topic 1

Systole definition

Phase of the heartbeat where the heart muscle contracts

Diastole

Phase of the heartbeat where beat where the heartbeat relaxes

Atrial systole

• two atria contract increasing blood pressure

• Increase in blood pressure causes the atrioventricular valves open and blood flows from atrium to ventricle

• Semilunar valves are closed

Ventricular systole

• ventricles contract increasing blood pressure

• Increase in blood pressure causes the atrioventricular valves closed to prevent backflow

• Increase in blood pressure causes semilunar valves open

• Blood moves from the ventricles to the aorta and pulmonary artery

Label the heart

Pathway of blood through the heart

Body - vena cava - right atrium - tricuspid valve (open) - right ventricle - semi lunar valve (open) + tricuspid valve (close) - pulmonary artery - lungs (blood becomes oxygenated) - pulmonary veins - left atrium - bicuspid valve (open) - left ventricle - semi lunar (open) + bicuspid (close) - aorta - body

Cardiac muscle

Made up of cells connected by cytoplasmic bridges, which enables electrical impulses to pass through the tissue. It contains large numbers of mitochondria and myoglobin molecules.

Key differences between arteries and veins

Veins have

• wider lumen

• Thinner walls

• Less collagen, smooth muscle and elastic fibres

• Valves

Veins and arteries similarities

Walls of both vessels contain collagen, elastic fibres and smooth muscle. Both have a lumen

What makes up inner layer of arteries and veins

• single layer of simple endothelial cells - flat + smooth so blood can flow

What makes up Middle layer of arteries and veins

• Circularly arranged elastic fibres and smooth muscle

What makes up outer layer of arteries and veins

Collagen

What is endothelium

A type of epithelium that lines the interior surface of blood vessels. It is a thin layer of simple squamous cells called endothelial cells

What are elastic fibres

Allows the vessels to stretch and recoil so they don’t rupture when pressure comes in. NOT contracting as doesn’t require energy/ATP

What is smooth muscle

For constriction and dilation - relaxes to allow more blood flow to area and contracts to restrict blood flow. (Vasoconstriction + vasodilation)

What is collagen

For strength and durability, flexible, connective tissue

Features of capillaries

• One cell thick

• Join arterioles to venules

• 10 micrometres in diameter

Network of capillaries explained

• blood pressure decreases as it moves from artery to arteriole to capillaries

• Capillaries are 1 cell thick which slows blood down so gas exchange can happen

• Once blood flows through capillaries its deoxygenated and moves into the venules and then veins

Why do veins have valves

• low blood pressure so blood can backflow and veins make sure blood flows in 1 direction

Haemolymph

= a fluid equivalent to blood in most invertebrates

What is diffusion

Movement of molecules from an area of high concentration to an area of ow concentration down a concentration gradient

Ficks law

Rate of diffusion is proportional to SA:V ratio x difference in conc / length of diffusion path

Open circulatory system

Consists of a heart that pumps haemolymph through short vessels and into a large cavity called haemocoel

Organism with an open circulatory system have:

• low metabolic rate

• Large SA:V

• = sufficient diffusion rate between haemolymph and cells of O2/CO2

Closed circulatory system

Blood is fully enclosed within blood vessels at all times

Organisms with closed circulatory systems:

• High metabolic rate + low SA:V

• generate high pressure so blood travels faster, more efficient transport system

• Overcomes limitations of diffusion

Single circulatory system

• 1 system

• Higher BP than no blood vessels BUT not too high to damage capillaries

• Not as efficient

Double circulatory system

• 2 systems

• Pump 1: low blood pressure in lungs to protect capillaries in lungs

• Pump 2: boosts the blood pressure for rapid and effective delivery of oxygen/glucose

Daphnia practical

• place daphnia on cavity slide, using a few strands of cotton wool to immobilise the daphnia

• Take heart rate fore using a microscope to observe the heart rate

• Add caffeine solution to the daphnia and allow daphnia to acclimatise

• Repeat for each caffeine conc 3x and calc a mean

Course of events that lead to atherosclerosis

• endothelium is damaged

• Damage triggers inflammatory response

• White blood cells engulf (by phagocytosis) saturated fats or cholesterol

• White blood cells become fatty, enlarged cells called foam cells

• Atheroma formation i middle layer of artery

• Calcium salts and fibrous tissue form plaque

• Lumen narrows > raised blood pressure

Blood clotting process

• thromboplastin release from damaged cells and platelets

• Thromboplastin + Ca2+ salts + K+ causes cascade of events

• Conversion of prothrombin to thrombin

• Thrombin (enzyme) that causes conversion of (Soluble) fibrinogen to (insoluble) fibrin

• Fibrin forms a tangled mesh to trap red blood cells and platelets to make a blood clot

What does atherosclerosis cause

• increases risk of a blood clot forming coronary arteries, leading to a heart attack (myocardial infarction)

• Or a blood clot forming in arterial es in brain, resulting in a stroke

What does a heart attack cause

• lack of oxygen/glucose reaching heart muscle cells

• Anaerobic respiration of affected heart muscle cells

• Lactic acid production (pain)

