Circulatory System

The heart pumps about 3,600 gallons of blood each day

720

Circulatory– Every organism must exchange materials

with its environment.• The purpose of the circulatory system is to

facilitate this exchange.

– All but the simplest animals have circulatory systems with three main components:

• A central pump• A vascular system• The circulating fluid

Which one is his left arm?

Which one is his Which is the right side and which is the left?

Blue Blood & Red Blood

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Open and closed circulatory system

The Role of the Cardiovascular System in

Homeostasis– The cardiovascular system performs

several homeostatic functions:• Controlling chemical balance• Controlling the composition of the blood• Regulating body temperature • Distributing hormones• Defending against foreign invaders

The Heart• The human heart is located near the

center of your chest.• The heart is enclosed in a protective sac

of tissue called the pericardium. • The heart has two sides and four

chambers.– The two sides are divided by a septum (wall).– Prevents mixing of oxygen-poor blood and

oxygen rich blood.

• The upper chamber which receives blood is the atrium.

• The lower chamber that pumps blood out of the heart is the ventricle

Pericardium

Atrium and Ventricle

Septum

Pulmonary valve

Right atrium

Tricuspid valve

Right ventricle

Left atrium

Aortic valve

Mitral valve

Left ventricle

Myocardium• The muscle of the

heart• Strong and thick• Composed of

spontaneously contracting cardiac muscle fibers

• Can conduct electricity like nerves

• It’s blood supply comes from the coronary arteries

Myocardium (heart muscle) shown in red

Epicardium(Outer surface

of myocardium)

Endocardium(Inner surface of myocardium)

The Human Cardiovascular System

– In the human cardiovascular system,• The central pump is the heart.• The vascular system is the blood vessels.• The circulating fluid is the blood.

– In humans and other vertebrates, the three components of the cardiovascular system are organized into a double circulation system.

• There are two distinct circuits of blood flow.• The pulmonary circuit.• The systemic

circuit.

• The systemic circuit carries blood between the heart and the rest of the body.

• The pulmonary circuit carries blood between the heart and the lungs.

Structures of the Heart• Valves

– Prevents backflow of blood– Keep blood moving in one

direction

– Between the chambers

– At junctions of artery and chamber

Tricuspid valve

Pulmonary veins

Mitral valve

Left atrium

Pulmonary valve

Aortic valve

Right atrium

Valves seen from above

Chordea tendinea

Pulmonary valve

Inferior Vena CavaVein that brings oxygen-poor blood from the lower part of the body to the right atrium

Tricuspid ValvePrevents blood from flowing back into the right atrium after it has entered the right ventricle

Pulmonary ValvePrevents blood from flowing back into the right ventricle after it has entered the pulmonary artery

Pulmonary VeinsBring oxygen-rich blood from each of the lungs to the left atrium

Superior Vena CavaLarge vein that brings oxygen-poor blood from the upper part of the body to the right atrium

AortaBrings oxygen-rich blood from the left ventricle to the rest of the body

Pulmonary ArteriesBring oxygen-poor blood to the lungs

Aortic ValvePrevents blood from flowing back into the left ventricle after it has entered the aorta

Mitral ValvePrevents blood from flowing back into the left atrium after it has entered the left ventricle

Heartbeat– The pacemaker, or SA (sinoatrial)

node, sets the tempo of the heartbeat.– The pacemaker is composed of

specialized muscle tissue in the wall of the right atrium.

Blood Vessels

If the heart is the body’s “pump,” then the “plumbing” is the system of arteries, veins, and capillaries.

• Arteries carry blood AWAY from the heart.– Aorta large blood vessel carries through the

body back to the heart.

• Veins carry blood toward the heart.• Capillaries allow for exchange between the

bloodstream and tissue cells.

Aorta

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• Blood still moves through the veins against the force of gravity.

• As skeletal muscles contract, they help squeeze the blood along.

Blood Pressure The force that blood exerts against the

walls of your blood vessels is called blood pressure.

• Blood pressure is the main force driving the blood from the heart to the capillary beds.

• A pulse is the rhythmic stretching of the arteries caused by the pressure of blood forced into the arteries during systole.

• Blood pressure decreases when the heart relaxes

• Systolic (arteries and ventricles contract) and diastolic (arties and ventricles relax)

– 120/80 is a normal adult

Disorders of the circulatory system

• Atherosclerosis- fatty deposits (plaque) build up on the walls of the arteries. – Leads to high blood pressure

(hypertension) – Can cause blood clots– Can cause heart attack– Can cause a stroke

Cardiovascular disease accounts for 40% of all deaths in the United States.The leading cause of death in the United States is heart attack.

