Movement of molecules around the body Flashcards
What are the 3 main fluid compartments?
1) intracellular 2) Extracellular - divided into 2 compartments - Interstitial - Plasma
What makes up 1/3 of the Total body weight?
extracellular fluid 3/4 extracellular = interstitial 1/4 extracellular = intravascular
What makes up 3/4 of the total body weight?
Intracellular = water, solutes, nutrients and gases
What is diffusion of uncharged solutes?
movement due to a solute concentration difference - occurs because of random motion of solute molecules
What is diffusion of charged solutes?
Electrolytes will also diffuse down a concentration gradient. - influenced by charges of particles around them = extra level of complexity around them
What is Osmosis?
Special type of diffusion -flow of water across a membrane that is permeable to water but not to solutes -Higher water concentration to a region of lower water concentration (higher solute concentration) - Water ‘follows salt’
What is oncotic or colloid pressure?
osmotic pressure generated by large molecules such as plasma proteins which cannot pass across the membrane
What is Fick’s Law?
The factors governing the rate of diffusion across membranes Expressed as:
What is the main difference between extracellular and intracellular fluid makeup?
Extracellular: protein is 0 Intracellular: Lots of potassium, but lower amounts of all other elements
What is Molarity?
Concentration (g/L)/ Molecular weight
What is Molality?
Moles of solute/Kg solvent
What is Osmolarity?
Osmostic concentration: concentration of particles/L in solution and is independent of the size or weight of the particles = number particles/mole X concentration/L
What is Osmolality?
Concentration of particles/Kg = number particles/mole X concentration/Kg
True or false: Osmolarity approximates osmolality when solutions are dilute?
True
What mostly determines osmolality/osmolarity concentrations?
Sodium ions
What is isotonic?
concentration of solutes on both sides of the membrane is equal and NO water movement occurs -haemorrhage fluid loss is isotonic
What is a hypertonic compartment or solution?
Higher concentration of solute outside (higher osmotic pressure) than inside the cell (lower osmotic pressure) *Net movement of water out of cell & cell shrinks & crenates* -Vomiting/diarrhea
What is a hypotonic compartment or solution?
when the solution outside of the cells has a lower osmotic pressure than the cytoplasm of the cells, the solution is hypotonic with respect to the cells *water moves into cell & cell expands - haemolysis: cholera, haemorrhagic gastroenteritis
What are teh 5 main parts of the cirulatory system?
heart: cardiac muscle contracts to pump blood around the body arterial system: distributes blood from the heart to the capillaries venous system: Acts as a reservoir for blood and returns blood to heart Lymphatic system: returns proteins and fluids back to blood
What are the functions of the circulatory system?
- exchange of substances with environment 2. transport of substrates and O2 to cells 3. Removal of metabolites and CO2 from cells 4. Thermoregulation 5. Immune cells and mediators
What do the capillaries do?
They are the most key part = exchange of fluid ( nutrients and metabolic products) between blood and interstitial fluid
What type of capillaries are these?
Continuous: - muscle - skin - lung - fat - connective tissue contain narrow junctions (clefts) & small, coated pits (caveolae) allowing hydrophobic molecules to pass
what type of capillaries are these?
Fenestrated: - kidneys - intestines - endocrine glands - joints Contains pores or fenestrae - permeable to small molecules = Much larger gaps
What type of capillaries are these?
Discontinuous: - bone marrow - liver - spleen = wide gaps between endothelial cells = permeable to large molecules
What are Neural capillaries?
Virtually just water can get across this one - maintains blood brain barrier
What are the three types of movement that allow substances to cross capillary walls?
- Diffusion 2. Transcytosis and pinocytosis 3. Bulk flow via Starling’s Forces - hydrostatic and osmotic forces
What are the functions of the lymphatic system?
- controls blood and interstitial fluid volume 2. specific transport systems - absorption of fat from gut 3. turnover of extracellular matrix constituents 4. defence systems
Where can lymph re-enter the lymphatic system?
- Left side: head and neck thoracic cavity - upper limb (Main entrance) 2. Right side: head and neck thoracic cavity - upper limb
What is Oedema?
Swelling of tissues due to excess fluid - generally due to the heart
What is lymphoedema?
Lymphatic system is not working properly - lymphatic themselves are directly affected Primary cause = lack of sufficient lymphatic vessels - blocked or damaged lymphatics
