- intracellular fluid: fluid inside cells - 40% body weight - 2/3 body water - maintains shape of cell - moves across membrane via osmosis

- extracellular fluid: fluid outside cells - 20% body weight - 1/3 body water - made up of: ISF, plasma volume and lymph, and transcellular fluid

Plasma Membrane Flashcards by Annie Yen

ICF (5 things)

intracellular fluid: fluid inside cells
40% body weight
2/3 body water
maintains shape of cell
moves across membrane via osmosis

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ECF (4 things)

extracellular fluid: fluid outside cells
20% body weight
1/3 body water
made up of: ISF, plasma volume and lymph, and transcellular fluid

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Plasma volume and lymph (three things)

in blood and lymphatic vessels
1/4 ECF
5% body weight

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How is plasma volume and lymph separated from ISF?

separated by capillary wall

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Where do the exchange between plasma, lymph, and ISF occur?

capillary beds

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Transcellular fluid (three things)

in specialized areas
very small % of body weight
stable volume

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Examples of transcellular fluid

cerebral spinal fluid

- aqueous humor

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Where is most of the body weight?

ICF

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Most important cation in ICF?

K+

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Important cation for cell function?

Ca2+

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Most important anion in ISF?

Cl-

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Important ECF buffer

HCO3-

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What do proteins act like in the ICF?

act as major anions

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What does the cell membrane separate?

ICF and ECF

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Functions of the cell membrane

regulate exchange w/ environment
cell communication
structural support

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How does cell membrane regulate exchange w/ environment?

provides permeability barrier and highly selective filter

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How does cell membrane help w/ cellular communication?

receptors and signal transduction pathways for hormones and neurotransmitters

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Cell membrane contains:

adhesion molecules and surface antigens

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Adhesion molecules allow for:

anchoring
tissue organization
intracellular communication
cell shape

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Types of junctions (3 types)

gap
tight
anchoring

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Major adhesion molecules (4 of them)

cadherins
integrins
immunoglobulin superfamily CAMs
selectins

Cadherins:

cell-cell junctions
adherens junctions
desmosomes
Ca2+ dependent

Integrins:

mostly found in cell-matrix junctions

- help w/ cell signaling

Example of immunoglobulin superfamily CAMs and its function

nerve cell adhesion molecules (NCAM): responsible for nerve cell growth during nervous system development

Selectins:

temporary cell-cell adhesion

Surface antigens function

important for recognition of "self" vs. "nonself"

Model of plasma membrane structure

fluid mosaic model

Plasma membrane is made of

lipids (50%), proteins (50%), and carb

Phospholipids:

- core structure - organized in bilayer - have polar head and nonpolar tail

Why are phospholipids of plasma membranes amphipathic?

has polar (hydrophilic) phosphate head and nonpolar (hydrophobic) tails

Orientation of phospholipids in plasma membrane?

polar heads on the outside and nonpolar fatty acyl tail chains are on the inside

Nonpolar tail of plasma membrane forms what?

permeability barrier to H2O soluble molecules

Cholesterol

- hydrocarbon ring structure | - about 20% of total membrane lipid

Functions of cholesterol in plasma membrane

- stabilizes membrane at body temp (37 C) - increases membrane fluidity - reservoir of precursor molecules for steroid hormones

Protein types:

- integral / intrinsic | - peripheral / extrinsic

Integral / intrinsic proteins:

- 70% of membrane proteins - embedded in membrane - transmembrane protein: spans membrane completely

Functions of integral / intrinsic proteins:

- carriers - enzymes - channels - receptors

Peripheral / extrinsic:

- either on outside or inside of plasma membrane | - often are enzymes

T/F: phosphatases remove phosphate group from protein.

T/F: kinases remove phosphate group from protein.

Carbohydrates:

- 2-3% of membrane lipid - glycoproteins: made of carb and proteins - glycolipids: made of carb and phospholipids

Functions of glycoproteins / glycolipids:

- cell-cell communication - structural stability - immune response

Example of membrane transporters

- carriers | - channel proteins

T/F: Carriers change conformation

Channel proteins form:

- open channels | - closed channels

Types of gated channels:

- mech - voltage - chem

Structural proteins are found in:

- cell junctions | - cytoskeleton

Membrane enzymes:

- activated by membrane receptors | - functions in: metabolism and signal transfer

Functions of membrane receptors:

- receptor mediated endocytosis - signal transfer - open and close chem gated channel

Order of concentration of ions in ECF (highest to lowest)

Na+, Cl-, K+

Order of concentration of ions in ICF (highest to lowest)

K+, Na+, Cl-