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.

Outlines

00:00

💓 Understanding Cardiovascular Disease

The paragraph delves into the functioning of the cardiovascular system and how it delivers glucose and oxygen to cells while removing waste. It introduces two types of cardiovascular diseases: atherosclerosis and blood clotting. The focus is on atherosclerosis, which begins with damage to the endothelium due to risk factors like high blood pressure and high LDL levels. This damage triggers an inflammatory response, leading to the recruitment of white blood cells. These cells absorb LDL cholesterol, leading to the formation of an atheroma behind the endothelium. Over time, the atheroma can calcify and lose elasticity, forming a plaque that narrows the artery lumen.

05:03

🚫 Consequences of Narrowed Artery Lumen

This section discusses the consequences of atherosclerosis, specifically how the narrowing of the artery lumen due to plaque formation reduces blood flow. This reduction in blood flow leads to decreased oxygen and nutrient supply to cells, as well as impaired waste removal. The decreased concentration gradients around tissue cells slow down the rate of diffusion. This can reduce cellular respiration, leading to a decrease in ATP production, which is essential for cell function. If cells cannot function properly due to lack of ATP, the tissue they are part of can die.

10:06

🩸 Blood Clotting and Its Impact

The final paragraph addresses blood clotting, another cardiovascular disease process. It explains how damage to the endothelium exposes collagen fibers, which activates platelets and initiates the clotting process. Platelets form a temporary plug and activate enzymes that convert fibrinogen into insoluble fibrin, creating a mesh that traps more blood cells and platelets, forming a clot. While clotting is a normal response to repair damage, in individuals with cardiovascular disease, this process can occur too frequently. Blood clots can break free and obstruct arteries, further reducing blood flow, oxygen supply, and CO2 removal. This can lead to a decrease in the concentration gradient for diffusion, insufficient cellular respiration, and inadequate ATP production, ultimately impairing cell function.

Keywords

💡Cardiovascular System

The cardiovascular system refers to the heart and blood vessels working together to circulate blood throughout the body. It ensures that oxygen and glucose are delivered to cells, and carbon dioxide and waste are removed efficiently. In the video, the system’s function is essential to understanding how diseases like atherosclerosis and blood clotting can disrupt these processes.

💡Atherosclerosis

Atherosclerosis is a cardiovascular disease characterized by the buildup of plaques in the arteries. The script explains that it begins with damage to the endothelium, which triggers an inflammatory response. White blood cells absorb cholesterol and fats, leading to the formation of an atheroma, which narrows the arterial lumen and reduces blood flow, impacting oxygen and nutrient delivery to cells.

💡Endothelium

The endothelium is the thin layer of cells that lines the interior surface of blood vessels. In the video, damage to the endothelium is the initiating factor in both atherosclerosis and blood clotting. This damage can be caused by high blood pressure or other factors, leading to inflammatory responses or exposure of collagen fibers that further complicate cardiovascular function.

💡Inflammatory Response

The inflammatory response is the body's natural reaction to injury or infection. In the context of atherosclerosis, it occurs when the endothelium is damaged, leading to the recruitment of white blood cells. These cells absorb fats and cholesterol, contributing to the formation of plaques. The video emphasizes how this response, which is normally protective, becomes harmful in cardiovascular diseases.

💡White Blood Cells

White blood cells are part of the immune system and are involved in defending the body against infections. In atherosclerosis, they are recruited to the site of endothelial damage where they absorb LDL cholesterol and fats, forming foam cells and contributing to plaque formation. The presence of white blood cells in the arterial wall is a critical step in the development of the disease.

💡LDL Cholesterol

Low-density lipoprotein (LDL) cholesterol is often referred to as 'bad cholesterol' because high levels can lead to plaque buildup in the arteries. In the video, individuals with high LDL are more prone to atherosclerosis as white blood cells absorb LDL, forming the atheroma that narrows the arterial lumen and disrupts blood flow.

