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bmsc 207 > mod 2 - cells & tissues > Flashcards

mod 2 - cells & tissues Flashcards

1
Q

2 main compartments of body

A
  1. anatomical - body cavities
  2. functional - body fluid compartments
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2
Q

3 body cavities

A
  1. cranial cavity - brain & spinal cord
  2. thoracic cavity - lungs & heart
  3. abdominopelvic cavity - GI tract & reprod. organs
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3
Q

2 categories of functional (body fluid compartments)

A
  1. ECF (extracellular fluid) - plasma & interstitial fluid (surrounds most cells)
  2. Cells (ICF)
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4
Q

compartments are seperated by what?

A

membranes

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5
Q

original cell membrane theory

A

single layer of lipids

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6
Q

membrane consists of ?

A

phospholipid bilayer

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7
Q

functions of cell membrane

A
  1. physical isolate (isolate ICF & ECF)
  2. regulation of exchange w environ. (movement across membrane)
  3. communication between cell & its enviro (respond & interact w external environ)
  4. structural support (proteins in CM)
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8
Q

actual composition of CM

A

lipids, proteins & small amount of carbs
- more metabolically active the membrane, the more proteins it contains

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9
Q

are all CM created equally?

A

no - ex: RBC membrane (49%) has more protein than myelin membrane around nerve cells (18%)

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10
Q

3 types of lipids found in CM

A
  1. phospholipid - main type of CM
  2. sphingolipids - larger than phospho.
  3. cholesterol
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11
Q

phospholipid structure

A
  • polar head (hydrophilic)
  • non polar fatty acid tail (hydrophobic)
  • amphipathic
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12
Q

phospholipids form/arrange themselves how ?

A

1.bilayer - sheet
2. micelles - droplets (lipid digestion)
3. liposomes - aqueous center

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13
Q

phospholipid chemical structure

A
  • glycerol backbone
  • phosphate polar head
  • hydrophobic fatty acid tail
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14
Q

sphingolipid structure

A
  • lipid rafts (longer than phospho)
  • lipid anchor proteins
  • sphingosine backbone
  • phosphate grp. or sugar (
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15
Q

cholesterol functions

A
  1. increases viscosity of CM - choles. thickens/stiffens CM & makes it flexible r
  2. decreases permeability
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16
Q

current model of CM is known as what

A

fluid mosaic model
- CM is fluid/moveable
- proteins dispersed throughout
- extracell. surface contains glycoproteins & glycolipids

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17
Q

CM proteins categories

A
  1. integral proteins - integrated into CM
  2. perishable proteins - not integrated into CM (can be chemically removed w/o disrupting CM)
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18
Q

each cell has how many diff. types of proteins inserted into the CM

A

10-50 diff. types of proteins in CM

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19
Q

integral proteins include:

A
  1. transmembrane proteins - spans entire protein
  2. lipid anchored proteins - integrated into lipid (typically into FA tails or linked thru sugar anchor)
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20
Q

roles of integral proteins

A
  1. membrane receptors
  2. cell adhesion molecules
  3. transmembrane movement (channels, carriers pores, pumps etc)
  4. enzymes
  5. mediators of intracell. signalling
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21
Q

peripheral proteins can be attached to

A
  1. integral proteins
  2. loosely attached to phospho. head
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22
Q

peri. proteins roles

A
  1. participate in intracell. signalling
  2. form inner cytoskeleton
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23
Q

lipid anchored proteins are associated with what kind of lipid

A

sphingolipid
- attach to FA tails
- high cholesterol content 3-5x

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24
Q

lipid anchored proteins can be in what kind of region

A

more viscous regions - higher cholesterol content

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25
Q

2 types of lipid rafts

A
  1. planer - lots of integral proteins (channels etc), important for cell signal transduction
  2. caveolae - “little caves”, form indentations, important for cell signal transduction also
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26
Q

2 categories of CM carbs

A
  1. glycoproteins - protein w carb attached
  2. glycolipids - lipid w carb attached
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27
Q

functions of 2 diff. CM carbs (glycoprotein & glycolipid)

A
  1. glycoprotein
    - form glycocalyx (protective coat)
    - cell to cell recognition/interaction
  2. glycolipid
    - cell to cell recognition/interaction
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28
Q

what is considered solvent of life

A

water
- most important molecule in body (~60% of body)

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29
Q

how much of the body’s water is found in cells vs out of cells?

A

in cells: ICF - 65%
out of cells (ECF): 35% - plasma (25%), interstitial fluid (75%)

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30
Q

in general who has more water (males or females)

A

males
- women have more adipose tissue

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31
Q

EC & IC compartments are in a ??

A

osmotic equilibrium
- fluid concentration is equal: the amount of solute per volume solution

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32
Q

osmosis definiton

A

movement of water across a membrane in response to a solute concentration gradient

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33
Q

T/F: water cannot move freely between IC & EC spaces

A

false

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34
Q

what structure allows water to move between IC & EC spaces?

