B7.2 Heart Flashcards
Define the circulatory system
system of blood vessels
Purpose of valves
ensure that blood circulates in one direction
What is the heart
muscular organ
Define arteries (2)
large blood vessels
carry blood away from heart
Define capillaries (3)
tiny blood vessels
from network throughout ever tissue
connect arteries to veins
Define veins (2)
large blood vessels
carry blood towards heart
What happens when arteries get farther from the heart (2)
become narrower
divide more
Define arterioles (2)
narrow vessels
connect arteries to capillaries
Why is mammalian circulatory system called double circulation
blood passes through heart twice
Why does blood leaving the right side of the heart have low pressure (2)
blood does not travel far to lungs
lower pressure stops damage to capillaries in lung
Why does blood leaving the left side of the heart have high pressure
has to travel throughout body and back to heart
Define the septum (2)
layer of tissue
separates right and left side of heart
Name the 4 chambers of the heart
right atrium
right ventricle
left atrium
left ventricle
Name of blood vessels which provide blood to heart (2)
coronary arteries
coronary veins
How does deoxygenated blood flow into the heart (6)
blood arrives at heart from vena cava
enters right atrium
contraction of right atrium moves blood to right ventricle passing one-way valve
contraction of right ventricle moves blood to pulmonary artery and to lungs
valve at entrance of pulmonary artery closes to stop backflow into right ventricle
valve between ventricle and atrium closes to stop backflow into atrium
How does oxygenated blood flow out of the heart (5)
enters left atrium from lungs through pulmonary vein
left atrium contracts and passes blood to left ventricle through valve
left ventricle contracts and moves blood out through aorta to body
valve at entrance of aorta closes to stop backflow into left ventricle
valve between atrium and ventricle closes to stop backflow of blood into atrium
Define heart rate (2)
measure of how frequently the heart beats
measured in beats per minute
Why may heart rate vary (4)
age - children usually have faster beat than adults
fitness - more muscle in heart hence pumps more blood
illness
drugs
True or false? The harder you exercise the faster your heart beats
True
How is a heart attack caused
a full blockage of cholesterol
What factors increase risk of blockage in coronary arteries (2)
high level of saturated fats in diet
smoking may damage artery lining
Name of blood vessels associated with lungs (2)
pulmonary vein
pulmonary artery
Name of blood vessels associated with kidneys (2)
renal vein
renal artery
Define the vena cava
vein that carries blood to heart
Define he aorta
artery that receives blood from heart
Characteristics of arteries (3)
thick/elastic muscular walls
narrow central space (lumen)
high pressure
Characteristics of capillaries (2)
thin walls - one cell thick
low pressure
Characteristics of veins (3)
thin walled
large lumen
low pressure
How does artery structure relate to its function (2)
thick walls don’t burst from high pressure
elastic walls maintain blood pressure
How does capillary structure relate to its function
thin walls increase diffusion rate
What substances does blood contain (4)
plasma
red blood cells
white blood cells
platelets
Define plasma (3)
yellow coloured liquid
mainly consists of water
carries soluble nutrients, ions,
hormones, wastes (carbon dioxide), minerals throughout body
Characteristics of red blood cells (2)
biconcave shape
no nucleus - allows them to carry more haemoglobin
Define haemoglobin (2)
protein that transports oxygen
gives red blood cells red colour
Define platelets (2)
small fragments of much larger cells
protects body from infection by causing blood to clot
Function of white blood cells (2)
part of immune system
defend body against disease
Define antibodies
chemicals which attack pathogens
Define phagocytosis
killing pathogens by engulfing them
Purpose of circulatory system (2)
deliver oxygen/nutrients (glucose) to cells for respiration
remove waste products e.g carbon dioxide
Advantages of double circulation (2)
maintains concentration gradient by preventing oxygenated and deoxygenated blood from mixing
enables difference in pressure of blood exiting right and left side of heart
What percentage does plasma make of total blood
55%
What percentage do white blood cells/platelets make of total blood
less than 1%
What percentage do red blood cells (erythrocytes) make of total blood
45%