💡Plaque

A plaque is a buildup of substances, such as fats, cholesterol, and cellular waste, that occurs in the arteries. In atherosclerosis, the plaque forms behind the endothelium, hardens over time, and causes the arteries to lose their elasticity. This calcification restricts blood flow, which leads to reduced oxygen and nutrient delivery to tissues, as described in the video.

💡Blood Clotting

Blood clotting is a process where platelets and fibrin form a clot to stop bleeding. However, in cardiovascular disease, excessive clotting can occur, leading to blockages in arteries. The script explains how damage to the endothelium exposes collagen fibers, activating platelets and leading to the formation of a clot that can obstruct blood flow, similar to atherosclerosis.

💡Thrombin

Thrombin is an enzyme that plays a key role in the blood clotting process by converting fibrinogen into fibrin. In the video, thrombin is activated following the exposure of collagen in damaged blood vessels. The fibrin then forms a mesh that traps red blood cells and platelets, leading to the formation of a stable clot. This clotting process can become dangerous when it blocks blood flow to vital organs.

💡ATP

Adenosine triphosphate (ATP) is the energy currency of the cell, produced during respiration. In the video, reduced blood flow due to narrowed arteries or blood clots leads to decreased oxygen supply, which in turn lowers the rate of cellular respiration. This reduction in ATP production prevents cells from functioning properly, and in extreme cases, can lead to tissue death.

Highlights

The cardiovascular system's role in delivering glucose and oxygen to cells and removing carbon dioxide and waste.

Cardiovascular diseases primarily affect the heart and blood vessels.

Two main types of cardiovascular diseases: atherosclerosis and blood clotting.

Atherosclerosis begins with risk factors damaging the artery's endothelium.

Damage to the endothelium triggers an inflammatory response and recruitment of white blood cells.

White blood cells absorb saturated fats and cholesterol from LDLs, leading to atheroma formation.

Atherosclerosis involves the development of plaques that can calcify and lose elasticity.

Atheroma formation narrows the blood vessel lumen, reducing blood flow.

Reduced blood flow affects oxygen and carbon dioxide exchange, impacting cellular respiration.

Decreased cellular respiration leads to reduced ATP production and potential cell death.

Blood clotting involves damaged endothelium exposing collagen fibers, activating platelets.

Platelet activation leads to the formation of a temporary platelet plug and the clotting cascade.

Thrombin converts fibrinogen into fibrin, forming a mesh that traps more blood cells and platelets.

Blood clots can obstruct arteries, reducing oxygen supply and CO2 removal from cells.

In cardiovascular disease, clotting processes occur too frequently, leading to health complications.

Blood clots can break free and travel, potentially causing further obstructions in the circulatory system.

The consequences of blood clots include reduced blood flow, oxygen supply, and cellular respiration.

Without sufficient ATP, cells dependent on the affected artery cannot function properly.

