Circulatory system (Chapter 5) Flashcards
Function of circulatory system
- delivers oxygen and nutrients to cells and removes CO2 and wastes
- Maintains pH of body fluids
- Maintains body temperature
2 circulation systems
- Pulmonary Circulation – to the lungs to gain
oxygen and remove carbon dioxide and then back to the heart - Systemic Circulation – delivers oxygen to the rest of the body and then takes waste CO2 back to the heart
Arteries
Always carry blood away from the heart
Carry oxygenated blood, except for the pulmonary artery
Have thick, muscular and elastic walls to pump and accommodate blood
They carry blood under variable pressure; pressure increases when blood is pumped through artery and then decreases as the ventricles relax again
Have a small lumen
Vasoconstriction
Smooth muscle in walls of vessels that have been injured or broken constrict immediately to reduce the diameter of the lumen which reduces blood flow through them
Vasodilation
blood vessels dilate (smooth muscle in artery walls relax), increases blood flow to an organ
Veins
- Carry de-oxygenated blood towards the heart
- have valves to prevent backflow of blood
- blood pressure is constant and relatively low
- have thin walls with no elastic or muscular fibres
- have a large lumen
3 layers of arteries and veins
The TUNICAE - tunica externa, tunica media & tunica interna.
Capillaries
carry blood close to cells so cells can get rid of their wastes and get their oxygen and nutrients. walls are only 1 cell thick to make diffusion more effective
the cardiac cycle (what happens in one beat of the heart)
- Two phases: Systole - heart muscle contracts (pumping blood) and Diastole - heart muscle relaxes (filling with blood)
Process of systole and diastole
- Atria contract forcing blood into ventricles (atrial systole)
- Ventricles then contract forcing blood into the major arteries (ventricular systole
- Then they all relax and atria fills with blood (diastole)
How is a platelet plug formed?
- inside of vessel walls are damaged causing them to become rough
- platelets stick to the rough wall of the vessel, then all platelets stick together forming a platelet plug at the site
- Platelets also release substances that act as vasoconstrictors on the walls of the vessel, which enhances and prolongs vasoconstriction
What are the two antigens and which blood types have the antigens?
- Antigen A and Antigen B
- each blood group has their antigens and O has neither
Antibodies
- Blood type A produced anti-B antibodies and vice versa
- AB produces neither and O produces both
Sinoatrial node (SA node) and atrioventricular node (AV node)
- capable of initiating nerve impulses without outside influence of nervous system.
- SA node – is located in the wall of Right atrium, below the opening of superior vena cava.
- AV node – is located between the 2 atria near the atrioventricular valves.
Components of blood
55% Plasma, <1% White blood cells and platelets, 45% red blood cells
Red blood cells
- Also called ERYTHROCYTES
- RBCs are circular and ‘biconcave disc’ shaped, meaning they are thinner in the middle with thicker edges - This increases SA for oxygen to bind, while still allowing room
for haemoglobin molecules - RBCs have no nucleus - This allows it room to carry a Haemoglobin molecule, which can combine with Oxygen.
White blood cells
- Also called LEUCOCYTES
- They remove dead or injured cells and invading micro-organisms by engulfing them (phagocytosis).
Coagulation steps
- Activity of clotting factors in the blood plasma increases
- A series of reactions results in the formation of a thread-like protein called FIBRIN
- The fibrin threads create a MESH network
around the platelet plug covering it’s surface
and sealing the inside of the wound. - More erythrocytes, leucocytes, platelets and plasma get
trapped by this network of fibrin. - This build up of material is called a blood clot
(THROMBUS). - The threads stick to the damaged blood vessel
and hold the clot in place. - After the clot is formed, the network of threads
contracts, pulling the edges of the damaged vessel
together. This is known as CLOT RETRACTION. - As the clot retracts, a fluid called SERUM is squeezed out of the cut.
- The serum dries and a scab is formed over the
wound to prevent entry of micro-organism
Each blood group, antigen and antibody they have, which types they can receive blood from and which types they can donate to.
Blood group A
Antigen: Antigen A
Antibody: Anti-B
Can receive blood from: A or O
Can donate blood to: A or AB
Blood group B
Antigen: Antigen B
Antibody: Anti-A
Can receive blood from: B or O
Can donate blood to: B or AB
Blood group AB
Antigen: Both antigens
Antibody: Neither antibodies
Can receive blood from: All
Can donate blood to: AB
Blood group O
Antigen: Neither antigen
Antibody: Both antibodies
Can receive blood from: O
Can donate blood to: All
