Exam #1 Flashcards
Body functions act as a _____________ unit.
Integrated/interdependent
Most cells are exposed to the ___________ environment.
Internal
Cells live in an _______ environment.
Aqueous
How are body compartments separated?
By epithelial membranes (membranes tend to be semipermeable).
Total body water can be divided into….
Intracellular fluid and extracellular fluid.
What is plasma?
Fluid surrounding blood cells.
What does interstitial mean?
(Fluid) Between
What are the two characteristics of exchange between external and internal environments?
1) It is indirect.
2) Only occurs in certain systems: lungs, G.I. tract, and kidneys.
What are examples of mechanisms that homeostasis maintains/controls?
Temperature, blood pressure, and molecular concentration.
What does disruption of homeostasis lead to?
Disease and/or death.
Homeostasis requires…
Organ system integration.
In negative feedback, if a regulated variable increases, the system responds to make it……
Decrease.
What are the three general body structures that underlie negative feedback?
1) Receptor
2) Integrating center
3) Effector organs
What signal does the integrating center (in negative feedback) receive?
Afferent signal.
What signal does the effector organs (in negative feedback) receive?
Efferent signal.
How does fever enhance immune responses?
Increases mobility of leukocytes, phagocytosis, and T cell proliferation.
How does a fever increase the body temperature set point?
The white blood cells notice the pathogen and secrete pyrogens, like interleukin. Interleukin causes the hypothalamus in the brain to reset the set point upwards.
What is an example of a positive feedback loop being terminated?
Na+ channels cause a rapid influx of sodium, but eventually closes. This causes K+ to leave.
What are some examples of surfaces covered by epithelial cells?
Skin, lungs, glands, stomach, intestines, and blood vessels.
What type/s of muscle cells execute voluntary movement?
Skeletal.
What type/s of muscle cells execute involuntary movement?
Cardiac and smooth.
What are the afferent and efferent mechanisms of neurons?
Afferent: receiving information from receptors or other neurons.
Efferent: transmitting information to muscles, glands, or other neurons.
What is the composition of lipids?
Heterogenous chemical structure with sterol rings, long hydrocarbon tails.
Glycerol head with fatty acid tails.
What are the functions of lipids?
Membrane structure, energy storage, and intracellular/intercellular signaling.
What are the types of lipids?
Triglycerides, ketones, phospholipids, eicosanoids, and steroid.
What does amphipathic mean?
Hydrophilic and hydrophobic in nature.
The cell membrane is a phospholipid bilayer. What does the hydrophobic nature of the membrane serve?
It makes it a barrier for water soluble substances: ions, glucose, amino acids, etc.
How is the degree of saturation determined?
By the number of double bonds. The more double bonds, the more saturated that substance is.
What does the degree of saturation affect?
The fluidity of the lipid.
Unsaturated = kinked and don’t pack well together.
Saturated = straight and can pack together well.
What is a function of adipose cells?
To store/metabolize fatty acids to help maintain blood glucose/energy levels near homeostasis.
Steroids are derived from…
Cholesterol.
Cholesterol makes up ____ of membrane lipids.
50%
Polysaccharides are derived from…
Photosynthesis.
Are polysaccharides polar or nonpolar?
Polar, so they dissolve in water.
What are the functions or polysaccharides?
Building blocks of other macromolecules, energy source, and modify structure/function of other macromolecules.
Monosaccharides are the building blocks of….
Polysaccharides AND nucleotides.
Monosaccharides join via _________ to form polymers.
Glycosidic bonds
What types of polysaccharides modify the functions of other macromolecules?
Glycolipids function in the adhesion of membranes.
Glycoproteins function in trafficking and folding of proteins.
Nucleic acids are a template for ________.
Proteins
What are functions of DNA?
Stores the genetic code in the nucleus, template for transcription and replication.
Proteins are composed of ___ amino acids.
20
What dictates amino acid interactions and ultimate protein folding?
R-group chemistry
Amino acids are linked via ______ bonds.
Peptide, which is a strong covalent
What is the function of chymotrypsin?
Cuts other proteins in digestion, attacks peptide bonds of digested material.
What is the function of enzymes?
Increase the likelihood os chemical reactions but do not allow new reactions.
Once an enzyme stabilize transition state intermediate…
It allows a faster reaction.
What does ATP synthetase do?
Positions ADP and PO4 sufficiently close to allow them to chemically bond to form ATP.
What do anabolic reactions require?
Energy input (stored as potential energy).
What do anabolic reactions produce?
Synthesis of large molecules from smaller ones.
What do catabolic reactions produce?
A release of energy. Its purpose is to break down large molecules into smaller products.
The law of mass action determines…
the direction of a reaction
What does an increased concentration of reactants cause in a reaction?
Push forward TOWARDS products.
What does an increased concentration of products cause in a reaction?
Push reaction in reverse.
What are two things that SOME enzymes require to form an appropriately folded active site?
Cofactors or coenzymes.
What are some factors that affect enzyme rates?
Temperature, pH, enzyme/substrate concentration, affinity for the substrate, and allosteric interactions.
What happens to the rate of an enzyme if the substrate concentration is increased?
It increases as well.
What happens to the rate of an enzyme if the affinity for that substate is increased?
It increases as well.
How do allosteric interactions affect enzyme rates?
A chemical modulator binds to the enzyme at a DIFFERENT location than the active site, which changes the enzyme conformation. This change particular occurs in the active site shape.
Either activates or inhibits the enzyme.
How do covalent modifications affect enzyme rates?
This typically happens after an allosteric interaction occurs. An enzyme (like kinase) may activate an enzyme once it has transitioned, while another enzyme (phosphotase) reverses the activation. The enzyme returns to its original shape.
What are some components of a cell membrane?
Amphipathic lipids and proteins (enzymes, receptors, transporters, and cytoskeletal anchors).