1. Heart and Blood Vessels
Circulatory System
Heart and Blood Vessels

2. Crash Course

3. The circulatory system is the system that transports materials around the body to and from the cells.

4. Question: Why do humans need a circulatory system whereas bacteria and simple organisms do not?
Answer: Because a complex organism such as a human has many cells that are far from the outside environment where nutrients would come from. The system brings the materials to the cells that would not normally receive them.

5. Humans have a closed circulatory system: This means that the blood is always contained in tubes and vessels.

7. Parts of the Circulatory System
The human circulatory system is composed of the following:
1. Blood Vessels
2. Heart
3. Blood

8. Blood Vessels Arteries Structure: Thick, elastic
Smallest arteries are called arterioles
DO NOT CONTAIN VALVES
Function: Transport blood AWAY from the heart to the organs and tissues of the body.

9. Blood Vessels Veins Structure: Thin and slightly elastic
Smallest veins are called venules
Contain VALVES – to help blood flow back to the heart against the force of gravity
Function: To RETURN blood from the body tissues to the heart.

10. Blood Vessels Capillaries Structure:
Microscopic blood vessels that connect arterioles and venules
Thin walled and narrow
Blood cells pass through them in single file
Function: Allows material and gas exchange between the body cells and the blood.

12. The Heart
Structure:
A four chambered muscular organ located in the chest cavity of a human.
Made of cardiac muscle.
It is covered by a pericardium that protects it.
Pericardium: A tough membrane that surrounds the heart.

14. Function: Pump blood around the body supplying the cells with nutrients and removing wastes (CO2) from the cells.

30. Video Time

31. Blood Flow through the Heart
Deoxygenated blood from the body enters the ______________via the __________and ______________________.
Here the blood is passed through the _____________to the _______________.
right atrium
inferior
superior vena cava
tricuspid valve
right ventricle

32. The right ventricle contracts and forces blood up through the ___________ valves and out through the left and right _________ arteries.
This brings blood to the ________ to be oxygenated.
semilunar
pulmonary
lungs

33. Oxygenated blood from the lungs returns to the heart via the left and right ___________ veins to the ____________.
The blood is passed to the _____________ through the __________ valve.
The left ventricle contracts and pushes blood through the semilunar valves and out through the _______ to the body.
pulmonary
left atrium
left ventricle
bicuspid
aorta

34. The Heartbeat Cycle The human heartbeat occurs in two main stages.
These two stages are:
Diastole
Systole

35. Diastole relaxing The stage where the heart is _________
During this stage the A-V valves (bicuspid, tricuspid) are open and the semilunar valves close. The ventricles fill with blood.
relaxing

36. Systole contracting The stage where the heart is ___________
During this stage the ventricles contract. This causes the A-V valves to close and the semilunar valves to open. Blood is forced out through the semilunar valves to the lungs and body.

38. Video Time

39. The “LubDub” sound of the Heartbeat
The “LubDub” sound of the heartbeat is caused by the closing of the heart’s valves.
Lub Sound -- caused by the closing of the A-V valves (tricuspid, bicuspid).
Dub Sound -- caused by the closing of the semilunar valves.

40. Heart Sounds

41. Crash Course

42. CONTROL OF THE HEARTBEAT
The heart is caused to beat regularly by a structure called the _______________ (S - A node) or the _____________.
sinoatrial node
PACEMAKER

43. How it Happens
An electrical impulse from the brain is received by the S-A node (pacemaker) in the right atrium. The SA node sends a signal to the A-V node (atrioventricular node) in the right ventricle. This electrical impulse causes the heart (ventricles) to contract.

44. The pacemaker controls the heartbeat for a human from the time they are born until they die or the pacemaker gives out.

45. Q. What happens if the pacemaker gives out?
A. The person’s heart will stop beating because the ventricles are not receiving electrical impulses causing them to contract.

46. A person whose pacemaker gives out can get an ___________ one inserted into their chest.
artificial

47. CONTROL OF THE HEART RATE
The heart rate (speed) at which the heart beats is controlled by two nerves.
______________________ in the Medulla Oblongata: Nerve in the brain that causes the heart to speed up when needed.
____________: Nerve in the brain that causes the heart to slow down when needed
Cardioaccelerator nerve
Vagus nerve

49. The medulla sends a message to the SA node to cause an impulse to be sent to the AV node causing the heart to contract more or less in an attempt to set the heart rate.

50. BLOOD PRESSURE
Blood Pressure: A measure of the pressure blood exerts on the walls of blood vessels.

51. Q. How is blood pressure measured?
A. Blood pressure is measured using a blood pressure cuff or Sphygmomanometer.

52. Blood Pressure = 𝑠𝑦𝑠𝑡𝑜𝑙𝑖𝑐 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑑𝑖𝑎𝑠𝑡𝑜𝑙𝑖𝑐 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒
It measures the pressure in an artery while the heart is contracting (_______________) and the pressure while the heart is resting (_______________). A simple fraction is calculated using the following formula:
Blood Pressure = 𝑠𝑦𝑠𝑡𝑜𝑙𝑖𝑐 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑑𝑖𝑎𝑠𝑡𝑜𝑙𝑖𝑐 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒
systolic pressure
diastolic pressure

53. For example: A person with a pressure 120/80 means that the person has a pressure of 120 while the heart is contracting and 80 when the heart is relaxing.
P.S. Normal blood pressure is different for each person but is usually around 120/80. (high is over 140/90)

54. Divisions of Circulation

55. There are two types of circulation that happen in the human organism.
Pulmonary circulation
Systemic circulation

56. Pulmonary Circulation

57. Systemic Circulation

58. Coronary Circulation

59. Hepatic-portal Circulation

60. Renal Circulation

62. Coronary Artery
Supplies blood to nourish the heart muscles

63. Coronary Sulcus
Encircles the heart like a crown (corona = crown). The atria are found above and the ventricles are found below this blood vessel.

64. What happens when there is a blockage within the coronary artery?
The blood flow to the heart muscles will be blocked, leading to a heart attack.

65. Anterior Interventricular Sulcus
Marks the front (ventral) position of the heart. This vessel follows the septum that separates the right and left ventricles.

66. Apex
The pointed end of the heart. Only the left ventricle forms the heart apex.

67. Pericardium The double-walled sac around the heart. Function:
Protects and anchors the heart
Prevents overfilling of the heart with blood
Allows for the heart to work in a relatively friction-free environment

69. Myocardium
Cardiac muscle layer forming the bulk of the heart

70. Why do you think there is a thicker layer of myocardium in the ventricles than compared to the atria?

71. Why do you think there is a thicker layer of myocardium in the left ventricle than compared to the right ventricle?