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Circulatory, and Respiratory Systems
Chapter 38
Functions of the Circulatory System
• The Circulatory System allows cells to:
– Receive oxygen and nutrients.
– Get rid of waste products.
• This system consists of:
– Blood
• Carries important substances throughout the body
– Heart
• Pumps blood throughout the body
– Blood Vessels
• Channels that bloods travels through
– Lymphatic system
• A part of the Immune system
• Aside from these functions this system distributes heat
throughout the body to regulate body temperature.
Blood Vessels both
• Circulate blood throughout the body and
• Help keep the blood flowing to and from the
heart.
• There are 3 major blood vessels:
– Arteries
– Capillaries
– Veins
Arteries
Smooth Muscle
Endothelium
•
•
Oxygenated blood is carried away
from the heart due to arteries.
Characteristics:
–
–
–
–
•
Strong
Thick-walled
Elastic
Durable
Arteries are unique because they
are able to withstand high pressure
exerted by blood as it is pumped by
the heart.
Connective Tissue
Endothelium
Capillaries
• As blood vessels branch out, at the
ends, they turn into capillaries.
• Capillaries are microscopic blood
vessels.
• Capillary thickness is only 1 cell thick,
due to diffusion.
– Diffusion allows for the exchange of
important substances and waste products.
• **During exercise capillaries can grow in
size to compensate in order to bring
more oxygen and reduce the amounts of
wastes in the body**
Veins
• Receives blood from the
capillaries.
• They carry oxygen-poor blood
(deoxygenated blood) back to
the heart.
• Located near skeletal muscles
• Large veins have flaps of tissue
called valves.
Smooth Muscle
Connective Tissue
– Valves prevent blood from
flowing backward.
Endothelium
The Heart
• It is a muscular organ about
the size of your fist and is
located at the center of your
chest.
• This organ pumps blood
throughout the body.
• Pumps oxygenated blood to
the body and deoxygenated
blood to the lungs.
Structure of the Heart
• Capable of conducting electrical
impulses for muscular
contractions.
• Divided into four chambers
– Right/Left Atrium (receive blood
returning to the heart)
– Right/Left Ventricles (pump blood
away from the heart)
• Valves separate the atria and
ventricles.
– Contain large blood vessels that
carry blood away from the heart.
How the Heart Beats
• Phase 1:
– The atria fills with blood
– The atria contract, filling the ventricle with blood.
• Phase 2:
– The ventricles contract to pump blood out of the heart.
– Blood travels to the lungs, and to the rest of the body.
• Found in the right atrium is a group of cells called the
pacemaker or Sinoatrial node (SA).
– Its function is to receive internal stimuli about the body’s oxygen
needs, and then responds by adjusting the heart rate.
Blood Pressure
• Blood pressure is a measure of how much pressure is
exerted against the vessel walls by the blood.
• The contraction of the heart (systole) causes the blood
pressure to rise to its highest point.
• The relaxation of the heart (diastole) brings the
pressure down to its lowest point.
• The normal blood pressure of an adult is 120/80.
(Systolic/Diastolic pressure).
Blood Components
• Blood is made up of:
–
–
–
–
Plasma
Red Blood Cells (RBC)
White Blood Cells (WBC)
Platelets
Plasma
•
•
•
•
It is the clear yellow fluid portion of blood.
50% of the blood is made out of plasma.
90% of plasma is water; 10% is dissolved materials.
Plasma transports broken down digested food such as
glucose and fats. It also transports vitamins, minerals,
and chemical messengers such as hormones.
• There are 3 plasma proteins that help give plasma its
color and help it perform these functions:
– Regulation of Water
– Produce WBC
– Forms blood clots.
Red Blood Cells
•
•
•
•
Carry oxygen to all of the body’s cells.
RBCs are made in the marrow of bones.
RBCs have no nuclei and only live around 120 days.
RBCs mostly consist of iron protein called hemoglobin.
– Hemoglobin chemically binds with oxygen molecules and
carries oxygen to the body’s cells.
Platelets
• Platelets are cell fragments that play important part in
forming blood clots.
• When a blood vessel is cut, platelets collect and stick to
the vessel at the site of the wound.
