1. 7.0 TRANSPORT SYSTEM 7.1 Mammalian Heart and its regulation
7.2 Lymphatic System: Role in Transport

2. 7.1 Mammalian Heart and its Regulation
OBJECTIVES :
Illustrate the structure of the heart.
2. Explain the initiation of heart beat and control of heart rate.
3. Explain the cardiac cycle.
Discuss the factors affecting heart beat.
5. Briefly explain cardiovascular diseases such as hypertension, myocardial infarction and arteriosclerosis.

4. The heart is located in the chest between the lungs, behind the
The heart is located in the chest between the lungs, behind the sternum and above the diaphragm.
Its size is about that of a fist, and its weight is about g.
The whole of the heart is surrounded by a conical-shaped sac called the pericardium.

5. A HUMAN HEART ? How to draw…

6. Mammalian Heart : Structure and Function
External Heart Anatomy

7. Coronary arteries supplying the capillaries of the cardiac muscle with oxygenated blood.

8. The heart wall has three layers:
1. Epicardium
2. Myocardium
3. Endocardium

9. Internal Heart Anatomy valves consist of flaps of connective tissue.
Atrioventricular valves
Between each atrium and ventricle.
prevent the backflow of blood into the atria when the ventricles contract.
Bicuspid – 2 flaps
Tricuspid – 3 flaps
Semilunar valves
-found at the base of the pulmonary artery and the aorta.
-prevent the backflow of blood into the ventricles when they relax.
Pulmonary
Aortic
Right ventricle
Chordae tendinae
Papillary
muscles

10. The heart has 4 chambers:
Atria :
The top two chambers that receive blood from the body or lungs.
2. Ventricles :
The bottom two chambers.
right ventricle - pumps blood to the lungs to pick up oxygen.
left ventricle - pumps blood to the rest of the body and is the strongest chamber.

11. Atria – thin walled
The right atrium
receives blood from the vena cava (returning deoxygenated blood to the heart).
Links to the right ventricles by the tricuspid valve.
The left atrium
receives blood (highly oxygenated blood) from the pulmonary veins.
The left ventricle receives blood from the left atrium through the bicuspid valve
When the atria contract, blood passes into the lower chambers, called ventricles.
Ventricle – thick walled
When the right ventricle contracts,
it pumps blood out through the pulmonary semilunar valve into the pulmonary artery.
When the left ventricle contracts,
it pumps blood out through the aortic semilunar valve into the aorta.
has walls that are three times the thickness of the right ventricle because it has to generate enough force to pump oxygenated blood throughout the body.

12. - which are anchored to the muscular wall of the ventricles.
The ventricles have much thicker walls because they have to develop enough pressure to force the blood further.
The edges of atrioventricular valves are supported by non-elastic strands, the chordae tendinae,
- which are anchored to the muscular wall of the ventricles.
- prevent the valve from being blown inside out.
Pulmonary
vein
Vena cava

13. Aorta
Is the largest blood vessel in the body; with an inner diameter about 2.5 cm
Carries oxygenated blood from the left ventricle to the system circulation.
Pulmonary arteries
carry the blood from the right ventricle to both of the lungs.
There the blood is oxygenated and sent to the left atrium in the heart.
Pulmonary veins
- carry the oxygenated blood back to the left atrium in the heart.
Superior vena cava
return blood back to the right atrium from the upper part of the body.
It is one of the largest veins in the body.
Inferior vena cava
- carrying the blood back to the Right Atrium from the lower part of the body.

