Lecture Exam Flashcards

Question

Calcium ion

Answer 1

Hardens bone and teeth • Muscle contraction • Exocytosis (including release of neurotransmitter • Blood clotting • Second messenger in hormonal stimulation of cells

Answer 2

Required for ATP production

Answer 3

Concentration determines pH of blood and other fluids of the body

Answer 4

Alters nerve cell responsiveness to stimulation Component of stomach acid (HCI) Chloride shift in erythrocytes

Answer 5

Conversion of COz gas to HCO; which is transported in the blood Buffering of pH in blood

Answer 6

As Ca2(PO4)2, it hardens bone and teeth Component of phospholipids (membranes) Component of nucleotides, including ATP and nucleic acids (DNA and RNA) Most common intracellular anion Intracellular buffer

Answer 7

Dissociation is the separation of ions that occurs when a solid ionic compound dissolves. This is a chemical change as chemical bonds are broken during dissociation. Nonionic compounds do not dissociate in water. Dissolution refers to the process of solute dissolving in solvent and it is a physical change.

Answer 8

• Transports. Substances are dissolved in water and moved throughout the body in water-based fluids (e.g., blood and lymph) • Lubricates. Water-based fluids located between body structures decrease friction (e.g., serous fluid between the heart and its sac, synovial fluid within joints • Cushions. The force of sudden body movements is absorbed by water-based fluids (e.g., cerebrospinal fluid surrounding the brain and spinal cord Excretes wastes. Unwanted substances are eliminated in the body dissolved in water -Temperature (specific heat and heat of vaporization)

Answer 9

Mixtures: Suspension- large solutes scatter light and settle if mixture is not in motion like blood Colloid- smaller solutes scatter light but do not settle like gelatin Solution- smallest solutes do not scatter light or settle like soda Emulsion: a polar and non polar substance form an emulsion when agitated

Answer 10

Lipids, carbohydrates, nucleic acids and proteins Lipids are not polymers Dehydration synthesis- dimer is formed hydrolysis- dimer is broken

Answer 11

Triglycerides- glycerol and three fatty acids Focus on energy storage in adipose and structural support Phospholipids- organic group, phosphate, glycerol, and two fatty acids Major component of cell membranes Steroids- progesterone, testosterone, bile salts, and cholesterol Component of plasma membranes and regulatory molecules released by endocrine glands Eicosanoids- 20 carbon lipid-based signaling molecules that play a unique role in innate immune responses. The multiple types of eicosanoids, such as prostaglandins (PGs) and leukotrienes (LTs), allow the innate immune cells to respond rapidly to bacterial invaders.

Answer 12

Carbohydrates Liver serves as glucose bank by storing glycogen and breaking down glycogen. Gluconeogenesis- liver forms glucose from non carbohydrate sources

Answer 13

Monosaccharides- Galalactose and fructose (six carbon sugars) Ribose and deoxyribose (five carbon sugars) Disaccharides- Sucrose, lactose, and maltose

Answer 14

Nitrogenous base, phosphate group, sugar OH in RNA H in DNA ATP- adenine nitrogenous base, triphosphate group, and ribose Nucleotide containing molecules: NAD+/FAD

Answer 15

Primary: linear sequence of amino acids joined by peptide bonds Secondary: structural patterns within a protein from hydrogen bonds formed between amino acids Tertiary: final 3 dimensional shape of a protein which contains repeating secondary structures like globular or fibrous Quaternary: molecule composed of two or more separate proteins l

Answer 16

Chemical energy: triglycerides/glucose/ATP Kinetic energy: electrical energy/mechanical energy/sound energy/radiant energy

Answer 17

First law: energy cannot be created or destroyed Second law: energy can turn to heat as it is transferred and entropy increases

Answer 18

Carbon dioxide + water <—> carbonic acid (CO3H2) <—> bicarbonate (CO3H-) + acid (H+)

Answer 19

Lactose the substrate binds to lactase creating induced fit. Bond is broken between glucose and galactose. Products (glucose and galactose) are released and enzyme is free to bind again

Answer 20

Glucose monomers the substrate binds to glycogen synthase creating induced fit. Bond is formed between glucose and glucose monomers. Products (glycogen) is released and enzyme is free to bind again

Answer 21

Increasing the concentration of the substrate increases the rate of reaction up to enzyme saturation

Answer 22

Protein is rigid at cooler temperatures. Body temperature is 37 C. Optimum temperature for enzyme is 40 C. At high temperatures, enzyme denatures as bonds break.

