circulatory system Flashcards
function of circulatory system
transport of nutrients, oxygen and wastes from and to the cells
why is it called a double circulatory system
It is called a double circulatory system becauseblood passes through the heart twice per circuit
blood composition
blood is composed of:
- plasma, 55%
- white blood cells and platelets about 4%
- red blood cells about 41%
plasma
- 55%
- transport of nutrients - glucose , amino acids
- wastes (carbon dioxide, nitrogenous wastes)
- Clear pale yellow liquid
- Consists of mostly water, dissolved organic and inorganic solutes, dissolved plasma proteins (salts, glucose, amino acids, vitamins, urea, proteins and fats)
erythrocytes
- red blood cells ~40%
- transport of oxygen in the form of oxyhaemoglobin
- small allowing it to pass through narrow capillaries
- flattened disc shape which provides a large surface area, allowing rapid diffusion of oxygen
- contains haemoglobin which absorbs oxygen in the lungs and releases oxygen in the rest of the body
- doesn’t have a nucleus which increases the amount of space in the cell for haemoglobin however limits their life span to only 120 days on average
- percentage (40%) is called haematocrit
leucocytes
- white blood cells ~1%
- involved in immune system as it plays an important role in fighting infections
- Body defence from microorganisms
- a number of different leucocytes e.g. neutrophils (most common)
- contain enzymes to digest pathogens
- colourless, have a multi-lobed nucleus
- two main ones: lymphocytes and macrophages
- macrophages engulf and digest micro-organisms
- lymphocytes produce antibodies
platelets/thrombocytes
- ~4%
- involved in blood clotting – collect in fibres of fibrin forming a clot.
- do not have a nucleus, but has distinct mitochondria
- irregularly shaped
functions of blood
TRP:
- Transport: transports nutrients, oxygen and hormones to the tissues, removes wastes such as CO2 and urea
- Regulation: helps to keep the body’s pH within its homeostatic range, helps in regulating the body’s temperature
- Protection: prevents blood loss if blood vessels are damaged, protects the body against pathogens and toxins
transport of oxygen
3% of oxygen is carried in the blood plasma and the other 97% is carried in haemoglobin
Haemoglobin is able to combine with oxygen to form a compound, called oxyhaemoglobin and oxyhaemoglobin can breakdown easily to release oxygen
Oxyhaemoglobin breaks down into haemoglobin, in places where the concentration of oxygen is low
Oxyhaemoglobin is bright red, and that’s what makes the arteries that carry oxygenated blood, bright red and haemoglobin is dark red or purplish in colour, which makes the veins that have deoxygenated blood dark red
*some exceptions: pulmonary arteries and pulmonary veins
transport of carbon dioxide
carbon dioxide is carried in the blood and number of ways it can be carried in plasma which is 78%. It can combine with the haemoglobin molecules to form a compound called carbaminohaemoglobin 22%
co2 is produced during cellular respiration in body cells. erythrocytes carry the co2 that is produced to the lungs. erythrocytes that carry co2 pass through the capillaries where it diffuses out of the capillaries and into the alveoli. this is as the co2 follows a concentration gradient as there is less co2 in the alveoli and more co2 in the capillaries. after the co2 diffuses into the alveoli it is expelled through the process of expiration also known as exhaling.
transport of nutrients and waste
nutrients and wastes (metabolic wastes) is dissolved and transported in plasma
nutrients are the essential elements and molecules that are obtained from the food we eat
(metabolic) wastes are substances produced by the cells that cannot be used and would be harmful if allowed to accumulate
blood clotting process
- smooth muscle in the vessel wall, contract (vasoconstriction) reducing blood flow
- so membranes of blood vessel become sticky, which leads to either
→ Walls of blood vessels sticking to each other or
→ platelets stick to the vessel wall and each other forming a plug - platelets, release a series of clotting factors
- these factors lead to soluble fibrinogen, present in blood plasma to form insoluble fibrin
- this fibrin forms a mesh, trapping formed elements in the blood
- this seals the tear
- this pulls the torn edges closer together, reducing the size of the tear
acronym for blood clotting
VSPFMSR
vivi saw peter fitting marvellous silver raincoats
blood flow
inferior/superior vena cava→ right atrium →tricuspid valve(av valve) → right ventricle → pulmonary semilunar valve → pulmonary artery → lungs (oxygenating blood) → pulmonary vein→left atrium → bicuspid valve (left av valve) → left ventricle → aortic semilunar valve →aorta → head & body
arteries
carry blood Away from heart
