Exam 1 Flashcards
anatomy
the study of the structures of living organisms
physiology
the study of how living organisms function
homeostasis
the maintenance of the relatively constant internal environment
internal environment (2)
- extracellular fluid= interstitial fluid and plasma
- intracellular fluid= cytosol
components of a feedback system (3)
-receptor= monitors the value of a variable and sends info to control/integrating center
-control/integrating center= establishes set point and compares the incoming info to that set point
-effector= based on signals from the control/integrating center, changes in the activity of the effector can change the value of the variable
negative feedback
-when any deviation from the set point is made smaller (resisting the change)
-ex. regulation of blood pressure, body temperature, and blood sugar levels
positive feedback
-when a deviation occurs, the response is to make the deviation greater (much less common than negative feedback)
-ex. childbirth, opening on sodium channels associated with action potentials, platelet-plug formation during blood clotting
what are cells measured in?
micrometers (microns)
what size are most human cells?
10 to 15 micrometers
Plasma Membrane
defines the boundaries of the cell, controls interactions with other cells, and controls movement of materials in and out of the cell
-appears as a pair of dark parallel lines
what % of lipids in the plasma membrane are phospholipids?
75%
what percent of lipids in the plasma membrane are cholesterol molecules?
20%
What makes up 5% of membrane lipids?
glycolipids
glycolipids
-help form glycocalyx ( a carb. coating on the surface of the cell with enables the body to distinguish its own healthy cells with other things)
what types of proteins are membrane proteins categorized as?
integral/transmembrane proteins or peripheral proteins
membrane proteins- receptors
-usually specific for one kind of chemical messenger
-chemical signals/messengers that cannot enter cell might bind to surface receptors
membrane proteins- enzymes
-some embedded proteins are enzymes that can catalyze certain reactions
membrane proteins- channel proteins
2 types: leak channels & gated channels
leak channels- always open
gated channels- may be ligand-gated, voltage gated, or mechanically gated
membrane proteins- carrier proteins
-transmembrane proteins that bind to glucose, electrolytes, and other solutes then transfer them to the other side of the membrane
-if they have to work against a concentration gradients, they’re called pump and they consume ATP
membrane proteins- cell-identity markers
-glycoproteins contribute to the glycocalyx, which enables the body to distinguish its own healthy cells from other things (diseased cells, invading organisms, etc.)
membrane proteins- cell-adhesion molecules
-allows cells to adhere to one another and to extracellular material
how permeable is the plasma membrane?
selectively permeable
selective permeability def.
something can act as both a barrier and a pathway between the cytosol and extracellular fluid
rates of diffusion thru a membrane depend on: (5)
- temperature
- molecular weight of the molecule
- steepness of the concentration gradient
- membrane surface area
- membrane permeability to that molecule
aquaporin
allows water to travel thru the plasma membrane
tonicity
the ability of a solution to affect the volume of fluid in a cell
what is facilitated diffusion?
-carrier-mediated transport of a solute thru a membrane down its concentration gradient
-no energy required!
what is active transport?
-a carrier protein moves a substance across a cell membrane against its concentration gradient
-energy (from ATP) is required!
how many of the calories that you use each day go towards the actions of the pump?
half
functions of the sodium-potassium pump
- regulation of cell volume- more ions are pumped out than in, so it prevents cellular swelling
- maintenance of a membrane potential- the inside of the cell is more negatively charged than the outside
- heat production- heat is released as ATP is used for the pump
vesicular transport
-large amounts of material are moved inside bubble-like vesicles made of membrane
-endocytosis
-exocytosis
endocytosis
-phagocytosis
-pinocytosis
-receptor mediated endocytosis