14. Septum
separates the right and left sides of the heart
There are two separate regions of the septum.
1) Interatrial septum that separates the atriums
- only present in the fetal period and is open during this period.
- closes at the time of birth.
2) Interventrial septum that separates the ventricles
- suppose to be closed all the time but sometimes an opening is present at birth.
Function of valve :
1. Permit flow of the blood from atrium to ventricle
2. Prevent backflow of the blood into the atrium from ventricle
3. Semilunar valve prevent backflow of blood into the ventricle

15. INITIATION OF HEART BEAT AND ITS CONTROL

17. Control of the Heartbeat ( Cardiac conduction system)
Cardiac muscles continues to contract rhythmically even after the heart has been removed from the body.
The cardiac muscle in the heart is `myogenic’. It contracts and relaxes automatically and does not depend on stimulation by nerves.
The stimulus of contraction of the heart originates in a specific region of the right atrium called the sinoatrial node (SAN).
This is located near the entrance of the superior vena cava.
The SAN determine the basic rate of heart beat and is therefore known as the `pacemaker’.

18. The SAN send out electrical impulses to the rest of the atria.
These impulses spreads out over the atria walls.
So both right and left atria contract at the same time.
The impulses do not pass down to the ventricles.
It is important that the ventricles do not start to
contract until the atria have finished contracting.
The delays (0.1 second) ensures that the ventricles do not start to contract before they fill with blood.

19. The impulse then reaches a second node, the atrioventricular node (AVN) which lies between the two atria.
To allow blood to be forced upwards into the arteries, the ventricles need to contract from the apex upwards.
To achieve this, the new wave of excitation from the AVN is conducted along Purkinje fibres, which collectively make up the Bundle of His.
Impulses are conducted rapidly and spread out from there to all parts of the ventricles.

20. Description of the cardiac cycle :
SAN send out a rhythmic electric impulse that is transmitted to the entire atrium.
then through the AVN and Purkinje tissue to the entire ventricle.

21. Summary of Cardiac Conduction System
SAN
Wall of right atrium & wall of left atrium
AVN
Purkinje fibres
(Bundle of His)
Apex of ventricles
Contraction
Of right
ventricles
Contraction of left ventricle

22. http://www. nhlbi. nih. gov/health/dci/Diseases/hhw/hhw_electrical

23. MECHANISM OF CARDIAC CYCLE

24. CARDIAC CYCLE (HEARTBEAT)

25. The cardiac cycle is the sequence of events of a heartbeat by which blood is pumped round the body.
It is described in terms of alternate contractions (systole) and relaxation (diastole).
The time taken for one cardiac cycle of contraction and relaxation is 0.8 seconds when the heart is beating at a rate of 75 beats per minute.
Contraction and relaxation occurs as follows.
Atrial diastole
Atrial systole
Ventricular systole.
Ventricular diastole.
Systole – heart muscle contracts and the chambers pump blood.
Diastole – heart muscle relax and the chambers fill with blood.

26. Oxygenated blood flows from pulmonary vein into the left atrium.
a) Atrium diastole
Both atrium relaxed.
Oxygenated blood flows from pulmonary vein into the left atrium.
Deoxygenated blood flows from vena cava into the right atrium.
b) Atria systole
Both the atria contract simultaneously.
The blood passes down to the ventricles.
The atrioventricular valves open due to the pressure of blood against them.
pulmonary
vein
vena cava

27. c) Ventricular systole
The thick muscular walls of the ventricles contract,
The pressure in the ventricles rises and closes the atrioventricular valves, preventing blood from returning to the atria.
The closing of the atrioventricular valves, produces the first heart sound, describe as `lub’.
The pressure forces open the semilunar valves of the aorta and pulmonary artery and blood enters these vessels.
d) Ventricular diastole
The ventricles relax.
The pressure inside the ventricles drops below that in the aorta and pulmonary artery.
Blood under high pressure in the aorta and pulmonary artery cause the semilunar valves to shut, preventing blood from going back into the ventricles.
This produces the second heart sound `dub’.

28. Completion of One Heartbeat
For a human at rest with a pulse of about 75 beat per minute, one complete cardiac cycle takes about 0.8 sec.
During the relaxation phase (atria and ventricles in diastole)
lasting about 0.4 sec, blood returning from the large veins flows into atria and ventricles.

