Haemodynamics Flashcards
Cardio Vascular Functions
Brings nutrients + gas to and wate away from all body cells, thermoregulation, immune system and endocrine signalling medium
What do we infer about capillary design based on fick’s first law
Capillaries branched network leaves a smaller distance between vessels and cells (increased flux). Circulation system is designed to maintain concentration gradient. Area exposed to blood flow is high due to capillary densty
Relationship between % cardiac output distribution and % o2 consumed by region
Typically similar. Outliers are the kidney as it filters blood from all over the body and requires extra O2 to function and the skin as it is given more bloood then it’s cells need for metabolism for thermoregulation
How long does it take for an erythrocyte to moove through an adult system at rest
< 1 min
2 Systems
Systemic (heart-body-heart, high pressure = high ressistance, blood oxygenated out of heart) and pulmonary (heart-lungs-heart, low pressure = low ressistance, blood deoxygenated out of heart)
What is driving force of blood pressure in systems
pressure gradient formed by beating heart
Arteries and arterioles Outline
Thick layer of smooth muscle, elastin (enabling to return back to shape) and collagen fibres. Arterioles contain more muscle while arteries contains more elastic properties
One explanation of increased blood pressure
Blood vessels become more stiff with age as elastic components wear down
Veins and Venules Outline
Thin walls (little internal muscle or elastic components), low pressure, contain valves and external muscle pumps, better capacitance (more blood volume) then arteries
Microcirculation Exchange
Capillaries exchange substances between cells and vessels. Thin walls and large surface area (high capillary density)
3 Types of Capillary
Continuous, fenestrated and sinusoidal (discontinues)
Continuous Capillaries Outline (most common)
Endothelial cells lie ontop of eachother like slates. Makes flow difficult. Eg at the blood brain barrier
Fenestrated Capillaries Outline
Gaps (windows) through cells. Enables small lipophilic molecules to pass through. Eg at kidney nephron
Sinusoidal Capillaries Outline
The widest gaps possible through cells. Allows erythrocytes (and other bloood cells through)
Movement of molecules between/across cells
Blood - Endothelium - ICF
How large (lipophobic) molecule move across cells
Receptor mediated endocytosis (vesicular)
Diffusion Movement
Solutes move from areas of high to low conc and solvent will follow
Osmosis Movement
Solutes remain static. Liquids move to balance osmoality
Osmotic Pressure Def.
Physical force opposing liquid movement. Proportional to osmoality
Starling’s Hypothesis Outline
Blood flow out of capillaries aims to balance pressures in vessel. Balances Hydrostatic pressure and osmatic pressure
Hydrostatic pressure Outline
Pushes fluid forward (out of vessel). Net hydrostatic pressure = hydrostatic capillary - hydrostatic interstitial
Colloid Osmatic Pressure / Oncotic PressureOutline
Holds fluid in vascular compartment (via plasma proteins). Net = Oncotic in capillaries - oncotic in interstitial
Net filtration pressure Outline
Net pressure pushing blood out of capillaries = net hydrostatic - net onoctic pressure
Cjanges in blood pressure in body
Low capillary pressure = aretriole constriction, results in shock. Increase capillary pressure = venous pooling (heart failure)
