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What is the purpose of the circulatory system?
- 1. transports gases from the respiratory system, nutrients form the digestive system and waste materials from the excretory system.
- 2. regulates body temperature and transports hormones.
- 3. protects against blood loss and toxic chemicals introduced to the body.
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what are hormones?
body communication chemicals.
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what are the three main types of blood vessels?
- arteries
- veins
- capillaries
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What is the difference between arteries and veins?
- arteries carry blood from heart to parts of the body
- veins carry blood back to the heart.
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what are capillaries?
tiny vessels separating arteries and veins. these are the sites where gases, nutrients and other materials are transferred to the cells and wastes move into the blood.
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what is the functional unit of the circulatory system?
capillaries.
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Describe the structure and features of arteries.
- have thick and highly elastic walls.
- arteries can expand when blood flows through it during the contraction of ventricles and then snaps back during the relaxation of ventricles. this keeps pushing blood where it needs to be as long as the pumping of the heart.
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what are the three layers in arteries and what are they made of?
- inner layer: endothelium cells that line the lumen of all vessels.
- middle layer: smooth muscle cells and elastic fibres
- outer layer: elastin and collagen
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why do arteries have a small circumference?
because then there's higher pressure in the arteries.
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how much of blood is in your arteries at any given time?
30%
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describe the features and structure of veins.
they have thin non-elastic walls with a larger inner circumference (less pressure). skeletal muscles beside the vein flex and squeeze the blood to help propel blood forward. they contain one way valves to prevent backflow (blood from flowing backwards)
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what is a lumen?
the space inside of a blood vessel.
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what is the smallest blood vessel?
capillaries.
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describe the features and structures of the capillaries.
smallest blood vessel. the capillary wall is made up of a singular layer of cells. (endothelial) this allows gas exchange to be more effective. red blood cells travel in single file.
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where is blood flow the slowest in the human body and why?
the capillaries to provide more time for diffusion to take place.
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what are the functions of the capillaries?
they play a key role in the absorption, transport and release of nutrients, gases or wastes produced in the digestive, respiratory and excretory systems.
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what controls the constriction and dilation of blood vessels?
nervous system.
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what is the difference between blood vessel constriction and blood vessel dilation?
vasoconstriction is an increase of blood flow near the skin to help release heat whereas vasodilation is a decrease in blood flow near the skin to conserve heat.
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what are the purposes of the heart?
- 1. pump blood through the body.
- 2. ensure blood moves in only one direction
- 3. separate oxygen-rich blood from oxygen-poor blood.
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what stops the heart from becoming fatigued?
cardiac muscles relax briefly before contractions.
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how many chambers are there in the heart? which kinds of animals have this many?
4, mammals and birds.
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What's the difference between the atria and the ventricles?
the atriums are the top two chambers of the heart and the ventricles are the bottom two. the atrium fills with blood returning back to the heart and drops it into the ventricles through the atrioventricular valves.
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what separates deoxygenated and oxygenated blood?
the septum
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how many valves does the heart contain?
4
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what are atrioventricular valves?
they separate the atrium from the ventricle. (tricuspid valve and bicuspid valve)
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what is the tricuspid valve and where is it located?
the tricuspid valve has 3 flaps and separates the right atrium from the right ventricle. it is on the right side of the heart.
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what is the bicuspid valve and where is it located in the heart?
it separates the left atrium from the left ventricle. and it is on the left side of the body.
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whats another name for the bicuspid valve?
mitral valve.
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why does the heart need 4 valves?
to ensure blood flows in the right direction.
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what are semilunar valves?
valves that act as doors that separate the ventricles and the aorta/pulmonary arteries. (pulmonary valve and aortic valve.)
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what does the pulmonary valve do?
acts as the doorway from the right ventricle to the pulmonary arteries that take blood to the lungs.
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what does the aortic valve do?
acts as a doorway from the left ventricle to the aorta
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where does oxygen-poor blood enter the right atrium?
through the inferior and superior vena cava.
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what are the pulmonary arteries?
they are where the right ventricle pumps oxygen-poor blood to be carried to the lungs for gas exchange.
