Exam 1 Study Guide Flashcards
(49 cards)
How are anatomy and physiology complimentary?
Form dictates function
What are the levels of structural organization of the human body? Explain the hierarchy from the chemical level to the organismal level?
Chemical Level: composed of atoms that combine to form molecules. Molecules combine to form organelles.
Cellular Level is composed of many cells. Cells with similar functions combine to form tissues- epithelial, connective, muscle, and nervous.
Tissues combine to create organs, a discrete structure that carries out a specific function.
An organ must have at least 2 tissues; usually has all 4.
Organs work together to make up organ systems.
Organ systems make up the organism.
Define homeostasis. Identify the two organ systems that play the most important role in maintaining homeostasis. What is homeostatic control? Explain the process of homeostatic control and identify the main components of the control system.
Homeostasis is the maintenance of a stable internal environment despite a constantly changing external environment.
The two organ systems that play the largest role are the endocrine and nervous systems.
Control mechanisms of the body contain at least three elements that work together: receptor(s), control center, and effector(s).
Explain negative and positive feedback mechanisms. Provide examples of these negative and positive feedback mechanisms in the body. Identify which feedback mechanism functions in homeostatic control. Understand why negative and positive feedback mechanisms are important in the body.
Negative feedback mechanisms reduce the effect of the original stimulus, and are essential for maintaining homeostasis. Body temp, heart rate, BP, breathing rate and depth, and blood levels of glucose and certain ions are regulated by negative feedback mechanisms.
Positive feedback mechanisms intensify initial stimulus, leading to an enhancement of the response.
Rarely contribute to homeostasis, but blood clotting and labor contractions are regulated by such mechanisms.
May have only local effects. For example, blood clotting is accelerated in injured vessels, but does not normally spread to the entire circulation.
Why do we care about chemistry and biochemistry in anatomy and physiology?
Chemical reactions underlie all physiological processes—movement, digestion, the pumping of your heart, and even your thoughts.
What is an atom? Explain the structure of an atom and the two different models. What are the subatomic particles? What are their sizes, charges, and locations in the atom?
The planetary model of the atom is a simplified model of atomic structure depicting electrons moving around the nucleus in fixed, generally circular orbits. But we can never determine the exact location of electrons at a particular time because they jump around following unknown trajectories.
The orbital model is more useful for predicting the chemical behavior of atoms. Depicts probable regions of greatest electron density by denser shading (haze is called the electron cloud).
P+ = 1 amu N = 1 amu e- = 0 amu
What are the most common elements in the human body? What elements are present in sparse amounts?
Four elements—carbon, oxygen, hydrogen, and nitrogen—make up about 96% of body weight, and 20 others (calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium, iodine, iron, chromium, cobalt, copper, fluorine, manganese, molybdenum, selenium, silicon, tin, vanadium, zinc) are present in the body, some in trace amounts.
How do atoms interact? Explain the three types of bonds, being specific about the electron interactions occurring in those bonds. Give examples of where these bonds occur.
An ionic bond is formed by the transfer of one or more electrons from one atom to the other. The atom that gains one or more electrons is the electron acceptor. It acquires a net negative charge and is called an anion. The atom that loses electrons is the electron donor. It acquires a net positive charge and is called a cation.
Electron sharing produces molecules in which the shared electrons occupy a single orbital common to both atoms. Molecules formed are electrically balanced and are called nonpolar molecules (because they do not have separate and poles of charge).
A molecule’s shape helps determine what other molecules or atoms it can interact with. It may also result in unequal electron pair sharing, creating a polar molecule (dipole), especially in nonsymmetrical molecules containing atoms with different electron-attracting abilities.
Hydrogen bonds form when a hydrogen atom, already covalently linked to one electronegative atom (usually nitrogen or oxygen), is attracted by another electron-hungry atom, so that a “bridge” forms between them.
Although hydrogen bonds are too weak to bind atoms together to form molecules, they are important intramolecular bonds (literally, bonds within molecules), which hold different parts of a single large molecule in a specific three-dimensional shape. Some large biological molecules, such as proteins and DNA, have numerous hydrogen bonds that help maintain and stabilize their structures.
