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Class Notes for Health Unit 4 Circulation and Respiration
The cardiovascular system consists of the heart, arteries veins
and capillaries. It supplies the body with O2, nutrients and
removes CO2 and waste products produced by the cells.
The Heart
The heart is a hollow, muscular four chambered pump. It is
approximately the size of a fist and is divided into two sides.
Auricles/Atriums- upper chambers
Ventricles- lower chambers
The chambers are separated by valves which permit the blood to
flow in one direction only from the auricle to the ventricle on the
same side.
Tricuspid Valve- right side
Bicuspid Valve- left side
The human beat beats an average of 72 beats per minute at rest
Arteries- carry blood away from the heart. Carry highly
oxygenated blood. Have thicker walls than veins and are set
deeper in the body than veins. Arterial blood is bright red due to
the high O2 content.
Veins- carry blood toward the body. Carry highly deoxygenated
blood, have thinner walls than arteries and is a darker red color
giving the name of “blue blood”.
Capillaries- minute vessels that connect arterioles (small
arteries) and venules (small veins). Capillaries have a semipermeable membrane which allows some substances like food
and gas to pass through the cell membrane.
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Blood- body fluid composed of approx. 78% water and 22%
solids
Blood has several components
1. Plasma- fluid part of blood
2. Hemoglobin- iron protein which blood its red color
3. Platelets- particles in blood that allow it to clot or
coagulate and stop bleeding
Path of Circulation
The superior and inferior vena cava deposit deoxygenated
blood into the right atrium. The blood passes through the
tricuspid valve into the right ventricle.
The blood flows through the pulmonary artery to the lungs.
Here it exchanges carbon dioxide for oxygen. The blood returns
to the left atrium through the pulmonary vein.
The blood passes through the bicuspid valve into the left
ventricle.
The blood now flows through the aorta (largest artery) to begin
bringing food and O2 to every cell.
Blood Groups
All humans are in one of four blood types: A, B, AB or O.
The letters refer to a protein or antigen on the surface of red
blood cells.
Each type is also grouped by its Rhesus factor or Rh factor.
Blood is either Rh+ or Rh-. Rhesus refers to the Rhesus monkey
in which the protein was first discovered.
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In a transfusion, the donated blood must be accepted by the
recipient’s blood or the red blood cells will clump together
causing clots that can block a vessel and cause death.
Type O- is considered the “universal donor” because it can be
donated to people of any blood type.
Type AB+ is the “universal recipient” because these patients
can receive any blood type.
“Rare Blood” refers to any type that requires more than 200
donors in order to find it.
Respiratory System
Respiration- the exchange of carbon dioxide for oxygen
When air is inhaled it enters the nasal cavity, travels to the
larynx (voice box), through the trachea (windpipe) to the
bronchial tubes and into each lung.
Bronchial tubes divide into smaller bronchioles and eventually
into tiny air sacs called alveoli. The capillaries surrounding the
alveoli exchange the CO2 for O2.
Respiration is accomplished via the contraction of the
diaphragm (large flat muscle under the rib cage).
The size of the larynx (voice box) varies with individuals.
During puberty the growth of the larynx is more rapid in males.
This causes an increase in the length of the vocal folds.
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Voice- is the result of air being driven out of the lungs which
vibrates the vocal folds. The volume and force of the air
determine the loudness or intensity of the voice.
Lungs- two cone shaped organs separated by the heart. The
right lung is larger and broader than the left lung (the
diaphragm is raised on the right side to accommodate the liver).
Costal breathing- upper ribs move first then the abdomen.
Diaphragmatic breathing- abdomen bulges out first then the
rib cage raises. This is deeper breathing.
Disorders of the Circulatory and Respiratory Systems
Hypertension- is high blood pressure indicated by readings of
greater than 130/90 when at rest. Influenced by heredity, diet,
weight, lack of exercise and stress
Arteriosclerosis- is hardening of the arteries caused by the
collection of plaque (fatty deposits of cholesterol)
Coronary Thrombosis- seizure of the heart muscle
(myocardium) or better known as a heart attack. Also called a
myocardial infarction (infarct is the death of tissue due to lack
of O2)
Apoplexy- stroke caused by a hemorrhage (burst artery) in the
brain. Loss of consciousness followed by paralysis are
symptoms
Pneumonia- inflammation in the lungs causing fluid to
accumulate in the lung tissue which affects breathing. Carries a
30% mortality rate if not treated
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Asthma- an allergic reaction to any substance (allergen)
causing a constriction in the bronchial tubes. Patient may use an
MDI (metered dose inhaler) to dilate the breathing passages
Emphysema- alveoli burst leaving open spaces in the lung
tissue (tissue does not regenerate). Associated with smoking,
damp, cold weather or working in extremely dusty environments
(construction or mining)