1. 11.2 Structure and Function of the Heart
Hollow organ located between your lungs made mostly of muscle
Pumps oxygen-poor blood to your lungs and oxygen-rich blood to your entire body
When the heart contracts blood is pumped out and when your heart relaxes blood enters the heart
For the average person at rest, the entire process of pumping and filling the heart takes _________
this is known as the cardiac cycle
0.8 seconds

2. The pericardium is a protective sac that encloses the heart
Filled with fluid that lubricates the surface of the heart and roots of the major blood vessels
Humans and other mammals have a four chambered heart comprised of the:
Right Atrium
Right Ventricle
Left Atrium
Left Ventricle

3. Atria Ventricles The two upper chambers
Receive blood returning to the heart
Pump the blood into the ventricles
Contain thin walls
Ventricles
The two lower chambers
Receive blood from atria
Pump the blood out of the heart
Contain thick muscular walls

4. Valves in the heart prevent blood from flowing backward
The valves located between the atria and ventricles are called atrioventricular valves
left atrium to left ventricle = left atrioventricular valve AKA bicuspid valve (or mitral valve)
right atrium to right ventricle = right atrioventricular valve AKA tricuspid valve
The valves located between the ventricles and the arteries are called semilunar valves
left ventricle to aorta = aortic valve
right ventricle to pulmonary artery = pulmonary valve

5. With each heartbeat the valves open allowing blood to flow through
Then the valves close preventing blood from flowing back
When the valves close they cause the familiar “lub dub” sound of the heart
The “lub” sound is the atrioventricular valves closing
The “dub” sound is the aortic and pulmonary valves closing
Video: Human Heartbeat 30 seconds

6. The heart is one organ that functions as two pumps
One pump pushes blood to the lungs
One pump pushes blood to the entire body
The two pathways of blood are referred to as the:
Pulmonary Circuit
Systemic Circuit
Follow along the diagram on page 312
Return to slide 3, show ventricle wall thickness difference for the circuits

7. In the Pulmonary Circuit:
Oxygen-poor blood travels from the right side of your heart through the pulmonary arteries to your lungs
In the lungs blood picks up O2 and releases CO2
Oxygen-rich blood travels from lungs through the pulmonary veins to the left side of the heart
Note: Artery/Vein classification is only for direction!
We inhale oxygen and exhale carbon dioxide

8. In the Systemic Circuit
Oxygen-rich blood from the lungs enters the left atrium and it is then pumped into the left ventricle
Blood is then pumped by the left ventricle through the aorta
The aorta is the artery that supplies the oxygen-rich blood to all of the systems of the body
Aorta -> Arteries -> Arterioles -> Capillaries

9. Capillaries -> Venules -> Veins -> Vena Cava(s)
From the capillaries oxygen and nutrients diffuse out of the blood and carbon dioxide and other wastes diffuses in
This deoxygenated blood will now will now return to the heart passing through the superior vena cava and inferior vena cava
Capillaries -> Venules -> Veins -> Vena Cava(s)
Oxygen-poor blood from the body enters the right atrium and it then pumped into the right ventricle, which pumps the blood to the lungs through the pulmonary arteries (pulmonary circuit begins again)
The superior vena cava is supplied by the upper body and the inferior vena cava is supplied by the lower body
Video: Heart Circulation 5min but skip from 45sec to 2min mark (animation pauses)

10. The heart itself also needs a blood supply
The heart receives very little oxygen and nutrients for its own cells from the blood it pumps through its chambers
Instead a pair of arteries called coronary arteries branch from the aorta which cover the surface of the heart to supply the heart with oxygen and nutrients
The coronary sinus is a collection of veins joined together to form a large vessel that collects deoxygenated blood from the heart and delivers it to the right atrium

11. Located in wall of right atrium
The heart of a physically mature human beats over __________ times per day!
Averaging times per minute
Heartbeat is effected by age, fitness, emotions
A specific region of your heart muscle is known as the pacemaker because it sets the rate at which your heart contracts
Located in wall of right atrium
Generates electrical impulses that spread to a region of the heart called the atrioventricular (AV) node
times
Heartbeat is effected by age, fitness, emotions
Tissues working together to form organs, organs in systems, systems in organisms

12. The contracting ventricles send blood to the rest of the body
First the atria contract and blood is forced into the ventricles which are relaxed
Then the ventricles contract and pump blood into the arteries while the atria are relaxed
The contracting ventricles send blood to the rest of the body
Therefore the pacemaker ensure that the heart beats in a rhythmic cycle
This cycle repeats about every second when at rest
The pacemaker is controlled by both the nervous system and the endocrine system
Sets of nerves with opposing antagonistic action, one to speed up heart rate and the other to increase heart rate, also hormones/chemicals to adjust hear rate
Homework: read and make notes on Blood Pressure pg , pg. 317 #2-15