4- circulation

Question 1

components of blood

Answer 1

blood is composed of plasma and blood cells (erythrocytes and leucocytes)

Question 2

plasma

Answer 2

• the liquid component of blood making up about 55% of bloods total volume
• 90% water, glucose, proteins, ions/urea, co2/ antibodies/ hormones

Question 3

role of plasma

Answer 3

transports blood cells, nutrients, waste products, antibodies and chemical signals throughout the body

Question 4

erythrocytes (red blood cells)

Answer 4

• structure: biconcave, disc-shaped cells lacking a nucleus, for more space for haemoglobin
• role: carry oxygen from lungs to the tissues and bring carbon dioxide back to the lungs

Question 5

leucocytes (white blood cells)

Answer 5

• structure: fragments of cytoplasm derived from a bone marrow cell called a megakaryocyte
• role: involved in clotting to prevent excessive bleeding. when an injury occurs, platelets gather at the site and stick to the lining of the injured blood vessel to form a plug, or blood clot. they also release chemicals that promote clotting

Question 6

function of blood- transport

Answer 6

• blood acts as the primary transportation medium in the body
• oxygen transport: erythrocytes carry oxygen from the lungs to tissues
• nutrient transport: nutrients absorbed from the digestive system are transported to cells
• waste removal: blood carries waste products from cells to excretion organs
• hormone transport: blood carries hormones from the glands to their target organs

Question 7

function of blood- defence

Answer 7

• blood plays a key role in the body’s defence mechanism
• immune response: leucocytes protect against infectious diseases and invaders
• clotting: platelets help form clots to prevent excessive bleeding and facilitate wound healing

Question 8

function of blood- formation of lymph and tissue fluid

Answer 8

• tissue fluid formation: also known as interstitial fluid, this fluid surround the cells in tissues. it is formed from blood plasma that seeps out of capillaries, providing cells with nutrients and oxygen and removing waste products
• lymph formation: lymph is derived from tissue fluid that enters lymphatic capillaries. it is crucial for the immune system as it carries lymphocytes, and it returns excess tissue fluid and leaked plasma proteins back to the bloodstream

Question 9

blood clotting sequence:

Answer 9

• vessel injury: injury to a blood vessel triggers the clotting process
• platelet plug formation: platelets adhere to the damaged site and form a temporary plug formation
• release of clotting factors: platelets release clotting factors, including thromboplastin
• activation of prothrombin: thromboplastin converts prothrombin into thrombin
• fibrin clot formation: thrombin transforms soluble fibrinogen into insoluble fibrin, which forms a mesh over the wound

Question 10

role of platelets in blood clotting

Answer 10

• adhere to the site of injury, creating a plug
• release clotting factors, including thromboplastin, that initiate the coagulation cascade

Question 11

role of plasma proteins

Answer 11

• thromboplastin plays a key role in the conversion of prothrombin to thrombin
• prothrombin is converted into its active form, thrombin
• fibrinogen is transformed into fibrin, which forms a mesh to stabilise the platelet plug

Question 12

stages leading to atherosclerosis

Answer 12

• endothelial injury: the process begins with damage to the inner lining of arteries
• LDL accumulation: low density lipoproteins father in the artery wall, creating fatty streaks
• oxidation and macrophage attraction: LDL undergoes oxidation, attracting macrophages
• foam cells formation: macrophages consume oxidised LDL, transforming into foam cells
• plaque development: foam cells die and accumulate, causing atheroma or plaque formation
• plaque rupture: plaque rupture can initiate clot formation, blocking the artery

Question 13

effects of atherosclerosis on health

Answer 13

• restricted blood flow: narrowing of arteries limits blood supply to organs and tissues
• heart attack risk: if coronary arteries (to cardiac muscles) are affected, a heart attack can occur
• stroke risk: blockage in carotid arteries (to brain) can lead to a stroke
• peripheral artery disease: obstruction in leg arteries can cause peripheral artery disease

Question 14

risk factors for atherosclerosis development:

Answer 14

• high cholesterol: particularly high levels of LDL
• high blood pressure: hypertension damages the endothelium
• smoking: smoking causes endothelial damage
• diabetes: high blood sugar levels can contribute to atherosclerosis
• obesity: obesity can lead to high cholesterol and hypertension
• sedentary lifestyle: lack of physical activity increases obesity and diabetes risks
• age and gender: men and older individuals are at a higher risk
• family history: genetic predisposition towards heart disease