Cardiovascular System Flashcards
What is the circulatory system?
Circulatory System= a network of organs and vessels responsible for the flow of blood, nutrients, gases and hormones to and from the cells in the body.
it is aka the cardiovascular system
What are the main functions of the cardiovascular system? (4 main functions)
- to transport oxygen and carbon dioxide around the body
- to distribute nutrients and transport waste
- to maintain body temperature
- to circulate hormones
What are the two types of circulatory systems?
- Open Circulatory System
2. Closed Circulatory System
What is an open circulatory system?
In an open circulatory system blood is contained in blood vessels for only part of the time. Blood bathes the internal organs directly.
Open circulatory systems are found in smaller organisms.
What is a closed circulatory system?
Closed circulatory systems are found in large complex organisms.
Blood is always found in blood vessels.
Materials are exchanged between the blood and cells.
What are the main components of the circulatory system?
Main components= heart, blood, blood vessels
What are the types of blood vessels? (3 types)
Arteries, veins, capillaries
What are arteries/what is their structure/what do they do?
Arteries= thick muscle and elastic fibres
smaller in diameter and very flexible-they stretch under pressure and recoil to move blood along.
All arteries except the pulmonary artery carry oxygenated blood away from the heart.
arteries can withstand high pressure from the heart
there are no valves in arteries
Arterioles-what are they/what do they do?
Arteries branch into arterioles
Arterioles can contract and relax
vasoconstriction= reduction in diameter of blood vessel, decreases blood flow
vasodilation= increase in diameter of blood vessel, increases blood flow
What are veins/what is their structure/what do they do?
veins= thin muscle and elastic fibres that are larger in diameter and elastic but not flexible. Valves are present.
Low pressure
All veins except the pulmonary vein carry deoxygenated blood to the heart.
venules= small vessels that carry blood back to the heart
What are the 2 major strategies that help with the flow of venous blood against gravity?
- valves in veins prevent blood from flowing backwards against the flow.
- skeletal muscles pump blood towards the heart.
What are capillaries/what is their structure/what do they do?
capillaries= the smallest type of blood vessels with extremely thin walls (walls are 1 cell thick)
little flexibility and no valves present in the capillaries.
the capillaries connect arterioles to venules
gas exchange occurs in the capillaries
Where/how does gas exchange happen in the circulatory system?
Diffusion occurs in the capillaries (this is where the exchange of gases occurs)
Particles of high concentration move to an area of low concentration.
Blood Vessels Summary Breakdown:
what are the types of blood vessels?
what are their purposes/what is their structure?
Arteries - Arterioles - Capillaries - Venules - Veins
arteries= thick-walled blood vessels that carry oxygenated blood away from the heart
veins= thin-walled blood vessels that carry deoxygenated blood towards the heart
capillaries= narrowest of all blood vessels, RBCs travel in single file
branching of capillaries increase the surface area available for diffusion. Connects the arterial and venous systems.
What causes bruises?
The capillaries have walls that are only one cell thick and are very fragile. The capillaries can get ruptured through impact.
When this happens the blood contained within them gets released into the spaces between the tissues.
This produces discolouration/swelling known as a bruise.
What is blood made up of?
Blood= plasma, red blood cells, white blood cells, platelets
Plasma- what is it/what is it made up of?
Plasma= a straw-coloured liquid that makes up 55% of blood
90% of plasma= H2O (temperature reg.)
Remaining 10% of plasma consists of:
Proteins, dissolved nutrients and wastes, dissolved gases and hormones
*the proteins transport fatty acids, vitamins, fight viral/bacterial infections, support clotting
Red Blood Cells (RBCs)- what are they/what do they do?
RBCs= aka ERYTHROCYTES
lifespan= 100-120 days
RBCs= disc-shaped/thinner in the centre (increases surface area/flexibility)
RBCs are produced in bone marrow
RBCs lose nuclei with maturity (hence their disc shape) thus they can’t replace proteins, grow or divide
RBCs contain hemoglobin
Hemoglobin molecules found in RBCs- what happens with the hemoglobin molecules and their iron atoms?
Red blood cells contain hemoglobin
Each RBC has ~250 million hemoglobin molecules
Each hemoglobin molecule contains 4 iron atoms
Each iron atom forms a weak bond with oxygen in lungs
Hemoglobin binds to CO2 after releasing O2 at tissues
White Blood Cells (WBCs)- what are they/what do they do?
WBCs= aka LEUKOCYTES WBCs= round-shaped make up <1% of blood, they are 10μm in size (μm= micrometres) produced in bone marrow Lifespan= 12 hrs to 200 days
WBCs guard against infection, fight parasites and attack bacteria
when fighting infection WBCs increase in number
Macrophages= special type of WBC that have the ability to locate and “eat” particles (bacteria, viruses, fungi, etc…)
What are macrophages?
Macrophages= special type of WBC that have the ability to locate and “eat” particles (bacteria, viruses, fungi, etc…)
What are platelets/what do they do?
Platelets= aka THROMBOCYTES
platelets have no nucleus, <1% of blood, 1-3 μm in size (μm=micrometres)
platelets= disc-shaped with rigid edges
last ~8-10days
Platelets break off special cells in bone marrow
Platelets are cell fragments responsible for blood clotting
They stick to the site where blood vessel is damaged by breaking apart and releasing clotting factors.
Platelets activate reactions resulting in fibrin protein which traps RBCs and platelets forming a clot/scab.
What forms a clot/scab?
Platelets are cell fragments responsible for blood clotting
They stick to the site where blood vessel is damaged by breaking apart and releasing clotting factors.