Answer 23

Product of one enzyme becomes the substrate for a different enzyme in the complex

Answer 24

Many metabolic pathways are regulated by negative feedback by a product

Answer 25

Occurs in cytosol Six carbon glucose molecule turns to two three carbon pyruvate molecule Metabolic pathway Energy molecules produced: 2 ATP and 2 NADH produced If no oxygen is present, lactate is produced to regenerate NAD+ to continue glycolysis

Answer 26

With the presence of oxygen in mitochondria Pyruvate becomes 2 Acetyl CoA and one CO2 per pyruvate Multienzyme complex Energy molecules produced: 1 NADH per pyruvate Pathway doesnt work if oxygen is not present

Answer 27

With the presence of oxygen in mitochondria 2 Acetyl CoA (from each glucose) become 2 CO2 and 1 CoA per one Acetyl CoA Metabolic pathway Energy molecules produced: 3 NADH, 1 ATP, 1 FADH per one Acetyl CoA Pathway doesnt work if oxygen is not present

Answer 28

1. Electrons transferred from NADH and FADH2 through electron carriers in cristae. O2 is the final electron acceptor 2. Energy of electrons falling is used by H+ pumps to move H+ up its concentration gradient from the matrix to the outer compartment 3. ATP synthase harnesses the kinetic energy of the H+ falling down its concentration gradient to bond P and ADP to make ATP

Answer 29

Pyruvate turns to lactate thanks to lactate dehydrogenase by changing NADH to NAD+ 1) cellular respiration processes requiring oxygen decrease, including the activity of the electron transport chain. Electrons remain with the NADH and FADH2 molecules and NADH and FADH2 accumulate. This is accompanied by decreased levels of NAD+ and FAD. 2) The cell becomes increasingly dependent upon glycolysis, a metabolic pathway that requires NAD+ to continue 3) Extended low-oxygen conditions ultimately result in the complete shutdown of glycolysis within the cell because of the lack of NAD+ 4) NAD+ must be regenerated if glycolysis is to continue.

Answer 30

Entry point for 1) Fatty acids > They enter at the citric acid cycle 2) Amino acids: > Depends on specific type of amino acid. some enter at glycolysis, the intermediate stage, or the citric acid cycle.

Answer 31

A cofactor is a non- protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes. Cofactors can be considered “helper molecules” that assist in biochemical transformations but do not bind to enzyme

Answer 32

a) ATP formation (Endergonic reaction) > The high-energy chemical bond of ATP is formed by a dehydration reaction between ADP and P1. Energy is required and is supplied by the energy-releasing oxidation of fuel molecules. b) Splitting ATP (Exergonic reaction) > The high-energy chemical bond of ATP is split by hydrolysis to form ADP and P1

Answer 33

Metabolic pathway > composed of numerous enzymes to convert a specific substrate to the final product. > The product of one enzyme is the substrate for next enzyme in the pathway. > Metabolic pathways can be regulated by negative feedback that involved a product that serves as an allosteric inhibitor binding to an enzyme early in the pathway. Multienzyme complex: > physically attached to each other through noncovalent bond to form the complex > these attached enzymes work in a sequence of reactions > 2 major advantages: - the product from one chemical reaction is immediately bound to the next enzyme in the multienzyme complex. - the enzymatic pathway can be regulated by controlling the single complex rather than multiple individual enzymes. Explain the role of negative feedback in enzyme regulation

Answer 34

Plasma Membrane: Barrier separating the cytoplasm from the interstitial fluid. Nucleus: Cellular structure housing DNA or a group of cell bodies in the central nervous system. Cytoplasm: All cellular contents contained between the plasma membrane and the nucleus; includes cytosol, organelles, and inclusions.