Blood&

The Lymphatic System

Components of blood

• Plasma- 90% water 10% dissolved gases, salts, nutrients, enzymes, hormones, waste products and proteins.– Allows blood to clot

• Red blood cells (erthrocytes)-Transport oxygen– Contains protein hemoglobin

• Contains iron which gives it the red-ish color• Made in red bone marrow• Circulate for about 120 days destroyed in liver and

spleen

Components of blood• White blood cells- (Leukocytes)

Attack foreign substances or organisms. (Army)– Also made in red bone marrow– Phagocytes “eating cells” are a

type of white blood cells that engulf and digest foreign cells

• Platelets- (thrombocytes) are bits of cytoplasm pinched off from larger cells in the bone marrow– Fibrinogen is a membrane-wrapped

protein found in plasma.

Break in Capillary Wall

Blood vessels injured.

Clumping of Platelets

Platelets clump at the site and release thromboplastin. Thromboplastin converts prothrombin into thrombin..

Clot Forms

Thrombin converts fibrinogen into fibrin, which causes a clot. The clot prevents further loss of blood..

Lymphatic system

• The lymphatic system has two main functions:

• Return tissue fluid to the circulatory system • Fight infection

• The fluid is known as lymph.• The organs of the lymphatic system are

lymph nodes, packed with white blood cells that fight infection.

Figure 24.7

– The lymphatic system

Respiratory System

• What is Respiration?• At the cellular level- The release of

energy from the breakdown of molecules in food in the presence of oxygen. Blood carries oxygen and carbon dioxide between the lungs and trillions of cells throughout the body.

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Figure 23.UN1

Human Respiratory System

• Purpose- To bring about the exchange of oxygen and carbon dioxide.

• With each breath air enters the body fills the lungs, where gas exchange takes place.

• The respiratory system consists of the nose, pharynx, larynx, trachea, bronchi, and lungs.

Figure 23.17

• Air moves through the nose to a tube at the back of the mouth called the pharynx (throat).

• Pharynx serves as a passageway for both air and food.

• From the pharynx air moves into the trachea (windpipe).

• A piece of cartilage called the epiglottis covers the entrance to the trachea when you swallow

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The Larynx• The larynx contains two highly elastic

folds of tissue known as the vocal cords.

• From the larynx, air passes through the trachea into two large passageways in the chest cavity called bronchi.

• Each bronchus leads into one of the lungs.

• Inside the lung the large bronchus subdivide into even smaller bronchi, which lead to even smaller passageways called bronchioles.

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Lungs must be kept clean

• In order to keep the lung healthy, the air must be warmed, moistened and filtered.

• Large dust particles get trapped by little hairs lining the entrance to the nasal cavity.

• A mucus moistens the air and traps inhaled particles of dust and smoke.

• Cilia sweep the trapped particles and mucus away from the lungs towards the pharynx.

Bronchioles

• The bronchioles continue to subdivide until they reach a series of dead ends, these are millions of tiny air sacs called alveoli.

Figure 23.18

Alveoli

• There are about 350 million aveoli in a healthy lung, providing an enormous surface area for gas exchange.

• Alveoli carry out the process of gas exchange in the lungs.

• Grouped in clusters like grapes

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The Air that you Inhale & Exhale

Inhale:• 21% oxygen• 0.04% carbon dioxide

Exhale: • Less than 15% oxygen• 4% Carbon dioxide

How is breathing Controlled?

• Medulla Oblongata• Cells in its breathing center monitor

the amount of carbon dioxide in the blood.

• As the Carbon dioxide levels rise, nerve impulses from the breathing center cause the diaphragm to contract, bringing air into the lungs.

• The higher the carbon dioxide levels the stronger the impulse.

– The breathing control centers increase or decrease breathing rate in response to CO2 levels in the blood.

Taking a Breath– Breathing is the alternating process of

inhalation and exhalation.

Tobacco and The Respiratory System

• Smoking tobacco damages and eventually destroys the lungs.

• Tobacco contains 3 harmful substances:– Nicotine: stimulant– Carbon monoxide: poisonous gas that

blocks the transportation of oxygen by hemoglobin in the blood.

– Tar: is a cancer causing substance.

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Statistics

• Only 30% of male smokers live to the age of 80.

• 55% of nonsmokers live to 80• 160,000 people in the US are

diagnosed with lung cancer each year.• Smoking causes:

– Bronchitis (acute, chronic)– Emphysema– Lung cancer