1. Chapter 5 Cardiovascular System: Heart and Blood Vessels
Mader, Sylvia S. Human Biology. 13th Edition. McGraw-Hill, 2014.

2. Points to Ponder What are the functions of the cardiovascular system?
What is the anatomy of the heart and blood vessels (veins and arteries)?
How is the heart beat regulated?
What is blood pressure?
What are common cardiovascular diseases and how might you prevent them?

3. Cardiovascular system
Includes heart and blood vessels
Brings nutrients to cells that are bathed by tissue fluid and helps get rid of wastes
Exchanges with tissue fluid and not directly with cells
Blood is refreshed in
Lungs: gas exchange
Kidneys: water and salt retained, waste excreted
Intestine: nutrient intake
Liver: amino acid uptake and remove toxin
Lymphatic vessels help this system by collecting excess fluid surrounding tissues and return it to the cardiovascular system

4. What are the function of the cardiovascular system?
5.1 Overview of the cardiovascular system
What are the function of the cardiovascular system?
Generate blood pressure via heart contractions
Transport blood via blood vessels
Exchange of nutrients and wastes at the capillaries refreshes blood and tissue fluid
Regulate blood flow as needed

5. What is the main pathway of blood in the body?
5.2 The types of blood vessels
What is the main pathway of blood in the body?
Heart – arteries – arterioles – capillaries - venules – veins – back to the heart…

6. Arteries and arterioles:
5.2 The types of blood vessels
Arteries and arterioles:
Carry blood away from the heart
Their walls have 3 layers:
Thin inner epithelium
Thick smooth muscle layer
Outer connective tissue
elastic tissue to absorb pressure
Strong walls support vessel when blood enters under pressure
Arterioles are small arteries that regulate blood pressure
Muscle fibers contract  vessel constricts
Muscle fibers relax  vessel dilates
Regulate blood pressure

7. Capillaries: Microscopic vessels between arterioles and venules
Made of one layer of epithelial tissue only
Form beds of vessels where exchange with body cells occurs
Combined large surface area
Only certain capillaries are open at any given time
After eating, capillaries serve the digestive system are open
Those that serve the muscles are closed
Precapillary sphincters contract, and blood moves from arteriole to venule by way of an arteriovenous shunt

8. Blood Vessels

9. Exchange at the capillary beds is primarily a result of osmotic and blood pressure
Causes water to move from capillary to tissue fluid
Osmotic Pressure created by presence of salts and plasma proteins
Causes water to move in the opposite direction
At arterial end of capillaries
Blood pressure is higher than osmotic pressure of blood
Water exits a capillary at this end
Midway along the capillaries
Two forces are equal and cancel each other out
No net movement of water
Solutes diffuse according to their concentration gradient
Oxygen and nutrients out and CO2 and waste into capillary
Venule end of capillaries
Blood pressure decreased, osmotic pressure is greater in blood
Water tends to move into the capillary

10. 5.6 Exchange at the capillaries
Exchange at the capillary beds is primarily a result of osmotic and blood pressure

11. Lymphatic Capillaries
Collects excess tissue fluid
once collected in lymphatic capillaries  lymph
Lymph is returned to the systemic venous blood at
the subclavian veins of the shoulder

12. 5.2 The types of blood vessels
Veins and venules:
Venules are small veins that receive blood from the capillaries
Venule and vein walls have 3 layers:
Thin inner epithelium
Thick smooth muscle layer
Outer connective tissue
Wall is thinner and can expand to a greater extent
70% of blood in veins  blood reservoir
If blood lose occurs veins constrict to provide more blood to body
Veins carry blood toward the heart
Veins that carry blood against gravity have valves to keep blood flowing toward the heart

13. How can you tell the difference between an artery and vein?
5.2 The types of blood vessels
How can you tell the difference between an artery and vein?

14. 5.3 The heart is a double pump
Anatomy of the Heart
A large, muscular organ consisting of mostly cardiac tissue called the myocardium
Serviced by the coronary artery and cardiac vein
Muscle fibers branched and joined at intercalated disks
Allow atrium and ventricles to contract simultaneously
It is surrounded by a sac called the pericardium
Supports and protects the heart
Consists of two sides, right and left, separated by a septum
Consists of 4 chambers:
2 atria (thin walled) and 2 ventricles (thick walled)

15. 5.3 The heart is a double pump

16. Anatomy of the Heart
2 sets of valves keep blood flowing in the right direction:
atrioventricular valves (AV valves)  between atria and ventricle
Supported by chordae tendineae attached to papillary muscles
Prevent valve from inverting when the heart contracts
Right = tricuspid, Left = bicuspid (mitral valve)
semilunar valves  between ventricle and attached vessels
Pulmonary semilunar valve and aortic semilunar valve
The valves give the resulting “lub” and “dup” sound of the heart

