3.2 transport in animals Flashcards
double circulatory system
blood flows through the heart twice on each complete circuit of the body
single circulatory system
blood flows through the heart once for each circuit of the body
need for a transport system in large animals
- all animals need oxygen + nutrients to grow and survive
- need to remove waste products so they dont build up and become toxic
- large animals mean diffusion distance is too long, and not efficient enough to supply all the requirements
3 factors that influence the need for a transport system
- size
- SA:V
- level of metabolic activity
how does size affect need for a transport system
- cells inside a LARGER organism are further from surface
- greater diffusion distance
- diffusion too slow to supply all requirements
- ALSO, outer cells use up supplies so less reaches the cells deep inside
how does SA:V affect need for a transport system
- small animals = LARGE sa:V
-for each unit3 of tissue in their body they have a sufficient area through which exchange can occur
how does level of metabolic activity affect need for a transport system
- animals need energy to move, which requires oxygen for aerobic respiration
- animals that keep themselves warm (eg mammals) need even more energy
3 features of a good transport system (humans)
- effective fluid or medium to carry nutrients, oxygen and waste around the body (blood)
- a pump to create pressure to push the fluid around the body (heart)
- exchange surfaces to allow substances to enter the blood and leave where needed (capillaries)
fish type of circulatory system
single
mammals type of circulatory system
double - 2 separate circuits
pulmonary circulation
circuit that carries blood to longs to be oxygenated
systemic circulation
circuit that carries the oxygen and nutrients around the body to the tissues
single circulatory of fish disadvantages
- blood pressure drops as blood passes through capillaries of the gills
- blood has a low pressure as it flows towards the body, so flows slowly
- limited rate at which oxygen and nutrients are delivered to respiring tissues and co2 and urea are removes
why is it not a problem that fish circulatory system is only single and bad
- fish are less metabolically active than mammals as dont maintain body temperature
- so need less energy
-single circulatory delivers sufficient oxygen and nutrients for their needs
of the 2 circulatory systems WITHIN double, which carries blood at a higher pressure
systemic (oxygenated blood to respiring tissues)
why must pressure be lower in pulmonary circulation
to not damage the delicate lung capillaries
arteries
carry blood away from heart
arterioles
small blood vessels, distribute blood from an artery to the capillaries
closed circulatory system
blood held in vessels
open circulatory system
blood not held in vessels
disadvantage of open circulatory system
- bp low so slow blood flow
- circulation of blood affected by (or lack of ) body movements
- slower delivery of o2 and nutrients
- slower removal of co2 and other wastes
what bathes tissues and cells in OPEN circulatory
blood
what bathes the cells in CLOSED circulatory
tissue fluis
advantages of closed circulatory system
- higher bp, so quicker blood flow
- more rapid delivery of oxygen and nutrients
- more rapid removal of CO2 and other wastes
- transport independent of body movements
what do all blood vessels have
endothelium
endothelium
- thin inner lining layer
- smooth to reduce friction with the blood
why is the artery wall thick
to withstand high pressure
artery lumen? (2)
- small to maintain high pressure
- inner wall folded to allow lumen to expand as blood flow increases
three layers of wall
innermost to outermost
- tunica intima
- tunica media
- tunica adventitia
tunica intima
- endothelium
- elastic tissue
tunica media
- smooth muscle + elastic tissue
tunica adventitia
- collagen
-elastic tissue
purpose of elastic tissue
stretch and recoil to withstand blood pressure, and MAINTAIN
purpose of smooth muscle
- strengthen walls to waistband pressure
- contract and narrow lumen to reduce blood flow
purpose of collagen
protects blood vessels from damage by over stretching
why do arteries near the heart have more elastic tissue
- stretch and recoil
- evens out fluctuations in blood pressure created by the heart
arteriole walls contain
smooth muscle
why is it important arterioles have smooth muscle
- can contract to constrict diameter of lumen
- increases resistance to flow and reduces rate of blood flow
- can divert the flow of blood to regions of the body that demand more oxygen
capillary lumen
- very narrow
- diameter of red blood cell
- RBCs squeeze through as they pass along, helping the transfer of o2
capillary walls (2)
- single layer of flattened endothelial cells -> short diffusion distance for materials being exhcanged
- leaky walls -> allows plasma and dissolved substances to leave the blood
venules
connect capillary to vein
vein lumen
large
- low pressure blood, reduces friction
vein walls (2)
- less thick
- thinner collagen, elastic tissue and smooth muscle as dont need to stretch and recoil as low pressure
veins contain …
Valves
purpose of valves
prevent back flow of blood
how is some blood in the veins moved
- thin walls mean contraction of surrounding skeletal muscle flattens vein
- pressure applied to blood, forcing it to move along
hydrostatic pressure
exerted by a fluid when pushing against the sides of a vessel
lymph
fluid in lymphatic system
oncotic pressure
pressure created by osmotic effects of solutes
blood contains
PLASMA
What does blood plasma contain (7)
dissolved substances
- o2 + co2
- glucose
- amino acids
- hormones
- platelets
-RBCs
where is blood
contained in vessels (closed circulatory )
difference in tissue fluid v blood plasma
- tissue fluid doesnt contain cells or plasma proteins
how is tissue fluid formed
- blood flowing to tissues is in the CAPILLARIES
- at the arterial end of the capillary, the blood has a high hydrostatic pressure. the pressure pushes the blood fluid out of the capillaries through the capillary wall.
- the fluid that leaves consists of plasma with dissolved nutrients and oxygen (tissue fluid)
- RBC,WBC, Platelets are all too large to be pushed out of the small gaps in the capillary wall
how does tissue fluid re enter blood
- bp at VENOUS end of capillary is lower
- some tissue fluid returns to the capillary carrying co2 and other waste into the blood
does all tissue fluid return to the blood?
NO
Some is directed to the lymphatic system, which drains excess tissue fluid out of the tissues and returns it to the blood via the subclavian vein in the chest
fluid in the lymphatic system
lymph (similar to tissue fluid with more lymphocytes)
how do lymph nodes become swollen
- tissue is infected -> capillaries more leaky -> more fluid directed into the lymph system
compare the pressures in blood plasma, tissue fluid and lymph
blood plasma: - high hydrostatic, more negative oncotic
tissue fluid: - low hydrostatic, less negative oncotic
lymph: - low hydrostatic, less negative oncotic
hydrostatic pressure of blood…
pushes fluid out into the tissues
hydrostatic pressure of tissue fluid…
pushes fluid into capillaries
oncotic pressure is always
negative
oncotic pressure of blood…
pulls water back into blood
result of all the forces
creates a pressure gradient
- fluid pushed out of capillary at arterial end
- fluid pushed into capillary at venule end
right side of heart
pushes deox blood to the lungs to be oxygenated
left side of heart
pumps ox blood to the rest of the body
coronary arteries
- surface of heart
- supply oxygenated blood to the heart muscle
atria
upper chambers
ventricles
lower chambers