Physiology Lab - Cellular Physiology

anatomy

study of the structure and description of the human body

physisology

study of biological functions and processes of the human body under basal conditions

basal

normal

cellular physiology

study of the biochemical and biophysical processes occurring within cells

systemic physiology

study of the regulation of physiological processes within the body by homeostatic reflexes

pathophysiology

study of abnormal biochemical and biophysical processes that occur in disease

homeostasis

the dynamic constancy of the internal physiological environment while buffering the challenges of the external environment

Feedback control mechanism steps

1. stimulus produces change in variable
2. change detected by receptor/sensor
3. input: information sent along afferent pathway
4. output: information sent along efferent pathway
5. response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis

Lay terms of feedback mechanism

stimulus, receptor, control center, effector, response

Negative feedback system

response of the control system is negative or opposing to the stimulus; most systems in the body

Example of negative feedback system

Stimulus: weather increased body temp
Receptor: thermoreceptor
Control center: hypothalamus
Effector: sweat glands
Response: sweating

positive feedback system

the response of the control system is positive or promoting the stimulus; act to amplify the initial response to the stimulus; continues until the stimulus is removed

Positive feedback system examples

child birth and blood coagulation

plasma membrane

serves as an external cell barrier that is selectively permeable

amphipathic

both hydrophyllic and hydrophobic

phosphate heads

hydrophillic

fatty acid tails

hydrophobic

molecules that can cross plasma membrane without assistance

- small uncharged molecules
- non-polar molecules
- fatty molecules
- water (slowly; fast transfer requires mechanism)

Passive transport

substance moves down its concentration gradient, from area of high concentration to low concentration

Simple diffusion

natural movement from high to low concentrations; unassisted transport (no integral protein)

Facilitated diffusion

substances passively moves down its concentration gradient with the help of a protein molecule

channel mediated

special transport proteins create hydrophilic tunnels in the lipid bilayer; facilitate the transport of small, polar molecules and ions

carrier mediated

special transport proteins carry the substance across; facilitate transport of large polar molecules

active transport

transport of a substance across a cell membrane against the concentration gradient

primary active transport

carrier proteins pump the molecules against the concentration gradient; direct use of cellular energy

secondary active transport

downhill movement of one molecule drives the uphill movement of another molecule; indirect use of energy (uses established concentration gradient to power its transport)

vesicular transport

bulk transport of substances into or out of the cell

endocytosis

substances are taken into the cell by modifying the plasma membrane structure

phagocytosis

cell eating; cell engulfs large particle by forming projecting psuedopods around it and enclosing it within the membrane sac (phagosome)

pinocytosis

cell drinking; enfolding of plasma membrane carries a drop of extracellular fluid containing solutes into the cell in tiny membrane-bound vesicle

exocytosis

substances are released from the cell into the extracellular environment; most secretion processes

osmosis

passive diffusion of water against concentration gradient through plasma membrane (hypotonic to hypertonic)

hypotonic solution

lower solute concentration, higher water concentration, net movement of water out of this side

hypertonic

higher solute concentration, lower water concentration, net movement of water toward this side

isotonic

equal solute and solvent concentration on both sides; water molecules continue to cross membrane but no net movement

tonicity

measure of potential difference in osmotic pressure gradient of two solutions separated by a semipermeable membrane

outside of cell is hypertonic to inside of cell

cause the blood to shrivel

outside of cell is hypotonic to inside of cell

causes the blood to lyse

epigenetics

mechanisms by which genes can be switched on and off but genes themselves are not altered