Answer 35

Membrane-bound: Enclosed within a membrane. The membrane separates the organelle's contents from the cytosol so that the specific activities of the organelle can proceed without disruption from other cellular activities. Membrane-bound organelles include the endoplasmic reticulum (rough and smooth), Golgi apparatus, lysosomes, peroxisomes, and mitochondria Non-membrane-bound: Not enclosed within a membrane. These structures are generally composed of protein and include ribosomes (either free within the cytosol or attached [bound] to the external surface of the endoplasmic reticulum), the centrosome, proteasome, and the cytoskeleton. Cell inclusions are not considered organelles, but rather are aggregates (clusters) of a single type of molecule.

Answer 36

Maintain integrity and shape of a cell, obtain nutrients and form chemical building blocks, and dispose of wastes.

Answer 37

Physical barrier: Establishes a flexible boundary, protects cellular contents, and supports cell structure. Phospholipid bilayer separates substances inside and outside the cell. 2. Selectively permeable boundary: Regulates entry and exit of ions, nutrients, and waste molecules through the plasma membrane. 3. Electrochemical gradients: Establishes and maintains an electrical charge difference across the plasma membrane. 4. Communication: Contains receptors that recognize and respond to molecular signals.

Answer 38

Phospholipid: Lipid that forms bilayers of the plasma membrane. Cholesterol: Type of steroid found in the plasma membrane. Glycolipids: Lipid with an attached carbohydrate.

Answer 39

Integral proteins: Embedded within, and extend completely across, the phospholipid bilayer. Many integral membrane proteins are glycoproteins, which are proteins with attached carbohydrate groups. These carbohydrates (like those of glycolipids) extend like "sugar antennac" from a cell's external surface. These molecules contribute to the glycocalyx. Peripheral proteins: Not embedded within the lipid bilayer. They are attached loosely to either the external or the internal surfaces of the membrane and are often "anchored" to the exposed parts of an integral protein.

Answer 40

Transport proteins: Provide a means of regulating the movement of substances across the plasma membrane. Cell surface receptors: Bind specific molecules called ligands. Identity markers: Communicate to other cells that they belong to the body. Enzymes: May be attached to either the internal or the external surface of a cell for catalyzing chemical reactions. Anchoring: Sites secure the cytoskeleton (the internal, protein support of a cell) to the plasma membrane. Cell-adhesion proteins: Are for cell-to-cell attachments.

Answer 41

Passive processes: Do not require expenditure of cellular energy Substances move down their concentration gradient Active processes: Require expenditure of cellular energy. Involve either the movement of a substance up its concentration gradient or the formation or loss of a vesicle

Answer 42

Movement of solutes Involves concentration gradient, spreading out, and equilibrium Diffusion is the movement of either ions (e.g. Na+) or molecules (e.g., glucose) down their concentration gradient. Diffusion occurs due to the kinetic energy of the ions or molecules.

Answer 43

Simple Diffusion: Molecules that are small and nonpolar move into or out of a cell down their concentration gradient by simple diffusion. These molecules move unassisted across the plasma membrane (i.e., they do not require a transport protein). Facilitated Diffusion: Small solutes that are charged ions or polar molecules are effectively blocked from passing through the plasma membrane by the nonpolar phospholipid bilayer. Their transport either into or out of the cell, down their concentration gradient, must be assisted by plasma membrane proteins in a process called facilitated diffusion. Two types of facilitated diffusion-channel-mediated diffusion and carrier-mediated diffusion

Answer 44

Carrier-Mediated Diffusion: Carrier proteins change shape to transport small, polar molecules across the plasma membrane (glucose carrier protein) Channel-Mediated Diffusion: lons move down their concentration gradient through water-filled channels. Leak channels: always open Gated channels: protein required to open

Answer 45

Permeable to water Non-permeable (Charged. polar. large) Hydrophilic polar heads Hydrophobic non polar tails

Answer 46

Osmosis: (os-mô'sis; osmos = a thrusting) is the passive movement of water through a semipermeable (or selectively permeable) membrane. This movement occurs in response to a difference in relative concentration of water on either side of a membrane. Osmotic Pressure: The pressure exerted by the movement of water across a semipermeable membrane due to a difference in water concentration. The steeper the gradient, the greater the amount of water moved by osmosis and the higher the osmotic pressure.

