Unit Two Cardiovascular System Flashcards
Explain why we need a circulatory system
Because humans have large surface areas
It provides at least five major functions that are essential to life
What is the function of the arteries, veins and capillaries
Blood circulated from the heart through the arteries to the capillaries, then to the vein before returning back to the heart it’s blood moved away from the heart,
Why is it important that the blood pressure is higher in the capillaries than on the tissue
Allows for pressure filtration
Describe connective tissue
For support and to bind other tissues together
Contains elastic fibres
Describe smooth muscles
Regulated blood flow by contracting and relaxing
Thinner layer than arteries
Describe endotheliums
A thin membrane that lines the inside of the heart and blood vessels
Why is it important that the walls of the arteries are elastic
To accommodate the surge of blood after each contraction of the heart
Explain the terms vasodilation and Vasoconstriction and describe how this occurs
-contractions the diameter of central lumen decreases this decreases blood flow
Relax causing vasodilation. The diameter of the central lumen increases and this increases blood flow
Explain importance of vasodilation and vasoconstriction to blood flow
Contract causing vasoconstriction- reduce blood flow to extremities can reduce heat loss, divert blood flow to muscles
Relax causing vasodilation. Redirect blood to extremities or where blood is needed
What is the function of capillaries
Allow exchange of substances carried in the blood with the body tissues
Describe endothelium
Wider central lumen than arteries
Describe valves
Stops the back flow of blood
What is tissue fluid
A watery fluid that is around cells. And contains essential substances for life
How does oxygen get into tissue fluid
Diffusion
What substances is delivered to tissue
Water
Nutrients
White blood cells
WWN
What substances are taken away from the tissue
CO2
How is the osmotic pressure of blood maintained
Most of the tissue fluid returns to the blood
Explain the movement of fluid
Blood goes in
Tissue fluid comes out
Tissue fluid comes back in
List the substances contained in the returning tissue fluid
Co2
Metabolic waste
Water
99% of tissue fluid returns to the blood. What happens to the other 1%
Becomes lymph
What is the function of the heart
To pump blood around the body to supply oxygen and nutrients to cells and to remove waste products
Where does the left ventricle pump blood
To the whole body
Where does the right ventricle pump blood
Deoxygenated blood to the lungs via the pulmonary artery
Define heart rate
No. Of beats per minute
Define stroke volume
Vol of blood pumped out by the ventricle during contraction ie per beat
Define cardiac output
The volume of blood pumped through each ventricle per minute
(Normally 5L/ minute)
What is responsible for the heart sound heard with a stethoscope
AV + SL valves opening and closing
Describe the stages of the cardiac cycle
Diastole
Atrial and ventricular diastole(0.4 sec)
During diastole, blood returning to the atria flows (passively) into the ventricles through the open atrio-ventricular
AV valves
AV valves open SL valves closed
What does there term myogenic mean
This means that it does not need an electrical impulse for in order to contract
Describe the function of the sino atrial node
The timing of cardiac muscle cell contraction is controlled by impulses from the SAN spreading through the atria causing atrial systole
Describe the function of the atrio-ventricular node
Impulses from the AVN travel down fibres in central walls of the ventricles causing ventricular systole
Why is it important that there is coordination in this sequence of events
So heart can pump blood efficiently
What is an electrocardiogram (ECG)
Impulses in the heart generate currents that can be detected by an electrocardiogram
In an electrocardiogram what is the points
- Atrial systole
- Ventricular systole
- Diastole
Describe the effect of the sympathetic nervous system on heart rate
Releases a noradrenaline which increases the heart rate
Describe the effect of the parasympathetic nervous system on the heart rate
Releases acetylcholine which decreases the heart rate
How is blood pressure generated
By the contractions of the heart
How is blood pressure measured
Sphygmomanometer
The cuff is inflated to stop blood flow in the artery
The cuff then deflates gradually the blood starts to flow(detected by a pulse) at systolic pressure
The blood flows freely through the artery and a pulse is not detected at diastolic pressure
What is a systolic pressure measuring
the pressure of your blood when your heart is contracting
What is the diastolic pressure measuring
the pressure of your blood when your heart is relaxing
What is a Typical blood pressure reading
120/80 mmHg
What is a typical blood pressure reading from a hypertensive patient
Over 140/90 mmHg
What medical conditions can hypertension(high blood pressure) lead to
Coronary heart disease
Strokes
What is the main cause of atherosclerosis
Build up do fatty materials
High cholesterol
Of what material is the plaque composed
Consists of cholesterol, fibrous material + calcium
Where does the plaque form
Beneath endothelium
As the atheroma what happens to the properties of the arteries
Lumen narrows
Loses elasticity
As the atheroma what happens to blood flow
Becomes restricted
Name the cardiovascular diseases associated with atherosclerosis
Angina
Heart attack
Stroke
Prepubertal vascular disease
What is a thrombus and how does it occur
A blood clot
During damaging of the endothelium of the artery
Discuss the role of the enzyme prothrombin in blood clot formation
Clotting causes reactions resulting in the conversion of the inactive enzyme prothrombin do its active form thrombin
thrombin causes molecules of the plasma protein fibrinogen to form threads of fibrin
What is an embolus
A piece of a blood clot, foreign object or other bodily substance becomes stuck in a blood vessel.
