Transport in humans

Transport in Humans

Learning outcomes

• At the end of this topic, you should be able toExplain the importance of the circulatory system in

linking all systems of the organism togetherDescribe the structure and function of the heart in

moving blood around the bodyDescribe the structure and function of the blood

vesselsDescribe the structure and function of the blood in

supporting life

Lesson outline

1. What is a circulatory system?2. Characteristics of our circulatory system3. The heart4. The blood vessels5. The blood6. Health problems in the circulatory system

1. What is a circulatory system?

1. What is a circulatory system?

• Circulatory system = – A type of transport system, transporting

substances around the body via the blood

• Transport system = – Transports substances around the body – Can be via blood or lymph

2. Characteristics of our circulatory system


A. Why do we need a circulatory system?

B. What are circulatory systems like?

C. How is our circulatory system special?


A. Why do we need a circulatory system?

• Thinking time: – How are substances transported in simple,

unicellular organisms?

– We are complex, multicellular organisms

Pg 139


A. Why do we need a circulatory system?– All cells need to

• Receive oxygen and nutrients• Remove waste products

– Relying on diffusion alone to transport substances to all cells in multicellular organisms is

• Not good enough• Not fast enough

Pg 139


A. Why do we need a circulatory system?– Cells in multicellular organisms are organized into

systems• E.g. Digestive system• Cells Tissues Organs Systems

– A transport system is needed to carry substances from 1 part of the body to another

Pg 139


B. What are circulatory systems like?– Circulatory systems need

1. A transport fluid/medium2. A pump to move the fluid along3. A system of vessels in which the fluid moves

= Heart = Blood vessels = Blood

Pg 139


B. What are circulatory systems like?– Our circulatory system consists of

1. The heart2. Arteries3. Arterioles 4. Blood capillaries 5. Venules6. Veins The blood vessels (more later)

Pg 152


B. What are circulatory systems like?– Open circulatory systems

• Blood (transport fluid) leaves blood vessels and comes into contact with body tissue

• Found in arthropods e.g. insects, spiders and crabs• Nutrients obtained directly from blood surrounding

organs• BUT, movement of blood is slow and poorly controlled• AND, blood supply is not regular or guaranteed, so

organisms can only grow to limited size

Pg 151


B. What are circulatory systems like?– Closed circulatory systems

• Blood does not leave blood vessels or come into contact with body tissues

• Found in humans and all vertebrates (with backbone)• Better control of movement of blood (pump)• Regular and guaranteed supply of blood (pump)

Pg 151


C. How is our circulatory system special?– The transport system in mammals is divided into

• Blood system carries blood• Lymphatic system carries lymph

Pg 139


C. How is our circulatory system special?– Double circulation

• In all mammals• The blood passes through the

heart twice in 1 complete circuit

Pg 155, 156


C. How is our circulatory system special?– Pulmonary circulation

• Blood from heart to lungs and back• Pulmonary arteries: Heart lungs• Pulmonary veins: Lungs heart,

oxygenated blood– Systemic circulation

• Blood from heart to rest of body• Arteries: Heart rest of body

(except lungs), oxygenated blood• Veins: Body Heart, deoxygenated blood

Lungs

Round the

body

Pg 155, 156

LR

3. The Heart

3. The Heart

A. Structure and Function of the heart

B. The Path blood takes through the heart

C. The Cardiac Cycle

D. Blood Pressure

3. The Heart

A. Structure and Function of the Heart– Size: About the same as a clenched fist– Shape: Roughly conical– Location: Behind the chest bone

Between the two lungs• Inside pericardium (double

membrane with fluid in between)Function: helps to reduce friction when heart is beating

Pg 157

3. The Heart

A. Structure and Function of the Heart– You need to

be able tolabel:

