers - flexible, but only slightly elastic

Collagenous fibers - great tensile strength – can resist considerable pulling force

Collagenous fibers ligaments – connect bone to bone tendons – connect bone to muscle

dense connective tissue - contains abundant collagenous fibers and appears white – sometimes called white fibers

loose connective tissue has sparse collagenous fibers

Elastic fibers are composed of bundles of microfibrils embedded in a protein called elastin.

Elastic fibers - branch and form complex networks in various tissues

Elastic fibers - very elastic, not as strong as collagenous

Elastic fibers are in vocal cords, air passages of respiratory system

Elastic fibers - sometimes called yellow fibers

Reticular fibers - very thin collagenous fibers.

Reticular fibers - highly branched, forming delicate supporting networks in a variety of tissues

Loose Connective Tissue or Areolar Tissue - Forms delicate, thin membranes

Loose Connective Tissue or Areolar Tissue - Mainly fibroblasts widely scattered in a gel-like ground substance that contains many collagenous and elastic fibers that are secreted by the fibroblasts.

Loose Connective Tissue or Areolar Tissue - Binds skin to underlying organs and fills spaces between muscles.

Adipose Tissue or Fat - Adipocytes store fat droplets in cytoplasm

Adipose Tissue or Fat - Cushions joints and some organs ( kidneys )

Adipose Tissue or Fat - lies beneath skin forming insulating layer

Adipose Tissue or Fat - stores energy in fat molecules

Reticular Connective Tissue - Composed of thin, collagenous fibers in a three-dimensional network

Reticular Connective Tissue - Supports walls of certain internal organs, such as the liver, spleen, and lymphatic organs.

Dense Connective Tissue - Consists of many closely packed, thick, collagenous fibers, a fine network of elastic fibers, and a few cells.

Dense Connective Tissue - regular – fibers are very strong, binds body parts together, as parts of tendons and ligaments – poor blood supply, so tissue repair is slow

Dense Connective Tissue - irregular – thicker, interwoven, more randomly organized fibers – allows the tissue to sustain tension exerted from many different locations – found in the dermis

Elastic Connective Tissue - Consists of yellow, elastic fibers in parallel strands or in branching networks.

Elastic Connective Tissue - collagenous fibers and fibroblasts between these fibers

Elastic Connective Tissue - attachments between vertebrae ( ligamenta flava ), within the walls of some internal hollow organs such as larger arteries, some portions of heart, and the larger airways.

Cartilage - Rigid connective tissue that provides support, frameworks, attachments, protection of underlying tissues, and forms structural models for many developing bones.

Cartilage - Matrix composed of collagen fibers in gel-like ground substance rich in a protein-polysaccharide complex ( chondromucoprotein ) and contains a lot of water.

Chondrocytes ( cartilage cells ) - occupy lacunae, small chambers.

cartilage structure is enclosed in a covering called perichondrium

Cartilage - Lacks a direct blood supply, blood vessels are in perichondrium, so cells receive nutrients by diffusion

cartilage - heals slowly and chondrocytes do not divide frequently.

Three types of cartilage based on their different types of intercellular material: hyaline cartilage, elastic cartilage, fibrocartilage.

hyaline cartilage – most common type – very fine fibers in matrix, appears somewhat like white glass

hyaline cartilage - soft part of nose, supporting rings of respiratory system, on the ends of bones, parts of embryo’s skeleton begin as hyaline cartilage “models”

elastic cartilage – more flexible than hyaline because of the elastic fibers in matrix

elastic cartilage - framework for external ears and parts of the larynx

fibrocartilage – very tough, containing many collagenous fibers

fibrocartilage - shock absorber for structures subjected to pressure – intervertebral discs, pads in the knees, and between pelvic bones

Bone - Most rigid of connective tissues – its hardness due to calcium phosphate and calcium carbonate in its matrix. Large amount of collagen in matrix, these fibers flexibly reinforce the mineral components.

Bone - Supports body structures, protects organs in thoracic and cranial cavities, forms blood cells, attachment for muscles, stores inorganic salts.

Bone - Matrix deposited by osteocytes ( bone cells ) in thin layers called lamellae, which form concentric circles around capillaries located in central, or Haversian canals.

osteocytes are located in lacunae rather evenly spaced in lamellae

lamellae around an osteonic canal make up an osteon

osteon – many of these cemented together form the substance of bone.