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how does oxygenated blood enter the left atrium?
through pulmonary veins.
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what is the largest blood vessel?
aorta.
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what is the aorta?
it is where the left ventricle pumps blood through to get to all your body's tissues.
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what are the two main branches of the circulatory system?
- pulmonary pathway.
- systemic pathway.
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what is the pulmonary pathway?
transports oxygen-poor blood to your lungs for oxygenation and removal of waste (CO2)
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what is the systemic pathway?
transports oxygen-rich blood to deliver nutrients and remove wastes from cells throughout the body
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what is the coronary pathway?
it provides blood to the muscle tissues of the heart using the right and left coronary arteries.
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what stimulates the heart to beat?
an electrical impulse that comes from the heart itself.
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what does the SA node do?
The sinoatrial node stimulates the muscle cells to contract and relax rhythmically. it does this by sending an electrical signal that spreads over the left and right atrium which makes them contract.
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what does the atrioventricular node do?
the AV node transmits the signal it receives from the SA node through a group of fibres called the bundle of his. these fibres then relay the signal through two bundle branches and to the Purkinje fibres which initiates the contraction of the left and right ventricles.
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what can measures the amount of electrical impulse the SA node gives out?
electrocardiogram.
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what does a p wave mean on an electrocardiogram?
the atrium contracted.
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what does a q wave mean on an electrocardiogram?
it means the atrium relaxed.
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what does a r wave mean on an electrocardiogram?
it means the ventricle contracted.
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what does an s wave mean on an electrocardiogram?
the ventricle relaxed.
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what does a T wave mean on an electrocardiogram?
it means the electrical impulse returned to the SA node so it can be re-used.
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what happens if the valves don't close all the way?
it can cause heart murmur.
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what can heart murmur cause?
usually harmless but sometimes to compensate for the valves not closing all the way the heart will beat faster which requires much more energy and your heart will become jacked which will make it bigger.
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what is blood pressure?
when blood passes through blood vessels it exerts pressure on the vessel walls.
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what is systolic pressure?
maximum blood pressure that occurs during ventricular contraction. during systolic pressure, blood is forced out of the pulmonary arteries/aorta which increases the pressure in these arteries.
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what is diastolic pressure?
the lowest pressure before the ventricles contract again. during diastolic pressure, the atrium contracts and the ventricles relax. and the pressure inside the aorta and pulmonary valves decreases.
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what does systole mean?
the ventricles contract when they become full. this pressure shuts the atrioventricular valves (AV) and opens the semilunar valves and blood rushes to the arteries (pulmonary/aorta)
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what does diastole mean?
the arteries contract when full and the ventricles relax while blood fills them. the AV valves open up and the semilunar valves close.
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how do you measure blood pressure?
using a machine called the sphygmomanometer (blood pressure cuff) which measures in millimeters per mercury (mmHg)
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what is the average blood pressure?
- systolic; 120
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- diastolic; 80
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What's another word for high blood pressure?
Hypertension
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what can cause hypertension?
in active lifestyle, obesity, alcohol use, etc
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what can hypertension cause?
heart attacks, strokes or kidney disease.
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what is arterioscolosis?
a condition where the artery walls thicken and lose their elasticity.
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what is atherascerlosis?
a type of arteriosclerosis, plaque (LDL) builds up inside the artery walls causing blood flow to decrease and blood pressure to increase.
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how is atherosclerosis caused?
high cholesterol, smoking, obesity.
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what can atheroscerlosis lead to?
Angina (coronary vessel gets blocked), blood clots, shortness of breath, heart attack or heart failure.
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what are treatments for atheroscerlosis?
- aspirin to prevent clots.
- clot-busting medecine.
- angioplasty which is inserting a tube into a clogged artery to remove plaque and placing a stent which increases artery diameter.
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what is a coronary bypass operation?
an operation carried out to remove blockages in the coronary artery found in the heart. they do this by taking a vein/artery from somewhere else in the body and making a new path for blood to flow in the heart.
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