What are organic molecules? What are inorganic molecules?
Contain carbon and are made by living things. All organic compounds are covalently bonded molecules, and many are large.
All other chemicals in the body are considered inorganic compounds. These include water, salts, and many acids and bases. Inorganic compounds are generally defined as compounds that lack carbon.
Organic and inorganic compounds are equally essential for life.
What are macromolecules? What are the four groups of macromolecules we covered in class? What are their monomers? What are their polymers?
Macromolecules are large complex molecules containing thousands of atoms.
Most macromolecules are polymers,
which are chainlike molecules made of many smaller, identical or similar subunits (monomers) by dehydration synthesis.
Only two polysaccharides are of major importance to the body: starch and glycogen. Both are polymers of glucose. Only their degree of branching differs.
Electronegativity and electropositivity
In general, small atoms with 6 or 7 valence shell electrons, such as oxygen, nitrogen, and chlorine, are electron-hungry and attract electrons very strongly, a capability called electronegativity. On the other hand, most atoms with only one or two valence shell electrons tend to be electropositive. Their electron-attracting ability is so low that they usually lose their valence shell electrons to other atoms. Potassium and sodium with one valence shell electron, are good examples of electropositive atoms.
Dehydration Synthesis
Monomers are joined together by this.
a hydrogen atom is removed from one monomer and a hydroxyl group is removed from the monomer it is to be joined with. As a covalent bond unites the monomers, a water molecule is released. This removal of a water molecule at the bond site occurs each time a monomer is added to the growing polymer chain. The opposite reaction in which molecules are degraded is called hydrolysis
Hydrolysis
describes the chemical reactions involved in the digestion of proteins and carbohydrates in the small intestine
The reaction in which molecules are degraded is called hydrolysis (water splitting). In these reactions, a water molecule is added to each bond that is broken, thereby releasing its building blocks (smaller molecules).
cell cycle
The cell is rapidly growing during G1 of interphase. During the S phase of interphase, the cell continues to grow and DNA is replicated. In G2 of interphase, the cell is making final preparations to divide. In the mitotic phase (M phase) of the cell cycle, the cell divides to produce two daughter cells.
gene
a segment of DNA that carries instructions for the production of one polypeptide chain
Triglycerides
Consist of glycerol and three fatty acids.
Major form of stored energy in the body.
Fat deposits (in subcutaneous tissue and around organs) protect and insulate body organs.
Phospholipid
A phospholipid consists of a glycerol backbone with two fatty acids, a phosphate group, and a nitrogen-containing group.
What are enzymes? What macromolecule are enzymes? What is their function? What is their structure? What is their mechanism of action?
Enzymes are biological catalysts that regulate and accelerate biochemical reactions. Enzymes accelerate biochemical reactions by reducing the activation energy needed to form bonds between reactants. Importantly, enzymes have specificity - they can only accelerate specific biochemical reactions. Additionally, they are not used up. This means that they can accelerate one biochemical reaction right after another.
Enzymes and proteins in general rely on their structure. Without their structure, they are rendered inactive. When a protein unfolds and loses its shape, this is called denaturation. This can occur due to changes in temperature (heat) or shifts in pH outside of the physiological range. Depending on how drastic the unfolding, denaturation can be reversible or irreversible.
What is the “energy currency” of the cell? Describe its structure and function. Explain why it is considered the energy currency of the cell.
The structure of ATP is a nucleoside triphosphate, consisting of a nitrogenous base (adenine), a ribose sugar, and three serially bonded phosphate groups. ATP is commonly referred to as the “energy currency” of the cell, as it provides readily releasable energy in the bond between the second and third phosphate groups.
What is the pH scale? What actually is the pH referring to? What pH range would be alkaline (basic)? Acidic? Neutral? How is pH written or expressed? Why is pH important?
pH is a measure of the concentration of hydrogen and hydroxyl ions in a solution. The pH scale extends from 0 to 14. If the concentrations of hydrogen and hydroxyl ions is equal, the pH is neutral and 7. If there are more hydrogen ions than hydroxyl ions, the solution is said to be acidic with a pH less than 7. If there are more hydroxyl ions than hydrogen ions, the solution is said to be basic with a pH greater than 7.