A

aquaporin channels
- 13 diff. types
- allows for short & longterm water regulation/balance

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35
Q

T/F: osmotic equilibrium equals chemical/electrical equilibrium

A

False: many solutes are ions w/an electrical charge —> electrical disequilibrium
- thus body compartments are in a state of chemical disequilibrium

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36
Q

osmotic pressure definition

A

the pressure that would have to be applied to oppose & prevent osmosis

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37
Q

osmolarity describes what

A

the number of particles in solution
- helps to predict the movement of water by knowing the concentrations of each solution

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38
Q

how is osmolarity different from molarity

A

osmolarity looks at the osmotically active particles vs entire molecules

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39
Q

osmolarity formula

A

molarity (mol/L) x particles/molecules (osmol/mol) {dissociation constant} = osmolarity (osmol/L)

ex: 1M glucose x 1 osmole/mole glucose = 1 OsM glucose

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40
Q

what is the normal osmolarity in the human body

A

280-296 mOsm (milli-osmoles)

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41
Q

3 ways to describe osmolarity solutions

A
  1. isosmotic (equal) - solutions have identical osmolarities
  2. hyperosmotic (greater than): describes the solution w the hugger osmolarity
  3. hyposmotic (less than): describes the solution w the lower osmolarity
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42
Q

tonicity describes what

A

cell volume changes (qualitative description)

43
Q

tonicity definition

A

describes a solution & how that solution would affect cell volume if a cell were place in that solution & allowed to come to equilibrium

44
Q

3 categories of tonicity

A
  1. hypotonic - cell swells (solution is hypotonic)
  2. isotonic - cell stays the same (solution is isotonic)
  3. hypertonic - cell shrinks (solution is hypertonic)
45
Q

tonicity vs osmolarity

A

tonicity: no units, not measurable
- compares a solution & a cell
- tells u ab cell volume in a solution
- depends on the concentration of non-penetrating solutes

osmolarity: has a unit, measurable
- used to compare 2 solutions
- doesn’t tell u ab a cell placed a solution
- depends on the nature of solutes (whether or not they can cross the CM)

46
Q

between the extracellular & intracellular compartments, what is in equilibrium?

A

fluid concentration

47
Q

T/F: water can move freely between the ECF & ICF

A

True

48
Q

cell membranes are ____ ______

A

selectively permeable

49
Q

2 kinds of CM transport

A
  1. passive - no energy needed
  2. active - energy needed
50
Q

what crosses the CM is depend on what

A
  1. properties of CM (lipid & protein composition)
  2. the substance itself (size & lipid solubility)
51
Q

simple diffusion definition

A

movement of molecules from an area of higher concentration to an area of lower concentration

52
Q

7 properties/rules of simple diffusion

A
  1. no energy needed
  2. high conc. to low conc.
  3. continues until equilibrium is reached
  4. diffusion occurs faster when
    - higher conc. gradients
    - over shorter distances
    - at higher temp
    - smaller molecules
  5. in an open system or across a partition that separates 2 diff. systems
  6. larger membrane surface area = faster diffusion
  7. membrane permeability to a molecule depends on
    - the molecule’s lipid solubility
    - molecule size
    - lipid comp. of the membrane
53
Q

how does membrane size affect simple diffusion

A

larger surface area of membrane allows for a faster rate of diffusion

54
Q

5 factors that influence simple diffusion across a CM

A
  1. concentration gradient
  2. membrane surface area
  3. lipid solubility
  4. molecular size
  5. composition of lipid layer
55
Q

simple diffusion can occur what kind of molecules

A

small uncharged, lipophilic molecules
- O2, CO2, NH3 etc
- lipids
- steroids

56
Q

ficks law of diffusion

A

rate of diffusion is proportional to surface area x concentration gradient x membrane permeability

57
Q

membrane permeability equation

A

membrane permeability = lipid solubility / molecular size
- changing comp. of lipid layer can increase/decrease permeability

58
Q

mediated transport

A

CM proteins help w the movement of substances

59
Q

2 types of mediated transport

A
  1. facilitated diffusion
  2. active transport
60
Q

2 types of membrane transport

A
  1. carrier proteins
  2. channel proteins
61
Q

channel protein definition

A

made of membrane spanning protein subunits that create a cluster w cylinders w a pore in the centre
- named after the substance that passes thru

62
Q

what determines what can pass thru a channel protein

A
  1. size of pore
  2. charge within centre of pore (amino acids lining pore determine the charge)
63
Q

2 types of channel proteins

A
  1. open channels “leak channels” - channels are open 24/7 (ex: aquaporins)
  2. gated channels - typically closed, gate or ball & chain model
    - chemically gated (ligand, confirmation change)
    - voltage gated
    - mechanically gated (sensitive to CM deformation)
64
Q

channel proteins allow what kinda diffusion

A

facilitated diffusion

65
Q

carrier protein definition

A

large complex protein
- change conformation to move molecules
- slow
- 3 kinds

66
Q

types of carrier proteins

A
  1. uniport carriers - only moves 1 kind of substrate
  2. cotransporters
    - symport (move 2+ substrates in same direction)
    - antiport (move substrates in opposite directions)
67
Q

steps of carrier proteins

A
  1. passage open to one side
  2. transition state/conformation w both gates open
  3. passage open to other side
68
Q

carrier proteins can move what molecules

A

small organic molecules that can’t move thru channels

69
Q

facilitated diffusion uses ….