• Death of affected heart muscle cells

Carbohydrates

• Group of substances used as both energy sources and structural materials

• contain C, H, O with the general formula Cx(H2O)y

3 main groups of carbohydrates

• monosaccharides

• Disaccharides

• Polysaccharides

Monosaccharides

• simple sugars with the general formula (CH2O)n where n = 3-7

• sweet taste

• Cause sharp rise in blood sugar

• Reducing sugars - ca be tested by Benedict’s

Disaccharides

“Double sugars” formed by 2 monosaccharides through condensation reactions forming glycosidic bonds

Polysaccharides

Large molecule formed from many monosaccharides joined together by glycosidic bonds formed through condensation reactions

Structure of alpha glucose

Structure of beta glucose

What are the properties of glucose

• large molecule - transported via facilitated diffusion using channel proteins

• Polar so hugely soluble in water

• Main form in which carbs are transported around the body

3 important monosaccharides

• glucose

• Fructose

• Galactose

Fructose

Very soluble and the main sugar in fruits and nectar. It’s sweeter than glucose.

Galactose

• not as soluble as glucose

• Important role in the production of glycolipids and glycoproteins

Ribose

• a 5-carbon (pentose) monosaccharide present in RNA nucleotides

• formula C5H10O5

• Deoxyribose is the pentose sugar present in DNA nucleotides (- a O)

3 disaccharides

• maltose

• Sucrose

• Lactose

Monosaccharides that make up maltose

Alpha glucose + alpha glucose

Monosaccharides that make up sucrose

Alpha-glucose and fructose

3 polysaccharides

• starch

• Glycogen

• Cellulose

1,4 glycosidic bonds cause

Straight chains

1,6 glycosidic bonds cause

Branches

Propertie of glycogen and starch that name them good energy storage molecules

• they are compact so can store lots of energy in a small area

• They cannot dissolve so they have no osmotic effect on a cell

• They cannot dissolve so they cannot move out of a cell

Amylose

Straight chain molecule that only contains 1,4 glycosidic bonds, forms a helix

Amylopectin

Branched has 1,4 and 1,6 glycosidic bonds

Glycogen functions

• highly branched structure allows it to be hydrolysed very quickly to release glucose quickly for respiration

How is a triglyceride synthesised

The formation of 3x ester bonds during 3x condensation reactions between 1x glycerol and 3 fatty acids

Saturated lipids

• no double carbon-carbon bonds in hydrocarbon chain

• Solids at room temperature as due to shape they can form stronger intermolecular bonds and there is not enough energy at room temperature to break them

Unsaturated lipids

• liquids at room temperature because they form weaker intermolecular bonds

• 1 or more double carbon-carbon bonds in their hydrocarbon chain

Properties of lipids

• waterproof because the fatty tail is hydrophobic

• Very compact

• better for energy release than carbohydrates or proteins

• Lipids are non-polar and insoluble in water and so good for storage

• Conduct heat slowly therefore they provide thermal insulation

Risk factors for CVD

• genetic predisposition

• Diet high in saturated fats

• Diet high in salt

• Old age

• Gender

• High blood pressure

• Smoking

• Inactivity

• Too much alcohol

How does genetic predisposition increase risk of CVD

alleles that result in high blood cholesterol levels

How diet high in saturated fats increases risk of CVD

Faster plaque development

How diet high in salt increases risk of CVD

Higher BP

How old age increases risk of CVD

Loss of elastic fibres in arteries > increase in BP

How high bp increases risk of CVD

Risk of damage to endothelium lining arteries

How gender (male) increases risk of CVD

Lack of protective oestrogen

How smoking increases risk of CVD

Toxins in blood that damage endothelium lining arteries

How inactivity increases risk of CVD

High BP

How too much alcohol increases risk of CVD

Toxins in blood that damage endothelium

Which type of cholesterol is linked to CVD

LDL

Treatments for CVD

• antihypertensives

• Statins

• Anticoagulants

• Platelets

Benefits and risks of anrihypertensives

Benefits: lowers bp

Risks: BP too low, dehydration

Benefits and risks of statins

Benefits: lowers blood cholesterol levels

Risks: liver damage, muscle pain, headache/dizziness

Risks and benefits of anticoagulants

Benefits: Reduces risk of blood clotting

Risks: uncontrolled bleeding

Risks and benefits of platelet inhibitors

BEnefits: reduces risk of blood clotting

Risks: uncontrolled bleeding

Types of antihypertensives

Beta blockers

Diuretics

ACE inhibitors

BMI

body mass index calculated by dividing weight in kg by height in metre squared. The value obtained is then compared to a chart.

Waist-to-hip ratio

Can be used to determine how likely a person is to get heart disease based on the distribution of fat in the body. A value above 1 = health risk

HDL

• High density lipoprotein

• ‘Good’ cholesterol

• Formed from unsaturated fats, protein and cholesterol and transports from body tissues to the liver

• Reduces cholesterol levels and risk of atherosclerosis

LDL

• low density lipoprotein

• Bad cholesterol

• Formed from saturated fats protein and cholesterol and transports cholesterol from the liver to the blood

• This then causes cholesterol levels to increase and that’s why its linked to atherosclerosis

Vit C practical