Chapter 20: Respiratory and

Circulatory Systems

20.1 What is Respiration?

• Respiration: The process that moves oxygen and carbon dioxide between the atmosphere and the cells inside the body.

Oxygen moves into the body in three stages:

1. Ventilation: Moves air over the tissues in the lungs where gas exchange occurs. “Breathing.”

2. Oxygen diffuses into the bloodstream.3. Oxygen diffuses from the bloodstream to the

cells.

Carbon dioxide leaves the body in the same pathway in reverse.

Stage 1 - Ventilation:

• “Breathing.”

• Inhalation: Air is pulled into the lungs.• Exhalation: Air is pushed out of the lungs.

Inhalation

• Diaphragm and muscles between the ribs contract.• Diaphragm moves down; ribs move up and out.

- which makes the space in the chest cavity bigger.- Air pressure inside decreases.- Air is sucked into the lungs and expands them until the pressure inside the chest is equal to the pressure outside the chest.

Exhalation

• Diaphragm and muscles between ribs relax.• Chest cavity goes back to its original position– Pushes air out of the lungs.

• Inhalation requires energy.• Exhalation does not require energy.

Stages 2 and 3 – Gas exchange

• Air in the lungs is technically not “inside” the body.

• In stage 2, the oxygen enters the body by diffusing across the lung tissue into the bloodstream.

• Oxygen diffuses into the blood because the concentration of oxygen in blood is less than the concentration of oxygen in the air.

• Carbon dioxide diffuses into the alveolus (air) because the concentration of carbon dioxide in the air is less than the concentration of carbon dioxide in the blood.

• In stage 3, the oxygenated blood reaches the cells.

• Oxygen diffuses from blood to cells.• Carbon dioxide diffuses from cells to blood to

be carried back to the lungs.

Respiration inside cells

• Cellular respiration: The process of using oxygen to break down glucose and other nutrients to release energy (which is stored in ATP).– Waste product: Carbon dioxide.

20.2 The Respiratory System

• The respiratory system includes the lungs and passageways to the lungs.

• Jobs of the respiratory system:– Supplies body with oxygen for cellular respiration.– Removes waste carbon dioxide from the body.

• Air enters the body through the nose and mouth.

• Nose: Warms and moistens the air. Mucus cleans and filters the air.

• Pharynx: Back of the throat where nose and mouth are connected. Shared by the respiratory and digestive systems.

• Epiglottis: Flap of cartilage that keeps food out of the windpipe.

• Larynx: Voice box. Contains vocal cords, which vibrate when air is forced through them to produce sound.

• Trachea: The windpipe. Reinforced with C-shaped rings of cartilage.

• Bronchi: the two tubes that the trachea splits into in the chest. One leads to each lung.

• In the lungs, the bronchi split into smaller and smaller bronchioles, each of which end in an alveolus.

• The walls of the alveoli are wet, which makes diffusion easier.

• They are also coated with surfactant – a slippery substance that keeps alveolar walls from sticking together.

• Cells along the respiratory tract have cilia (hair-like projections) that sweep mucus out of the lungs.

• The mucus traps dust and pollen.• Cilia push it up to the throat, where it can be

swallowed, sneezed out, or coughed up.

Respiratory disorders

• Common cold: A virus attacks the cells of the nose and pharynx.

• Bronchitis: A virus infects the bronchi, which swell and produce extra mucus.

• Pneumonia: Infection in the lungs. Alveoli swell and fill with fluid.

• Asthma: Not an infection. Bronchi contract. Triggered by allergies, stress, or exercise.

Heimlich Maneuver

• Abdominal thrusts that can push an object out of the trachea of a choking person.

• It works because pushing up on the diaphragm forces a puff of air out of the lungs and through the trachea, which can push the object out of the trachea.

20.3 The Body’s Transport System

• The cardiovascular (circulatory) system includes the heart, blood, and blood vessels.

• It has three jobs in the body:– Moves molecules around the body.– Regulates the body’s fluids and temperature.– Helps protect the body from disease and infection.

The Circulatory System

Transportation:

• The cardiovascular system transports:– Oxygen from lungs to cells– Carbon dioxide from cells to lungs– Nutrients, salts, vitamins, and water from small

intestine to cells– Wastes from cells to kidneys– Drugs to the liver– Hormones from glands to tissues

Regulation of Fluids

• Cell metabolism (all of the chemical reactions in the cell) creates ions (charged particles).

• The ions move into the spaces around the cells.

• Osmosis causes water to also move out of the cells.

• Blood removes excess ions to slow osmosis.

Regulation of Temperature:

• Blood absorbs heat from warm areas of the body and moves it to cooler areas.

• Conserves heat when environment is cold:– Blood vessels near skin constrict to keep the blood

away from the cold.• Gives off heat when body is too warm:– Blood vessels near skin open up and let blood near

the surface to cool off.