Semi-lunar valve

Semi-lunar valve

Pg 157, 158

3. The Heart

A. Structure and Function of the Heart– 4 chambers– 2 on each side

• Function: double circulation– Upper chambers: atria

(singular: atrium)– Lower chambers: ventricles– Dividing wall: median septum

• Function: prevent mixing of oxygenated and deoxygenated blood

Pg 157

3. The Heart

A. Structure and Function of the Heart– Atria (Singular: atrium)

• Blood moves from atria to ventricles• Relatively thinner muscular walls• Function: Forces blood

into ventricles

Pg 157

3. The Heart

A. Structure and Function of the Heart– Ventricles

• Blood moves from ventricles out of the heart• Relatively thicker muscular walls• Function: Left ventricle

(pumps blood around body) is thicker than right (pumps blood to lungs)

Pg 157

3. The Heart

A. Structure and Function of the Heart– 2 sides separated by median septum– Left side: Oxygenated blood– Right side:

Deoxygenated blood

• ‘Hole in the heart’

Pg 157

3. The Heart

B. The Path blood takes through the heart– Blood passes from

the atria to ventriclesvia the valves• Flaps of tissue• Function: Prevent

backflow of blood• So that blood flow is

unidirectional

Pg 158

3. The Heart

B. The Path blood takes through the heart– Valves: 2 types in the heart

1. Atrioventricular= tricuspid [3 cusps] (right)+ bicuspid [2]/mitral (left)

2. Semilunar(half-moon, see )

Pg 158

3. The Heart

B. The Path blood takes through the heart– Valves have

chordae tendinae• Cord-like tendons• Function: To prevent

valves from inverting

Pg 158

3. The Heart

B. The Path blood takes through the heart– Label the parts of the

heart in your handout

– You will need to refer to it as we go through this section

Pg 158

3. The Heart

B. The Path blood takes through the heart1. We will start in the

right atrium• This receives

de-oxygenated bloodfrom the rest of the body (except lungs)

• Via the superior and inferior vena cava

Pg 158

3. The Heart

B. The Path blood takes through the heart2. The right atrium

contracts• Tricuspid valves open

3. De-oxygenated bloodflows into the right ventricle

Pg 158

3. The Heart

B. The Path blood takes through the heart4. The right ventricle

contracts• Tricuspid valves close• Semilunar valves open• Closing and opening:

due to blood pressure

5. The right ventricle relaxes• Semilunar valves close

Pg 158

3. The Heart

B. The Path blood takes through the heart6. Meanwhile, blood

leaves for the lungs• Right ventricle walls

thinner than left• Less force needed to

pump blood to lungs• Via pulmonary artery• Blood travels more

slowly than in aorta

Pg 158

3. The Heart

B. The Path blood takes through the heart– Why is it good that

blood travels more slowly in the pulmonary arterythan in the aorta?

Pg 158

3. The Heart

B. The Path blood takes through the heart7. Blood from the lungs

returns to the leftatrium• Oxygenated blood• Via the pulmonary

veins

Pg 158

3. The Heart

B. The Path blood takes through the heart8. The left atrium

contracts• Bicuspid valves open

9. Oxygenated bloodflows into the left ventricle

Pg 158

3. The Heart

B. The Path blood takes through the heart10. The left ventricle

contracts• Bicuspid valves close• Semilunar valves open

11. The left ventriclerelaxes• Semilunar valves close

Pg 158

3. The Heart

B. The Path blood takes through the heart12. Blood leaves for the

rest of the body• Via the aorta• Thicker walls; more

force needed to pump blood

– Coronary arteries• Branch off from aorta• Bring O2 and nutrients

to heart muscles

Pg 158

3. The Heart

B. The Path blood takes through the heart– As blood travels

along the aorta• Other arteries will

branch off• Bring O2 and nutrients

to other tissues

Pg 158

3. The Heart

B. The Path blood takes through the heart– Steps 1 -6:

• Right side of heart• De-oxygenated blood

– Steps 7-12:• Left side of heart• Oxygenated blood

Pg 158

3. The Heart

B. The Path blood takes through the heart– Steps 1-6 and 7-12

• Are happeningsimultaneously

• Left and right atria contract together

• Then left and right ventricles contracttogether

Pg 158

3. The Heart

C. The Cardiac Cycle

Pg 159

3. The Heart

C. The Cardiac Cycle– There are 4 stages

• Corresponding to steps in the path of blood through the heart

• Occurs in left and right sides simultaneously• Stage 1: (Step 1 / 7)• Stage 2: (Steps 2 and 3 / 8 and 9)• Stage 3: (Step 4 / 10)• Stage 4: (Step 5 and 6 / 11 and 12)

