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Cell Interactions
Matt Hobbs
68
Physiology
Undergraduate 3
09/22/2011

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Term
What are all the constituents of body outside of cells?
Definition
The Extracellular Environment
Term
What water content of the body is divided into what two compartments?
Definition
Intracellular and Extracellular Compartments
Term
Extracellular water is found in what two substances?
Definition
Blood plasma (20%) and Tissue fluid (Interstitial fluid 80%)
Term
What is the material within of connective tissue, but outside of the cells?
Definition
Extracellular Matrix
Term
What term describes cells ability to allow some substances to cross the cell membrane while preventing others from
doing so?
Definition
Selective Permeability
Term
What two types of mechanisms move substances across the cell membrane?
Definition
Carrier-mediated transport and non-carrier-mediated transport
Term
Based on energy requirements what are the two types of membrane transport?
Definition
Passive Transport & Active Transport
Term
What type of membrane transport requires ATP?
Definition
Active Transport
Term
What is the movement of a substance from an area of high concentration to an area of low concentration?
Definition
Diffusion
Term
If the concentration of a substance is different between two areas, what exists between the areas?
Definition
A concentration gradient
Term
What are water channels within a membrane?
Definition
aquaporins
Term
What is the diffusion of water across a membane?
Definition
osmosis
Term
What are proteins within the cell membrane that enable the passage of substance through the membrane?
Definition
Carrier Proteins
Term
What are proteins that allow the passage of ions through the cell membrane?
Definition
ion channels
Term
What are proteins may open or close to allow or prevent the passage of ions through the cell membrane?
Definition
gated ion channels
Term
What factors influence the rate of diffusion?
Definition
the magnitude of the concentration gradient, permeability of the membrane, the temperature of the solution, the surface area of the membrane
Term
What is the amount of pressure that would have to be exerted to prevent osmosis?
Definition
osmotic pressure
Term
What term describes the effect of a solution on the osmotic movement of water?
Definition
tonicity
Term
What term describes a solution that has the same tonicity as plasma?
Definition
isotonic
Term
What term describes a solution that has a tonicity lower than plasma?
Definition
hypotonic
Term
What term describes a solution that has a tonicity greater than plasma?
Definition
hypertonic
Term
What happens to cells in a hypertonic solution?
Definition
They shrink
Term
What happens to cells in a hypotonic solution?
Definition
They swell up and are likely to burst
Term
What type of solution is used for irrigation of body cavities and wounds?
Definition
isotonic
Term
What is the concentration of an osmotic solution?
Definition
osmolality
Term
What type of sensors respond to osmolality?
Definition
osmoreceptors
Term
Where in the body are osmoreceptors found?
Definition
the hypothalamus
Term
What hormone is release in response to an increase in the osmolality of the blood?
Definition
antidiuretic hormone (ADH, also known as vasopressin)
Term
What is the function of ADH?
Definition
to decreases the production of urine
Term
What general category of structures transport large molecules such as glucose and amino acids through the cell
membrane?
Definition
protein carriers
Term
Protein carriers cannot be directly observed. What three characteristics indicate that they exist?
Definition
Specificity, Competition, Saturation
Term
What limit is reached when the carrier proteins for a particular substance are saturated?
Definition
Transport Maximum (Tm)
Term
What type of transport across a cell membrane requires a protein carrier but does not require ATP?
Definition
Facilitated Transport
Term
The transport carriers for the facilitative diffusion of glucose are designated with what letters?
Definition
GLUT
Term
The protein carrier for glucose in skeletal muscles is GLUT4. Why is it necessary to designate the carriers for
glucose with different numbers?
Definition
Various Isoforms exist
Term
Protein carriers do not remain in the cell membrane, but are inserted when the cell is stimulated as by exercise and
insulin in skeletal muscle. What structures store the carriers within the cell?
Definition
Vesicles
Term
What is the movement of molecules and ions against their concentration gradients, from lower to higher
concentrations and thus requires ATP?
Definition
Active Transport
Term
What type of transport across a cell membrane occurs when the hydrolysis of ATP is directly required for the
function of the carriers?
Definition
Primary Active Transport
Term
What four steps occur in primary active transport?
Definition
the binding of the substance to be transported to the carrier, the phosphorylation of the carrier — a change in the configuration of the carrier, a hinge-like action of the carrier releasing the substance on the opposite side of the membrane
Term
What term is often used to refer to primary active transport carriers?