Answer 47

When water crosses the plasma membrane of a cell by osmosis, the cell either gains or loses water with an accompanying change in the cell's volume. The ability of a solution to change the volume or pressure (sometimes called the tone) of the cell by osmosis is called tonicity. hypotonic: water enters the cell because solute concentration higher inside hypertonic: water leaves the cell because solute concentration higher outside

Answer 48

Primary active transport: Uses energy derived directly from the breakdown of ATP. This breakdown also provides the phosphate group that is added to the membrane transport pump, resulting in a change in the protein's shape and the subsequent movement of a solute across the membrane such as sodium potassium pump Secondary active transport: Also called cotransport, or coupled transport, secondary active transport involves the movement of a substance (e.g., Na+) down its concentration gradient to provide the energy to move a different substance (e.g., glucose, H*) up its concentration gradient like symport/antiport.

Answer 49

Exocytosis: The means by which either large substances or large amounts of substances are secreted from the cell. Vesicle comes close to plasma membrane, fuses with membrane, membrane opens up and vesicle releases toxins into interstitial fluid Endocytosis: The cellular uptake of either large substances or large amounts of substances from the external environment into the cell. Phagocytosis (cellular eating), pinocytosis (cellular drinking), receptor-mediated endocytosis (uses receptors on the plasma membrane to bind specific molecules within the interstitial fluid, bringing molecules into the cell)

Answer 50

Resting Membrane Potential (RMP): The membrane potential when a cell is at rest is more specifically called the resting membrane potential (RMP). Two cellular conditions are significant in establishing and maintaining an RMP.

Answer 51

First, a cell has an unequal distribution of ions and charged molecules across the plasma membrane. Second, the relative amounts of positive and negative charges are not equally distributed at the plasma membrane. K+: Potassium (K) diffusion is the most important factor in establishing the specific value of the RMP. Movement of K+ is dependent upon its electrochemical gradient. Na+: Sodium (Na+) diffusion into cells occurs simultaneously to the loss of K+ from the cell, and it is dependent upon its electrochemical gradient. Sodium ions enter the cell through Na+ leak channels moving down their chemical concentration gradient from the interstitial fluid into the cytosol.

Answer 52

cell-cell recognition: animal cells can interact through physical contact with the molecules protruding from their surfaces

Answer 53

Channel-linked receptors: (or chemically gated channels) Permit ion passage either into or out of a cell in response to ligand binding. Enzymatic receptors: Function as protein kinase enzymes and are activated to directly phosphorylate (add a phosphate to) other enzymes within the cell. * G protein-coupled receptors: Also involve protein kinase activation; note that these protein kinase enzymes are activated indirectly through the G protein that serves as an intermediate molecule.

Answer 54

Lysosomes: Small, membranous sacs/ Contain digestive enzymes formed by Golgi/ Participate in digestion of unneeded substances/ Digest contents of endocytosed vesicles Peroxisomes: Membrane-enclosed sacs/ smaller than lysosomes/ Pinched off vesicles from rough ER/ Proteins are incorporated to serve as their enzymes/ Metabolic functions include * Role in chemical digestion * Beta oxidation * Lipid synthesis

Answer 55

Ribosomes: Protein synthesis: 1. Bound ribosomes synthesize proteins destined to be incorporated into the plasma membrane, exported from the cell, or housed within lysosomes. 2. Free ribosomes synthesize proteins for use within the cell. Functions of Centrosomes 1. Synthesis: Organize microtubules (proteins of cytoskeleton) and support their growth in nondividing cells 2. Cell division: Direct formation of spindle fibers in dividing cells Functions of Proteasomes 1. Protein digestion: Degrade proteins that are damaged, incorrectly folded, or no longer needed 2. Quality assurance: Control the quality of exported cell proteins Functions of Cytoskeleton 1. Structural support and organization of cell: Maintain cell shape and organize organelles (all cytoskeleton proteins) Provide internal support to plasma membrane and microvilli (microfilaments) Stabilize desmosome cell junctions (intermediate filaments) 2. Cell division: Separate chromosomes during cell division (microtubules) Split cell into two daughter cells by cytokinesis (microfilaments) 3. Movement: Facilitate cytoplasmic streaming (microfilaments) Serve as track for movement of organelles and vesicles (microtubules) Participate in muscle contraction (microfilaments) Contractile proteins of cilia and flagella (microtubules)