17. 5.3 The heart is a double pump

18. Two cardiovascular pathways in the body
Pulmonary circuit: the right side of the body that brings blood from the body to the heart and the lungs
Systemic circuit: the left side of the heart that brings blood to the entire body to deliver nutrients and rid it of wastes

19. Blood flow through the heart
1. Inferior and superior vena cava (1) dump oxygen poor blood into the right atrium (2)
2. Right atrium sends oxygen poor blood through AV valve (tricuspid)
3. Right ventricle (3) oxygen poor blood through the pulmonary semilunar valve
4. 2 pulmonary arteries (4) that lead to the lungs (5) where blood becomes oxygenated
5. Pulmonary veins (6) bring oxygen rich blood from the lungs back the left atrium (7)
6. Left atrium sends blood through AV valve (bicuspid/mitral)
7. Left ventricle (8) is large and muscular to pump blood through aortic semilunar valve
Aorta (9) and to the rest of the body (10)
Arterioles from the artery branch into capillaries, where exchange takes place, and then venules join into the vein
Eventually blood will be pumped back to each vena cava(1)

20. Visualizing blood flow through the heart
5.3 The heart is a double pump
Visualizing blood flow through the heart

21. How do the structure of the vessels and heart match their functions?
5.3 The heart is a double pump
How do the structure of the vessels and heart match their functions?
The left ventricle is much more muscular than the right ventricle (pumps to the lungs) because the left ventricle must pump blood to the entire body
Heart sends blood out under pressure into the arteries
The arteries are more muscular than veins to withstand the higher pressure exerted on them
The veins have a thinner wall and a larger center to store blood

22. How does the heartbeat occur?
5.3 The heart is a double pump
How does the heartbeat occur?
Heartbeat = cardiac cycle
During systole
the atria contract together followed by the ventricles contracting together
This is followed by diastole
a rest phase, when the chambers relax
This cardiac cycle, heartbeat, on average occurs 70 times/minute
Lub:
increased pressure of blood inside ventricle forces the cusps of the AV valve to shut
Dub:
Pressure of blood inside a ventricle causes the semilunar valves (pulmonary and aortic) to open
Ventricle relaxes and blood in the arteries pushes back, causing the semilunar valves to close

23. Cardiac Cycle

24. How is the heartbeat controlled?
5.3 The heart is a double pump
How is the heartbeat controlled?
1. Internal control:
Node tissue in two locations of the heart
The sinoatrial (SA) node in the right atrium
initiates the heartbeat and causes the atria to contract
Also known as pacemaker, keeps heartbeat regular
This impulse reaches the atrioventricular (AV) node, in the right atrium
send a signal down the AV bundle and Purkinje fibers that causes ventricular contraction
These impulses travel between gap junctions at intercalated disks
Allow electrical current to flow from cell to cell

25. How is the heartbeat controlled?
2. External control:
heartbeat is also controlled by
cardiac center in the medulla oblongata of the brain
Parasympathetic (resting) and sympathetic (fight or flight) portions of the nervous system
Hormones released by adrenal medulla, such as epinephrine and norepinephrine, stimulate the heart

26. Visualizing the heartbeat

27. Visualizing the gap junctions at the intercalated disks
5.3 The heart is a double pump
Visualizing the gap junctions at the intercalated disks

28. What is an electrocardiogram (ECG)?
5.3 The heart is a double pump
What is an electrocardiogram (ECG)?
A record of the electrical changes in the heart muscle during a cardiac cycle
The atria produce an electrical current when stimulated by the SA node called the P wave
The contraction of the ventricles is the QRS complex
The recovery of the ventricles is called the T wave
Looking at these electrical changes allows doctors to detect abnormalities

29. How does a “normal” and abnormal ECG compare?

30. Pulse Pulse = rhythmic expansion and recoil of an arterial wall
Arterial walls pulse whenever the left ventricle contracts
Can be felt in any artery that runs close to the body’s surface
Commonly used
Radial Artery: palm side of wrist
Carotid Artery: either side of the trachea in the neck

31. 5.4 Features of the cardiovascular system
What is blood pressure?
The pressure against a blood vessel wall, usually measured in a brachial artery in the arm
The highest pressure is during blood ejection from the heart called the systolic pressure
The lowest pressure is the diastolic pressure when the ventricles relax
Average blood pressure is recorded at about 120/80 mmHg (systolic/diastolic)
Reminder: this is controlled by the arterioles
Systolic and diastolic blood pressure decrease with distance from the left ventricle