– Stage 4 returns the heart to Stage 1

Pg 159

3. The Heart

C. The Cardiac Cycle1. Both atria and ventricles relaxed– Blood flows into atria

• Right side: from vena cavae• Left side: from pulmonary veins

Pg 159

3. The Heart

C. The Cardiac Cycle2. Atria contract; blood goes into ventricles– Atrioventricular (Tricuspid & bicuspid) valves are

already open• Pressure in ventricles < pressure in atria

Pg 159

3. The Heart

C. The Cardiac Cycle3. Then ventricles contract (= ventricular systole)– Blood pressure in ventricles increases

• Atrioventricular valves forced to close (‘lub’ sound)– Blood pressure in ventricles > Blood pressure in

aorta• Semilunar valves forced open• Blood flows out of ventricles

Pg 159

3. The Heart

C. The Cardiac Cycle4. Ventricles relax (= ventricular diastole)– Blood pressure in ventricles decreases

• Semilunar valves close (‘dub’ sound)• Atrioventricular valves open again

Pg 159

3. The Heart

C. The Cardiac Cycle– Repeat stages 1-4!

– Atria and ventricles work alternately

Pg 159

3. The Heart

C. The Cardiac Cycle – Heartbeat – 1 Heartbeat = 1 Systole + 1 Diastole

• (ventricular contraction and relaxation respectively)– Marked by the ‘lub’ and ‘dub’ sounds– 0.8 seconds– Short pause between heartbeats– Average: 72 times/min

Pg 159

3. The Heart

C. The Cardiac Cycle – Heartbeat– What does your heartbeat rate depend on?

– It varies with• Age• Size• Health

Pg 159

3. The Heart

D. What is blood pressure?– It is the force that blood exerts on the walls of

blood vessels– Unit: millimetres (mm) of mercury

• mmHg– Instrument: sphygmomanometer

3. The Heart

D. What affects blood pressure?1. Within the bodya) Varies in different parts of the body

• In the circulatory system,• Where is blood pressure highest?• Where is blood pressure lowest?

b) Varies at different stages in the cardiac cycle• In the arteries,• When is blood pressure highest?

3. The Heart

D. What affects blood pressure?

3. The Heart

D. What affects blood pressure?2. Between people– Varies with

• Age• Physical activity• Emotion• Environment

3. The Heart – Blood pressure

D. Pressure changes in the heart– You need to remember the stages of the cardiac

cycle, as pressure changes are due to • Contraction of atria/ventricles• Opening and closing of valves

Left side –oxygenated blood

Atria Ventricle Bicuspid valve Semilunar valve

1 Relaxed Relaxed Open Closed

2 Contracts Relaxed Open Closed

3 Relaxed Contracts Closed Open

4 Relaxed Relaxed Open Closed


D. Pressure changes in the heart

Pg 161


D. Pressure changes in the heart– Let’s look at the left side (oxygenated blood) first– You can colour over the different lines in your

notesBlue: Pressure in atriumGreen: Pressure in ventricleRed: Pressure in aorta

Pg 161


D. Pressure changes in the LEFT side of the heart– You must know what the different graphs look like

• You may get a question about only 1 of the graphs• Or you may be asked to label

and describe the differentgraphs

– Let’s look at the left side (oxygenated blood) first

Pg 161


D. Pressure changes in the LEFT side of the heart1.

– Pressure in the left atrium increases slightly when it contracts

– This causes ventricular pressure to also increase slightly as blood enters

– Bicuspid valves are open

Pg 161



– Pressure in the left ventricle increases sharply as it starts to contract

– Once ventricular pressure >atrial pressure, bicuspidvalve closes to prevent backflow of blood

