cells part one Flashcards
whats cell (plasma membrane)
forms the external boundary of the cell. it separates cell from its external enviroment. regulates the transportation of substances into or out of the cell eg oxygen or glucose. it is selectively permamable
whats cytoplasm
consists of gel like substance in which numerous organelles are suspended. the organelles are small and varied structures of the body which provide structure and carry out various functions of the cell.
whats the nucleus
control centre of the cell. contained within its own membrane. within it is the nucleic acid DNA which contains the genetic informnation of the individual. DNA is responsible for directing protein synthesis and regulating the cell life cycle and function.
cell membrane fluids
flexible structure that defines the extent of the cell by separating two fluid compartments. Intracelluar fluid which is inside the cell and extracellular fluid which is outside the cell
what does cell membrane do
its selectivly permable membrane which regulates the transportation of substances into and out of the cell between the ICF and ECF.
what is cell membrane made up of
Phospholipid bilayer - double layer phospholipids, each lipid is composed of a hydrophilic phosphate head and two hydrophobic lipid tails
Proteins - numerous types of proteins are found, they funtion enzyme activity, cell to cell recognition, attachment to cytoskeleton, receptors for signal transduction and transportation of substances into and out of body
carbohydrates- some surface carbs form antigens on the cells surface which identify that cell as self to bodys immune cells
glycolipids - combined lipid and carbo
glycoprotein - combined protein and carbo
cholesterols - stabilize the membrane while allowing mobility and flexibility.
what fluids make up body
water accounts for 55-60% of body fluids. it is contained within two compartments. ICF and ECF. intracellular makes up majority of total body water fluids at 66%. ECF makes up the remaining outisde the cell at 33%. it is futher split up into plasma which takes up 8% (1/5) and interstitial fluid which takes up 25% (4/5)
whats is most common electrolyte in ICf and ECF
potassium in ICF and sodium in ECF
whats diffusion
diffuion of solutes across the cell membrane is driven by that solutes concentration gradient the difference in concentration of the solute between the ICF and the ECF when a solute diffuse it will always move down the concentration gradient. from high to low conc.
describe diffusion via protein channel
sodium ions move through a sodium cheannel down their concentration gradient.
describe diffusion via carrier protein
amino acids movr into a cell via a carrier protein beacuse there is less amino acids inside the cell
describe simple diffusion
carbon dioxide molecules move out of the cell through the phospholipid bilayer
whats osmosis
the diffusion of water. can occur during simple diddusion but mainly through special protein carriers called aquaporins. osmosis is based on the osmolarity between the icf and eco. the osmolarity should be equal, if not water will move between them this is called a fluid shift. water always moves from low osmolarity to high
whats a fluid shift
if water and or electrolyte intake and output are not balanced the ECF osmolarity changes and to composate there will be a fluid shift. fuild shift alters volume and size of the cells which can lead to celluar disfunction if these chnages are serve or sustained.
whats passive cell transport
occurs without the use of celluar energy and occurs via osmosis, diffusion or filtration
whats filtration
occurs acorss specially designed filtration barriers. its the movment of water and permeable substances across cell membrane due to the force of pressure. high pressure in one fluid compartment can push substances across the membrane into an area of low pressure.
whats active cell transport
requires the use of ATP to move substances cross the cell membrane against their concentration. from low to high conc
how does active transport work
solute transporter pumps are proteins that actively move dolutes across the cell membrane against their conc gradients. there are different types of pumps depending on the number of solutes being moved and their direction of movement. one of the most important is odium potassium pump, it pushes sodium out of cells and potassium into cells which is esstienal for healthy cell survival.
whats vesicular transport
describes the transportation of fluids containing large particles (macromolecules) across the plasma membrane. small membranous sacs called vesicles composed if phospholipids surround the fluid and the cell to be transported and release their contents on the other side of the membrane
exocytosis
vesicle formed within the cell bind to and fuse with the cell membrane then release their contents outside the cell
endocytosis
substances from the exterior of the cell are wrapped in a small bit of the phospholipids od the plasma membrane which pinches off and moves into the cell. a particular form of endocytosis includes phagocytosis which is the process by which certain body cells engulfs and then destroy microorganisms or large particles
most important electrolytes for body fluid balance and hormones that regulate them
sodium - aldosterone - stimulates kidney to retain sodium (eg decrease urine loss)
potassium - aldosterone - stimulates kidney to excrete potassium (eg increase urine loss)
calcium - parathyriod hormone - stimulates kidneys to retian calcium (eg decrease urine loss) stimulates increase intestinal absorption of calcium from diet and stimulates release of stored calcium form bones into blood. This all ensures the osmolarity between ICF and ECF is maintained and fluid shiftd avoided
water balance mechanisms
thrist mechanism - triggered when osmolarity of the plasma increases to encourage water consumption to decrease it. also triggered by signifigant losses in plasma volume as water consumption will increase blood volume. is controlled by hypothalamus
Anti diuretic hormone (ADH) - hormone that stimulates kidneys to retain water (eg decrease urine loss) while there is minimum amount of water that must be exerted by the kidneys each dayto ensure removal of certain solutes from the body. ADH can decrease water loss to this minimum to conserve water. ADH is released when osmolarity of plasma increases
cytoplasm main parts
cytosol - viscous fluid which suspends the other cytoplasmic contents. composed of mainly water but also proteins and solutes.
organelles - structures or machines in the cell that carry out specific cellular functions
inclusions - chemical substances that are present in some cell types
cytoplasm is everything between membrane and nucleus
whats anabolism and catabolism
anabolism - any process which larger molecules or structures are built from smaller ones. these are synthesis or genesis reactions which store energy and heat.
catabolism - any process that breaks down complex structures into smaller molecules. these are degenerative reactions which release energy and heat
whats BMR
basal metabolic rate. its the base rate of metabolic reactions (energy outputs) required to maintain only the body most essentail functions. to maintain BMR it will require minimum energy input (nutrition)
whats cellular metabolism
involves metabolic reactions taking place within a cell that utilise the nutrients from the diet
main components of cellular metabolism
anabolic reactions - facilitate energy storage and structural building/repairing
catabolic reactions - lead to step two and the generation of ATP. this step occurs within cytoplasm of the cells
whats cellular respiration
a series of catabolic reactions which generate atp. in most cases oxygen is required for this step and occurs inside the mitochondria of body cells.
cellular respiration cycle
pyruvic acid turns to Acetyl COA then to the krebs cycle which is a series of reactions that create 4 reduced co-enzymes. these undergo oxidative phosphorylation and electron transport chain which then creates lots of ATP
gluconeogenesis meaning
conversion of fats or proteins into glucose
lipolysis meaning
breakdown of triglycerides into glycerol and three fatty acids
glycogenesis meaning
formation of glycogen from glucose molecules (glycogen is long chains of glucose molecules for storage)
protein synthesis
formation of proteins from amino acids
glycolysis meaning
breakdown of glucose into pyruvic acid molecules
lipogenesis
formation of triglycerides from glycerol and fatty acids (may be derived from glucose)
transamination and deamination
removel of nitrogen/amine group from amino acid to convert it into a keto acid for entry into the Krebs cycle
glycogenolysis
breakdown into individual glucose molecules