Platelets activate reactions resulting in fibrin protein which traps RBCs and platelets forming a clot/scab.
What is anemia?
Anemia= low RBC or hemoglobin count (iron). Hence, not enough oxygen is being transported to the body and the person feels weak/tired.
What is blood pressure?
Blood pressure= the pressure exerted on the artery walls by the circulating blood.
normal BP of a young adult= 120/80 (120 is the symbolic pressure, 80 is the diastolic pressure)
BP= symbolic pressure/diastolic pressure
What is symbolic pressure?
symbolic pressure measures the force your heart exerts on the walls of your arteries each time it beats
what is diastolic pressure?
diastolic pressure measures the force your heart exerts on the walls of your arteries in between beats
what are the 3 main circuits of the circulatory system?
the circulatory system is broken down into 3 main circuits:
- Coronary Circulation- heart pumps blood to itself
- Pulmonary Circulation- carries blood from heart to lungs
- Systemic Circulation- carries blood from heart to rest of body
what is hepatic portal circulation?
Hepatic portal circulation involves the movement of blood from the digestive tract to the liver.
The Heart- structure/function
the heart is the hardest working muscle that is the size of a fist
the heart functions as 2 pumps:
- one pushes blood to lungs
- one pushes blood to body
What is a double circulatory system?
The human circulatory system is a double circulatory system.
This means that a circulatory system has 2 parts:
-the right side deals with deoxygenated blood
-the left side deals with oxygenated blood
This is so the oxygenated and deoxygenated blood don’t mix
What are the layers of the heart? (3 layers)
PERICARDIUM: fluid-filled membrane that prevents friction between the heart and other tissues/organs in the thoracic cavity
MYOCARDIUM: muscular tissue of the heart
ENDOCARDIUM: inside lining of the heart
The human heart- structure
The human heart is made of 4 chambers separated by the septum
Top 2 chambers= atria - thin walled (atria=plural, atrium=singular)
Bottom 2 chambers= ventricles - thick walled
What are the 2 types of valves in the heart?
- Atrioventricular Valves
2. Semilunar Valves
What are atrioventricular valves?
Atrioventricular valves are found between the atria and ventricles.
They open when the atria contract and they allow the ventricles to fill up.
When the ventricles are filled these valves close to prevent the flow of blood back into the atria.
What are semilunar valves?
Semilunar valves are found between the arteries and ventricles.
They open when ventricles contract.
The right ventricle sends blood to the pulmonary artery.
The left ventricle sends blood to the aorta.
The semilunar valves close to prevent flow of blood back into the ventricles.
Tracing the Flow of Blood (8 steps)
- Vena Cava (superior and inferior) returns blood from the rest of the body to the right atrium.
- The right atrium pumps blood thru the tricuspid valve into the right ventricle.
- The right ventricle pumps blood thru the pulmonary valve thru the pulmonary artery to the lungs to pick up oxygen.
- From the lungs the now oxygenated blood flows thru the pulmonary vein to the left atrium.
- Blood is pumped from the left atrium thru the bicuspid valve into the left ventricle.
- The oxygenated blood is pumped from the left ventricle thru the aortic valve thru the aorta (a major artery).
- Once thru the aorta the blood branches into different arteries then arterioles, then to the capillaries where the diffusion offices and nutrients occurs.
- The now deoxygenated blood returns back to the heart from all body cells thru venules then veins finally to the superior or inferior vena cava.
What does it mean that the heart is a myogenic muscle?
Since the heart is a myogenic muscle it can beat for a short time after it is removed from the body. This shows that heartbeat is initiated within the heart muscle itself and not the brain.
What is a myogenic muscle?
A myogenic muscle is a muscle that can contract and relax without input from an external source.
What triggers your heart beat?
Your heartbeat is triggered by electrical impulses that travel down a special pathway thru your heart:
- SINOATRIAL (SA) NODE- “natural pacemaker”, generates electrical signal and causes atria to contract
- ATRIOVENTRICULAR (AV) NODE- transmits signals from SA Node to muscles of ventricles
- BUNDLE OF HIS- sends impulse to purkinje fibres (found in walls of ventricles)
- PURKINJE FIBRES- cause ventricles to contract
What is an Electrocardiogram (ECG)?
An electrocardiogram (ECG) records the electrical impulses generated by a beating heart.
ECG consists of a P wave, T wave, and QRS complex
P wave- represents firing of SA node and contraction of atria
T wave- represents relaxing of ventricles and closing of semilunar valves (“dub” sound)
QRS complex- represents contraction of ventricles and closing of AV valves (“lub” sound)
What causes the “lub-dub, lub-dub” sound of the heart?
The “lub-dub, lub-dub” sound of the heart is caused by the closing of heart valves.
the “lub” sound= closing of AV valves
the “dub” sound= closing od semilunar valves
What is a pulse? Where can it be found?
Pulse= echo of the heartbeat
When the heart contracts it pushes blood to blood vessels and you feel the expansion of arteries.
Pulse can be found in the wrist/neck/ankles/thumb
What is blood pressure? What unit is it measured in/how is it measured? What causes BP to decrease?
blood pressure= the force of the blood on the walls of the arteries
measured in mmHg (millimetres of mercury) using a sphygmomanometer
normal BP= 120/80
BP= systolic pressure/diastolic pressure
systole (“to contract”)= the force the heart places on the walls of blood vessels as it pumps with each heartbeat
diastole (“to dilate”)= the pressure on the walls of blood vessels when the heart relaxes between beats
BP decreases as the distance from the left ventricle increases
What causes Blood Pressure to decrease?
Blood pressure decreases as the distance from the left ventricle increases.