What is thrombosis
A blood clot within blood vessels that limits the flow of blood
What medical condition can result from thrombosis
Heart attacks
Strokes
What medical conditions can result from an embolism
Stroke
Pulmonary embolism
Define the term peripheral vascular disease
A narrowing of the arteries, due to atherosclerosis not in brain or heart
Which arteries are most commonly affected and what are most common symptoms
Arteries in the legs
Pain in leg muscles
Deep vein thrombosis is a condition that effects the bejnd and not the arteries
A blood clot that forms deep in the leg
Why does DVT lead to an increased risk of pulmonary embolism
They can break off and result in pulmonary embolism must pass through the heart first and then to the lungs
What factors can increase the risk of DVT
Age
Sitting for a king time
Prolonged bed rest
Pregnancy
Birth control pill
hormone replacement surgery
Being overweight/obese
Smoking
What food in the diet is the principal source of cholesterol
A diet high in saturated fats
Butter meat sausages cheese cream chocolates
Where do animal cells synthesise cholesterol
Cholesterol is synthesised by all cells although 25% of total production takes place in the liver
List essential functions of cholesterol
To make sex hormones- testosterone, oestrogen, progesterone
How does cholesterol circulate in the body
Through the blood
the most important lipoproteins involved in cholesterol transport are high and low density lipoproteins. Describe them
LDL- transports cholesterol to body
HDL-transports excess cholesterol form the body cells to liver for elimination prevents too much cholesterol in the body.
Why are lower numbers of LDLs better
LDLs deposit cholesterol in arteries and can cause antherosclerosis so lower levels are better
Why are high levels of HDLs better
Removed cholesterol from body and takes it to liver to be removed
Explain why HDLs are sometimes referred to as good
They remove cholesterol from blood
How does the ratio of HDL/LDL in the blood determine the chances of atherosclerosis
A higher ratio of HDL to LDL will result in lower blood cholesterol and reduced chance of atherosclerosis
What effect does regular physical activity have on cholesterol levels
Tends to raise HDL levels and lowers blood cholesterol
How do certain drugs like statins reduce blood cholesterol levels
Reduce blood cholesterol by inhibiting the synthesis of cholesterol by liver cells
Why does chronically elevated levels blood glucose levels effect cells of the endothelium lining
Because of untreated diabetes
In larger arteries what damage does chronically elevated blood levels cause and what conditions can arise from this damage
Damaged blood vessels
Antherosclerosis may develop leading to cardiovascular disease
Stroke
Peripheral vascular disease
In smaller arteries and arterioles what damage does chronically elevated blood glucose levels cause and what conditions can arise
Haemorrhage of blood vessels in the retina
Renal (kidney) failure
Define glycogenolysis
Breakdown of glycogen into glucose 1 phosphate and glucose
Define gluconeogenesis
The synthesis of glycogen
What organs control the level of glucose in the blood
Pancreas
If blood glucose levels are low( less than 4g mol/L) what hormone is released and what effect does this have
Glucagon
Conversion of glycogen to glucose
Id blood glucose levels are high (more than 5 mol/L) what hormone is released and what effect does this have
Insulin
Activated the conversion of glucose to glycogen in the liver
How does the body respond to the excitement and stress of exercise include diabetes
Adrenaline stimulates glucagon secretion inhibits insulin secretion
describe diabetes
An inability to regulate blood glucose levels
Doefine hypoglycaemia
Low blood sugar
Define hyperglycaemia
High blood sugar
When does type one diabetes usually occur
Under the age of 20
Describe type one diabetes and any factors that can trigger this condition
Pancreas doesn’t produce enough insulin
Usually family history
Require an environmental trigger such as a viral infection or cold weather
How is type one diesbetes usually controlled
Regular doses of insulin
When does type two diabetes occur
Later in life
Describe type two diabetes and factors that can trigger the condition
Being overweight
Individuals produce insulin but their liver cells are less sensitive to it
Insulin receptors are decreased in the liver
This means that the liver cannot convert glucose into glycogen
How is tupe two diabetes usually controlled
Diet and exercise
Insulin replacement
Describe how levels of glucose in urine are used in the test for diabetes
The kidneys will remove some of this glucose and this will result in glucose appearing in urine
Describe how blood tests are used to test for diabetes
Takes you blood with a pin prick to check levels in your blood
Describe the glucose intolerance test
Measured after fast
Drink glucose solution
Changed in their blood glucose for at least the next two hours
Define obesity
Obesity is characterised by the excess body fat in relation to lean body tissue such as muscle
How is bmi calculated
Weight in kg/ height m2
BMI over 30 indicated obesity
Why is bmi not suitable for comparing individuals
Because someone could be identified as obese when their additional mass is actually muscle and not fat
Which two factors make the greatest contribution to obesity
High fat diet and exercise
Why should we limit fat and free sugars in our diet
The energy intake in the diet should be reduced by limiting fat and free sugars
In what way does exercise help control obesity
To increase energy expenditure and pressure lean tissue
How does exercise help prevent cardiovascular disease
Keeping weigh under control
Minimising stress
Reducing hypertension
Improving blood lipid profiles
What affects the dose of insulin a type one diabetic needs
Diet and exercise in the day
What is atherosclerosis
The build up of fatty material( cholesterol) ,fibrous material (calcium) build up and form an antheroma
Describe the structure of the heart
Enters, from body to right atrium,via vena cava
Leaves, to lungs,from right ventricle via pulmonary arteries
Enters,from lungs to left atrium via pulmonary vein
Leave,to body from left ventricle via aorta
