Human MovementBasic Anatomy and

Physiology

The Circulatory System

http://www.youtube.com/watch?v=mu2BLnI-afI

CIRCULATORY SYSTEM

The circulatory or cardiovascular system consists of

The HeartThe BloodBlood vessels

Together with the Lymphatic System, the Circulatory System:

Delivers oxygen and nutrients to cellsRemoves waste from cellsMaintains the balance of water in the body.

WEBSITE:The Heart: An online Explorationhttp://www.sin.fi.ed/biosci/biosci.html

BLOOD

A specialised type of connective tissueIt is a thick liquid with a metallic tasteBlood accounts for about 8% of our total body weightBlood volume in a healthy adult:

Male 5 – 6 L Female 4 – 5 L

Functions:Blood performs a number of specialised functions:

Transports nutrients, oxygen, carbon dioxide, waste products and hormones to cells and organs around the bodyProtects us from bleeding to death, via clotting, and from disease, by destroying invasive micro-organisms and toxic substancesActs as a regulator of temperature (vessels constrict to conserve heat or dilate to release heat to the surface for cooling), the water content in cells and body pH.

Composition of blood:

1. Solid component (Blood cells)

45% of total volume Red blood cells (erythrocytes), white blood cells

(leukocytes), or platelets (thrombocytes)

2. Liquid Component (Blood plasma)

55% of total blood volume Composed of 91.5% water and 8.5% of nutrients, waste

products, proteins, enzymes and hormones Straw coloured or yellowy solution Nutrients from the small intestine is absorbed into the

plasma and transported around the body

RED BLOOD CELLS

Contains an oxygen carrying pigment called Haemoglobin (Hb). This gives blood its red colour.

Oxygen (O2) is carried by Hb and transported from the lungs to all cells. This reaction forms oxyhaemoglobin (aided by iron molecules)

Carbon dioxide (CO2) is also transported this way. Formation is called carbaminohemoglobin

Life cycle is approximately 120 days and they are replaced at the rate of 2 million per second

They are produced in red bone marrow from stem cells

Red blood cells function is to transport O2 and CO2 around the body

PLATELETS

Small colour-less bodies that usually appear as irregular spindles or discs that are much smaller than RBC and WBC

Produced in red bone marrow

Life cycle is approximately 5 to 9 days

Platelets are involved in the process of clotting and they help to repair slightly damaged blood vessels

WHITE BLOOD CELLS

Slightly larger than red blood cells

Classified according to the presence or absence of granules in their cytoplasm

Life cycle is from a few hours to a few days

Produced in bone marrow and lymph tissue

They move to areas of infection or disease to engulf invading bodies (puss is the accumulation of WBC)

BLOOD VESSELS

HEART → ARTERIES → ARTERIOLES →

CAPILLARIES → VENULES → VEINS → HEART.

ARTERIES

Carry blood away from the heart to tissues

Thick elastic walls as blood is pumped through them at high pressure in surges

Three layers- endothelium lining- involuntary muscle- tough fibrous tissue

Surges are called heart beats

Pressure decreases as distance from the heart increases. Blood passes through small vessels called arterioles

VEINS

Carry blood from tissues back to the heart

Thinner walls and less elastic as pressure decreases as the blood gets closer to the heart

The contraction and relaxation of muscles assists the blood to stream back steadily to the heart

Valves prevent the blood from flowing back the wrong way against a force of gravity. After standing for a long time, legs can feel heavy and swollen. Blood pools in the lower legs because of gravity and lack of movement. Once moving, the muscles squeeze the blood up through the veins toward the heart.

Gravity affects blood flow – blood above the heart flows easily

CAPILLARIES

A very small network of vessels

One cell wide

Lie between arterioles and venules, connecting both systems

Semipermeable membrane where O2, CO2 and nutrients are exchanged between the blood and the cells of the body

Feeds muscles, joints, tissues and organs in clusters

THE HEART

Involuntary cardiac muscle

Pericardium is a triple layered bag that surrounds, anchors and protects the heart

Four hollow chambers- 2 atria- 2 ventricles

Atria act as receiving chambers for blood returning to the heart. Small and thin as they only pump next door

Ventricles are large as they propel the blood from the heart into circulation around the body

Dense connective tissue called valves, prevent the back flow of blood into the chambers by opening and shutting when the heart contracts and relaxes. Tricuspid and Bicuspid valves

Heart contracts and squeezes blood into arteries – systole

Heart relaxes and fills with blood – diastole

Pulmonary Artery has deoxygenated blood travelling in it. Other arteries have oxygenated blood. Being an artery it still travels away from the heart

Pulmonary veins have oxygenated blood. Other veins have deoxygenated blood.