29. 2) A brief period (about 0. 1 sec). of atrial systole forces all the
2) A brief period (about 0.1 sec) of atrial systole forces all the remaining blood out of the atria and into the ventricles.
3) During the remaining 0.3 sec of the cycle, ventricular systole pumps blood into the large arteries.

30. Pressure and Volume Changes during the Cardiac Cycle
When the atria contract (atrial systole) the ventricles relax (ventricular diastole), blood flows from the atria into the ventricles.
During ventricular systole and atrial diastole the cuspid valves closed and the blood is forced into the arteries. At the same time blood flows into the atria from the veins.
Blood will flow from high to low pressure, unless prevented by a valve.
The closure of the valves (cuspid and semi-lunar) is what can be heard using a stethoscope.

32. Pulse
Ventricular systole (contraction) forces a blood at high pressure through the arteries.
The expansion of the arteries can be felt as a `pulse’
particularly where the artery is near the skin surface.
The pulse is traditionally taken above the wrist (radial pulse).
Pulse - Wave effect that passes down the walls of arterial blood vessels when aorta expands and then recoils following ventricular systole.

33. ELECTROCARDIOGRAM (ECG)
Willem Einthoven
Is a test that measures the electrical activity of the heart.
The impulses generated during the heart cycle produce electrical currents that are conducted through body fluids to the skin.
As each wave of contraction spreads through the heart, electrical current spread into the tissues surrounding and onto the body surface.
The currents can be detected by electrodes and recorded as an electrocardiogram (ECG or EKG).
The pattern produced can be either shown on an oscilloscope screen or traced on paper.
The tracing is called an electrocardiogram and the apparatus used is an electrocardiograph.
The information obtained from an electrocardiogram can be used to discover different types of heart disease.

34. The P wave is caused by atrial contraction (systole)
QRS complex by ventricular contraction (systole)
- T wave by ventricular relaxation (diastole).

35. A normal tracing, shows five waves which are called P, Q, R, S and T.
An ECG begins with P wave.
The P waves is caused by atrial systole.
When SAN triggers an impulse,
the atrial fibers produce an electrical charge.
which represents the spread an impulse through the atria just before atria contraction.

36. The QRS waves is caused by ventricular systole.
QRS complex, reflecting the spread of an impulse through the ventricles before they contract.
The T waves coincides with ventricular diastole.
As the ventricles recover, current generated are reflected upon the graph as a T wave.
The heart then repeats it pattern of electrical impulses, generating a new P wave, QRS complex and T wave.

39. Phase 1
Contraction of the atrial musculature.
Pressure within the atrial chambers increases
A rapid flow of blood into the ventricles.
After atrial contraction is complete, the atrial pressure begins to fall.
The ventricular volumes are maximal (end diastolic volume – about 120ml).
Phase 2
Initiated by the QRS.
Rapid increase in intraventricular pressure.
AV valves close as intraventricular pressure exceeds atrial pressure. (first heart sound)
Ventricular pressure rises rapidly without a change in ventricular volume.

40. Phase 3
Intraventricular pressures exceed the pressures within the aorta and pulmonary artery; valves open and blood is ejected out of the ventricles.
Maximal aortic and pulmonary artery pressures are achieved.
Atrial pressure initially decreases.
Phase 4
The rate of ejection falls (T wave); ventricular pressure falls slightly below outflow tract pressure.
Atrial pressures gradually rise due to venous return.

41. Phase 5
Ventricles continue to relax and intraventricular pressures fall.
Semilunar valves abruptly close causing the second heart sound.
Ventricular volumes remain constant because all valves are closed.
Phase 6
Ventricular pressure fall below atrial pressure, the AV valves open and ventricular filling begins.
The opening of the AV valves causes a rapid fall in atrial pressures.
Phase 7
Ventricles continue to fill with the blood; intraventricular pressures rise.
Aortic pressure continues to fall.

42. Cardiac Output (CO)
Cardiac output - is the total volume of blood pumped by the ventricle per minute.
This volume depends on two factors :
- heart rate (HR)
- stroke volume (SV).
Determined by :
1. The amount of blood pumped by the left
(or right) ventricle during each beat.
2. The number of heart beats per minute.
The amount of blood ejected by ventricle during each contraction is called the stroke volume (SV).

