B4 Circulatory system Flashcards
What is blood
A tissue made up of platelets, WBCs & RBCs in plasma
What do platelets do
Responsible for triggering blood clotting at the sites of wounds
What are platelets made up of
Small cell fragments
They have no nucleus
What do RBCs do
Transport oxygen from lungs to all body cells
Function of haemoglobin in RBCs
Binds with oxygen in the lungs
Carries oxygen and releases it, delivering it to body cells for respiration
Function of RBC’s lack of nucleus
Frees up more space for haemoglobin
Maximises the amount of oxygen they can carry
Function of RBC’s biconcave shape
Creates a large surface area
Allows for rapid diffusion of oxygen
Function of RBC’s small size
Allows RBCs to pass through capillaries
What do WBCs do
Defends against infections
Function of WBC’s ability to change shape
Allows them to move through the blood vessels into body tissues
Allows them to engulf harmful microorganisms
Types of blood vessels
Capillaries
Veins
Arteries
Function of arteries
Transport blood from the hear to organs
Carry oxygenated blood (apart from pulmonary artery)
Function of elastic fibres in arteries
Allows them to stretch and recoil
Function of thick muscle wall in arteries
Strengthens them, enabling them to cope with the high pressure at which blood is pumped out by the heart
What are capillaries
Smaller vessels (one cell thick), branched off of arteries
What do capillaries do
Exchange food and oxygen into cells from the blood
Move waste products, e.g C02, into the blood from cells
Function of capillaries’ thin walls and proximity to body cells
Allows the efficient exchange of food, oxygen and waste products through diffusion
What are veins
Vessels formed from joined up capillaries that have passed through the body
What do veins do
Transport deoxygenated blood from organs back to the heart (apart from pulmonary vein)
Function of thin walls (in comparison to arteries) in veins
Veins carry blood at a lower pressure than veins
Function of wide cross-section (lumen) in veins
Low blood pressure hinders blood
Veins have a wider lumen through which blood can flow to counteract this
Function of valves in veins
Prevents back flow of blood
What does the pulmonary artery do
Transports de-oxygenated blood from the heart to the lungs
What does the pulmonary vein do
Transports oxygenated blood from the lungs to the heart
What is the aorta
The artery that leaves the heart from the left ventricle and carries oxygenated blood to the body
What are atria
The upper chambers of the heart
What are coronary arteries
The blood vessels that supply oxygenated blood to the heart muscle
What is the double circulatory system
The circulation of blood from the heart to the lungs is separate from the circulation of blood from the heart to the rest of the body
What does epidermal mean
Cells that make up the epidermis or outer later of an organism
What is plasma
The clear yellow-liquid part of the blood that carries dissolved substances and blood cells around the body
What is the pulmonary artery
The large blood vessel that takes deoxygenated blood from the right ventricle of the heart to the lungs
What is the pulmonary vein
The large blood vessel that carries oxygenated blood from the lungs back to the left atrium of the heart
What is the ven cava
The large vein that brings deoxygenated blood from the body into the heart
What are ventricles
The lower chambers of the heart that contract to force blood out of the heart
What are white blood cells
Blood cells involved with the immune system
What do phagocytes do
Kill microorganisms
Surround and engulf microorganisms
Kill by enzymic digestion
What do lymphocytes do
Produce antibodies
Produce antitoxins
What do antibodies do
Bind to pathogens, killing them or binding them together
Pathogens clumped by antibodies are easy for phagocytes to engulf
What do antitoxins do
Neutralise toxins produced by microorganisms
What is the sino-atrial node do
In the top of the right atrium
Sends electrical pulses, carried through the atria, causing them to attract
The impulse travels to the atrioventricular node
What is the atrioventricular node
In the bottom corner of the right atrium
Receives electrical pulses from the sino-atrial node
Redirects impulses through conducting fibres in the septum
When the impulse reaches the apex, it travels up the ventricle walls, causing them to contract from the bottom up
What is diastole
The phase of a heartbeat when the heart muscle relaxes and allows the chambers to fill with blood
Occurs in the delay between the impulse from the sino-atrial node reaching the atrioventricular node
What is systole
The phase of a heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries
Occurs when impulses reach the apex of the septum and travel up the ventricle walls
What is arrhythmia
Problem with the rate or rhythm of the heartbeat
What is tachycardia
Heart beating too fast
What is bradycardia
heart beating too slow
What is atrial fibrillation
Irregular or fast beat leading to palpitations
What are palpitations
Rapid, strong, or irregular heartbeats due to agitation, exertion or illness
What is a stent
A wire-mesh inserted into a vessel
Allows blood to move more freely through a previously blocked or narrowed coronary artery
What does having a stent involve
Stents are carried out under local anaesthetic- this is safer than general anaesthetic, rarely involves complications and only requires a short hospital stay
In rare cases, stents can cause blood clots and lead to a heart attack
What can be done if a stent is not appropriate for a patient
A heart bypass where the affected artery is replaced
This is expensive, invasive, high risk and requires general anaesthetic
What are statins
Medicines that help to lower levels of low-density lipoprotein cholesterol in the blood by reducing its production in the liver
High levels of LDL cholesterol can lead to atherosclerosis and cardiovascular disease
What is atherosclerosis
The hardening and narrowing of arteries
What is cardiovascular disease
A disease of the heart or arteries
Mainly:
Coronary heart disease- restricted blood supply to the heart
Angina- Sharp chest pain
Heart attack- sudden block of blood supply to the heart
Stroke- Block of blood supply to the brain
What are the risks of statin use
Can interact with other medicines, increasing the risk of side effects, such as muscle damage
May cause side effects
May negatively interact with grapefruit juice.
What are the top chambers of the heart called
Atria
What are the bottom chamber of the heart called
Ventricles
What is the thorax
The top part of your body
Separated from the bottom half of the body by the diaphragm
How does air travel through the lungs
Enters through the mouth/nose Through the trachea Splits into the bronchi Splits into bronchioles Arrives as alveoli where gas exchange takes place
What happens in the alveoli
The blood in capillaries running past the alveoli contains a lot of CO2
This allows CO2 to transfer out of the blood and O2 to transfer into the blood as the concentration gradient is high
How does blood travel through the body
Blood flows into the two atria from the vena cava and the pulmonary vein
The atria contract, pushing the blood into the ventricles
The ventricles contract, forcing blood into the aorta and the pulmonary artery, out of the heart
The blood then flow through arteries to the organs then though veins to the heart