What is the plasma membrane? Describe its structure in detail, including all of its constituents: membrane lipids, membrane proteins, membrane carbohydrates. Describe the functions of each membrane component. What are the functions of the membrane? What does the membrane function depend on?
Extracellular material includes extracellular fluid, cellular secretions, or extracellular matrix. Intracellular content includes the nucleus (control center of the cell) and the cytoplasm (intracellular fluid + organelles outside the nucleus). The plasma membrane acts as a selectively permeable barrier between the extracellular and intracellular material, allowing only certain substances into or out of the cell.
The plasma membrane is composed of membrane lipids, membrane proteins, and membrane carbohydrates. Membrane lipids include phospholipids and cholesterol (a steroid). The phospholipids make up the majority of the membrane lipids (80%) and form a fluid lipid bilayer due to the chemical properties of the phospholipid’s structure. The polar (hydrophilic) head groups in each layer orient themselves outward toward the extracellular material or intracellular material, and the nonpolar (hydrophobic) tails in each layer orient themselves inward toward one another. Polar molecules want to be by other polar molecules, and nonpolar molecules want to be by other nonpolar molecules. Therefore, the polar head groups want to be by water, the main constituent of both intracellular and extracellular fluid, and the nonpolar tails want to be by each other hiding from water.
The remaining 20% of the membrane lipids are cholesterol molecules. Cholesterol inserts itself into the lipid bilayer because it has both polar and nonpolar regions. Cholesterol is composed of four interlocking nonpolar hydrocarbon rings and a polar hydroxyl group. Therefore, cholesterol can interact with both the hydrophobic and hydrophilic regions of the lipid bilayer. Cholesterol is much stiffer than the phospholipids, providing some rigidity and stability to the plasma membrane.
Membrane carbohydrates include glycolipids (sugar + lipid) and glycoproteins (sugar + protein) which make up the glycocalyx - a fuzzy, sticky, carbohydrate-rich region on the extracellular surface of the cell. Membrane carbohydrates function in identification/recognition, adherence, and communication.
Membrane proteins insert themselves into the lipid bilayer (integral proteins) or on the surface of the lipid bilayer (peripheral proteins). Membrane proteins could be found on the extracellular or intracellular face of the plasma membrane and are constantly changing their position in the lipid bilayer. Membrane proteins have many potential functions including communication, adherence to surrounding cells or extracellular matrix material, transport, acting as enzymes, or recognition.
What are the two types of cellular extensions? Provide a description of the cellular extensions, their structure, and their functions. Identify what cytoskeletal element is involved in its structure. Where might these cellular extensions exist in the body? Give examples.
Cellular extensions include microvilli or cilia. Both are plasma membrane protrusions composed of cytoskeletal proteins. Microvilli are fingerlike extensions on the cell surface composed of a cytoskeletal protein called actin. Microvilli function to increase the surface area of the cell.
Cilia are protrusions of the plasma membrane made of a cytoskeletal protein called microtubules. Cilia function to perform ciliary action, where they whip back and forth across the plasma membrane attempting to sweep substances in one direction across the plasma membrane.
What are the three types of cell junctions? Describe each junction in detail, including its structure and function, and provide an example of where it can be found.
Cell junctions at the plasma membrane include tight junctions, desmosomes, or gap junctions.
Tight junctions are composed of interlocking proteins that form a tight seal between the cells. They function to prevent molecules from passing between cells.
Desmosomes are composed of cadherins, which create a sort of molecular velcro to anchor the cells together. They function to resist mechanical stress.
Gap junctions, or communicating junctions, are composed of channels called connexons that allow molecules to pass between cells as a form of communication.
Phagocytosis
the process by which a cell uses its plasma membrane to engulf a large particle and, phagosome fuses with lysosome.
The cell engulfs a large particle by forming projecting pseudopods (false feet) around it and enclosing it within a membrane sac called a phagosome. The phagosome is combined with a lysosome. Undigested contents remain in the vesicle (now called a residual body) or are ejected by exocytosis. Vesicle may or may not be protein coated but has receptors capable of binding to microorganisms or solid particles.