32. Blood Pressure

33. How is blood pressure categorized?
5.4 Features of the cardiovascular system
How is blood pressure categorized?

34. What is important about blood flow?
5.4 Features of the cardiovascular system
What is important about blood flow?
Blood flow is under the highest pressure in the arteries but remember the thick, muscular walls
Blood flow is slower in the capillaries which is important to allow time for exchange between cells
Blood pressure is minimal in the veins and venules but blood flow increases

35. If blood pressure is so low in the veins why does the blood flow increase? Venous Return Depends on:
Skeletal muscle contraction
Compression forces blood past valves
Breathing
- inhale, chest expand and decrease pressure in thoracic cavity. Blood flows from higher pressure (abdominal cavity) to lower pressure (thoracic cavity)
- exhale, reverse but valves prevent back wash
Valves

36. The heart’s blood supply: Coronary circulation
5.5 Two cardiovascular pathways
The heart’s blood supply: Coronary circulation
There are small coronary arteries that supply the heart with oxygen rich blood that are separate from the systemic and pulmonary pathways of the body
First branch off of the aorta, just above the aortic semilunar valve
Aorta  coronary artery  arterioles  coronary capillary bed  venules  converge at cardiac veins  right atrium

37. What is the hepatic portal system?
5.5 Two cardiovascular pathways
What is the hepatic portal system?
A system that brings blood from the digestive tract rich in amino acids and glucose to the liver
The liver synthesizes blood proteins and stores the glucose as glycogen
The liver also plays a role in purifying blood from the digestive tract
Finally, the blood exit the liver via the hepatic vein and blood will return to the heart via the inferior vena cava

38. Why should we care about cardiovascular disease?
5.7 Cardiovascular disorders
Why should we care about cardiovascular disease?
Cardiovascular disease (CVD) is the most common cause of death in the western world

39. Disorders of the blood vessels:
5.7 Cardiovascular disorders
Disorders of the blood vessels:
Hypertension/high blood pressure
Atherosclerosis
Stroke
Heart attack
Aneurysm

40. 5.7 Cardiovascular disorders
Hypertension
High blood pressure results when blood moves through vessels at a rate higher than normal often due to arterial plaque
140/90 mmHg is considered hypertension
A silent killer because there are few symptoms
Can lead to a heart attack, stroke or kidney failure

41. Atherosclerosis A build up of plaque in blood vessels
5.7 Cardiovascular disorders
Atherosclerosis
A build up of plaque in blood vessels
Plaque that is stationary is called a thrombus and an embolus when it detaches and can move to distant sites
Associated with a stroke, heart attack and aneurysm

42. Stroke Also known as a cerebrovascular accident (CVA)
5.7 Cardiovascular disorders
Stroke
Also known as a cerebrovascular accident (CVA)
Usually occurs when a cranial artery is blocked or bursts
Part of the brain dies dues to lack of oxygen
Symptoms may occur including numbness of hands or face, difficulty speaking and inability to see in one eye

43. Heart attack Also known as a myocardial infarction (MI)
5.7 Cardiovascular disorders
Heart attack
Also known as a myocardial infarction (MI)
Part of the heart dies due to lack of oxygen
Can begin with angina pectoris, a pain that radiates down the left arm due to a blockage of a coronary artery

44. Aneurysm A ballooning of a blood vessel
5.7 Cardiovascular disorders
Aneurysm
A ballooning of a blood vessel
Atherosclerosis and hypertension can weaken a vessel and cause ballooning
The most commonly affected is the abdominal artery or the arteries leading to the brain

45. How are disorders of the blood vessels treated?
5.7 Cardiovascular disorders
How are disorders of the blood vessels treated?
Dissolving blood clots:
t-PA is a drug that dissolves clots
Treating clogged arteries:
Bypass surgery: usually a vein from the leg is taken and used to bypass a clogged artery
Stents: wire mesh cylinder inserted into a clogged artery to hold it open
Angioplasty: a tube with a balloon is inserted into the clogged area and the balloon is then inflated to open the vessel
A stent and angioplasty may be used in combination

46. Disorders of the heart and its treatment
5.7 Cardiovascular disorders
Disorders of the heart and its treatment
Disorders:
Heart failure is when the heart no longer pumps properly
Treatments:
Left ventricular assist device(LVAD)
Heart transplant either natural or artificial

47. 5.7 Cardiovascular disorders
Health Focus: The do’s and don’ts for prevention of cardiovascular disease?
Do not smoke
Do not abuse drugs
Keep your weight down to decrease chances of hypertension and Type II diabetes
Eat a healthy diet
Low in saturated and trans fats
Low in cholesterol
Know your blood cholesterol
Exercise