43. In a resting adult, SV averages 70 ML and HR is about 75 beats per minute.
Thus the average CO in a resting adult :
CO = stroke volume X beats per min
= 70ML X 75/min
= 5250 ML/min or 5.25 L/min
A person with this stroke volume and resting pulse of 75 beats/min has a cardiac output of 5.25 L/min.
CO can increase about fivefold during heavy exercise.

44. FACTORS AFFECTING HEART BEAT

45. CARDIOVASCULAR REGULATION THAT INVOLVES NERVES AND HORMONES.
Although the pacemaker (SAN) triggers the heartbeat, it does not mean that the heart is not supplied with any specific nerves.
In fact, the control of the cardiac cycle in humans and other mammals is through the autonomic nervous system.
The autonomic nervous system is located in the hindbrain known as medulla oblongata.

46. The SAN is supplied with two sets of nerves:
a) Parasympathetic nerve / vagus
b) Sympathetic nerve
Both these sets of nerves do not trigger the heartbeat, but can affect the activity of the pacemaker as to influence the rate of the heartbeat.
a) Parasympathetic nerve / vagus
- Stimulation of the parasympathetic nerve causes a release of acetylcholine in the SAN, the AVN and the heart muscle.
This slow down the rate of heartbeat.
b) Sympathetic nerve
- Stimulation of the sympathetic nerve causes a release of noradrenalin.
- Noradrenalin increases the rate of heartbeat.

48. CARDIOVASCULAR DISEASES

49. Cardiovascular diseases
Myocardial infarction
Hypertension
Arteriosclerosis

50. Myocardial infarction (MI)
Non-medical term = heart attack; consequence of ischemic heart disease.
Means there is death of some of the muscle cells of the heart as a result of a lack of supply of oxygen and other nutrients (infarct).
This lack of supply is caused by closure of the artery (coronary artery) that supplies that particular part of the heart muscle with blood.
The tissue beyond the obstruction dies and is replaced by non-contractile tissue, the heart looses some of its strength.

51. Coronary Arteries and Plaque

52. Most heart attacks were caused from the slow closure of an artery; infarct is large since a large artery is closed.
Death may occur suddenly where there is,
Acute cardiac failure due to shock.
Severe arrhythmia (irregular heart rhythm) due to disruption of the conducting system.
Rupture of the ventricle wall, usually within two weeks of the infraction.

53. In minor blockages - rupture of the cholesterol plaque,
causes blood clotting within the artery, blocking the flow of blood.
The heart muscle which is injured can cause irregular rhythms which can be fatal, even when there is enough muscle left to pump plenty of blood.
When the injured area heals, it will leave a scar.
but there is often plenty of good muscle left to pump the heart, and recovery can be quite complete.

54. Hypertension Hypertension means high blood pressure.
Normal blood pressure is 120/80, any value above 140/90 indicates hypertension and 160/95 is considered dangerous.
Systolic blood pressure is consistently over 140 (represents the pressure generated when the heart beats).
Diastolic blood pressure is consistently over 90 (represents the pressure in the vessels when the heart is at rest).
Uncontrolled hypertension may damage
Heart (heart enlarges and demands more oxygen),
Brain (stroke which ruptures cerebral arteries supplying brain)
Kidney (glomerular arterioles are narrowed and deliver less blood)

55. Blood pressure is determined by the amount of blood pumped by the heart, and the size and condition of the arteries.
Other factors can affect blood pressure, including volume of water in the body; salt content of the body; condition of the kidneys, nervous system, or blood vessels; and levels of various hormones in the body.
Symptoms :
tiredness
confusion
vision changes
heart failure
blood in urine
nosebleed
irregular heartbeat
ear noise or buzzing
angina-like chest pain (crushing chest pain)

56. Factors increase the risk of hypertension
a tendency in the family to suffer hypertension,
Obesity,
Smoking,
diabetes Type 1 or Type 2,
kidney diseases,
high alcohol intake, excessive salt intake,
lack of exercise,
certain medicines, such as steroids and certain kinds of diet pills.