• Platelets release chemicals that produce a protein
called fibrin.
– Fibrin is known as the clotting actor, it weaves a network of
fibers across the cut traps blood platelets and RBCs.
White Blood Cells
• These are the disease fighters.
• They are produced in bone marrow.
• They alert the body if they are being invaded by
foreign substances. Some produce chemicals to
fight these invaders.
• WBC’s have nuclei and can live for months or
even years.
Circulatory System Disorders
• Blood clots due to fat deposits can reduce flow of
oxygen-rich and nutrient-rich blood traveling through the
arteries.
– This is known as atherosclerosis.
• Signs include high blood pressure and high cholesterol levels.
– Due to arteries blocked it makes the heart work harder.
– This disease can produce stroke or heart attacks.
– Heart attacks occur when blood does not reach the heart
muscle.
– Strokes occur when clots form in blood vessels supplying
oxygen to the brain.
• Ruptured vessels can lead to internal bleeding.
• Lack of oxygen can lead to death of brain tissue.
Circulatory System Disorders
• Anemia: is the condition in which the oxygen-carrying ability
of the blood is reduced. Eventually anemia may result from
blood loss or nutritional deficiencies.
• While many parts of the body help make red blood cells, most of
the work is done in the bone marrow. What is bone marrow
again?
• Healthy red blood cells last between 90 and 120 days. Parts of
your body then remove old blood cells. A hormone called
erythropoietin made in your kidneys signals your bone marrow
to make more red blood cells.
• Hemoglobin is the oxygen-carrying protein inside red blood
cells. It gives red blood cells their red color. People with anemia
do not have enough hemoglobin.
Respiratory System
Section 2
The Importance of Respiration
• The function of the respiratory system is to
sustain cellular respiration by supplying oxygen
to body cells and remove carbon dioxide waste
from cells.
Breathing and Respiration
• The respiratory system undergoes 2 processes:
1) Air enters the body through breathing.
• Breathing is the mechanical movement of air into and out
of your lungs.
– Gases are exchanged in the body.
• External respiration is the exchange of gases between the
atmosphere and the blood, which occurs in the lungs.
• Internal respiration is the exchange of gases between the
blood and the body’s cells.
1. Air enters through your nose.
The Path of Air
Hairs within the nose filter out
dust and other particles from the
air.
2. Filtered air then passes through the upper throat called the
pharynx.
3. The epiglottis allows air to pass from the larynx to a long tube,
known as the trachea or windpipe.
4. The trachea branches into 2 tubes called bronchi, which lead to
the lungs.
5. At the lungs gas exchange takes place.
6. At the bronchi, the tubes branch out into smaller tubes called
bronchioles.
7. The bronchioles then travel into an air sac called the alveolus
(alveoli). (Site where gas exchange occurs)
Gas exchange in the lungs
• Air travels to individual alveoli where O2 diffuses
across the moist, thin walls into capillaries and
then into RBCs.
• The O2 then is transported by the blood to be
released to tissue cells in the body during
internal respiration.
• Also CO2 moves in the opposite direction in the
alveoli. It crosses capillary walls, and then
diffused out during external respiration.
Breathing
• The brain directs the rate of breathing by responding to
internal stimuli that indicate how much oxygen the body
needs.
– When the concentration of CO2 gets high in the blood, the
breathing rate increases because the cells need more O2
• Inhalation is the act of taking air into the lungs.
– During inhalation the diaphragm contracts, causing the chest
cavity to expand as the diaphragm moves down allowing air
to move into the lungs.
– During exhalation the diaphragm relaxes and returns to its
normal resting position, reducing the size of the chest cavity
as the diaphragm moves up.
Respiratory Disorders
• Some include:
– Asthma: irritation of pathways; bronchioles constrict.
– Bronchitis: pathway is infected, coughing and mucus
is produced.
– Emphysema: alveoli no longer work properly.
– Pneumonia: infection of lungs causing alveoli to
collect mucus.
– Pulmonary tuberculosis: infection of the lungs
causing a small surface area to inflate.
– Lung cancer: uncontrolled cell growth
Is it
really
worth
it?