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Respiratory System and
Circulatory System
The Need for Oxygen
 Oxygen
is used to get energy from food
 Nutrients that were broken down in digestion are
turned into energy by the mitochondrion
 Single-celled organisms get oxygen from the
environment by diffusion
 Humans require a respiratory system
Bronchiole
Pharynx
Nasal cavity
Larynx
Right lung
Right
bronchus
Right
bronchioles
Ribs
Trachea
Left lung
Left
bronchus
Left
bronchioles
Capillaries
Diaphragm
Alveoli
Pathway of Air
 1.
Air enters though the nasal cavity
 Tiny hairs called cilia filter dirt and other particles
 Dirt and other particles can also be trapped by
mucus
 Cilia sweep the trapped particles out through the
mouth
 2. Pharynx and larynx (voice box)
 3. Trachea: has rings of cartilage to keep it
open
 Also has cilia and mucus
 4.
Trachea branches off into two bronchi
 5. Bronchi branch off into small bronchioles
 6. Each bronchiole ends in a microscopic
alveolus (air sac)
 Surrounded by capillaries
 Oxygen diffuses from the air in the alveoli to the
blood in the capillaries
 Carbon dioxide diffuses from the blood in the
capillaries into the air in the alveoli
 7. Reverse the pathway for exhalation
Breathing
 The
lungs have no muscles and cannot move on
their own
 We breathe using the muscles between our ribs
and a large muscle under the lungs called the
diaphragm
Diseases
 Most
diseases are caused by tobacco smoke
 Tobacco smoke paralyzes the cilia so they
cannot sweep out the particles from the smoke
 These particles cause cancer in the lungs and
other organs
 Bronchitis: the bronchial tubes swell and become
inflamed

Mucus accumulates and blocks the airway, making
breathing difficult and painful
 Asthma:
the walls of the bronchi contract and
narrow the airway

The lungs cannot fill or empty normally
 Emphysema:
the alveoli lose their ability to
expand to take in air

The lungs can no longer inflate and less air is taken in
 Pneumonia:
the alveoli fill with liquid and
breathing is difficult

Caused by a bacterial or viral infection
A Transport System
 Required
to move materials to every cell in the
body
 Ex: nutrients and oxygen
 Wastes need to be taken away from the cells
 Ex: carbon dioxide
 Blood that contains oxygen is called oxygenated
 Blood that does not contain oxygen is called
deoxygenated
Aorta
Vena cava
Pulmonary
arteries
Pulmonary
arteries
Pulmonary
veins
Left atrium
Right atrium
Left ventricle
Right ventricle
Vena cava
Aorta
The Heart
 Four-chambered
muscle
 Top chambers = atria

Right atrium and left atrium
 Bottom

chambers = ventricles
Right ventricle and left ventricle
 The
heart has valves between the chambers to
prevent the blood from flowing backwards
Blood Vessels
 Arteries
carry oxygenated blood away from the
heart and to all the cells
 Very elastic and very thick-walled
 Veins carry deoxygenated blood from the cells
back towards the heart
 Not as elastic and not as thick as arteries
 Capillaries are very tiny blood vessels where
nutrients and gases are exchanged

Only 1 cell thick
the heart, blood flows from arteries 
arterioles  capillaries  venules  veins
 The aorta is the largest artery
 The vena cava is the largest vein
 From
Blood
 Most
of the blood is a clear light yellow fluid
called plasma
 Red blood cells (RBCs) carry oxygen to the
cells and carry carbon dioxide away from cells
 The protein hemoglobin gives RBCs their red
color and lets them carry oxygen
 Hemoglobin contains iron
 White blood cells (WBCs) fight diseases
 Platelets help blood to clot
Blood Pressure
 As
blood moves through the arteries, the artery
walls exerts a pressure on the blood

This is your blood pressure
 The
pressure when your heart contracts is the
systolic pressure

Usually 120
 The
pressure when your heart relaxes is the
diastolic pressure

Usually 80
 Normal
blood pressure is 120/80
Diseases
A
heart attack occurs when coronary arteries
become blocked


Coronary arteries supply the heart with blood
Heart muscle that cannot get blood dies
 Atherosclerosis
is the gradual build up of layers
of cholesterol on the insides of arteries



Shrinks the inside of the arteries and hardens them
The artery can become blocked, causing a heart
attack
If the artery is in the brain, it can cause a stroke
 Hypertension

is high blood pressure
Makes you more likely to have a heart attack or a
stroke
 Cardiovascular
disease can be prevented or
reduced by eating healthy, exercising, and not
smoking