Edexcel (SNAB) A level biology: atherosclerosis and blood clotting (topic 1)

Summary

This script discusses cardiovascular diseases, focusing on atherosclerosis and blood clotting. It explains how endothelium damage leads to inflammation and white blood cells absorbing LDLs, forming atherosclerotic plaques that narrow blood vessels. This narrowing impedes blood flow, reducing oxygen and nutrient delivery, and impairing waste removal, leading to cellular dysfunction and tissue death. Blood clotting, another issue, can obstruct arteries, further reducing blood flow and causing similar cellular issues.

Takeaways

• 💓 **Cardiovascular System Function**: The heart and blood vessels work together to deliver glucose and oxygen to cells and remove carbon dioxide and waste efficiently.
• 🚫 **Cardiovascular Disease Types**: There are two main types of cardiovascular diseases: atherosclerosis and blood clotting.
• 🛑 **Atherosclerosis Process**: Begins with risk factors causing damage to the artery's endothelium, leading to an inflammatory response and the recruitment of white blood cells.
• 🔍 **White Blood Cell Role**: White blood cells absorb saturated fats and cholesterol from LDLs, leading to the development of an atheroma behind the endothelium.
• 📈 **Atheroma Development**: Over time, the atheroma can calcify, lose elasticity, and form a plaque, which is a key indicator of atherosclerosis.
• 🌐 **Lumen Narrowing**: The atheroma bulges into the lumen of the artery, narrowing it and reducing blood flow.
• 🚫 **Consequences of Narrowed Lumen**: Reduced blood flow leads to decreased oxygen and CO2 exchange, affecting the rate of diffusion and cellular respiration, potentially leading to cell death.
• 🩸 **Blood Clotting Process**: Damaged endothelium exposes collagen fibers, activating platelets and initiating the clotting cascade.
• 🔄 **Clotting Cascade**: The activation of prothrombin to thrombin converts fibrinogen into insoluble fibrin, forming a mesh that traps more blood cells and platelets, creating a clot.
• ⚠️ **Risk Factors**: High blood pressure and high levels of LDL in the blood are risk factors that can lead to cardiovascular disease.
• 🚑 **Disease Impact**: In cardiovascular disease, the processes of inflammation and clotting occur too often, leading to obstructions that reduce blood flow and cellular function.

Q & A

What is the primary function of the cardiovascular system?

The primary function of the cardiovascular system is to ensure that glucose, oxygen is delivered to cells efficiently, and that carbon dioxide and waste are effectively removed from cells.

What are the two types of cardiovascular diseases mentioned in the script?

The two types of cardiovascular diseases mentioned are atherosclerosis and blood clotting.

What causes atherosclerosis to begin?

Atherosclerosis begins with various risk factors causing damage to the endothelium of the arteries, which are under high pressure.

What is the role of white blood cells in the development of atherosclerosis?

White blood cells are recruited to the site of endothelial damage, absorb saturated fats and cholesterol from circulating LDLs, and form foam cells behind the endothelium, leading to the development of an atheroma.

What is an atheroma and how does it affect blood flow?

An atheroma is a collection of white blood cells that have absorbed LDLs, forming a bulge into the arterial lumen, which narrows the lumen and reduces blood flow.

How does the narrowing of the arterial lumen due to atheroma impact cells?

Narrowing of the lumen reduces blood flow, which in turn reduces oxygen supply and CO2 removal. This reduces the concentration gradient around tissue cells, slowing down the rate of diffusion, and ultimately reducing cellular respiration and ATP production, which can lead to cell death if cells cannot function.

What initiates the blood clotting process?

Blood clotting is initiated when the endothelium is damaged, exposing collagen fibers that activate platelets in the blood.

What is the role of platelets in blood clotting?

Activated platelets form a temporary platelet plug and trigger the conversion of prothrombin to thrombin, which converts fibrinogen into insoluble fibrin, forming a mesh that traps more red blood cells and platelets to form a blood clot.

How can blood clots formed due to cardiovascular disease affect the body?

Blood clots can become free from the blood vessel and obstruct arteries, reducing blood flow, oxygen supply, and CO2 removal from cells, which can lead to insufficient respiration, reduced ATP production, and cell dysfunction or death.

What are the risk factors that predispose individuals to developing cardiovascular diseases as described in the script?

The risk factors include high blood pressure that causes damage to the endothelium and high levels of LDL cholesterol in the blood.

How do the processes of inflammation and blood clotting normally function in the body?

Inflammation and blood clotting are part of the body's natural healing and repair mechanisms. Inflammation helps to heal or repair damaged tissues, while blood clotting seals up blood vessels to prevent leakage of the transport medium.