Unit 4a - Circulation Basics Flashcards
Functions of the Circulatory system (5)
-diffusion, convection, transportation, transportation of heat, production of heat
3 basic components of the cir sys.
- circulatory fluid 2. pump 3. Vascular system
Characteristics of an open system
- incomplete system of vessels - most invertebrates -low blood flow and BP -slow return of blood to the heart
Characteristics of a closed system
- enclosded system of vessels -vertebrates, some inverts -higher blood flow and BP -blood/tissue exchange across capillary walls
Advantages of a closed system
- control velocity and distribution of blood -increase in metabolic rate and body mass -enable evolution of glomerula kidney
Undivided vs. divided blood (pros of divided)
- undivided= no separation -divided= complete or partial separation pros of divided= increased BP to body, increased metablolic rate and body mass
Evolutionary trend to become O2 breathers
- increase in o2 uptake -increased size- energy goes up - need separation of blood as well as an effecient blood transportation system -increase in BP and flow
3 types of vessels
arteries, veins and capillaries
what is the structure of the vessels
- all have an endothelial lining -arteries and veins have connective tissue (elastic and collagenous fibres) and smooth muscles
how does cross-sectional area affect velocity
-small cross section-= highest velocity = arteries, aorta
how does the large area of the capillaries influence the ability and speed of O2 delivery
- large area, velocity is low- spends a lot of time going through, allows lots of diffusion to occur
Tunica media and tuica adrentitia
tunica media- muscle layer around the endothelium tunica adrentitia= outer fibrous layer
How does the tunica media differ between large and medium arteries
large= elastic (needs to expand) medium= muscular
Compliance
-the elasticity of the aorta walls allows for dampening of the oscillation of the heart to allow for continuous blood flow
Arteries- Characteristics
- large= low resistance, low pressure drop -pressure is determined by the volume of blood and the wall properties - in charge of maintaining blood flow - thick muscular wals to withstand high pressure -PRESSURE RESERVOIR
What two factors can cause pressure in the arteries to increase and decrease respectively?
increase in cardiac output= increase in pressure increased flow into capillaries= decrease in pressure
Veins- Characteristics
- large diameter, low pressure, \ -VOLUME RESERVOIR (50% of blood) -smooth muscles, sympathetitc adrenegetic fibres —-these are less elastic- will tear if pressure is hight -venous blood flow is affected by muscle contractions and valves (expansion of the chest helps move venous blood to the heart)