A&P 2.14 cell membranes & cellular transport Flashcards
Plasma membrane
Cell membrane and boundary, maintains its integrity,
Protein molecules embedded in the plasma membrane perform various functions
Basic cell anatomy
Plasma membrane
Nucleus
Cytoplasm
Nucleus
Holds the genetic code which dictates protein synthesis, thereby playing an essential role in other cell activities, namely cell transport, metabolism and growth
Cytoplasm
Gel-like substance, includes various organelles suspended in a watery fluid called cytosol (intercellular fluid)
Components of the plasma membrane
Phospholipid bilayer
Membrane proteins
Phospholipid bilayer
Maintains cell integrity
Made of membrane proteins and receptor molecules allow for transport of molecules, hormones, and other chemicals involved in signal transduction
Enzymes catalyze specific reactions that regulate metabolic reactions
Phospholipid bilayer consists of
Six main types of proteins in the cell membrane
Layer is studded with membrane proteins performing various functions
Two layers: hydrophobic (lipid) tails and hydrophilic (phosphate) heads
Membrane layers
Phospho head - outer - water liking
Lipid tail - inner - water hating
Membrane proteins
Act as channels or carriers of molecules - controls transport of water soluble molecules from one compartment to another
Bind molecules outside the cell that form connections between cells & other structures (tissue fibers or other cells)
Those that bind to support filaments within the cytoplasm maintain shape and movement
Membrane proteins
Glycoproteins
Are proteins in the membrane that act as markers that recognize cells or organelles
Functions of membrane proteins
Formation of a channel
Transporter proteins
Receptor proteins
Membrane proteins
4
Ion channels
Carriers (transporters)
Receptors
Cell identity markers
Ion channels
Pores or holes through which specific ions can flow to get into or out of the cell (most ion channels are selective - one type of ion)
Carriers (transporters)
Selectively move a polar substance or ion from one side of the membrane to the other
Receptors
Cellular recognition sites, recognizes and binds a specific type of molecule ( insulin receptor)
Cell identity markers
Enable a cell to recognize other cells of the same kind or identify foreign cells (blood type)
Elements defined
Substances that cannot be broken down into a simpler form by ordinary chemical means (pure)
96 % of the human body is composed of
4 major elements:
Carbon
Oxygen
Nitrogen
Hydrogen
Compounds
More than one element combined
Classes of compounds
2
Inorganic
Organic
Inorganic compound
70% +- of our body is water (the most abundant and important compound)
Organic compound
Presences of carbon and they are protein, carbohydrates, lipids and nucleic acids ( RNA & DNA)
Carbon hydrogen bond
Transport across the membrane
2 types
Passive
Active
Passive transport
Movement of substances down a concentration gradient until equilibrium is reached,
Does not require cellular energy in the form of ATP
Particles move using energy they already have
Three types of passive transport
Diffusion
Osmosis
Facilitated diffusion
Diffusion
Movement of a substance by kinetic energy down a concentration gradient until equilibrium is reached
Simple diffusion
Passive movement of a substance through the lipid bilayer of the plasma membrane
Tendency of small particles to spread out evenly within a given space
Requires a concentration gradient
Measurable concentration difference between areas
Osmosis
Movement of WATER molecules through/across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration
Facilitated diffusion
Passive movement of a substance down a concentration gradient aided by ion channels and carrier molecules
Active transport
Defined
Movement of substances against a concentration gradient
Requires cellular energy in the form of ATP
Active transport
How it works
Transport in which the cell expends energy to move a substance across the membrane against its concentration gradient aided by MEMBRANE PROTEINS that act as PUMPS
Use energy supplied by ATP
Particles are actively PULLED across the membrane
Transport across the plasma membrane
2 types
Endocytosis
Exocytosis
Transport in vesicles
Movement of substances into or out of a cell in vesicles that bud from the plasma membrane
Requires energy supplied by ATP
Endocytosis
Movement of substance into a cell in vesicles
Endocytosis
2 types
Phagocytosis
Pinocytosis
Phagocytosis
“Cell eating”
Movement of a solid particles into a cell after pseudopods engulf it
Pinocytosis
“Cell drinking”
Movement of extracellular fluid into a cell by in folding of plasma membrane
Exocytosis
Movement of substances out of a cell in secretory vesicles that fuse with the plasma membrane and release their contents in to the extracellular fluid
How do neurotransmitters interact with the plasma membrane?
They bind to receptors on their surface
OBTURATOR internus
A, I, O
A -lateral rotation and extension of the femur
O - proximal attachment - internal surface of OBTURATOR membrane and rim of the pubis and ischium
I - distal attachment - medial aspect of the greater trochanter
OBTURATOR externus
A, O, I
A -lateral rotation and extension of the femur
O - proximal attachment - external surface of the OBTURATOR membrane and the rim of the pubis and ischium
I - distal attachment - medial aspect of the greater trochanter
Quadratus femoris
A, I, O
A -lateral rotation and extension of the femur
O - proximal attachment - upper part of the ischial tuberosity
I - distal attachment - just inferior to the greater trochanter (linea quadrata)