Transcripts

you know once we looked at the

functioning of the cardiovascular system

we then have to look at cardiovascular

disease okay so you look at the heart

the blood vessels and we know how they

work together to ensure that glucose

oxygen is delivered to cells efficiently

and that carbon dioxide and waste are

effectively removed from cells okay now

let's look at how cardiovascular disease

affects that so there's two cardio

vascular disease types that you need to

know about the first is atherosclerosis

and the next one is blood clotting okay

so know these events basically and be

able to explain their consequences so

let's go now atherosclerosis

one begins with various kind of risk

factors causing damage to the

endothelium usually of the artery okay

because those are the ones that have the

high pressure in them

okay so damage to the endothelium the

damage to the endothelium causes an

inflammatory response again I'm going

over the mark scheme points here so it's

gonna be very succinctly but you need to

explain this as a story so damage to the

endothelium causes an inflammatory

response that causes the recruiting the

recruiting of white blood cells very

important okay so the white blood cells

so you got damage to the endothelium

here and the white blood cells come

along and in they go okay behind the

endothelium the white blood cells end up

here okay now once they're there the

white blood cells white blood cells

absorb

now remember this these people the

people that are most likely to have

these events occurring are gonna have a

they're gonna have high blood pressure

causing damage to the endothelium and B

they are going to have a diet on diet

but they're gonna have high levels of

LDL in their blood so white blood cells

absorb saturated fats and cholesterol

saturated fats and cholesterol from

circulating LDLs and we'll come back to

this we'll review this as well but

individuals with a high risk or a high

risk of developing cardiovascular these

disease are gonna have high blood

pressure that causes damage to the

endothelium and they're gonna have high

circulating LDLs in their blood so the

white blood cells absorb saturated fats

and cholesterol from LDLs and this

causes the development of the atheroma

okay behind behind the endo behind the

endothelium okay and the last point

would be remember we're summarizing here

not too much information that as as this

develops so so the atheroma can become

can become calcified

okay calcified and loses elasticity

loses elasticity to form a plaque and

atherosclerosis

plaque these are the key points right

here okay now I will stop there so

basically what's happening is damage to

the endothelium happens the white blood

cells arrive and as the white blood

cells arrive as they absorb more and

more LDLs

from the circulation okay there they're

forming foam cells behind the

endothelium the endothelium is still

covering them endothelium is still

covering them but as as they're

absorbing more and more LPL's this

atheroma is causing a bulge in to be

into the lumen oh that's a key point

that I forgot atheroma forms behind

endothelium narrows lumen how could I

forget that narrows lumen okay and we're

going to come back to this as to what

consequence is going to have okay this

is a key point

actually let's just follow through

immediately okay so we've got narrows

lumen and let's look at the consequences

then of this if the lumen is narrowed it

reduces blood flow if it reduces blood

flow it will reduce co2 supply or bear

in mind co2 removal okay if the blood is

not flowing properly it's going to

reduce this and therefore it will reduce

the concentration gradients around the

tissue cells reduces the concentration

gradient and therefore this reduces the

rate of

diffusion and the key point is that if

you're not supplying oxygen and you're

not removing co2 this reduces

respiration this reduces the rate of

respiration in cells and therefore

reduces that ATP in the cells and

therefore cells cannot function cells

cannot function okay

and if the cells cannot function the

tissue will die right so that's that so

let's look at blood clotting then

remember everything blood clotting again

we're gonna look at how the different

risk factors can initiate these events

but the first event of blood flowing is

damaged damaged endothelium exposing

collagen exposed exposing collagen

fibers from behind the endothelium so

remember we said that the artery has

this thick elastic tissue elastic layer

will the reason the thing that makes it

elastic is collagen

okay collagen fibers but upon damage

those collagen fibers get exposed and to

these activates platelets in the blood

so the platelets in the blood are

activated okay and when they're

activated they form a platelet plug the

form a platelet plug which is temporary

okay but also they this causes the

activation activation of another kind of

enzyme as in the blood activation of the

enzyme from prothrombin to thrombin

okay activation of pro programming into

the active enzyme thrombin and what from

Bandhan does is it converts soluble

soluble protein fived reno gen soluble

protein fibrinogen into insoluble fiber

in okay and this forms these traps so

fibrin the fibrin mesh traps more red

blood cells red blood cells and more

platelets ie the positive feedback more

more red blood cells and more platelets

to form a blood clot okay now under

normal situation just like with

atherosclerosis under normal system

situation the inflammatory response is

just there to kind of heal or repair the

damage same with blood crying it's there

to seal up the blood vessel so that the

blood vessel doesn't leak the transport

medium however in people with

cardiovascular disease these processes

are happening too often and too much

okay so what happens as a result of the

formation of blood clots in blood

vessels so blood clots blood clots can

kind of become free from the blood

vessel so blood clots can obstruct can

obstruct arteries and when they obstruct

an artery again they is the same thing

they reduce blood flow therefore they

reduce

the oxygen supply and the removal of co2

from cells and this reduces the

concentration gradient which reduces the

rate of diffusion which means that

there's not enough respiration happening

in cells and therefore they don't create

enough ATP and without ATP the cells

that were dependent upon this artery for

their supply and removal cannot function

okay so this is cardiovascular disease

let's move on