Regulation of Temperature:

• Countercurrent systems: Blood vessels carrying blood in opposite directions lie near each other. The warm blood warms up the cool blood.

Protection:

• Blood contains cells that attack bacteria and viruses.

• Blood contains the materials needed to clot (stop the bleeding of a cut).

20.4 Heart and Blood Vessels

• The heart is located inside the ribcage between the lungs. It is muscular and the size of a fist.

• It has four chambers:– Atria: the two smaller upper chambers• Singular: Atrium.

– Ventricles: the lower two chambers.

Pathway of blood through the heart:

• Oxygen-poor blood enters the right atrium from two large veins (venae cavae).

• The atria contract and push the blood through the tricuspid valve into the right ventricle.

• The ventricles contract, and the blood is pushed from the right ventricle to the lungs to release carbon dioxide and pick up oxygen.

• Oxygen-rich blood enters the left atrium.

• The atria contract and push the blood through the bicuspid valve to the left ventricle.

• The ventricles contract, and the blood is pushed through the aorta to the body.

• This two beat pattern (atria contract, then ventricles contract) makes the “lub-dub” sound of the heart.

Blood vessels:

• Arteries: Carry blood away from the heart.– Have thick, elastic walls that expand and store

energy when the heart beats and pushes blood against them, and slowly release that energy between heart beats to keep the blood flow smooth.

– Arteries divide and get smaller as blood moves away from the heart, which slows blood down.

• Capillaries: Microscopic blood vessels that connect arteries and veins.– Walls are one-cell thick.– Blood moves slowly to allow nutrients and oxygen

to diffuse into surrounding cells and wastes to be picked up.

• Veins: Carry blood back to the heart.– Thin-walled. Have one-way valves to keep blood

from moving backwards.– Contractions of skeletal muscles squeeze veins to

move blood past the valves.

Blood pressure:

• The force that blood exerts on artery walls.– Systolic pressure: First number. Pressure when

ventricles contract.– Diastolic pressure: Second number: Pressure

when ventricles relax.

Pulse:

• The waves between ventricle contraction and relaxation.– How fast the heart is beating.

Heart rate:

• Set by the pacemaker (a bundle of cells on top of the right atrium).

• The pacemaker sends regular electrical impulses to both atria to make them contract.

• This makes a second set of cells at the base of the right atrium fire another electrical signal that makes the ventricles contract.

An EKG shows the electrical activity in the heart.

20.5 Blood:

• Liquid tissue.• Contains:– Red blood cells.– White blood cells.– Platelets.– Plasma.

Red blood cells: (the most numerous in your blood)

• Carry oxygen and carbon dioxide.• Have no nucleus. Each side is pushed in,

which makes for a thin, flexible cell with a large surface area for oxygen diffusion.

• Hemoglobin: The protein in red blood cells that 4 oxygen or carbon dioxide molecules bind to.

Sickle cell anemia

White blood cells:

• Immunity.• Many different types:– Some engulf and destroy foreign organisms.– Some cause swelling around a wound.– Some reduce swelling.– Some produce antibodies.• Antibodies: Proteins that detect and bind to foreign

proteins.

Platelets:

• Fragments of cells that stick to damaged tissues and to one another to form a clot to stop bleeding.

• Also releases a chemical that make a network of fibrin proteins (creates a scab).

Plasma:

• The liquid part of the blood.• Mostly water, but also proteins, minerals,

vitamins, small organic molecules and waste products.

Lymphatic system:

• Filters the fluid part of the blood and produces some white blood cells.

• Includes thymus, spleen, tonsils, lymph nodes, and lymph vessels.

• Excess fluid (lymph) in the tissues enters the lymph vessels.

• Lymph nodes filter the lymph.• White blood cells made by the thymus and

spleen enter lymph nodes and trap and destroy foreign particles.

Blood types:

• Antigen: Protein on the surface of a cell that can cause an immune reaction.

• On red blood cells, there are three antigens that could be present.– A– B– Rh

• You could have all, none, or some of these antigens.

Blood types:

• A: Has A antigens, and antibodies against B• B: Has B antigens, and antibodies against A• AB: Has A and B antigens, and no antibodies

against A or B• O: Has no antigens, and antibodies against A

and B.

Blood types:

• Positive: Has the Rh antigen.• Negative: Does not have the Rh antigen, and

has antibodies against Rh.

20.6 Circulation in the Body

• Circulation: Blood movement

Systemic circulation:

• Blood movement through the body.

Pulmonary circulation:

• Blood movement through the lungs.– Pulmonary arteries: Carry oxygen-poor blood

from the heart to the lungs. • These are the only arteries that carry oxygen-poor

blood.– Pulmonary veins: Carry oxygen-rich blood from

the lungs to the heart.• These are the only veins that carry oxygen-rich blood.

Coronary circulation:

• Blood movement to the heart tissue.– Coronary arteries branch off of the aorta.– Coronary veins drain directly into the right atrium.