Pg 161



– When ventricle pressure > aorta pressure, semilunar valve opens

– Aorta pressure increases, but later decreases as blood is moved away

– Rate of increase of ventricular pressure slows

Pg 161



– Ventricle begins to relax, causing semilunar valve to close to prevent backflow of blood

– Atrial pressure begins to increase as blood starts flowing in again

Pg 161



– Left ventricle remains relaxed– Ventricular pressure

decreases further

Pg 161



– Once ventricular pressure < atrial pressure, bicuspid valves open again

Pg 161



– Both left atria and ventricle are relaxed– Blood flows into ventricle– Ventricular pressure

gradually increases again

Pg 161



– Cardiac cycle repeats itself

Pg 161


D. Pressure changes in the heart– Let’s look at the right side (de-oxygenated blood)

now– Pattern of pressure

changes is similar (look at your handout)

– BUT much smaller magnitude

4. The Blood Vessels


• We will be looking at

1. Arteries – Arteriole = small artery

2. Veins– Venule = small vein

3. Capillaries

Pg 153


• Function– To transport blood

around the body• Structure of arteries and veins

– Wall has 3 layers• Endothelium (innermost layer, 1 cell thick)• Middle layer (Smooth muscle + Elastic fibres)• External layer (Connective tissue)

– Lumen• Space enclosed by the wall

Pg 153, 154

4. The Blood Vessels - Arteries

• Definition: Blood vessels that carry blood AWAY from the heart

• Structure– Thick, muscular and elastic walls– Elastic wall much thicker in

arteries near the heart– No valves– Lumen smaller than that of vein with same

diameter

Pg 153, 155

Questions

• What is the function of the smooth muscle?

• What is the function of the elastic tissue?

• What would happen if the arteries were less elastic?


• Function– To withstand immense pressure of blood as it is

forced out of the heart– Elastic fibres enable artery wall to stretch and recoil

(Recoil = spring back)so that blood is pushed along the artery in spurts

– Smooth muscle contracts• Artery constricts (lumen narrower, less blood/unit time)

– Smooth muscle relaxes• Artery dilates (lumen wider, more blood/unit time)

Pg 153, 155

Thinking question

• How does pulse come about?


• Related to heartbeat– When you feel your pulse, you are feeling the recoil

of artery walls– Ventricular contraction (systole) Arteries dilate– Ventricular relaxation (diastole) Arteries recoil– Helps blood to move along arteries in a series of

waves (Pulse wave)• Heart pumping is not the only mechanism

Pg 153, 162


• Main arteries of the body– Pulmonary artery – Aorta/aortic arch

• Arteries to the head, neck & arms• Dorsal aorta (continues on)• Hepatic artery (to liver)• Arteries to stomach & intestines• Renal arteries (1/kidney)• Arteries to legs

Pg 162

What can happen if there is a fault to the veins?

http://www.binsons.com/prod57/images/greens/services/aching-legs-varicose-veins.jpg

4. The Blood Vessels - Veins

• Definition: Blood vessels that carry blood BACK to the heart

• Structure– Middle wall layer much thinner

• Less muscular• Less elastic tissue

– Has semilunar valves– Skeletal muscles present around the veins– Lumen larger than that of artery with same

diameter

Pg 154, 155

Questions

• Compare and contrast arteries and veins

– In terms of wall thickness, presence of valves, lumen diameter (Past year O level qn)

• How do these differences relate to their functions?


• Function– Blood flow slower and smoother

• Much lower blood pressure– Semilunar valves

• Prevent backflow of blood– Skeletal muscles

• Increase pressure exerted on the veins

• Help move blood along more quickly

Pg 154, 155


• Main veins of the body– Pulmonary veins [to left atrium]– Superior vena cava [from head, neck and arms to

right atrium]– Inferior vena cava [from rest of body to right

atrium]• Hepatic veins (from liver)• Hepatic portal vein (from stomach and intestines, to liver)

‘Portal’ carries blood from 1 capillary network to another• Renal veins (from kidneys)

Pg 163

4. The Blood Vessels - Capillaries

• Definition:Microscopic thin-walled blood vessels that carry blood from

an arteriole to a venule• Structure

– Walls have 1 layer• Endothelium only• 1-cell thick• Small gaps

between cells– Extensive network

Pg 153, 164

Questions

• Why is an extensive network of capillaries required?