Answer 56

Microvilli are thin, microscopic projections. They extend from the surface of the plasma membrane and are supported by microfilaments. Microvilli function to increase the surface area of the plasma membrane for more efficient membrane transport. Cilia contain supportive microtubule proteins and are enclosed by the plasma membrane. Cilia are usually found in large numbers on the exposed surfaces of specific cells such as those that line portions of the respiratory passageways . The beating of these cilia moves mucus and any adherent substances along the cell surface toward the throat, where it may then be expelled from the respiratory system. Flagella are similar to cilia in basic structure—however, they are longer and wider (50 μm in length and about 0.5 μm in width), and when present, there is usually only one. The function of a flagellum is to help propel an entire cell.

Answer 57

Cell junction: The intercellular connectivity in between the plasma membranes of adjacent cells of animal tissue is cell junction. These are formed by a complex of multi proteins. Types: Tight junction: This junction is between the cells with tight stitches. Substances must pass through the epithelial cells, rather than between them. Small intestines contain tight junctions that prevent corrosive digestive enzymes that are within the lumen of the intestine from moving between cells and damaging internal body structures. Gap junction: This junction connects two adjacent cells of cytoplasm containing six membrane proteins (connexions). They provide a direct passageway for substances to travel between neighboring cells. Ions, glucose, amino acids, and other small solutes pass directly from the cytoplasm of one cell into the neighboring cell. They are found where the flow of ions between cells would allow for the spread of electrical activity, such as in cardiac muscle, coordinated activities such as beating of the cilia, or in neurons of the brain. Desmosomes junction: This junction is disc-shaped and found in the plasma membrane. They provide resistance to mechanical stress at a single point. Cells of tisues exposed to stress, such as the external layer of the skin and cardiac muscles contain desmosomes.

Answer 58

The nucleolus is a spherical structure found in the cell's nucleus whose primary function is to produce and assemble the cell's ribosomes. The nucleolus is also where ribosomal RNA genes are transcribed. The nuclear envelope separates the contents of the nucleus from the cytoplasm and provides the structural framework of the nucleus. It consists of two phospholipid bilayers: an outer membrane and an inner membrane.

Answer 59

Chromosomes are the structures made up of chromatin. Chromatin is the threads of DNA that get condensed to form chromosomes. Genes are the segments of DNA that code for proteins. Hence, each chromosome is made up of DNA and contains many genes because of segments of DNA. Each chromosome has multiple genes.

Answer 60

Transcription: Occurs within the nucleus by RNA polymerase. Pre-mRNA is formed from ribonucleotides using DNA as a template. Pre-mRNA is then processed to form mRNA prior to leaving the nucleus. Translation: Occurs at ribosomes following transcription; mRNA is read to direct tRNAs in adding amino acids; a protein molecule is formed.

Answer 61

Initiation: DNA is unwound by enzymes to expose a segment of a gene; RNA polymerase attaches to promoter region of the gene. Elongation: RNA polymerase assists with complementary base pairing of free ribonucleotides with exposed bases of the template strand of DNA. Hydrogen bonds form between bases of DNA and the newly forming RNA molecule; this process continues as RNA polymerase moves along the DNA strand. Termination: RNA polymerase reaches the terminal region of the gene; newly formed RNA strand is released from the DNA strand. Transcription Is complete and DNA finishes rewinding into a double helix.

Answer 62

Initiation: Small subunit, large subunit, and charged tRNA with UAC anticodon Elongation: anti codon of a charged tRNA complementary base-pairs with codon of mRNA in A site Ribosome shifts down one codon. Additional amino acids delivered by tRNA base pair with mRNA until a stop codon is reached. Termination: Release factor binds with stop codon of mRNA; newly made protein releases

Answer 63

mRNA (messenger RNA): it provides the template for protein synthesis during translation. tRNA (transfer RNA): it brings amino acids and reads the genetic code during translation. rRNA (ribosomal RNA): it plays a structural and catalytic role during translation.

