2.3 animal transport Flashcards
2 types of circulatory systems
open
closed
what is an open circulatory system
the transport medium is moved into a large space in the body cavity
(haemocoel)
blood does not flow in blood vessels
who has an open circulatory system
insects
what is a closed circulatory system
the blood flows in. blood vessels
respiratory gases are transported in the blood
explain the circulatory system in an insect
blood is pumped from a dorsal tube-shaped heart and a dorsal vein that runs the length of the body into a large fluid filled body cavity known as the haemocoel
blood bathes the tissues directly and returns slowly to the heart
two types of closed circulatory systems
single
double
what is a single closed circulatory system
the blood moves through the heart once for each cycle around the body
who has single circulation
earthworms and fish
what is double circulation
the blood moves through the heart twice for each cycle around the body.
closed circulation in an earthworm
blood flows forward in the dorsal vessel (back) and back in the ventral (front) blood vessels that run the length of the body. vessels are connected by five pseudo hearts
what keeps blood pumping in earthworms
pumping action of the pseudo hearts and the thickened, muscular blood vessels
advantages of closed circulation
-for larger animals it allows them to control the flow of blood to certain parts of the body
- greater blood pressure generated so blood can flow faster
disadvantages of closed circulation
more energy is required
more complex as contains a network of vessels
3 main layers of the walls of arteries and veins
-tunica externa
-tunica media
-tunica intima
describe structure and function of tunica externa
made of collagen which resists overstreching
structure and function of tunica media
made of smooth muscle tissue
contraction of which regulates blood flow and maintains blood pressure
also made of elastic fibres for elastic recoil and to maintain pressure
structure and function of tunica intimacy
a single layer of smooth endothelium
which reduces friction and produces minimal resistance to blood flow
what are the only arteries that contain valves
aorta and pulmonary artery
structure of arteries
-thick muscle layer (can be constricted and dilated) to control the volume of blood
- thick elastic layer
-no valves as blood is under high pressure
-lumen is small
structure of capillaries
-one cell thick endothelium on a basement membrane
-smaller diameter which slows the rate of blood flow
-lots of capillaries=large total cross sectional area= large reduction in blood flow due to increased restriction
structure of arterioles
small arteries
-smooth muscle
- can constrict and dilate
structure of veins
-larger diameter, thinner walls, blood is at a lower pressure
-larger lumen
-valves to prevent back flow of blood
properties of the heart
consist of…..
-cardiac muscle walls
-coronary arteries (own blood supply)
-4 chambers (2 atria/2 ventricles)
- valves
role of the pump on the left
pumps out oxygenated blood to the body
role of the pump on the right
pumps out deoxygenated blood to the lungs
direction of blood : atria
artery to body
direction of blood: vena cava
vein from the body
direction of blood: pulmonary artery
artery to the lungs
direction of blood: pulmonary vein
vein from the lungs
where is the highest blood pressure (blood vessels)
aorta and arteries
rise and fall in pressure here= contraction and relaxation of the ventricles in the heart
blood pressure changes
arterioles
friction with vessel walls causes a pressure drop. have a large surface area and are narrow so there’s a substantial drop in pressure
what does pressure in the arterioles depend on
whether they are dilated or contracted.
blood pressure changes
capillaries
have a huge cross-sectional surface area, reduces pressure slows blood flow
what does reduced blood pressure do
slows blood flow
what does reduced blood pressure in the capillaries allow for
time for the exchange of substances
blood pressure changes in veins
pressure is low
what do the coronary arteries transport
oxygen, glucose and other metabolites
explain the journey deoxygenated blood takes
returns to the heart through the vena cava and enters the right atrium. once the right atrium has filled with blood the wall of the atrium contracts (increase in blood pressure) forces the tricuspid valve open and blood enters the right ventricle. once the right ventricle is full of blood, wall of the ventricle contracts from the apex which forces blood up. tricuspid valve shuts and the semi-lunar valve is forced open. blood is transported to the lungs
explain the journey of oxygenated blood
returns to the heart via the pulmonary vein. the left atrium fills with blood and then contracts. the bicuspid valve is forced open allowing blood to fill the left ventricle. once the left ventricle is full it contracts and forces blood upwards. (increases blood pressure) closes the bicuspid valves and forces the semi-lunar valve open. blood is forced into the aorta and onwards to the body at high pressure
what does the cardiac cycle describe
the sequence of events of one heartbeat
0.8 seconds
3 stages
what is the cardiac muscle contraction
myogenic which means it beats on its own. contraction is stimulated from the muscles. it does not need impulses from nerves to make it contract
systole
=
contraction
diastole
=
relaxation
3 stages of the cardiac cycle
atrial systole (ventricles in diastole)
ventricular systole (atria in diastole)
diastole (atria & ventricles) ventricles first
explain what happens in atrial systole
-atria contract
-blood flows through the atria-ventricular valves into the ventricles
-pressure is low (thin atrial walls)
- back flow is prevented (valves closing)
explains what happens in ventricular systole
- ventricles contract
- atrio-ventricular valves close (greater pressure in ventricles)
-semi-lunar valves in aorta & pulmonary arteries open
-blood flows into the arteries
-thick muscle walls generate greater pressures in the ventricles
-the left ventricular wall is partially thick and strong
why is the left ventricular wall thick and strong
it has to pump blood around the whole body
explain ventricular diastole
and then diastole
VD
-heart relaxes and pressure in the ventricles drops
- semi-lunar valves shut to prevent back flow of blood from the arteries
other:
-whole of the heart muscle relaxes
-blood flow from the veins flows into the atria
-cardiac cycle begins again
changes in pressure within the heart
(atrial systole)
-walls of atria contract, increases pressure in the atria. (still low)
trio-ventricular valves close as pressure in ventricles begin to increase