Human Physiology Flashcards
cell/plasma membrane
separates intracellular contents from extracellular environment
- guards internal structure and keeps products inside cell
- allows for transport in & out
protoplasm
inner matrix that contains water, electrolytes, proteins, carbs (cytoplasm contains organelles)
- water = majority of protoplasm
- proteins = polar & hydrophilic
- lipids = non-polar & hydrophobic
- carbs = rapid source of energy
nucleus
control center; contains most of the hereditary material
proteins
polar & hydrophilic, makes up 10-20% of protoplasm composition
- enzymes
- structural proteins
- ion channels
- receptors
lipid bilayer
basic fluid structure of membranes that serves as semipermeable barrier
* maintains fluid balance
comprised of:
> phospholipids (amphipathic) -hydrophilic head and hydrophobic tail
> cholesterol (hydrophobic)
integral proteins
require something to open membrane
-allows substance to change shape and enter
glycocalyx
participates in cell to cell recognition and adhesion
- fuzzy membrane (sugar coat)
- way for cells to identify others
functions of cell membrane
- physical isolation -> barrier
- regulates exchange w/ environment - maintains homeostasis
ex) prevents hyperkalemia and arrhythmia - monitor environment through extracellular fluid composition and chemical signals
- structural support- anchors cells/tissues
anchoring protein
integral/transmembrane protein that is a stabilizer
- attaches to inside or outside of structures
ex) skin intact and does not slough off normally
recognition proteins
integral/transmembrane protein that is an identifier
-labels cells as normal or abnormal
enzymes
integral/transmembrane protein that catalyzes rxns
receptor proteins
integral/transmembrane protein that bind & respond to ligands (lock & key)
ex) ions, hormones
carrier proteins
integral/transmembrane protein that transport specific solutes through membrane
channels
integral/transmembrane protein that regulate water flow & solutes through membrane
ex) facilitated diffusion in aqua porins
peripheral proteins
bound to inner or outer membrane
- integral protein
- allows substance to change shape & enter cell
cell junctions
form bonds w/ other cells/extracellular material
-attaching cells/communication between cells
» tight
» gap
» desmosomes
tight/occluding junctions
fused together between 2 cell membranes = impenetrable barrier
- prevents passage of water & solutes
- found only in epithelial tissue
ex) skin, GI tract
*burn pts experience fluid loss (not infection) which can lead to death
»_space; must monitor IV fluids
selective absorption of digestive tract
prevents bacteria from entering GI tract
ex) dissentaria & cholera -> disruption of barrier
gap junctions
strong adhesions between neighboring cells w/ cylindrical channels that permit ions and small molecules to pass between cells (ions, simple sugars)
- allows for rapid communication
ex) heart/intestines/smooth muscle require coordination of muscles to have same rate of contraction at the same time
desmosomes
Anchoring junctions that hold together
adjacent cells by thick protein filaments;
extend through cell
Ex) Areas of mechanical stress; epidermis belosa
Passive transport
no energy required
- diffusion
- filtration
diffusion
type of passive transport
- Simple
- Facilitated/Carrier-mediated transport
- Osmosis (aquaporins) - movement of water
active transport
requires energy
types include:
>primary- requires ATP directly to go against concentration gradient
>secondary- uses energy for transport of 1 substance for cotransport of 2nd substance
>vesicular transport - exocytosis, endocytosis
carrier mediated transport of big/lipid soluble ions & organic substrates
use energy (2/2 active transport) or via facilitated diffusion
specificity
characteristic of carrier mediated transport
-Carrier proteins combine specifically and reversibly
saturation limit
characteristic of carrier mediated transport in which rate depends on transport proteins, not substrate
ex) insulin brings glucose into cell
diffusion
movement of charged or uncharged particles
along a concentration gradient from an area of
higher concentration to one of lower concentration
-passive process
-no energy requires
osmosis
diffusion of water across the cell membrane -regulated by concentration of non- diffusible particles on either side of semipermeable membrane -net movement of water across a concentration gradient (from low concentration to high concentration)
hypotonic IVF
NS is not concentrated since it is 1/2 Na-
-water flows into cell
hypertonic IVF
water will flow out of cells
normal saline (NS)
Na+ and Cl- = about the same concentration in body
aquaporins
water channels that allows water to move -Movement continues until concentration of substances is equally diluted or until opposed by osmotic pressure
ADH
antidiuretic hormone stored in posterior pituitary gland
- secreted by hypothalamus
- goes to kidney -> distal tubular duct
- prompt aquaporins to open
- absorption of water -> reabsorption
SIADH
syndrome of inappropriate ADH
- too much of ADH -> drop in Na-
- Sodium Is Always Down Here*
Na- K+ pump
pumps out Na+ (3)
pumps K+ in (2)
! Maintains Na-K concentration
across membrane membrane
! Maintains normal cell volume
> electrogenic ( negative charge inside cell membrane)
> responsible for transmission of nerve and muscle signals along cell membrane
-reestablishes proper concentration of electrolytes
Endocytosis
Vesicular/Bulk Transport that requires ATP >cells surround and take in material ! Receptor-mediated - pinocytosis - phagocytosis
exocytosis
Vesicular/Bulk Transport that requires ATP
-Granules or droplets are released from the cell
pinocytosis
type of endocytosis involved in nutrient absorption
! Endosomes “drink” extracellular
fluid (Cell drinking) ! In-folding cell membrane
surrounds droplet of ECF with
dissolved molecules ! Important in nutrient absorption
(cells in intestine)
phagocytosis
type of endocytosis -Engulf large or solid objects in phagosomes (Cell eating) -Fuses with lysosome and contents digested Ex: macrophages, some WBC’s
exocytosis
Moves substances from interior of cell into extracellular space ! Substance to be released is enclosed in a vesicle ! Vesicle fuses to membrane and ruptures, spilling contents out of cell ex) Hormone secretion, NT release, mucus of secretion, ejection of wastes
filtration
Process by which fluid is forced through membrane from area of higher hydrostatic pressure to area of lower hydrostatic pressure -does not require energy ex) Filtration of plasma across renal - dependent on BP
intracellular compartment (ICF)
-Consists of fluid contained within all of the trillions of
cells in the body
-Larger of the two compartments
! approximately two-thirds of the body water in healthy
adults
! High concentration of K+
40% of body weight
extracellular compartment (ECF)
remaining 1/3 of body of water
-fluids outside the cells, including that
in the interstitial (¾) or tissue spaces and blood vessels (¼)
-high concentration of Na-
transcellular fluids
1% or less of the fluid in body
ex) CSF in brain
- vitreous humor in eye
- synovial fluid lubricates joints
- pericardial fluid in heart
- pleural fluid in lungs
composition of ECF
- large amounts of Na- and Cl-
- moderate amounts of bicarbonate
ex) pH in body - ABG - small quntities of K+, Mg, Ca+, Phos
composition of ICF
-Almost no calcium
-Small amounts of sodium, chloride,
bicarbonate, and phosphorus
- Moderate amounts of magnesium
-Large amounts of potassium
voltage gated channels
-Respond to changes in membrane potential -Have activation gates (opens) and inactivation gates (closes) -Characteristic of excitable membrane -Found in neural axons, skeletal muscle sarcolemma, cardiac muscle
