Section 3- Circulatory system Flashcards
What does double circulation mean?
Blood passes through the heart twice in every circulation of the body
What are the 2 circuits that make up the double circulation system in humans?
- Pulmonary circuit
- Systemic circuit
What are the advantages of having double circulation?
- Oxygenated and deoxygenated blood do not mix
- Allows different blood pressures in the systemic and pulmonary circuits
What is the name of the membranes encapsulated by the heart and what does it do?
Pericardium
Prevents over expansion
What is the name of the walls of the heart?
Myocardium
Cardiac muscle
What does myogenic mean?
The heart is able to generate its own electric activity
What blood vessel joins the right ventricle of the heart to the capillaries of the lungs?
Pulmonary artery
What blood vessel carries oxygenated blood away from the kidney?
Renal vein
What is the first main blood vessel that an oxygen molecule reaches after being absorbed from an alveolus?
Pulmonary vein
What are the names of the valves located between the atrium and ventricle?
Atrioventricular valves
What are the valves for?
Preventing back-flow of blood
What is the aorta?
Connected to left ventricle
Carries oxygenated blood to the body
What is the vena cava?
Connected to right atrium
Brings deoxygenated blood back from the tissues to the heart
What is the pulmonary artery?
Connected to right ventricle
Carries deoxygenated blood to the lungs
What is the pulmonary vein?
Connected to left atrium
Brings oxygenated blood back from lungs to heart
What are the coronary arteries?
The blood vessels that are supplied to the heart muscle
What is the cardiac cycle?
Sequence of events in 1 heartbeat
What are the 2 alternate beating phases of the heart called and what do they mean?
Systole = contraction
Diastole = relaxation
What controls the opening of valves?
Pressure in the relative chambers
What is atrial systole?
Contraction of atrial walls
Relaxation of ventricle walls
Forces remaining blood into ventricles from atria
What is ventricular systole?
Walls of ventricle contract whilst filling with blood
Increases blood pressure
Forces AV valves shut
What is ventricular diastole?
Atria and ventricle are relaxed
Blood returns to atria
As atria fills, pressure rises.
When pressure exceeds ventricles, AV valves open allowing blood into ventricles
SL valves shut as pressure is reduced from relaxation and recoil
When are the AV valves open?
Atrial systole
Diastole
When are the SL valves open?
Ventricular systole
When are the AV valves closed?
Ventricular systole
When are the SL valves closed?
Atrial systole
Diastole
What is cardiac output?
The volume of blood pumped around the body
what is stroke volume?
Volume of blood pumped by the ventricle in each heart beat
What is heart rate?
Number of times heart beats per minute
How do you calculate cardiac output?
Heart rate X stroke volume
How would an asthma attack cause the drop in the mean FEV?
- Muscle walls of bronchi contract
- Walls of bronchi secrete more mucus
- Diameter of airways reduced
- Flow of air reduced
Why do the semi-lunar valves open?
Pressure in ventricles exceeds pressure in the atrium
Why do the atrioventricular valves open?
Pressure in atria exceeds pressure in ventricles
What is the basic layering of arteries and veins?
Tunica adventitia
-Outer layer containing collagen/ elastic fibres
Tunica media
-Middle layer containing smooth muscle and elastic fibres
Tunica intima
-Endothelium (single layer of cells)
Lumen
-Hollow centre of tube
What are the specialised structure/ features of arteries?
Thick walls
-Transports blood at high pressure
Collagen and elastic fibres in walls
-Ensures blood remains at high pressure
Tick walls = narrow lumen
What are the specialised structure/ features of arterioles?
Lower pressure of blood
Thinner walls with elastic tissue (smooth muscle)
-Allows constrict and regulate blood flow to different areas of body
What are the specialised structure/ features of veins?
- Low pressure of blood
- Thinner walls
- Wide lumen
- Contains valves preventing backflow
What are the specialised structure/ feature of capillaries?
One cell thick
-Reduce diffusion distance
Take blood close to all cells to deliver and remove substances
What is tissue fluid?
Liquid that surrounds all cells
What is tissue fluid the result of the balance between?
- Hydrostatic pressure
- Osmotic pressure
What are the 3 types of tissue fluid?
Tissues fluid
Blood
Lymph
When does hydrostatic pressure occur?
Due to volume of blood pushing against walls of blood vessels
What is osmotic pressure?
A net loss of water from capillaries
How is tissue fluid formed?
- Hydrostatic pressure forces fluid out of the capillaries a the arterial end
Dissolved gases and nutrients move with it
Large plasms and proteins and cells do not
- Osmotic pressure: net loss of water from capillaries (due to hydrostatic pressure) gives blood more negative water potential
Water moves down water potential gradient into capillaries by osmosis
- Not all fluid passes back into capillaries
Excess output needs to be collected to avoid tissues swelling
Net excess is drained into vessels of lymphatic system
(the lymph)
Lymph drains back into circulatory system
What is the pressure division at the arterial end of the vessel?
hydrostatic pressure > osmotic pressure
What is the pressure division at the venous end of the vessel?
osmotic pressure > hydrostatic pressure
Why does tissue fluid accumulate in tissues of people who do not eat enough protein?
Less protein causes water potential to not become as negative so less water can be absorbed
How can blood cholesterol increase the risk of cardiovascular disease?
Low-density lipoproteins: transport cholesterol from liver to tissues
- leads to development of atheroma which leads to heart disease
How can diet increase the risk of cardiovascular disease?
High levels of salt raise blood pressure
High levels of saturated fat increase low-density lipoprotein levels hence blood cholesterol concentration
What is an atheroma?
Build up of fatty acid deposits, which forms within the endothelium of an artery
Can lead to thrombosis or an aneurysm
What is a stroke?
When an artery in the brain bursts and blood leaks into the brain tissue
Brain tissue becomes starved of oxygen
How does high blood pressure lead to an accumulation of tissue fluid?
High blood pressure = High hydrostatic pressure
Increased outward pressure from arterial end of capillary
More tissue fluid formed
Why is water potential of blood plasma more negative at venule end of capillary than arteriole end?
Water has left capillary
Proteins in blood are too large to leave capillary
Increasing higher concentration of blood proteins
How do capillaries running over the surface of the alveoli improve efficiency of gaseous exchange?
Delivers carbon dioxide to alveoli
Carrier oxygen away
What is the type of muscle found in the walls of the heart chambers?
Cardiac muscle
What is the process that creates pressure inside the heart chambers?
Contraction/ systole
How can higher than normal concentration of salt in blood entering capillaries lead to build-up of tissue fluid?
Results in lower water potential of tissue fluid so less water returns to capillary by osmosis.
How is the aorta adapted to its function?
Has folded inner lining
Allows maintenance of high pressure
Large muscular walls - contracting and recoiling
