Circulatory system Flashcards
What are the functions of the circulatory system
distribution of nutrients, support for metabolism (O2 delivery), distribution of water and electrolytes, transportation and distribution of hormones
What are the principle components of a circulatory system
Fluid that circulates through the system, mechanism that applies force to drive the fluid, system of tubes for the fluid to pass through, valves or septa to ensure unidirectional flow
Open circulatory system
incomplete system of vessels. Contains a circulating fluid called haemolymph which flows through vessels and freely percolates through intracellular spaces. Bathes internal organs and therefore directly reaches every cell of the body
Open circulation in insects
Use tracheal system to transport nutrients and CO2. Circulation can be less efficient when respiratory gases are handled through a separate system
Features of a closed system
complete and continuous system of blood vessels, blood, heart propels blood through vessels, intercellular spaces filled with interstitial fluid. Lymph in lymphatic vessels
Where does diffusion occur in the circulatory system
between blood vessels and interstitial fluid at the capillary bed
Requirements of an efficient circulatory system
Efficient O2 carriers in blood or haemolymph, efficient gas exchange and delivery of nutrients, diversification of oxygenated fluid to systemic organs and deoxygenated fluids to respiratory organs, fast flow of fluids
Flow rate formula
change in pressure/ resistance
pressure and resistance in a closed circulatory system
high change in pressure and high resistance
pressure and resistance in an open circulatory system
change in pressure is low and resistance is low
Functions of the mammalian cardiovascular system
distribution of O2 and nutrients, transportation of CO2 and removal of metabolic waste, distribution of water, electrolytes and hormones, thermoregulation, immune system infrastructure
arrangement of the mammalian cardiovascular system
4 chambered heart (unidirectional flow), blood supplies to systemic vascular bed run in parallel, pulmonary circulation runs in series, high pressure system
Components of a blood vessel
endothelium, smooth muscle, connective tissue
Function of the endothelium
lining of blood vessels, lines entire cardiovascular system, keeps blood in system, allows transfer between vessels and surroundings
where does the blood stream exchange things
through tissue fluid and endothelial cells. Junctional complex
Cycle of the circulatory system
heart, elastic arteries, muscular arteries, arterioles, capillaries, venuoles, veins, nheart
Elastic arteries function
smoothing. Catch blood that comes out of the heart and when the heart ventricle pumps it produces a burst of very high-pressure blood into the elastic arteries which expand, increasing their volume and reducing the pressure, when blood moves back out, elastic arteries shrink back in and increase the pressure again
Muscular arteries function
can be big and decrease in size as they get longer, muscles contract to control the diameter
arteriole function
controls blood flow to the capillaries at sufficient pressure
Capillary function
gas exchange. Thin and delicate
Venule function
Can exchange fluid with surroundings
General structure of blood vessels (except capillaries and sinusoids)
tunica intima (endothelium+CT), tunica media (smooth muscle + CT), tunica adventitia (CT), internal elastic lamina (IEL), extrernal elastic lamina (boundaries of t.media)
What is the arrangement of smooth muscle
long and thin, circular (controls diameter), narrow, small muscular artery + vein
Elastic arteries: aorta, pulmonary artery
very big lumen, thick walls, smooth muscle cells are contractile, elastic fibres organised into sheets, parallel to one another and run around the vessel, arranged concentrically and circular lumen, collagen to resist tension,
Blood supplies to large arteries
thick walls of busy, living vells that requiire gases, vessels above certain sizes have their own circulation in walls, walls too thick to receive adequate O2 nutrient supply and waste disposal from centre
What are muscular arteries lined with
endothelium
Arteriole structure
same structure as larger vessels. Thicker wall and smaller lumen
Capillary network
terminal arterioles that control blood flow to the capillary bed. Pressure must be enough to get blood flow but not too much to burst capillaries. Sinusoid - one cell thick
Continuous endothelium
sit on top of basement membrane, all sit in complete layer, found in most layers and exchange solutes and gases
Fenestrated endothelium
cells have pores between them, sit on top of intact basement membrane, found in capillaries in endocrine glands, exchange larger molecules (hormones)
Discontinuous endothelium
gaps between cells, gaps in basal lamina, cells don’t fit properly together, found in sinusoids, exchange whole cells, leaking tissue fluid
Venules and veins
thinner wall and larger lumen, bigger than capillaries, liquid exchange between plasma and tissue fluid, difference between venules and veins is the tunica media (vein is smaller), substantial T. adventita. Arterial pulse massages blood along vein, increases pressure in the veins. Muscle contraction squeezes and moves blood through valves
Valves
Folds of tunica intima (one way flow), valves point to the heart, pocket shaped structure
Blood (haemolymph) pressure
Difference between the pressure in the system and the ambient pressure (transmural pressure)
What are the 2 components of blood pressure
dynamic pressure (produced by the pump) and hydrostatic pressure of the fluid
What does the resistance of the system equal
sum of individual resistances of all elements
What can decrease resistance of the system
decreasing the number of resistors and adding more conductors
Artery function
conduit for blood to capillary beds, act as pressure resevoir to drive blood into arteries, damp oscillations in pressure and flow, control differential distribution to different organs and tissues