Anat & Phys Exam 1

Front 1

3 Components of a control mechanism

Back 1

1. Receptor (sensor)
2. Control center
3. Effector

Front 2

Effector

Back 2

-Receives output from the control center
-Provides the means to respond
-Effectors are muscles or glands
-Response acts to reduce or enhance the stimulus by feedback

Front 3

Negative feedback

Back 3

-The response reduces or shuts off the original stimulus - negates stimulus
-Ex. Regulation of body temperature; Regulation of blood glucose level

Front 4

Regulation of blood glucose levels, Ex. of Negative feedback

Back 4

1. Increased blood glucose level
2. Disrupts normal glucose level
3. Receptor on beta cell membrane
4. Beta cell releases insulin
5. Lowers blood glucose levels to normal

Front 5

Positive feedback

Back 5

-The response enhances or exaggerates the original stimulus so that output is accelerated
-May exhibit a cascade of amplifying effect
-Usually controls infrequent events, e.g.: Enhancement of labor contractions by oxytocin; Platelet plug formation and blood clotting

Front 6

Enhancement of labor by oxytocin, Ex. of positive feedback

Back 6

1. Cervix dilates
2. Stretches receptors
3. Hypothalamus
4. Posterior pituitary
5. Oxytocin
6. Uterine muscle contraction - uterus stretched and more oxytocin released
7. Moves baby

Front 7

Diabetes Mellitus

Back 7

-Type I, or juvenile diabetes
-Example of homeostatic imbalance
1. Increased blood glucose level
2. Disrupts normal glucose level
3. Receptor on beta cell membrane
4. Beta cell doesn't release insulin
5. Blood glucose levels remain above normal
6. Hyperglycemia

Front 8

Plasma membrane lipid composition

Back 8

-75% Phospholipids - Sphingolipids (Sphingomyelin & glycolipids)
-5%Glycolipids (lipids w/ polar sugar groups on outer membrane surface)
-20% Cholesterol (increases membrane stability and fluidity)

Front 9

Phospholipid structure

Back 9

-Phosphorus-containing group (polar end)
-Glycerol backbone
-2 fatty acid chains (nonpolar end)

Front 10

Cholesterol

Back 10

-Inserted into bilayer b/n phospholipids
-Polar hydroxl group of cholesterol molecule is close to the phospholipid head
-Effect on fluidity of membrane varies w/ temp
-High temps - cholesterol interferes w/ movement of fatty acid chains decreasing membrane fluidity and reducing permeability to small molecules
-Low temps - by interfering w/ interactions b/n fatty acid chains, cholesterol prevents membranes from freezing and maintains membrane fluidity

Front 11

Lipid rafts in plasma membrane

Back 11

-Discrete areas of the outer membrane that are enriched in cholesterol and sphingolipids
-Move laterally w/in the pm and may be associated w/ specific membrane proteins
-May function as stable platforms for cell-signaling molecules and the uptake of extracellular molecules by endocytosis

Front 12

Integral proteins in plasma membrane

Back 12

-Firmly inserted into the membrane (most are transmembrane)
-Function: transport proteins (channels & carriers), enzymes, or receptors

Front 13

Peripheral proteins in plasma membrane

Back 13

-Loosely attached to integral proteins or glycoproteins
-Include filaments on intracellular surface & glycoproteins on extracellular surface
-Function: enzymes, cell-to-cell links, provide support on intracellular surface, and form part of glycocalyx

Front 14

Microvilli

Back 14

Fingerlike extensions of the pm that increase the surface area of the cell

Front 15

Membrane junctions

Back 15

Glycolipids and glycoproteins, specialized interlocking regions, or specialized membrane junctions linking cells together. Include:
-Tight junctions
-Desmosomes
-Gap junctions

Front 16

Tight junctions

Back 16

-Integral proteins on adjacent cells fuse together to form an impermeable junction in order to prevent fluids and molecules from passing through the extracellular space b/n cells
-Control the movement of materials through cell

Front 17

Desmosomes

Back 17

-Adhering junctions that attach cells to one another
-Scattered along the sides of adjoining cells that prevent their separation and reduce the chance of tearing when a tissue is stressed
-Found in epi, skin, and heart muscle

Front 18

Gap junctions

Back 18

-Transmembrane proteins form pores that allow simple sugars, ions and small molecules to pass from cell to cell
-Present in cardiac and smooth muscle where ion passage from cell to cell synchronizes their electrical activity and contraction