Answer 64

Mitochondria: Oblong shaped organelles with double membrane/ Aerobic cellular respiration/ Complete digestion of fuel molecules to synthesize ATP Functions of Rough Endoplasmic Reticulum (Rough ER) 1. Synthesis: Synthesizes proteins for secretion, incorporation into the plasma membrane, and as enzymes within lysosomes 2. Processing molecules: Modifies proteins (e.g., adds carbohydrates to form glycoprotein, tags for shipping) and store proteins 3. Organelle formation: Helps form peroxisomes 4. Vesicle formation: Forms transport vesicles for shipping of proteins to Golgi apparatus Functions of Smooth Endoplasmic Reticulum (Smooth ER) 1. Synthesis: Site of lipid (e.g., steroid) synthesis 2. Processing molecules: Carbohydrate metabolism (e.g., glycogen synthesis) 3. Detoxification: Detoxifies drugs, alcohol, and poisons 4. Vesicle formation: Forms transport vesicles for shipping to Golgi apparatus Functions of Golgi Apparatus 1. Synthesis: Forms proteoglycans 2. Processing molecules: Modifies and stores protein (that was formed by rough ER) 3. Organelle formation: Synthesizes digestive enzymes for lvsosomes 4. Vesicle formation: Forms secretory vesicles for delivering components of the plasma membrane and releasing contents from the cell by exocytosis

Answer 65

epithelial tissue - polarity: has an apical surface which is exposed either to the external environment or to some internal body space. cellularity: composed almost entirely of tight packed cells. *Apical - free surface *Basal - under apical, surface of basement membrane *Lateral surfaces - between apical and basal

Answer 66

*physical protection - from dehydration, abrasion, and destruction *selective permeability *secretions - glands *sensation - sensory nerve endings that detect change

Answer 67

*endocrine glands - lack ducks and secrete their products called hormones directly into the blood Ex: thyroid and adrenal gland *exocrine glands - typically originate from and invagination of epithelium that burrows into the deeper connective tissue, secrete into the epithelial tissue my means of a duct Ex: sweat gland, mammary glands, and salivary glands

Answer 68

APOCRINE * Apical membrane pinches off and becomes secretion * For example mammary and ceruminous glands MEROCRINE Package secretions into vesicles, released by exocytosis * For example Lacrimal (tear) and salivary glands HOLOCRINE Ruptured cell becomes secretion like oil glands

Answer 69

ground substances, fibers, cells (Fibroblast/ Adipocytes/ Mesenchymal cells/ Fixed macrophages)

Answer 70

collagen fibers, reticular fibers, elastic fibers

Answer 71

Glycosaminoglycans, Glycoprotein, Proteoglycans,

Answer 72

Blood providing transport, Adipose providing energy storage, Bones providing mineral storage, Tendons connecting muscles to bones

Answer 73

MESENCHYME Structure Mesenchymal cells are stellate or spindle-shaped; ground substance is a viscous fluid with some immature protein fibers Function Origin for all other connective tissue types Location Throughout the body of the embryo and fetus MUCOUS CONNECTIVE TISSUE Structure Mesenchymal cells are stellate or spindle-shaped; ground substance is a viscous fluid; immature protein fibers are more abundant here than in mesenchyme Function Support of structures in umbilical cord Location Umbilical cord of fetus

Answer 74

The major types of connective tissue are connective tissue proper, supportive tissue, and fluid tissue.

Answer 75

1. Skeletal muscle is associated with the bony skeleton, and consists of large cells that bear striations and are controlled voluntarily. 2. Cardiac muscle occurs only in the heart, and consists of small cells that are striated and under involuntary control. 3. Smooth muscle is found in the walls of hollow organs [visceral], and consists of small, elongated cells that are not striated and are under involuntary control.

Answer 76

Structure Contains neurons, which have a cell body, dendrites, and an axon that extend from the cell body; also contains glial cells, which lack the processes seen in neurons Function Neurons receive, process, and transmit nerve impulses, whereas glial cells help protect, nourish, and support neurons Location Brain, spinal cord, and nerves

Answer 77

An organ is a structure that is composed of two or more tissue types that work together to perform specific, complex functions. The key to organ structure is that the different tissue types must work in concert. Epithelial tissue Connective tissue Muscular tissue Nervous tissue

Answer 78

The largest body membrane is the cutaneous membrane, also known as the skin, which covers the external surface of the body. The cutaneous membrane is composed of a keratinized stratified squamous epithelium (called the epidermis) and an underlying layer of connective tissue (called the dermis). Its many functions include protecting internal organs and preventing water loss.