ANATOMY OF THE HEART

ATRIUM: the receiving chamber of the heartVENTRICLE: the propulsion chamber of the heartSEPTUM: separates the two ventricles and the two atriumVENA CAVA: returns blood from the systemic system to the right atriumPULMONARY ARTERY: carries blood from the right ventricle to the lungs via the circulatory system PULMONARY VEIN: carries blood from the lungs to the left atriumAORTA: carries blood from the left ventricle to the systemic circuit around the bodyMYOCARDIUM WALLS: have different thicknesses depending on the pressure they are under eg atrium walls are thinner because it is easier to push blood into the ventriclesATRIOVENTRICULAR VALVES: these are forced shut as the ventricle pressure increases, preventing back flow of blood into the atria when the ventricles are pumping – they are bicuspid and tricuspidSEMILUNAR VALVES: prevent blood returning to the ventricles after they have completed contracting

SINUATRIAL VALVE: is the pacemaker. It controls contractions and is found in the right atria.

PULMONARY AND SYSTEMIC CIRCULATION

The heart is actually a double pump that serves two circulations.Two types of blood circuits are created:

Pulmonary circuit – circulates blood from the right side of the heart to the lungs and then back to the heart.Systemic circuit – pumps blood from the left side of the heart out to all body tissues and then back to the right side.

PULMONARY CIRCUITDeoxygenated blood from the body enters the right atrium via 3 veins, superior vena cava, inferior vena cava and coronary sinus. From here the blood flows into the right ventricle, which pumps it to the lungs via the left and right pulmonary arteries. In the lungs CO2 is released and O2 is picked up.

SYSTEMIC CIRCUITOxygenated blood then enters the left atrium via 4 pulmonary veins. The

blood flows into the left ventricle, from where it is pumped up through the aorta and out to the upper and lower

body via a number of arteries.

The cycleOxygen-poor blood from the body collects in the right atrium, which contracts, filling up the right ventricle

Right ventricle contracts and pushes blood to the lungs

In the lungs, blood loses carbon dioxide and picks up oxygen

Oxygen-rich blood returns to the left atrium, which contracts, filling up the left ventricle

Powerful contractions of the left ventricle, expels oxygen-rich blood in the aorta, from where artery branches distribute blood throughout the body.

In the muscles and body organs, blood releases oxygen and nutrients, and absorb food and water from the intestines. Liver processes nutrients, and together with kidneys, purifies the blood

Oxygen-poor blood returns to the heart through the veins. Another cycle begins.

SYSTEMIC CIRCUIT

This circuit has 4 major areas:

1.Coronary CirculationCoronary arteries feed the cardiac muscle

2.Portal CirculationBlood from the stomach and intestine returns through the liver and

then to the heart

3.Muscle circulationCirculation to the muscles

4.Skin CirculationCirculation to the skin

Hot weather → Blood vessels dilateCold weather → Blood vessels constrict

HEART RATE

Number of beats per minute

Resting heart rate is best taken when you first wake up in the morning. It is a good indicator of the efficiency and strength of the heart

Heart rate increases due to fear, excitement, exercise, food ingestion, illness, smoking, drugs, body position, age and temperature changes

Pulse is the pressure wave of blood continuing along the arteries

Measurement of pulse is best taken from the radial or carotid site. Take if for 6, 10, 15, 20 or 30 seconds and then multiply by 10, 6, 4, 3 or 2 respectively, to calculate your heart rate over a minute.

HEART SOUNDS

2 sounds that accompany blood movement

Blood moves in spurts rather than a constant flow

1st spurt, caused by the ventricular contraction (systole) this increases the pressure in the ventricles

The AV (tricuspid and bicuspid) valves shut quickly due to this pressure and this sharp closure makes the 1st sound

2nd sound occurs as the ventricle relaxes (diastole), the atria fills and the semilunar valves shut quickly

HEART DISORDERS

Abnormal heart rate: a regular heart rate lower than 60 and higher than 100 is abnormal.

Heart block: SA node fails to send impulses which tell the heart to contract. Ventricles contract at their own rate slower than the atria.

Arteriosclerosis: Hardening and narrowing of coronary arteries. If an artery blocks then myocardial infarction occurs (heart attack)

Myocardial Infarction: blood flow is interrupted to heart muscle. This tissue dies. Complete rest is needed. If a large area is starved of oxygen, death will occur

Heart muscle can become infected

Valves of the heart can become ineffective

Cardiomyopathy – virus of the heart causing heart to enlarge and harden making it ineffective. Death will result if the heart is not transplanted.

HEART RATE CONTROL

HR is controlled by the involuntary (autonomous) nervous system

Sympathetic System – heart beats faster

Parasympathetic System – returns heart to normal

Electrical impulses from these systems stimulate the atria to contract together. The impulses travel to the ventricles, which contract 0.1 seconds after the atria. The rate at which the sinoatrial node (pacemaker) sends impulses determines heart rate.

Blood flow through the body:

Use your text, notes and knowledge to arrange the following body processes into the correct order (no.1 and No. 12 are already done)

1. Deoxygenated blood to the right atrium2. Right ventricle3. Deoxygenated blood to the lungs4. Oxygenated blood from the lungs5. Left atrium6. Left ventricle7. To body via aorta, arteries and arterioles8. To capillaries9. To tissues, organs and muscles 10.To capillaries11.To veins12.Deoxygenated blood back to the right atrium

BLOOD PRESSUREBlood pressure is the pressure of the blood in the arteries as the heart pumps it around the body.