Definition
pump
Term
What common and important primary carrier transports Na+ out of the cell and K+ into the cell?
Definition
The sodium (Na+) Potassium (K+) pump
Term
The steep concentration gradient across the cell membrane serves what three functions?
Definition
to provide energy for coupled transport, to produce electrochemical impulses, to maintain ismotic pressure within the cell
Term
In what type of transport is the energy needed for the uphill movement of a substance obtained from the downhill
transport of Na+ into the cell?
Definition
secondary active transport (coupled transport)
Term
Two types of coupled transport exist. Which type occurs when the substance being moved goes in the same
direction as Na+, that is into the cell?
Definition
cotransport (symport)
Term
Two types of coupled transport exist. Which type occurs when the substance being moved goes in the opposite
direction as Na+, that is out of the cell?
Definition
countertransport (antiport)
Term
What is the transport of the products of digestion from the lumen of the intestine into the blood?
Definition
absorption
Term
What is the transport of molecules out of the filtrate in the kidneys back into the blood?
Definition
reabsorption
Term
In order for s substance such as glucose to be transported from the lumen of the intestine or kidney tubules, what
type of transport occurs at the apical surface of epithelial cells?
Definition
Cotransport (with Na+)
Term
In order for s substance such as glucose to be transported from the lumen of the intestine or kidney tubules, what
two types of transport occur at the basal surface of epithelial cells?
Definition
primary active transport of Na+ and K+ and facilitated diffusion of the substance crossing the cell
Term
Some molecules are too large to be moved by carrier proteins and are instead secreted from the cell when vesicles
containing them fusion with the cell membrane. What is this process called?
Definition
Exocytosis
Term
What process brings substances into the cell when those substances are too large to be moved by protein carriers?
Definition
Endocytosis
Term
What term refers to endocytosis and exocytosis?
Definition
bulk transport
Term
What is the potential difference or voltage that exists between the two sides of cell membrane?
Definition
membrane potential
Term
What is the potential difference across a cell membrane when the cell is in an unstimulated state?
Definition
resting membrane potential
Term
What term refers to how cells communicate with each other?
Definition
cell signalling
Term
In what type of cell signaling do cells within an organ secret regulatory molecules that diffuse through the
extracelluar matrix to nearby target cells?
Definition
paracine signaling
Term
In what type of cell signaling do cells by means of neurotransmitters through synapes?
Definition
synaptic signaling
Term
In what type of cell signaling to cells communicate through hormones?
Definition
endocrine signaling
Term
What molecules respond to the chemical signals produced by cells?
Definition
receptor proteins
Term
What substances allow a polar regulatory molecule binding with a receptor protein in the cell membrane to
influence actions deep within the cell?
Definition
second messengers
Term
What derivative of ATP is an important second messenger?
Definition
cyclic AMP (cAMP)
Term
What four steps generally take place as a polar regulatory molecule binds to a receptor on the cell membrane?
Definition
the regulatory molecule binds to a receptor, this activates an enzyme which produces cAMP from ATP, cAMP activates enzymes in the cytoplasm, the activated enzymes change the activity of the cell
Term
What is an association of three membrane-associated protein subunits, designated alpha, beta, and gamma, that is
regulated by guanosine nucleotides (GDP and GTP)? The protein subunits dissociate in response to a membrane
signal and, in turn, activate other proteins in the cell.
Definition
G-Protein
Term
What are the three subunits of a G-protein?
Definition
alpha, beta, gamma
Term
When a receptor is not bound to a regulatory molecule, what molecule is attached to the alpha subunit of the Gprotein?
Definition
GDP (guanosine diphosphate)
Term
When a regulatory molecule attaches to a receptor associated with a G-protein, what happens to the G-protein?
Definition
The alpha subunit release GDP and attaches to GTP (guanosine triphosphate) and dissociates from the beta and
gamma subunits.
Term
What happens when the alpha subunit of G-protein dissociates from the beta and gamma subunits and binds to
GTP?
Definition
Either the alpha subunit or the beta-gamma complex moves through the membrane and binds to the effector protein
(an enzyme or ion channel)
Term
What happens when a subunit of a G-protein activates its effector protein?
Definition
The alpha subunit splits GTP into GDP and Pi causing the subunits of the G-protein to reaggregate and bind to the
unstimulated receptor again
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