The Heart Ch. 46: Circulatory System

What is the heart? A specialized muscle that pumps blood through the body, which transports oxygen, carbon dioxide, nutrients and waste. A specialized muscle that pumps blood through the body, which transports oxygen, carbon dioxide, nutrients and waste.

Where is it? The heart is located in the middle of the chest, between the lungs. The heart is located in the middle of the chest, between the lungs. Its bottom is tipped to the left. Its bottom is tipped to the left. It is about the size of two fists. It is about the size of two fists.

Anatomy of the heart Left side- oxygenated Right side- deoxygenated

What does it look like? The pericardium is a tough saclike membrane that surrounds the heart and secretes a fluid to reduce friction. The pericardium is a tough saclike membrane that surrounds the heart and secretes a fluid to reduce friction.

Heart Chambers Heart is divided into four chambers. Heart is divided into four chambers. The upper chamber are the right and left atria. The upper chamber are the right and left atria. The lower chambers are the right and left ventricles. The lower chambers are the right and left ventricles.

Heart valves Valves are flaps of tissue that direct blood to flow only in one direction. Valves are flaps of tissue that direct blood to flow only in one direction. They prevent blood from entering that chamber that it just left. They prevent blood from entering that chamber that it just left. There are 4 heart valves There are 4 heart valves

Atrioventricular valves (AV) Separates the atrium from the ventricle. Separates the atrium from the ventricle. Right: tricuspid valve Right: tricuspid valve Left: bicuspid (mitral) valve Left: bicuspid (mitral) valve

Semilunar valves (SL) Separates the ventricles from vessels exiting the heart. Separates the ventricles from vessels exiting the heart. Right: pulmonary valve Right: pulmonary valve Left: aortic valve Left: aortic valve

Diagram of the Heart 1. Aorta- Largest artery in Body 2. Superior Vena Cava 3. Right Pulmonary Artery 4. Right Pulmonary Vein 5. Right Atrium 6. Tricuspid Valve 7. Right Ventricle 8. Inferior Vena Cava 9. Left Pulmonary Artery 10. Left Pulmonary Vein 11. Left Atrium 12. Bicuspid/Mitral Vale 13. Aortic Valve 14. Left Ventricle 15. Aorta 16. Septum

Pulmonary circulation 1. Vena cava (superior and inferior) from body 2. Right atrium 3. Right ventricle 4. Pulmonary artery to lungs

5. Pulmonary Veins 6. Left Atrium 7. Left Ventricle 8. Aorta (to body)

Heart Beat The heart contracts in waves, starting at the atria, followed by the ventricles. The heart contracts in waves, starting at the atria, followed by the ventricles.

The heart independently stimulates an electrical impulse at the sinoatrial node in the right atrium, which stimulates the atrioventricular node in the septum. The heart independently stimulates an electrical impulse at the sinoatrial node in the right atrium, which stimulates the atrioventricular node in the septum.

The heart pumps blood in two phases: In the systole phase, the ventricles contract and blood is pumped out of the heart. In the systole phase, the ventricles contract and blood is pumped out of the heart. In the diastole phase, the ventricles relax and blood rushes into the heart. In the diastole phase, the ventricles relax and blood rushes into the heart.

The lub dup sound of a heart beat is the close of the AV and SL valves. The lub dup sound of a heart beat is the close of the AV and SL valves

Pulse The pulse is caused by the contractions of the left ventricle. The pulse is caused by the contractions of the left ventricle. Blood surges through the arteries and the pressure causes the arteries to expand. Blood surges through the arteries and the pressure causes the arteries to expand.

Blood vessels Artery – – Carries blood away from the heart – – Made of a thick muscle layer – –Because the arteries feel the greatest amount of blood pressure.

Veins – –Carries blood back to the heart – – Made of a thinner muscle layer and contains valves. – –Because there is less blood pressure in the veins and valves prevent gravity from making blood flow backwards.

Capillary – –Thin vessels that allow the exchange of gases, nutrients, and waste between blood cells and other cells by the process of diffusion.

Gas Exchange Occurs in the alveoli of the lungs Occurs in the alveoli of the lungs Factors that facilitate exchange: Factors that facilitate exchange: –Alveoli are thin: one cell layer thick –Excellent capillary blood supply –Very large surface area –Moist lining helps in diffusion

Oxygen transfer Atmospheric oxygen: 21% Atmospheric oxygen: 21% O 2 readily diffuses from air in alveoli into the blood stream, where it is picked by the hemoglobin in red blood cells. O 2 readily diffuses from air in alveoli into the blood stream, where it is picked by the hemoglobin in red blood cells.

Carbon dioxide transfer The concentration of CO 2 is much higher in cells, so CO 2 readily diffuses out of cells into the blood. The concentration of CO 2 is much higher in cells, so CO 2 readily diffuses out of cells into the blood. 7% is dissolved in the plasma. 7% is dissolved in the plasma. 23% is carried by hemoglobin 23% is carried by hemoglobin 70% reacts with water to become carbonic acid (H 2 CO 3 ), which helps maintain blood pH. 70% reacts with water to become carbonic acid (H 2 CO 3 ), which helps maintain blood pH.

Mechanism of Breathing Diaphragm: muscle layer below the lungs and above the abdomen. Diaphragm: muscle layer below the lungs and above the abdomen.

Inspiration/ Inhale Process of taking in air. Process of taking in air. –Diaphragm contracts and pushes down the abdomen. –Rib cage expands. –Lung volume increases and fills with air because pressure outside lungs is greater than inside

Expiration/ Exhale Process of releasing air: Process of releasing air: Diaphragm and rib muscles relax Diaphragm and rib muscles relax Rib cage condenses. Rib cage condenses. Lung volume decreases and lungs deflate Lung volume decreases and lungs deflate

Human Respiratory System Sequence: Sequence:Mouth Nasal passages PharynxLarynxTracheaBronchi Lungs (brochioles— alveoli)

Cardiovascular Diseases

Atherosclerosis _________ and _________ of the arteries. _________ and _________ of the arteries. Arteries feel higher blood pressure and suffer more damage. Arteries feel higher blood pressure and suffer more damage. narrowing hardening

What happens? Inner lining of artery is damaged. Inner lining of artery is damaged. “Bad cholesterol”,_____, build up in the artery. “Bad cholesterol”,_____, build up in the artery. _______________engulf LDL but __________ and forms a ______, which clogs the artery. _______________engulf LDL but __________ and forms a ______, which clogs the artery. LDL White blood cells accumulate plaque

Complications Cardiovascular disease is the number ____ killer in America. Cardiovascular disease is the number ____ killer in America. Blood clots in coronary ______ causes damage and death of heart muscles. Blood clots in coronary ______ causes damage and death of heart muscles. Leads to myocardial infarction/ heart attacks. Leads to myocardial infarction/ heart attacks. one arteries

Blood _____ or ________ in blood vessels in the brain can lead to _______. Blood _____ or ________ in blood vessels in the brain can lead to _______. clotsruptures strokes

Causes Smoking Smoking High cholesterol High cholesterol High blood pressure/ hypertension High blood pressure/ hypertension Stress Stress Diabetes Diabetes Abdominal obesity Abdominal obesity Not eating fruits and vegetables Not eating fruits and vegetables Excess alcohol intake Excess alcohol intake Not exercising regularly Not exercising regularly