Every bone cell is fairly close to a nutrient source, since each central canal contains a blood vessel.

bone cells have cytoplasmic extensions that extend outward and pass through canaliculi to receive nutrients

Blood - Composed of cells ( red blood cells, white blood cells, and cellular fragments called platelets ) that are suspended in a liquid matrix, plasma.

Most blood cells form in hematopoietic tissues located in red marrow.

Membranes - actually organs since they are composed of two or more kinds of tissues grouped together and performing specialized functions.

Epithelial Membranes are Serous, Mucous, and Cutaneous

Serous membranes - line the body cavities that lack openings to the outside and reduce friction between the organs and cavity walls.

Serous membranes - consist of a layer of simple squamous epithelium and a thin layer of connective tissue

Serous membranes - cells of the membrane secrete watery serous fluid, which helps lubricate the membrane surfaces

Mucous - membranes line the cavities and tubes that open to the outside.

Mucous - consist of epithelium overlying a layer of loose connective tissue 1) the type of epithelium varies with the location of membrane

goblet cells secrete mucus

Cutaneous membrane - an organ of the integumentary system – more commonly called skin.

Three Types of membranes are: Membranes, Epithelial Membranes, and Synovial Membranes

Synovial Membranes - Line joint cavities

Synovial Membranes - Cells secrete synovial fluid.

MUSCLE TISSUES - The cells are sometimes called muscle fibers.

MUSCLE TISSUES - The cells are contractile – can shorten and thicken; as they do so, they pull at their attached ends.

Three types of muscle tissue: Skeletal, Smooth, and Cardiac.

Skeletal Muscle Tissue - Forms muscles usually attached to bones.

Skeletal Muscle Tissue - Voluntary muscle – controlled by conscious effort.

Skeletal Muscle Tissue - Long, narrow cells – up to more than 40 mm in length and less than 0.1 mm wide.

Skeletal Muscle Tissue - Have striations – alternating dark and light bands.

Skeletal Muscle Tissue - Multinucleate.

Smooth Muscle Tissue - The cells lack striations.

Smooth Muscle Tissue - Cells shorter than skeletal muscle and are spindle-shaped.

Smooth Muscle Tissue - Single nucleus in each cell.

Smooth Muscle Tissue - Comprise the walls of hollow internal organs, such as the stomach, uterus, urinary bladder, intestines, and blood vessels.

Smooth Muscle Tissue - Involuntary actions.

Cardiac Muscle Tissue - Found only in the heart.

Cardiac Muscle Tissue - Striated cells, joined end to end – cells are branched and interconnected in complex networks.

Cardiac Muscle Tissue - Junctions are called intercalated discs.

Cardiac Muscle Tissue - Involuntary control – can continue to function without being stimulated by nervous tissue.

Cardiac Muscle Tissue - Single nucleus in cell.

Two types of nervous tissues: Neurons and Neuroglia

NERVOUS TISSUES - Found in brain, spinal cord, and peripheral nerves.

Neurons - These are the basic cells of nervous tissue.

Neurons - Among the more highly specialized body cells.

Neurons - Sense changes in surroundings and respond by transmitting nerve impulses.

Neurons - Can coordinate, regulate, and integrate many body functions.

Neuroglia - These are supporting cells of the nervous system.

Neuroglia - Support, bind, carry on phagocytosis, provide nutrients, communication.

organ - two or more types of tissues grouped together and performing specialized functions

Skin - Composed of several kinds of tissues – one of the larger and more versatile organs of the body.

Skin - Protective covering, retards water loss, helps regulate temperature, houses sensory receptors, contains cells of the immune system, synthesizes various chemicals, and excretes small quantities of waste.

Epidermis - Outer layer of skin composed of stratified squamous epithelium.

Epidermis - Lacks blood vessels – receives nourishment from the dermal blood vessels.