Answer 79

Some joints in the body are lined by a synovial membrane that is composed of a specialized type of connective tis- sue. The cells within this membrane secrete a synovial fluid that reduces friction among the moving bone parts and distributes nutrients to the cartilage on the articular surfaces of bone.

Answer 80

A mucous membrane, also called a mucosa, lines passageways and compartments that eventually open to the external environment; these include the digestive, respiratory, urinary, and reproductive tracts. Mucous membranes perform absorptive, protective, or secretory functions or a combination of these functions. A mucous membrane is formed by an epithelium and an underlying connective tissue called the lamina propria. Often, this membrane is covered with a layer of mucus derived from goblet cells, multicellular glands, or both

Answer 81

A serous membrane lines body cavities that typically do not open to the external environment and covers the external surface of many organs. The membrane is composed of a simple squamous epithelium called mesothelium. Serous membranes produce a thin, watery serous fluid, or transudate (trans = across, sudo = to sweat), which is derived from blood plasma. Serous membranes form two associated layers: a parietal layer that lines the inside of the body cavity and a visceral layer that covers the surface of the internal organs. Between these two layers is a serous cavity, which is a potential space into which the serous fluid is secreted. The serous fluid reduces the friction between their opposing surfaces. Examples of serous membranes include part of the pericardium (which is associated with the heart), the pleura (associated with the lungs), and the peritoneum (associated with abdominal organs)

Answer 82

Ectoderm is initially located on the dorsal and external surfaces of the embryo. It is responsible for forming many externally placed structures, such as the epidermis of the skin, hair, nails, and exocrine glands of the skin. Thus, some but not all epithelial tissues are derived from ectoderm. Tooth enamel, the lens of the eye, and the adrenal medulla are derived from ectoderm, as is all nervous tissue such as the brain, spinal cord, and nerves. Mesoderm is the middle primary germ layer. It forms all muscle tissue and both the epithelial lining of vessels and the serous mem- branes that line the body cavities. Mesoderm becomes mesenchyme, which then goes on to form all connective tissues in the body. The dermis of the skin, adrenal cortex, heart, spleen, kidneys and ureters, and internal reproductive organs are mesoderm-derived. Endoderm becomes the innermost germ layer when the embryo undergoes shape changes. It forms the epithelial linings of the tym- panic cavity (middle ear) and auditory tube, as well as the digestive, respiratory, reproductive, and urinary tracts. Endoderm also forms organs such as the thyroid gland, the parathyroid glands, the thymus, and portions of the palatine tonsils, as well as most of the liver, gall- bladder, and pancreas.

Answer 83

Hypertrophy refers to an increase in the size of the existing cells in a tissue, although the number of cells remains constant. For example, skeletal muscle cells may hypertrophy when a person undergoes a long-term rigorous exercise regimen. Hyperplasia is an increase in the number of cells in a tissue. Developing a “callus” on the palm of your hand is an example of these skin cells undergoing hyperplasia. Shrinkage of tissue by a decrease in either cell size or cell number is called atrophy. Atrophy may result from normal aging (senile atrophy) or from failure to use an organ or a tissue (disuse atrophy). Metaplasia may occur as an epithelium adapts to environmental conditions. For example, smokers typically experience metaplastic changes in the epithelium of the trachea. The smoke and its by-products are the environmental stressors that change the normal pseudostratified ciliated columnar epithelium lining the trachea to a nonkeratinized stratified squamous epithelium. Dysplasia refers to abnormal tissue development. For example, cervical dysplasia may develop when a woman is exposed to the human papillomavirus. Dysplasias have the potential to turn into cancer (and thus are sometimes described as precancerous), but they also have the potential to revert to normal tissue. When tissue growth proceeds out of control, a tumor composed of abnormal tissue develops, and the condition is called neoplasia. Neoplasms (tumors) may be benign or malignant. Necrosis is the term for tissue death. Necrosis typically occurs due to tissue damage that is not reversible, and an inflammatory response.

Lecture Exam Flashcards

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