• By what mode of transport do capillaries carry out their function?

• What is diffusion?


• Function– Small gaps between cells

• Allow white blood cells to squeeze through (more later)

Pg 164, 165


• Function– Transfer of substances to tissue cells

– By diffusion– Down concentration gradient– Efficiency increased by

1. Extensive network2. Narrow capillary

lumen

Pg 164



– Diffusion• From capillaries into tissue fluid to cells• Dissolved food substances• Dissolved oxygen

Pg 164



– Diffusion• From cells into tissue fluid to capillaries• Dissolved waste products

– Transported to excretory organs for removal

Pg 164


• Tissue fluid/intercellular fluid/interstitial fluid – Definition

• Diluted blood plasma containing white blood cells, small solute molecules and ions

– Formation• Blood plasma forced out of arterial end of capillaries

– Function• Bathes the tissue cells, filling spaces between them• Carries substances in solution between tissue cells and

blood capillaries

Pg 164, 165


• Tissue fluid/intercellular fluid/interstitial fluid– Is related to lymph

• More tissue fluid is constantly leaving the capillaries• Forcing it into lymph capillaries• Forming lymph

– Lymph vessels• Lymph capillaries join, forming larger and larger vessels• Empty contents into vena cava (to right atrium)• Contents return to blood plasma

Pg 164, 165

5. The Blood

5. The Blood

A. Structure and composition of blood– Plasma– Red Blood Cells– White Blood Cells– Platelets

B. Blood groupsC. Functions of blood

– Transport – Protection– Organ transplant and tissue rejection

A. Structure and Composition of the blood

• Microscope picture of blood smear– Different types of blood cells– Blood is a tissue

because it contains cells(Cells make up atissue. A tissue can contain different kinds of cells)

Pg 140

A. Structure and Composition of the bloodBlood

55% plasma 45% blood cells and platelets

90% water 10% dissolved substances

Antibodies

Digested food

Mineral salts

Proteins for blood clotting

Excretory products

(Pale yellowish liquid)

Amounts kept relatively constant Pg 140


45% blood cells and platelets

Red blood cells

White blood cells

Platelets

55% plasma

Pg 141



Red blood cells White blood cells Platelets

55% plasma

= Erythrocytes = Leukocytes/leucocytes = Thrombocytes

Pg 141-143




55% plasma

- Ave 5 million/cm3 of blood (varies with gender and health)

- Produced by bone marrow

- Each cell lives about 3-4 months

- Destroyed in the ____________

- Haemoglobin broken down in the ______________Pg 141




55% plasma

Structure- What do you remember about its structure? (Recap: Cells, TB pg 25)

Pg 141




55% plasma

Structure- No nucleus (Function: more space for haemoglobin)

- Haemoglobin pigment (Function: )

- Circular, flattened biconcave disc (Function: )

- Elastic, can become bell-shaped (Function: Squeeze through blood vessels)

Pg 141




55% plasma

- Larger in size than erythrocytes, but fewer in number

- Ave 5000-10000/cm3 of blood

- Colourless (no haemoglobin)

- Most are also produced by bone marrow

Pg 142




55% plasma

Structure- Irregular in shape

- Has a nucleus

- Can move and change shape (Function: )

Pg 142




55% plasma

2 main types

- Phagocytes (different types have different names)

- Lymphocytes

- Function: To help the body fight disease

Pg 142




55% plasma

- Phagocytes- Structure: Nuclei have lobes and cytoplasm is granular

- Function: Engulf, ingest and digest foreign particles

- Lymphocytes- Structure: Nuclei are large and round (no lobes), cytoplasm is non-granular