Cells of the stratum basale ( deepest layer of epidermal cells ) divide and grow – as they enlarge, they push the older epidermal cells away from the dermis – as the nutrient supply diminishes with distance, the cells die

Cell membranes of older cells ( keratinocytes ) thicken and develop desmosomes which fasten them to each other.

keratinocytes cells begin to harden, a process called keratinization

keratinization – strands of tough, fibrous, waterproof keratin proteins are synthesized and stored within the cell

many layers of tough, tightly packed dead keratinocytes (Epidermis) cells accumulate forming an outermost layer called the stratum corneum

keratinocytes (Epidermis) - dead cells are eventually shed

Structure of epidermis varies from region to region – thickest on palms and soles of feet ( 0.8 – 1.4 mm thick )

epidermis - usually four layers can be distinguished: Stratum basale, stratum spinosum, stratum granulosum, stratum corneum, and stratum lucidum

epidermis - stratum basale ( stratum germinativum or basal cell layer ) – the deepest layer

epidermis - stratum spinosum – a thick layer

epidermis - stratum granulosum – a granular layer

epidermis - stratum corneum – a fully keratinized layer ( horny layer )

epidermis - stratum lucidum -- found in the thickend skin of the palms and soles

Epidermis is usually very thin, averaging 0.07 – 0.12 mm thick.

Production of epidermal cells is closely balanced with loss of dead cells from the stratum corneum.

Epidermis - calluses form where the skin is rubbed or pressed regularly on palms or soles

Epidermis - corns are keratinized conical masses on the toes

Epidermis - in psoriasis, the epidermis divides seven times more frequently than normal; excess cells accumulate, forming bright red patches covered with silvery scales

Melanocytes - produce the dark pigment melanin that provides skin color.

melanin - absorbs light energy and helps protect deeper cells from UV radiation

melanin - lie in deepest portion of epidermis

melanin - transferred to other cells by cytocrine secretion

Melanin - all people have about the same number of melanocytes – skin differences arise because of different amounts of melanin produced.

Melanin - more eumelanin, darker skin

Melanin - single, large granules result in darker coloring

Melanin - lighter skin color results from clusters of two to four small granules

Melanin - albinism - results from the absence of melanin producing cells – usually due to inheriting a mutant melanin gene

Melanin - pheomelanin - a reddish-yellow pigment found in lips

Melanin - sunlight, UV from sunlamps, and x-rays stimulate melanocytes to produce more melanin, thus darkening the skin.

blood in dermal vessels adds color to the skin.

well-oxygenated blood – skin appears pinkish

cyanosis - low-oxygenated blood – skin appears bluish

dilated blood vessels - causes reddening of skin

constricted blood vessels - causes the skin to pale.

carotene - consumption of too many yellow vegetables may cause an accumulation of the this pigment in the subcutaneous layer of skin.

jaundice - liver malfunction is sometimes indicated by a yellowish skin tone

Dermis - The inner layer of skin – binds the epidermis to underlying tissues.

Dermis - dermal papillae - Boundary between epidermis and dermis is uneven

dermal papillae - these give us fingerprints

dermal papillae - no two people have the same fingerprints – variations form as a fetus presses the developing ridges against the uterine wall

Dermis - Composed of irregular dense connective tissue that includes collagen fibers and elastic fibers in a gel-like ground substance. About 1.0 – 2.0 mm thick. - only about 0.5 mm thick on eyelids; may be as much as 3.0 mm thick on soles

Dermis - Contains muscle fibers, nerve cell processes, sensory receptors, blood vessels, hair follicles, sebaceous glands, and sweat glands.

Subcutaneous Layer - Also called the hypodermis.

Subcutaneous Layer - Beneath the dermis, consists of loose connective and adipose tissues.

Subcutaneous Layer - The elastic and collagen fibers in this layer are continuous with those of the dermis.

Subcutaneous Layer - Adipose tissue insulates, helping to conserve body heat.

Subcutaneous Layer - Contains major blood vessels that supply the skin – branches of these vessels form a network ( rete cutaneum ) between the dermis and subcutaneous layer.

The Skin Tissue Layers are: Epidermis, Dermis, and Subcutaneous Layer

ACCESSORY STRUCTURES OF THE SKIN: Nails, Hair Follicles, and Skin Gland

Nails - Consist of a nail plate that overlies the nail bed.

Nails - Specialized epithelial cells that are continuous with the epithelium of the skin produce the nail bed.

