Cell Physiology Flashcards
physiology
study of how living organisms function
integration
- how the systems of the body parts work together
- how each work towards function of a whole
- how they influence each other
homeostasis
the maintenance of a relative stable internal environment; central theme in physiology
variables maintained by homeostasis
- nutrient molecules (glucose)
- O2 and CO2
- waste products
- water/electrolytes
- pH (acidity)
- temperature
- blood pressure
loss of homeostasis
caused by illness or lead to illness
homeostatic control systems
- negative feedback
- positive feedback
- feedforward regulation
negative feedback
the primary mechanism by which body systems maintain homeostasis
set point temperature
37 degrees C
set points
can be reset in special cases
- elevated body temperature
- exercise and blood pressure
positive feedback
to produce rapid change / acceleration of a process
feedforward region
anticipates change in regulated variables and improves the body’s homeostatic responses to minimize deviation from the set point
extracellular fluid
- plasma
- interstitial fluid
intracellular fluid
mostly water inside cells
cells
structural and functional units of the body & the smallest unit of life
basic cell components
- nucleus
- cytoplasm
- plasma membrane
nucleus
contains DNA
cytoplasm
organelle and cytosol
plasma membrane
the gatekeeper of the cell / controls what goes in and out
- selectively permeable
plasma membrane physical / chemical properties
- hydrophobic
- lipophilic
- electrical potential
plasma membrane proteins
- for movement of molecules
- signaling
lipid bilayer
a double layer of lipid molecules containing embedded proteins and carbohydrates
lipid bilayer components
- lipids
- proteins
- carbohydrates
lipids
phospholipids and cholesterol
proteins
integral and peripheral
carbohydrates
attached to lipid (glycolipid) or to protein (glycoprotein)
phospholipids
amphiphathic
hydrophilic
- polar
- dissolves in water
- ECF
hydrophobic
- non polar
- doesn’t dissolve in water
- ICF
cholesterol membrane functions
- modulates membrane fluidity (increase cholesterol = more fluid)
- endocytosis
- intracellular signaling
peripheral
- on membrane surface
- – do not go in lipid bilayer
- often attached to integral proteins
- signal transduction / enzymes
integral
- span membrane
- hydrophilic / hydrophobic parts
types of integral membrane proteins
- receptors
- channels
- cell adhesions
- cell identity
glyoproteins
most integral proteins
glyolipids
10% of membrane lipids
glycocalyx
carbohydrate “coat” on outer surface of cell membrane
glyocalyx function
- create negatively charged surface
- cell-cell interactions
- receptors
- immune response
plasma membrane permeable to
- water and lipid soluble substances (ethanol, fatty acids, steroids)
- gasses (O2, CO2)
plasma membrane impermeable to
- large molecules (glucose, amino acids)
- charged (Na+, K+, etc.) molecules
- -> need carrier or vesicle to enter/exit
passive transport
- filtration
- diffusion
- facilitated diffusion
- osmosis
active (energy required)
- active transport
- endocytosis/exocytosis
filtration
occurs between cells and is based on differences in hydrostatic pressure
- moves water/molecules between compartments
hydrostatic pressure
fluid pressure – “pushing pressure”
- always flows from high pressure to low pressure
- required to stop osmosis
- equal with osmotic pressure at equilibrium
simple diffusion
- based on differences in concentration
- molecules move from high concentration to low concentration until equilibrium
- smaller molecules move faster
- occurs by random molecular motion
- energy comes from heat
net flux
net rate of material of transfer from one location to another = always greater from areas of higher concentration to areas of low concentration
facilitated diffusion
rate is limited by rate of conformational change of protein carrier
osmosis
net movement of water across a membrane from low solute concentration to high solute concentration
osmolarity
total solute concentration in solution
- includes ALL solutes (penetrating and non-penetrating)
osmotic pressure
- “pulling pressure”
- more solute means more water wants to flow
- will be equal to hydrostatic pressure at equilibrium
tonicity
ability of a solution to affect water movement and cell volume
- includes ONLY non-penetrating solutes
hypertonic solution
- cells shrink (crenation)
- waters flows out
- decrease cell volume
isotonic solution
- no change in cell volume
- no net movement
hypotonic solution
- cell swells (lysis)
- water flows in
- increase cell volume
penetrating solutes
- hydrophobic
- urea
- glycerol
- ethanol
non penetrating solutes
- hydrophilic
- ions
- glucose
active transport
- against concentration gradient
- requires ATP
- requires membrane proteins
- selective
- transport maximum
- –> can become saturated
active transport types
- primary active transport
- secondary active transport
primary active transport
- energy derived directly from ATP
- ex: Na+ / K+ ATPase (3 Na+ out / 2 K+ in)
secondary active transport
- uses energy from concentration differences generated by primary active transport (almost always)
- ex: Na+ / glucose cotransporter
endocytosis/exocytosis
- require ATP and many membrane proteins
- bulk movement of large molecules (proteins / bacteria)
endocytosis
digestion of bacteria
exocytosis
hormone / neurotransmitters released
endocytosis types
- pinocytosis
- phagocytosis
- receptor-mediated endocytosis
- transcytosis
pinocytosis
cell drinking
phagocytosis
immune cells
receptor mediated endocytosis
uptake of cholesterol and cell signaling
transcytosis
movement throughout the cell
ion channels
from ‘pore’ for ions to flow through membrane
- highly selective
- saturating (max flow)
cystic fibrosis
Cl- channel found in the lungs, pancreas, sweat glands, reproductive tract
- allows Cl- to flow out of epithelial cells into lumen
types of ion channels
- “leak channels”
- gated channels
leak channels
always open
gated channels
open/closed, under certain circumstances (key)
types of gated channels
- voltage gated
- ligand gated
- mechanically gated
voltage gated
open/close with change in voltage
ligand gated
opened by chemical (hormone, neurotransmitters, growth factor)
mechanically gated
physical force pulls channel open
- stretch, vibration, touch (sensory)
dendrites
receive information
cell body
process information
axon hillock
action potential begins
axon
action potential travels down (propagation)
axon terminal
neurotransmitters release
gated channels in dendrites
- leak
- ligand gated
- mechanically gated
gated channels in cell body
- lead
- ligand gated
gated channels in axon hillock
- high voltage gated Na+
- high voltage gated K+
gated channels in axon
- voltage gated Na+
- voltage gated K+
gated channels in axon terminals
- voltage gated Na+
- voltage gated K+
- voltage gated Cl-
