KEY CONCEPT The respiratory and circulatory systems bring oxygen and nutrients to the cells.

30.1 Respiratory and Circulatory Functions

KEY CONCEPT The respiratory and circulatory systems bring oxygen and nutrients to the cells.


Oxygen-poor blood

Oxygen-rich blood

The respiratory and circulatory systems work together to maintain homeostasis.• The circulatory system transports

blood and other materials. – brings supplies to cells – carries away wastes – separates oxygen-poor and

oxygen-rich blood


• The respiratory system is where gas exchange occurs.– picks up oxygen from inhaled air – expels carbon dioxide and water

nose

sinus

mouthepiglottis

trachea

lungs


The respiratory system moves gases into and out of the blood.• The lungs contain the bronchi, bronchioles, and alveoli. • Millions of alveoli give the lungs a huge surface area.• The alveoli absorb oxygen from the air you inhale.

alveolibronchiole


• Breathing involves the diaphragm and muscles of the rib cage.

• Air flows from areas of high pressure to low pressure.

Air inhaled.

Muscles contract andrib cage expands.

Diaphragm flattensand moves downward.

Air exhaled.

Muscles andrib cage relax.

Diaphragm relaxesand rises.


veins

arteries

The circulatory system moves blood to all parts of the body. • The system includes the heart,

arteries, veins, and capillaries. – heart pumps blood throughout body – arteries move blood away from

heart – veins move blood back to heart– capillaries get blood to and from

cells


– collecting waste materials– maintaining body temperature

• There are three major functions of the circulatory system.– transporting blood, gases, nutrients

30.3 The Heart and Circulation

KEY CONCEPT The heart is a muscular pump that moves the blood through two pathways.


The tissues and structures of the heart make it an efficient pump.• Cardiac muscle tissue works continuously without tiring.

NORMAL HUMAN HEART


• The heart has four chambers: two atria, two ventricles.• Valves in each chamber prevent backflow of blood.

• Muscles squeeze the chambers in a powerful pumping action.

aortic valve

left atrium

mitral valve

left ventricle

septum

pulmonary valve

right atrium

tricuspid

right ventricle


– SA node, or pacemaker, stimulates atria to contract– AV node stimulates ventricles to contract

SA node

VA node

• The heartbeat consists of two contractions.


• Blood flows through the heart in a specific pathway.

1

2 4

3


• Blood flows through the heart in a specific pathway.– oxygen-poor blood enters right atrium, then right

ventricle– right ventricle pumps blood to lungs– oxygen-rich blood from lungs enters left atrium, then left

ventricle – left ventricle pumps blood to body


The heart pumps blood through two main pathways.

• Pulmonary circulation occurs between the heart and the lungs.– oxygen-poor blood enters lungs– excess carbon dioxide and water

expelled– blood picks up oxygen – oxygen-rich blood returns to heart


• Systemic circulation occurs between the heart and the rest of the body. – oxygen-rich blood goes to organs,

extremities– oxygen-poor blood returns to

heart • The two pathways help maintain a

stable body temperature.

30.6 Lymphatic System

KEY CONCEPT The lymphatic system provides another type of circulation in the body.


Lymph is collected from tissues and returned to the circulatory system. • The lymphatic system collects fluid

that leaks out of the capillaries.– Lymph vessels have valves to

prevent backflow.– Lymph nodes filter the lymph

and destroy foreign matter.– Lymph vessels return cleaned

fluid to the circulatory system. • If lymph vessels or nodes are

damaged, lymph collects in an area.

heart

lymph nodes

lymph vessels


tonsils

thymus

spleen

The lymphatic system is a major part of the immune system.

• Structures in the lymphatic system help fight disease.– tonsils filter bacteria

and viruses– thymus develops white

blood cells – spleen filters lymph,

contains immune cells

• Lymphocytes help destroy pathogens, parasites, and foreign matter.

KEY CONCEPT The respiratory and circulatory systems bring oxygen and nutrients to the cells.

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