Nails - lunula at the base of the nail plate is the most active growing region. - cells divide, and newly formed cells are keratinized – gives rise to tiny, keratinized scales that become part of nail plate, pushing it forward over the nail bed

Hair Follicles - tubelike depressions extending from the dermis to the skin surface.

Hair Follicles - hair root is the portion of hair embedded in skin

Hair Follicles - hair shaft extends from the surface of the skin.

Hair Follicles - group of epidermal cells in the base of the root divide and grow, pushing older cells toward the surface

Hair Follicles - these older Epidermal cells become keratinized and die as they move away from nutrient source

Hair Follicles - at any time, 90% of the hair is in the growth phase

Hair Follicles - a healthy person loses 20-100 hairs per day

Hair Follicles - a hair typically grows for 2-6 years

Hair Follicles and epidermal cells develop from the same types of stem cells.

Genes determine hair color by directing the type and amount of pigment that melanocytes produce.

eumelanin - dark hair has more melanin than blonde hair

white hair has no melanin

red hair contains pheomelanin

gray hair is a mixture of pigmented and unpigmented

bundle of smooth muscle cells form the arrector pili muscle

arrector pili muscle - attaches to each hair follicle.

arrector pili muscle - hair stands straight up when muscle contracts

Each hair follicle has one or more sebaceous glands associated with it.

SKIN GLANDS: Sebaceous glands, Sweat glands, eccrine sweat glands, apocrine sweat glands, ceruminous glands, and ceruminous glands

SWEAT GLANDS: eccrine sweat glands, and apocrine sweat glands

Sebaceous glands - are holocrine glands usually associated with hair follicles.

Sebaceous glands - produce sebum – a mixture of fatty material and cellular debris

Sebaceous glands - keeps hairs and skin soft, pliable, and waterproof

Sebaceous glands - not found on soles and palms

Sebaceous glands - found on lips, corners of the mouth, parts of external reproductive organs

Sweat glands - or sudoriferous glands, are widespread in the skin.

Sweat glands - consist of a tiny tube that originates as a ball-shaped coil in the deeper dermis 1) coiled portion is closed at its deep end and lined with sweat-secreting epithelial cells

Eccrine sweat glands - are the most numerous

Eccrine sweat glands – respond throughout life to increased body temperature

Eccrine sweat glands – are merocrine glands

Eccrine sweat glands - common on forehead, neck, and back

Eccrine sweat glands - cause moisture on palms and soles when a person is emotionally stressed

Eccrine sweat glands - sweat carried by a duct that opens at the surface as a pore a) sweat is mostly water; contains small amounts of salts and wastes, such as urea and uric acid

Eccrine sweat glands - mostly water; contains small amounts of salts and wastes, such as urea and uric acid

Apocrine sweat glands - are merocrine sweat glands (as are eccrine sweat glands)

Apocrine sweat glands - secretions produce an odor as they are metabolized by skin bacteria

Apocrine sweat glands - ducts open into hair follicles

Apocrine sweat glands - become active at puberty

Apocrine sweat glands - respond to emotional upsets, fright, or pain – also during sexual excitement

Ceruminous glands - are found in the external ear canal and secrete wax

Mammary glands - secrete milk

SKIN FUNCTIONS - Retards water loss

SKIN FUNCTIONS - Houses sensory receptors.

SKIN FUNCTIONS - Epidermal dendritic cells, also known as Langerhans cells, play a role in initiating an immune response by phagocytizing harmful microorganisms

SKIN FUNCTIONS - Excretes small quantities of wastes.

SKIN FUNCTIONS - Plays a role in production of vitamin D.

SKIN FUNCTIONS - Helps regulate body temperature

Regulation of Body Temperature - Heat is a product of cellular metabolism. Cardiac and skeletal muscle cells, and liver cells are the major producers

Regulation of Body Temperature - When body temperature rises above set point, nerve impulses stimulate structures in the skin and other organs to release heat.

