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Volume 1

Cell and General Physiology

QuestionAnswer
Lipids make up __ % of the cell membrane by volume. 50%
What is the most abundant component of cell membrane, based on the number of molecules? Phospholipids
Other than phospholipids, what are two other types of lipids found on the cell membrane? glycolipids and cholesterol
What is the most abundant component of the cell membrane, based on weight? proteins
Proteins make up ___ % of the cell membrane by volume. 50%
Name 3 types of proteins on the cell membrane? channels, receptors, and enzymes
Define nonpolar. Nonpolar molecules have positive and negative charges uniformly distributed throughout the molecule; there is no net overall charge on the molecule.
Describe the dissolving properties of nonpolar molecules. (Lipo___ and Hydro___) Lipophilic and hydrophobic
Define polar. Polar molecules also have no net charge. They do however have a region with a cluster of positive charges and a region with a cluster of negative charges.
Describe the dissolving properties of polar molecules. (Lipo__ and Hydro__) Lipophobic and Hydrophilic
Which two of the following are nonpolar, which two are polar: Oxygen, glucose, water, and isoflurane. Oxygen and isoflurane are nonpolar; glucose and water are polar
Define Hydrophilic. Water loving: hydrophilic molecules are water soluble and not lipid soluble
Define Hydrophobic. Water hating: hydrophobic molecules are lipid soluble and not water soluble.
Define Lipophilic. Lipid loving: lipophilic molecules are lipid soluble and water insoluble.
Define Lipophobic. Lipid hating: Lipophobic molecules are water soluble and lipid insoluble.
What are two functions of the lipid bilayer? 1. Serves as a barrier to substances that are not small or are not lipid soluble. 2. Provides environment in which membrane proteins can function
What are the least likely substances to penetrate the lipid bilayer? ions such as Na+, K+, Cl-
What types of molecules readily penetrate the lipid bilayer? hydrophobic molecules and small uncharged polar molecules
What types of molecules do not penetrate the lipid bilayer. large uncharged polar molecules and ions
Give examples of hydrophobic molecules. IV and inhalational anesthetics, O2, N2, benzene
Give examples of small uncharged polar molecules. H2O, Co2, urea, glycerol
Give examples of large uncharged polar molecules. glucose, sucrose
Give examples of Ions. H+, Na+, HCO3-, K+, Ca++, Cl-, Mg++.
Explain exocytosis. In exocytosis, an intracellular vesicle "melts" into the surface membrane, before opening to the extracellular space and extruding its contents.
Explain endocytosis. In endocytosis, the surface membrane invaginates, pinches off, and becomes an intracellular vesicles containing extracellular fluid.
What are two older models of endocytosis? pinocytosis and phagocytosis
What is another name for pinocytosis? cell drinking
What is another name for phagocytosis? cell ingestion and digestion
What is the modern model of endocytosis? receptor mediated endocytosis
What is transcytosis? transcytosis is essentially a combination of endocytosis followed by exocytosis, resulting in transport into, across, and out of a cell.
What is an example of pinocytosis? proteins are reabsorbed from the proximal tubule of the kidney by pinocytosis
What is an example of phagocytosis? macrophages phagocytize bacteria
What is an example of exocytosis? neurotransmitters are released from nerve terminals by the process of exocytosis
Is endocytosis selective, or non-selective? non selective
Give an example of a coat protein. Clathrin
Describe the importance of receptors and clathrin in endo and exocytosis Receptors provide the specificity and clathrin provides the mechanism to convert a planar membrane into a spherical structure (vesicle). so that a cell knows what to bring into the cell or so that a specific substance can become concentrated in a vesicle
What are 4 types off receptors? receptors that control ion channels, receptors that control membrane bound-enzymes, catalytic receptors, and nuclear receptors.
What are examples of receptors that control ion channels? ligand gated ion channels, ionotropic receptors
How do receptors that control ion channels work? When a ligand (chemical, drug, neurotransmitter, hormone) attaches to its receptor, the channel opens and substances specific to the channel diffuse down their concentration gradients through it.
Give a physiologic example of a receptor that controls ion channels? At the neurotransmitter junction, ACh binds to the nicotinic receptor and the channel opens to sodium ions, which diffuse in, potassium ions, which diffuse out, and calcium ions, which diffuse in. Others: 5HT3, GABA, and glutamate receptors
What is an example of a receptor that controls membrane bound enzymes? metabotropic receptors
How do metabotropic receptors work? When a ligand attaches to its receptor, an enzyme on the cytoplasmic surface (inside) of the membrane is activated. A reaction inside the cell is accelerated by the enzyme.
What are the most common type of receptors that control membrane bound enzymes? G protein coupled receptors
What are other names for G protein coupled receptors? GPCR, 7 transmembrane, serpentine
Most adrenergic receptors, such as ACh receptors, are ____. GPCR
How do catalytic receptors work? When activated by a ligand, these integral plasma membrane proteins are either enzymes themselves or part of an enzymatic complex.