A

channels or carrier proteins

70
Q

facilitated diffusion characteristics

A
  1. move down their conc. gradient
  2. no energy needed (passive)
  3. stops once equilibrium is reached
71
Q

active transport definition

A

moving a molecule against its concentration gradient: typically low conc. to high conc.

72
Q

active transport characteristics

A
  • supports a state of disequilibrium (ex: certain ions)
  • needs energy (ATP)
  • uses carrier proteins
73
Q

2 types of active transport

A
  1. primary active transport - energy to move molecule comes directly from hydrolyzing ATP (ATPase)
  2. secondary active transport - uses potential energy stored in conc. gradient of 1 molecule to push another molecule against their conc. gradient
74
Q

primary active transport example

A

sodium potassium pump (antiport)
- moves Na out of cell & K into cell
- 3 Na out, 2 K in

75
Q

secondary active transport

A
  • can move in the same direction (symport) or opposite (antiport)
76
Q

secondary active transport example

A

sodium glucose transporter (SGLT)

  • Na follows gradient
  • Na binds to site, conform change
  • High affinity site for Na & Glu
  • Na release, conform change
  • Low affinity site for Na
  • Glucose releases
77
Q

3 properties of both active & passive carrier mediated transport

A
  1. Specificity
  2. Competition
  3. Saturation
78
Q

Specificity define

A

the ability of a transporter to move 1 molecule or closely related grp. of molecule
- ex: GLUT transporters moves only naturally occurring 6 carbon sugars

79
Q

competition define

A

a carrier may move several members of a related grp. of substances but these substances compete w 1 another

80
Q

saturation define

A

rate of transport reaching a max point

  • depends on conc. & # of transporters
  • transport normally increases w increasing conc. until transport max. is reached (all transporters are in used)
81
Q

if a channel gate opens in response to the binding of a ligand, it is said to be:

A

chemically gated

82
Q

vesicular transport definition

A

using bubble like vesicles to move macromolecules

83
Q

3 kinds of vesicular transport

A
  1. phagocytosis
    - vesicles using cytoskeleton (ex: WBC)
    - active transport
  2. endocytosis
    - transport into cell
    - membrane indents (smaller vesicles)
    - active transport
  3. exocytosis
84
Q

endocytosis 2 kinds

A
  1. non-selective
    - pinocytosis: allows ECF to enter
  2. selective
    - receptor mediated transport
85
Q

what is clathrin

A

“coated pits” - endocytosis

86
Q

what would move through endocytosis

A

protein hormones
growth factors
antibodies
plasma proteins
- large protein based molecules, lipophobic

87
Q

exocytosis define & characteristics

A

transport out of the cell

  • vesicles filled w large lipophonic molecules or waste left behind by lysosomes
  • can occur continuously or intermittently
  • needs ATP
  • regulated by calcium
88
Q

epithelial transport definition

A

substances entering or exiting often have to cross a layer of epi. cells (line lumen, surface of organs)

89
Q

absorption

A

epithelial transport from lumen of an organ to ECF

90
Q

secretion

A

from ECF to lumen of an organ

91
Q

epithelial transport examples

A
  • digestive tract
  • airways
  • kidneys
92
Q

3 mechanisms of epithelial transport

A
  1. transcellular: across/through epi. cells - ions
  2. paracellular: between tight junctions - ions
  3. transcytosis: larger substances (combination of endocytosis, vesicular transport & exocytosis)
93
Q

what 2 membranes must be crossed in transcellular transport

A

into body:

  1. apical membrane
  2. basolateral membrane (faces ECF)
94
Q

transporting epithelia polarized

A

polarized distribution of membrane transporters ensures one-way movement
- typically 1 is active transport & the other is facilitated transport

95
Q

example of transcellular transport

A

epithelial glucose transport

96
Q

compare epithelial transport energy needs

A
  1. paracellular (no ATP)
  2. transcellular (ATP)
  3. transcytosis (ATP)
97
Q

major cations & anions in body

A

cations -
intracellular: K+
extracellular: Na+

anions -
intracell.: phosphate ions, proteins
extracellular: Cl-

98
Q

overall body charge

A

electrical neutral
- even tho there is still an electrical disequilibrium

99
Q

ECF & ICF charges

A

ECF = slight excess of cations (+ charge)
ICF = slight excess of anions (- charge)

100
Q

2 factors that influence membrane potential

A
  1. uneven distribution of ion across CM (concentration gradients)
  2. membrane permeability to those ions
101
Q

nernst equation describes what

A

the membrane potential that would result if the membrane were completely permeable to only 1 ion

  • equilibrium potential for that ion
102
Q

how to calculate resting membrane potential

A

GHK equation: predicts membrane potential that results from contribution of all ions that cross the membrane
- takes into account all ions & their permeabilities

103
Q

resting membrane potential in most neurons

A

70 mV
- mainly due to K+
- Na+ contributes l slightly (v few Na+ leak channels)
- Cl- minimally (since equilibrium potential is close to resting membrane potential)

bmsc 207 (3 decks)

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