Hence it is the arteries that are mainly at risk of damage from high blood pressure.

Blood flow and blood pressure surge each time the heart contracts. The peak pressure is called the systolic pressure.

The pressure falls as the heart relaxes to fill. This lower pressure is called the diastolic pressure.

Blood pressure in each individual varies the whole time according to numerous influences such as posture (whether you are lying or standing), emotion, pain and sleep.

For example – blood pressure may be higher the first time that you visit a new doctor. Readings tend to become lower as the patient relaxes with subsequent visits.

The WHO (World Health Organisation) defines the following“Normal adult blood pressure is arbitrarily defined as a systolic

pressure equal to or less than 140mmHg together with a diastolic equal to or below 90 mmHg. Hypertension in adults is arbitrarily defined as a systolic pressure equal to or greater than 160 mmHg and/or diastolic pressure equal to or greater than 95 mmHg.”

FACTORS AFFECTING SYSTOLIC BLOOD PRESSURE

Short term factors include –

Smoking – increases blood pressure, as the capillaries constrict or reduce in size when the nicotine is present which increases the resistance to blood flew. This effect lasts for about 20 minutesExercise – increases BP and HR (heart rate)Fright, stress or anxiety – increases BPBody position – affects BP due to the pull of gravity. Standing increases BP while lying down decreases BP.

Long term factors include:

Diet – high intake of fat and salt can lead to a permanent increase in BP into the unhealthy range. Fatty deposits narrow the artery walls and lead to a loss of elasticity in artery wallsStress – can cause high BP due to an imbalance in hormone levels

Exercise – regular exercise can lead to a decrease in blood pressure when at rest, if blood pressure has been high

THE HEART

Stroke Volume (SV) – the volume of blood ejected into the aorta by one ventricle during contraction (systole)

Cardiac Output (Q) – the total volume of blood pumped from a ventricle per minute

Q = HR x SV

Blood pressure (BP) – it is the pressure exerted in systemic arteries by the contraction and relaxation of the ventricles. Blood flows along a pressure gradient from areas of higher pressure to areas of lower pressure.

BP is expressed in terms of mm of Mercury (mmHg)

Systole contraction ie 120 (Normal +/- 10)Diastole relaxation 80 mmHg

*BP can depend on sex, age, exercise and condition of the cardiovascular system.

THE EFFECTS OF EXERCISE ON THE HEART

During exercise, your heart rate will increase quite rapidly in proportion to the increase in workload intensity until a maximum point, where it levels off.

This point is called your maximum heart rate – HR max.

To determine HR max:220 – age = HR max

Heart rate is seen to rise with work intensity, as anyone knows after climbing a long flight of stairs. But unlike cardiac output and VO2, the relationship between

heart rate and absolute work intensity is variable across individuals; like your grandmother (Black line) and the marathon runner (Black line).

For training purposes it is often recommended that people exercise at certain percentages of their HR

•Long distance runners would tire quickly if working at 100% of HR max, therefore they train at lower intensities of 75 – 85%.

CARDIAC ADAPTATIONS TO EXERCISE

Cardiac Output – increases linearly with increases in intensity up to exhaustion

SV – increases due to more blood returning to the heart. Maximal SV occurs during sub-maximal work.

HR – increases as intensity increases up to a maximum

Systolic BP – increases linearly with increased exercise intensity due to an increase in Q.

Blood Flow – increased blood flow to working muscles and skin, 80 – 85% → muscles.

Blood Plasma Volume – decreases especially in hot weather due to increased sweating.

Other Adaptations:Increase in arteriovenous O2 differenceIncrease in blood acidity (more lactic acid)Decrease in muscle glycogenIncrease in coronary blood flow

*Over time with training, the heart undergoes other physiological changes:- it becomes stronger and in some cases slightly larger- resting heart rate will decrease

Immediate (Acute) Effects Area Long-Term (Chronic) Effects HR increasesCO increasesSV increasesIncreases coronary circulationMaximum HR may be reached

Heart Resting HR decreasesSV increases at test and exerciseIncreases blood supply to the heart muscle at rest and workIncreased size of left ventricleMaximum HR remains the same

Increased BP on artery wallsCapillaries and veins dilate to allow increased blood flowOne way valves in veins help return blood to the heart

ArteriesCapillariesVeins

Elasticity of artery walls is maintainedReduced build up of fatty deposits in arteriesDecreased risk of high BP and CV diseaseIncreased capillary supply to heart and skeletal muscles

Increased speed of blood flowIncreased temperature of musclesOxygen levels in venous blood decreases as the body uses more oxygen for exerciseBlood is redistributed from the internal organs to the working muscles

Blood Increased blood volumeIncreased haemoglobin’ countIncreased oxygen carrying ability

SUMMARY OF THE EFFECTS OF EXERCISE