Regulation of Body Temperature - temperature rises - dermal blood vessels dilate – more blood enters them and heat escapes to outside

Regulation of Body Temperature - temperature rises - deeper blood vessels constrict – diverting blood to the surface

Regulation of Body Temperature - temperature rises - heart beats faster, moving blood out of deep regions

For Types of Heat Loss: radiation, conduction, convection, and evaporation

Radiation - the primary means of body heat loss – infrared heat rays escape from warmer surfaces to cooler surroundings

Conduction – heat moves from the body directly into molecules of cooler objects in contact with its surface

Convection – losing heat to the moving air molecules that contact the body

Evaporation – eccrine sweat glands release fluid to surface of skin which then evaporates ( changes from a liquid to a gas ) carrying heat away from the surface

Heat Loss - When body temperature drops below the set point, the brain triggers a different set of responses in skin structures

Heat Loss - temperature drops - dermal blood vessels constrict, decreasing the flow to heat-carrying blood to the skin

Heat Loss - temperature drops - sweat glands remain inactive

Heat Loss - temperature drops - skeletal muscle cells may be stimulated to contract slightly - if this is not enough, small groups of muscles may contract rhythmically, causing the person to shiver, thus generating more heat

Problems in Temperature Regulation - On hot, humid days, the air may become saturated with water – the sweat glands may be activated, but the sweat cannot quickly evaporate.

Problems in Temperature Regulation - hyperthermia - the body temperature may rise

Problems in Temperature Regulation - if the air temperature exceeds the body temperature, the body may gain heat from the surroundings

Problems in Temperature Regulation - hypothermia -Prolonged exposure to the cold - begins with shivering and a feeling of coldness, may progress to mental confusion, lethargy, loss of reflexes and consciousness, and eventually, a shutting down of organs – fatal respiratory failure or heart arrhythmia may result if the body’s core temperature drops just a few degrees

Inflammation - This is a normal response to injury or stress

Inflammation - blood vessels dilate and become more permeable, allowing fluids to leak into damaged tissues

Inflammation - skin may become reddened, warm to the touch, and painful

Cuts - Shallow breaks in the skin stimulate the epithelial cells to rapidly divide and fill in the gap.

Cuts - Injury into the dermis or subcutaneous layers takes longer to heal.

Cuts - dermis or subcutaneous - blood vessels break and escaping blood forms a clot

Cuts - dermis or subcutaneous - tissue fluids and blood clot form a scab

Cuts - dermis or subcutaneous - fibroblasts begin forming new collagenous fibers that bind edges of wound

Cuts - dermis or subcutaneous - connective tissue matrix releases growth factors that stimulate certain cells to divide and regenerate the damaged tissue

Cuts - dermis or subcutaneous - blood vessels extend into area under scab

Cuts - dermis or subcutaneous - phagocytic cells remove dead cells and other debris

Cuts - dermis or subcutaneous - scab sloughs off – a scar may appear if the wound is extensive

Cuts - Granulation formation - may occur in the healing of large, open wounds. a. new branch of blood vessels and cluster of collagen-secreting fibroblasts

Three types of Burns: Superficial partial-thickness burn ( first degree ), Deep partial-thickness burn ( second degree ), and Full-thickness burn ( third degree )

Superficial partial-thickness burn ( first degree ) - a burn injuring only the epidermis – healing usually occurs within a few days to two weeks, with no scarring.

Deep partial-thickness burn ( second degree ) - a burn that destroys some epidermis as well as some dermis

Deep partial-thickness burn ( second degree ) - fluid escapes and forms blisters

Deep partial-thickness burn ( second degree ) - healing depends upon accessory organs that survive the injury – epithelial cells in these organs grow out onto the surface of the dermis, spread over it, and form a new epidermis – usually a complete recovery with no scarring ( unless an infection develops )

Full-thickness burn ( third degree ) - a burn that destroys the epidermis, dermis, and the accessory organs of the skin.

Full-thickness burn ( third degree ) - skin becomes dry and leathery, may vary in color from red to black to white

Full-thickness burn ( third degree ) - autograft - treatment may involve removing a thin layer of skin from unburned region of body and transplanting it to the injured area

Full-thickness burn ( third degree ) - allograft - a temporary covering from a cadaver, may be used if burn is too extensive

autografts and allografts can leave extensive scars

Full-thickness burn ( third degree ) - various skin substitutes may be used to temporarily cover extensive burns

Full-thickness burn ( third degree ) - skin substitutes - amniotic membrane and artificial membranes composed of silicone, polyurethane, or nylon together with a network of collagenous fibers

BISC-225 TEST 2 Flashcards

(445 cards)