What are examples of catalytic receptors? insulin, EPO, ANP and many growth factor receptors
What is another name for nuclear receptors? intracellular receptors
How do nuclear receptors work? These proteins, located in the cytosol or nucleus, are ligand activated transcription factors. These receptors link extracellular signals to gene transcription in the nucleus of the cell.
Most ___ ____ exert their cellular effects via nuclear receptors. steroid hormones
Describe the thickness and orientation of channels. they span the thickness of the lipid bilayer
What are proteins that span the membrane called? integral or transmembrane proteins
Where do receptor binding sites face? extracellular surface of lipid bilayer
Where are membrane enzymes anchored? intracellular surface of the lipid bilayer
Where are first messengers located? the extracellular side
Where are second messengers generated? intracellular side
What is signal transduction? the relaying of messages from the exterior to the interior of the cell
Where does the name transduction come from? latin 'traducere' means "to carry across"
Explain the mechanism of signal transduction. External signals are transferred to the cell interior when agonist, first messenger, opens channels or activates enzymes.
Explain the mechanism of signal transduction (continued). Signal transduction using receptors involves the action of an intermediary protein messenger, which transfers the signal from the receptor to an enzyme. G proteins are the best known proteins for relaying messages from receptors to enzymes.
G proteins have three subunits, what are they? gamma, beta, and alpha
What parts of the g protein can relay messages? alpha subunit and beta-gamma complex
What are variations of proteins called? protein isoforms
What are examples of protein isoforms? stimulatory G protein, inhibitory G protein, hemoglobin (adult, fetal, embryonic), adrenergic receptors (a and b families), PDE (III and V), ACh receptors (nicotinic and muscarinic)
G proteins relay messages from __ to ___. receptors to enzymes
Name second messengers. cAMP, cGMP, calcium, calmodulin, inositol triphosphate (IP3)
A given second messenger produces (the same/different) effects in different tissues. different
Second messenger action is ____- specific. tissue
Describe the action of cAMP in heart and bronchial smooth muscle. Increased cAMP in the heart increases Ca++, causing increased contractility. In bronchial smooth muscle, however, increased cAMP decreases Ca++, producing smooth muscle relaxation and bronchodilation
An increase in cardiac contractility is mediated by ____ and bronchodilation is mediated by ____. Both of these responses involve Gs and ____ _____. beta 1 adrenergic agonists; beta 2 adrenergic agonists; adenylate cyclase
The sodium potassium ATPase pump is found in (all, many, few) cells. all
The Na/K ATPase pump keeps intracellular __ high and intracellular __ low. K+ high, Na+ low
The Na/K pump uses energy derived from the breakdown of ATP to go through a series of ___ changes. shape
The Na/K pump moves __ sodium ions (in/out) in exchange for ___ potassium ions which are transported (into/out of) the cell. 3 NA out, 2 K into
When a protein changes shape, the protein is said to undergo a _____ change. conformational
Does insulin stimulate or block the Na/K pump? stimulates
Explain the role of insulin therapy in hyperkalemia. By stimulating the Na/K pump, insulin drives K into cells. It also opens glucose channels, which permits the tx of glucose into fat and skeletal muscle cells. The glucose component of the glucose-insulin therapy for hyperkalemia, prevents hypoglycemia
Do beta 2 adrenergic agonists cause hypo or hyperkalemia? hypokalemia
Explain the role of beta 2 adrenergic agonists on the Na/K pump. B2 agonists stimulate the Na/K pump. This action explains why ritodrine and terbutaline (beta agonists) promote hypokalemia. Beta agonists drive potassium into the cell by stimulating the Na/K pump.
What is an analogy for an agonist and its receptor? key fits into a lock and then turns the tumblers
Describe the action of a competitive antagonist. A competitive antagonist fits into a receptor but has no direct effect. The competitive antagonist prevents agonists from attaching to the receptor so nothing happens.
What is an analogy for a competitive antagonist? a ket that fits into a lock but cannot turn the tumblers; when the wrong key is in the lock, the correct key cannot be inserted.
What are the extra and intracellular concentrations of Na+ Extra: 145; Intra: 10
What are the extra and intracellular concentrations of K+ Extra: 4; Intra: 140
What are the extra and intracellular concentrations of Ca++ Extra: 2.0-2.5; Intra: <<1 (100nM)
What are the extra and intracellular concentrations of Mg++ Extra: 2; Intra: 50
What are the extra and intracellular concentrations of Cl- Extra: 105; Intra: 4
What are the extra and intracellular concentrations of PO4-- Extra: 2; Intra: 75
What are the extra and intracellular concentrations of HCO3- Extra: 24; Intra: 10
The Na/K pump is stimulated by: insulin, epinephrine, both, or neither both
The 5HT3 receptor is antagonized by ondansetron. What type of receptor is the serotonergic 5HT3 receptor? a. metabotropic b. ionotropic c. G-protein coupled d. enzyme-linked transmembrane ionotropic
Created by: valleyanesthesia