Moving blood through the body 5.2

5.2

Where is the heart located in the body

between the lungs in the mediastinum, and behind the sternum

what is the name and function of the membrane around the heart

the pericardium - holds the heart in place but allows it to move as it beats to prevent it from stretching

what muscle is the heart made of

cardiac muscle

what separates the left and right sides of the heart

the septum

what sides recieve/pump blood

Left - receives blood from lungs and pumps to body

Right - receives blood from body and pumps to lungs

what are the top and bottom chambers of the heart called

top - atria, bottom - ventricles

explain where blood goes in the hearts chambers

right atrium receives blood from body and passes to right ventricle

right ventricle pumps blood to lungs

left atrium receives blood from lungs and pumps it to left ventricle

left ventricle pumps blood to body

what wall is thicker and why

left ventricle wall is thicker to pump blood to all vessels in body

valves between atria and ventricles

atrioventricular valves

what are the tendons that hold the valves

chordae tendineae

what do the chordae tendineae attach to

the papillary muscles

what happens when the atrioventricular valves contract

the blood catches behind the flaps and the opening between atria and ventricle is sealed, so the blood must leave the heart through the arteries and not go back up into the atria

what are the semilunar valves

the valves that stops blood flowing back into the ventricles

structure of semilunar valves

three cusps that fill up and seal when blood tries to flow back into the ventricle

types of atrioventricular valves

tricuspid valve - right side, 3 flaps

bicuspid valve, - left side, 2 flaps

types of semilunar valves

pulmonary - right side

aortic - left side

what is circulation

the continuous flow of blood

what direction do arteries carry blood

away from the heart

what is the aorta

the largest artery that takes blood from left ventricle to body

what is the pulmonary artery

takes blood from right ventricle to lungs

what are the walls of an artery made of

smooth muscle and elastic fibers

how is blood kept moving and pressure maintained in the arteries

when ventricles push blood the arteries stretch, when ventricles relax the arteries recoil

what is the relaxation and contraction of arteries called and what is their purpose

vasoconstriction - reduces blood flow to an organ

vasodilation - increases blood flow to an organ

blood flow can be controlled to bodies needs

arterioles

small artery divisions, supply blood to capillaries, made of smooth muscle

what are vasodialators

waste substances that dilate arterioles to increase blood flow in muscle tissues to remove products of cellular respiration and supply these cells with oxygen and nutrients

capillaries

link between arteries and veins, carry blood close to every cell in the body, cell wall is only one layer of cells

veins

carry blood towards heart

what joins veins to capillaries

venules

what are the large veins that bring blood from body to right atrium

inferior vena cava - blood from below heart
superior vena cave - blood from above heart

what veins bring blood from lungs to left atrium

pulmonary veins - two for each lung

why is vein structure different to artery structure

they are thinner and not as elastic and contain valves due to their low pressure

what are the two ways our blood flow changes to suit different conditions

by changing output from heart and by changing diameter of blood vessels supplying the tissues

what is the cardiac cycle

the sequence of events that occur in one beat of the heart

systole

the pumping phase

diastole

the filling phase

atrial systole

contraction of atria forcing blood into ventricles

ventricular systole

forces blood into arteries

heart rate

the number of beats per minute

stroke volume

volume of blood forced from ventricle with each contraction

cardiac output

amount of blood leaving ventricles every minute