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Winter 2014 / Human Physiology > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

what are the components of Feedback Lopp

A

receptors: monitors a controlled condition
control center: determines next action
effector: receives directions from control center; produces a response that changes the controlled condition

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2
Q

what is NEGATIVE FEEDBACK LOOP?

A
  • original stimulus reversed
  • most feedback systems in the body are negative
  • used for conditions that need frequent adjustment
  • body temperature, blood sugar levels, blood pressure
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3
Q

what is POSITIVE FEEDBACK LOOP?

A
  • original stimulus intensified

- seen during normal childbirth

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4
Q

explain the Homeostasis of Blood Pressure

A
  • pressure receptors in walls of certain arteries detect an increase in BP (BP = force of blood on walls of vessels)
  • brain receives input and signals heart and blood vessels
  • heart rate slows and arterioles dilate (increase in diameter)
  • BP returns to normal
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5
Q

explain positive feedback during childbirth

A
  • stretch receptors in walls of uterus send signals to brain
  • brain releases hormone (oxytocin) into bloodstream
  • uterine smooth muscle contracts more forcefully
  • more stretch, more hormone, more contraction, etc.
  • cycle ends with birth of the baby & decrease in stretch
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6
Q

what is epidemiology?

A

how disease is transmitted

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7
Q

what is cytology?

A

study of cellular structure

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8
Q

what is cell physiology

A

study of cellular function

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9
Q

what are the 3 types of lipid molecules in cell membrane?

A

phospholipids
glycolipids
cholesterol

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10
Q

what are the characteristics of phospholipids?

A
  • comprise of 75% of lipids
  • phosholipid bilayer = 2 parallel layers of molecules
  • each molecule is amphipathic (has both polar & nonpolar region)
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11
Q

polar parts of phospholipids are?

A
  • the head

- hydrophilic and face on both surfaces a watery environment

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12
Q

non-polar parts of phospholipids are?

A
  • tails

- hydrophobic and line up next to each other in the interior

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13
Q

what are the characteristics of glycolipids with the cell membrane?

A
  • comprise 5% of lipids of he cell membrane

- carbohydrate groups form a polar head only on the side of the membrane facing the extracellular fluid

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14
Q

what are the characteristics of cholesterol within the cell?

A
  • comprise of 20% of cell membrane lipids
  • interspersed among the other lipids in both layers
  • stiff steroid rings & hydrocarbon tail are non-polar
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15
Q

what are Integral Proteins?

A
  • extend into or completely across cell membrane
  • all are amphipathic with hydrophobic portion hiding among the phospholipid tails
  • glycoproteins have the sugar portion facing the extracellular fluid to form a glycocalyx
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16
Q

what are Peripheral Proteins?

A
  • attached to either inner or outer surface of cell membrane and are easily removed from it
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17
Q

what are the functions of membrane proteins?

A
  • formation of Channel : allows specific substance to pass through
  • transporter Proteins: bind a specific substance, change their shape and move it across membrane
  • Receptor Proteins: cellular recognition site
  • cell identity marker: allow cell to recognize other similar cells
  • linker: anchor proteins in cell membrane or to other cells; allow cell movt; cell shape & structure
  • act as enzyme: speed up reaction
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18
Q

what decreases the fluidity of a membrane?

A

fluidity is reduced by presence of cholesterol, bc cholesterol increases stiffness of membrane, since it forms a hydrogen bonds with neighboring phospholipid heads

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19
Q

lipid bilayers have selective permeability, they are permeable to?

A
  • non-polar and uncharged molecules (such as oxygen, sterioids, CO2)
  • to water, which flows through the gaps that form in hydrophobic cores of membranes as phospholipids move about
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20
Q

In selective permeability of membrane, the transmembrane protein act as…?

A

specific channels to small & medium, polar and charged molecules

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21
Q

macromolecules are unable to pass through the membrane bc of their large size, what do they do?

A

they are passed through via vesticular transport

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22
Q

what is concentration gradient?

A

membrane can maintain difference in concentration of substance inside versus outside of membrane

  • more O2 & Na+ outside of cell membrane
  • more CO2 & K+ inside of cell membrane
23
Q

what is electrical gradient of membrane potential?

A

membrane can maintain a difference in charged ions between inside and outside of membrane

24
Q

gradients across the plasma membrane means?

A

substances move down their concentration gradient and towards the oppositely charged area
- ions have electrochemical gradients

25
Q

what is mediated transport?

A

moves materials with the help of a transporter protein

26
Q

what is nonmediated transport?

A

does not use a transporter protein

27
Q

what is active transport?

A

uses ATP to drive substances against their concentration gradient

28
Q

what is passive transport?

A

moves substances down their concentration gradient with only their kinetic energy

29
Q

what is vesicular transport?

A

moves materials across membranes in small vesicles- either by exocytosis or endocytosis

30
Q

what is the principle of diffusion

A

random mixing of particles in a solution as a result of the particle’s kinetic energy

31
Q

what happens in diffusion

A

more molecules move away from an area of high concentration to an area of low concentration

32
Q

what creates a faster rate of diffusion

A
  • the greater the difference in concentration between the 2 sides of membrane
  • higher temperature
  • increase in surface area
33
Q

what creates slow rate of diffusion?