- Function: Produce antibodies Pg 142




55% plasma

- Not true cells - But classified with cells when talking about composition of blood

- Membrane-bound fragments of cytoplasm

- Produced by bone marrow

- Function: Involved in blood clottingPg 143

B. Blood groups

• There are 4 possible blood groups– A– B– AB– O

• It is important to know your blood group for blood transfusions– Needed when a lot of blood is lost due to injury or surgery– Require compatible blood groups to be successful

Pg 143, 144

B. Blood groups - Antigens

• Blood group is determined by erythrocytes– By proteins embedded in the erythrocyte cell

membrane– Antigens

• They are found on all red blood cells

Pg 143, 144

B. Blood groups - Antigens

• Antigens correspond to the blood groups

– Antigens are represented by capital letters– There are only 2 antigens, A and B– There are 4 possible combinations

-A and BBA

OABBA

AntigenBlood group

Pg 143, 144

B. Blood groups - Antibodies

– Antigens are found on erythrocytes • Other components of blood respond to these

antigens (compatibility) – Lymphocytes produce antibodies

• Help to protect us against foreign particles• Recognize what ‘belongs to us’• Antibodies are part of the 10% dissolved substances in

plasma– Antibodies react with what is foreign to cause

clumping/agglutination of foreign particles or cellsPg 143, 144


• Antibodies – Are represented with small letters a and b– There are only 2 antibodies, but 4 possible

combinations– Antibodies are able to recognize antigens of the

same letter to cause clumping/agglutination

Pg 143, 144

– People with blood group AB have no antibodies against antigens A and B (NOT that they have no antibodies at all)


a and b

-

a

b

-

A and B

B

A

O

AB

B

A

AntibodyAntigenBlood group

Pg 143, 144

B. Blood groups – Blood transfusions

• What about blood cells donated in blood transfusion?– Antibodies are able to recognize their own blood

cells as ‘self’– Donated blood cells are ‘foreign’


a and bO

- AB

aB

bA

O (no antigens)

AB (antigens A and B)

B (antigen B)

A (antigen A)

Donor’s blood groupRecipient’s antibodies

Recipient’s blood group


• How come antibodies in the donor’s blood do not cause clumping of the recipient’s red blood cells?– It depends on the volume of blood

Vol of blood from donor << Total vol of blood in recipient– Donor’s blood is greatly diluted so antibodies in the

donor’s plasma will not have an effect on recipient’s erythrocytes

Pg 145

Question• Mr. Tan had an accident and lost a lot of blood. He

requires a blood transfusion. His blood group is A. Several people have come forward to offer to donate blood to him. His wife is blood group AB, his father is blood group B, while his brother is blood group O.

• Who can he accept blood from and why? Use the table given to determine the answer

• If Mr. Tan’s wife had been in the accident as well, could she have accepted blood from any of the other 2 donors? Why?

C. Functions of the blood

• 3 functions– Transport– Protection

• Protection against disease-causing organisms(phagocyctosis & blood clotting)

• Antibody production

Pg 146-150

C. Functions of the blood – 1. transport

• Transport medium – plasmaBlood

55% plasma 45% blood cells and platelets

90% water 10% dissolved substances

Antibodies

Digested food

Mineral salts

Proteins for blood clotting

Excretory products

(Pale yellowish liquid)

C. Functions of the blood – 1. transport

• Transport medium – red blood cells– O₂ is carried by red blood cells

• Red pigment haemoglobin (NOT an enzyme) has high affinity for O₂

• O₂ is released as blood passes tissues containing little oxygen. It then diffuses into tissue fluid to the tissue cells

• As blood returns to lungs, haemoglobin combines with O₂ in oxygen-rich environment again

Haemoglobin Oxyhaemoglobin

O₂ from lungs

O₂ to body tissuesPg 146-150

C. Functions of the blood – 2a. protection

• Protection against disease-causing organisms – white blood cells– Phagocytes

• Engulf, ingest and digest bacteria • Can also ingest dead body cells

Pg 146-150

C. Functions of the blood – 2a. protection

• Protection against disease-causing organisms – white blood cells– Lymphocytes

• Produce antibodies when stimulated by bacteria entering the bloodstream, which can

