Transcript 30.3 The Heart and Circulation

30.1 Respiratory and Circulatory Functions
KEY CONCEPT
The respiratory and circulatory systems bring oxygen
and nutrients to the cells.
30.1 Respiratory and Circulatory Functions
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
Oxygen-rich blood
Oxygen-poor blood
30.1 Respiratory and Circulatory Functions
• The respiratory system is where gas exchange occurs.
– picks up oxygen from inhaled air
– expels carbon dioxide and water
sinus
nose
mouth
epiglottis
trachea
lungs
30.1 Respiratory and Circulatory Functions
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.
alveoli
bronchiole
30.1 Respiratory and Circulatory Functions
• Breathing involves the diaphragm and muscles of the rib
cage.
• Air flows from areas of high pressure to low pressure.
Air inhaled.
Air exhaled.
Muscles and
rib cage relax.
Muscles contract and
rib cage expands.
Diaphragm flattens
and moves downward.
Diaphragm relaxes
and rises.
30.1 Respiratory and Circulatory Functions
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
arteries
veins
30.1 Respiratory and Circulatory Functions
• There are three major functions of the circulatory system.
– transporting blood, gases, nutrients
– collecting waste materials
– maintaining body temperature
30.3 The Heart and Circulation
KEY CONCEPT
The heart is a muscular pump that moves the blood
through two pathways.
30.3 The Heart and Circulation
The tissues and structures of the heart make it an
efficient pump.
• Cardiac muscle tissue works continuously without tiring.
NORMAL HUMAN HEART
30.3 The Heart and Circulation
• The heart has four chambers: two atria, two ventricles.
• Valves in each chamber prevent backflow of blood.
pulmonary valve
aortic valve
left atrium
right atrium
mitral valve
left ventricle
tricuspid
right ventricle
septum
• Muscles squeeze the chambers in a powerful pumping
action.
30.3 The Heart and Circulation
• The heartbeat consists of two contractions.
– SA node, or pacemaker, stimulates atria to contract
– AV node stimulates ventricles to contract
SA node
VA node
30.3 The Heart and Circulation
• Blood flows through the heart in a specific pathway.
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3
2
4
30.3 The Heart and Circulation
• 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
30.3 The Heart and Circulation
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
30.3 The Heart and Circulation
• 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.
30.6 Lymphatic System
Lymph is collected from tissues and returned to the
circulatory system.
• The lymphatic system collects fluid
that leaks out of the capillaries.
heart
– Lymph vessels have valves to
prevent backflow.
– Lymph nodes filter the lymph
lymph nodes
and destroy foreign matter.
– Lymph vessels return cleaned
lymph vessels
fluid to the circulatory system.
• If lymph vessels or nodes are
damaged, lymph collects in an
area.
30.6 Lymphatic System
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
tonsils
thymus
spleen
• Lymphocytes help destroy pathogens, parasites,
and foreign matter.