A
  • larger the size of diffusing substance, the slower the rate of diffusion
  • increasing diffusion distance
34
Q

when is equilibrium achieved in diffusion?

A

when molecules are evenly distributed

35
Q

what is osmosis

A

the net movt of water through a selectively permeable membrane from an area of high water concentration to an area of lower water concentration

36
Q

what are examples of osmosis?

A

diffusion through lipid bilayer

aquaporins (transmembrane proteins) that function as water channels

37
Q

when does osmosis ONLY occur?

A

only if membrane is permeable to water but not to certain solutes

38
Q

what are the effects of fluids on RBCs in lab?

A
  • water enters the cell faster than it leaves
  • water enters & leaves the cell in equal amounts
  • water leaves the cell
39
Q

normally the osmotic pressure of the inside of the cell is…

A

equal to the fluid outside of the cell

-cell volume remains constant (solution is isotonic)

40
Q

what is isotonic solution?

A

water concentration is the same inside and outside of cell, which results in no net movt of water across cell membrane

41
Q

what is hypotonic solution?

A

higher concentration of water outside of cell results in hemolysis (rupture of blood cell)

42
Q

whiat is hypertonic solution?

A

lower concentration of water outside of cell causes crenation (scalloped edge)

43
Q

what diffuses through the lipid bilayer and why is this important?

A
  • important for absorption of nutrients - excretion of wastes
  • nonpolar, hydrophobic molecules
44
Q

what is diffusion through membrane channels?

A
  • each membrane channel specific for particular ion (K+, CI-, Na+, or Ca+2)
  • slower than diffusion through membrane but still 1 million K+ through a channel in one sec
  • channels may be open all the time or gated (closed randomly or as ordered)
45
Q

what is facilitated diffusion?

A
  • substance binds to specific transporter protein
  • transporter protein conformational change move substance across cell membrane
  • facilitated diffusion occurs down concentration gradient only
  • rate of movt depends upon steepness of concentration gradient, number of transporter proteins
46
Q

describe the facilitated diffusion of glucose

A
  • glucose bindsto transport protein
  • transport protein changes shape
  • glucose moves across cell membrane (but only down the concentration gradient)
  • Kinase enzyme reduces glucose concentration inside the cell by transforming glucose into glucose-6-phosphate
  • transporter proteins always bring glucose into cell
47
Q

what is active transport?

A
  • movt of polar or charged substances against their concentration gradient
  • energy-requiring process: energy from hydrolysis of ATP (primary active transport); energy stores in an ionic concentration gradient (2ndary active transport)
  • exhibits transport maximums and saturation
  • Na+, K+, H+, Ca+2, I- and Cl-, amino acids and monosaccharides
48
Q

what is primary active transport?

A
  • transporter protein called a pump, it works against concentration gradient, requires 40% of cellular ATP
  • Na+/K+ ATPase pump (maintains low concentration of Na+ and high concentration of K+ in the cytosol; operates continually)
  • maintenance of osmotic pressure across membrane - cells neither shrink nor swell due to osmosis & osmotic pressure; sodium continually pumped out as if sodium could not enter the cell (factor in osmotic pressure of extracellular fluid); K+ inside the cell contribute to osmotic pressure of cytosol
49
Q

what is secondary active transport

A
  • uses energy stored in an ion concentration gradient to move other substances against their own concentration gradient
  • Na+/K+ pump maintains low concentration of Na+ inside of cells
    - provides route for Na+ to leak back in and use energy of motion to transport other substances
    - Na+ symporter proteins: glucose or amino acids rush inward with Na+ ions
    - Na+ antiporters protein: as Na+ ions rush inward, Ca+2 or H+ pushed out
50
Q

what is endocytosis?

A

bringing something into cell

51
Q

what is phagocytosis

A 
cell eating by macrophages & WBCs
- particles binds to receptor proteins
-whole bacterial or viruses are engulfed and later digested
-pseudopods extend to form phagosome
lysosome joins it
52
Q

what is pinocytosis?

A

cell drinking
no receptor proteins
no pseudopods form
nonselective drinking of extracellular fluid

53
Q

what is receptor-mediated endocytosis?

A

selective input

  • mechanism for uptake of specific substances - ligands
  • desired substance binds to receptor protein in clathrin-cpated pit region of cell membrane causing membrane to fold inward
  • vesicles become uncoated and combine with endosome
  • receptor proteins separate from ligands and return to surface
  • ligans are digested by lysosomal enzyme or transporter across cell - epithelial cell crossing accomplished
54
Q

what is exocytosis?

A

release something from cell

  • vesicles form inside cell, fuse to cell membrane
  • release their contents: digestive enzymes, hormones, neurotransmitters, or waste products
  • replace cell membrane lost by endocytosis

Winter 2014 / Human Physiology (4 decks)

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