57. Lifestyle changes may help control high blood pressure:
Lose weight if you are overweight. Excess weight adds to strain on the heart. In some cases, weight loss may be the only treatment needed.
Exercise to help your heart.
Adjust your diet as needed. Decrease fat and sodium - salt, MSG, and baking soda all contain sodium. Increase fruits, vegetables, and fiber.

58. Arteriosclerosis (ahr-tir-ee-oh-skluh-roh'-sis)
Arteriosclerosis is a Greek word which actually means "hardening of the arteries."
is a term used to describe several diseases that involve the cardiovascular system and the many arteries and vessels which make it up.
This occurs because of the deposition of calcium in vessel walls.
Vessels become thickened. There is a loss of elasticity. It can involve the arteries of the cardiovascular system, the brain, kidneys, upper and lower extremities.
Deposition of calcium in the internal layers of the arteries of the lower extremities, generally leads to an increase blood pressure.
If it involves both the inner and medial layers of smaller arteries the limbs, eyes, and internal organs. This condition causes decreased blood flow to these tissues which can create circulatory problems, peripheral vascular disease, impaired circulation to the eyes and kidneys causing blindness and kidney failure.

59. The Causative Factors
Hypertension, Diabetes mellitus, Smoking, Obesity
Symptoms
High blood pressure occurs as the arteries become hardened and ridged.
Peripheral Vascular Disease occurs as the circulation is impaired to the upper and lower extremities.
Recurrent Kidney infections.
Poor circulation to the fingers and toes.
Treatment is directed initially at relieving symptoms and causes such as high blood pressure.
Treatment of Diabetes
Stop Smoking
Reducing dietary calcium.
Increased dietary magnesium.
Weight Loss

60. 7.2 Lymphatic System: Role in Transport
Objectives :
Overview of human lymphatic system.
Role of lymphatic system in transporting lipids.

61. Component of Lymphatic System
Not all the tissue fluid return to the blood capillary.
About 10% of it enters a separate system of capillaries called the lymph capillaries.
These capillaries merge to form lymph vessels which possess valves and whose structure is similar to veins.
Once inside the lymph system, the tissue fluid is called lymph.
Lymph means colorless fluid; contain lymphocytes and consist mostly of water with dissolved salts, protein and fats.

63. \

64. LYMPHATIC SYSTEM

66. The lymphatic system consists of organs, ducts / vessel, and nodes.
Lymph organs include the bone marrow, lymph nodes, spleen, and thymus.
Bone marrow contains tissue that produces lymphocytes. B-lymphocytes (B-cells) mature in the bone marrow.
T-lymphocytes (T-cells) mature in the thymus gland.
Lymph nodes are areas of concentrated lymphocytes and macrophages along the lymphatic veins.
The spleen serves as a reservoir for blood, and filters or purifies the blood and lymph fluid that flows through it.
Ducts of the lymphatic system provide transportation for proteins, fats, and other substances in a medium called lymph.

68. Unlike blood, lymph is transported in one direction, from the tissue towards the heart (blood).
The lymph vessel from the right side of the head and thorax and the right arm combine to form the right lymphatic duct which drains into the right subclavian vein near the heart.
Lymphatic vessels from the left arm and lower part of the body form the thoracic duct which drains into the left subclavian vein.

70. Function in Transport and Immunity
Main functions of lymphatic system:  
to collect and return interstitial fluid, including plasma protein to the blood, and thus help maintain fluid balance, 
to defend the body against disease / pathogens by producing lymphocytes, 
to absorb lipids from the intestine and transport them to the blood.
Lymphocytes are produced in the lymph nodes.
- They have an important role in producing antibodies.
- so the lymph system is an important part of the body’s immune system.
- lymph nodes often swell up if you have an infection.