– Cause clumping/agglutination– Cause bacterial cell membranes to rupture– Neutralize toxins– Make viruses unable to bind to their host cells

• Antibodies have long-term protection: they remain in the blood long after the infection is over

Pg 146-150

C. Functions of the blood – 2b. protection

• Blood clotting– Stopping of blood flow at a wound is due to clotting

• Important to a) Seal the woundb) Prevent entry of bacteria

– Is the 1st line of defence• If bacteria does enter the bloodstream, phagocytes and

lymphocytes are the 2nd line of defence– Involves platelets, proteins and enzymes

Pg 146-150


• Blood clotting– A multi-step process involving enzymes

– Like in Nutrition,• There are inactive proteins that have to be activated • They have similar names e.g. prothrombin (enzyme)

fibrinogen (NOT an enzyme)

Pg 146-150


• Blood clotting

Platelets and damaged tissue

Thrombokinase

Produce

Inactive prothrombin

Active enzyme

Active prothrombin

Converts

Soluble fibrinogen

Insoluble fibrin threads

Converts

ClotEntangle red blood cells at the wound, forming

Pg 146-150


• Blood clotting– Does not normally occur in our blood vessels

• Due to presence of heparin which prevents clotting• Heparin is produced in the liver

– Thrombokinase released by platelets neutralizes the effect of heparin

– Haemophilia• Condition where ≥1 parts of the clotting process are

defective, so blood clotting cannot occur• Haemophiliacs can lose a lot of blood from simple injuries

Pg 146-150

6. Heart Disease

6. Heart Disease

• Heart disease = cardiovascular disease – cardio = heart– vascular = related to the vessels around the heart

• Types of heart disease– Coronary heart disease

• includes coronary artery disease, myocardial infarction (heart attack), thrombosis and angina

– Irregular heart beat (arrhythmias)• Includes cardiac arrest

6. Coronary Heart Disease (CHD)• While there are different kinds, they are all caused by

blockage or narrowing of coronary arteries

• Angina: (a feeling)– Chest pains due to lack of oxygen to cardiac muscle

• Heart attack: (an event)– Blood flow to parts of the heart are blocked– Cardiac muscle does not receive oxygen and nutrients– Cardiac muscle dies (this is irreversible)– This can be fatal

6. Causes of CHD

• Cholesterol and saturated fats deposited on the inner surface (endothelium) of the arteries– Narrows the lumen– Increases blood pressure– Increases risk of blood clots (as inner surface of

arteries is now rough, not smooth)• Thrombus = blood clot in the blood vessels• Thrombosis = having a blood clot in a blood vessel• Embolus = blood clot that is able to move within blood

vessels and cause a blockage away from the original site

6. Causes of CHD

• Atherosclerosis – The hardening of arteries– Due to the response of the white blood cells to fatty

deposits– One type of arteriosclerosis (hardening of any

arteries, for many different reasons)– There is also arteriolosclerosis (hardening of

arterioles)

6. Causes of CHD

• Blocked coronary arteries can start as early as childhood!– Unhealthy diet

• High in cholesterol• High in fat

– Smoking• Carbon monoxide and nicotine increase risk of heart

disease– Lack of exercise

6. Causes of CHD

• Other factors can increase your risk of CHD– Gender – Age– Family history– Emotional stress– Lifestyle

6. Risk of CHD

• Doctors assess your risk by looking at your– Gender– Age– Family history– Cholesterol level– Blood pressure level– Weight (or height/weight ratio)

– (See Risk Prediction chart)

6. Risk of CHD

Blood pressure/ Cholesterol

Risk of heart disease

Preventing CHD

• Healthy diet – Balanced– Low in cholesterol (LDL only, not HDL)– Low in saturated fats– Rich in fibre

• Stress management• Stop smoking • Exercise• If already at risk

– Medication e.g. statins lower cholesterol levels

Technology

Transport in humans