Download What Is Blood Pressure?

Ms. Franz
.4 AP Biology- MHS
March 3, 2008
Arteries
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Blood vessels that carry blood away from the
heart.
Carry oxygenated blood
Tough on the outside and smooth on the
inside
Have 3 layers: outer tissue layer, a muscular
middle and an inner layer of epithelial cells
Arteries
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The muscle in the middle is elastic and very
strong
Helps the heart pump the blood
When the heart beats, the artery expands and
fills with blood
When it relaxes, the artery contracts and
pushes the blood along
Arterioles
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Branch from the arteries
Receive blood from the arteries
They are smaller than the arteries
They are strong and relatively thick
Carry blood away from the heart to the tissues
of the body
Important in blood pressure (BP) regulation
Capillaries
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Branch from the arterioles
Very thin and fragile
Involved in the body’s release of excess heat
During exercise, your body and blood temperatures
rise. To release this excess heat, the blood delivers
the heat to the capillaries which rapidly release it to
the tissue
Your skin turns a flushed, red appearance
Ex) Hold your hand under hot water and it will
quickly turn red for the same reason
Capillaries cont.
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Blood can only pass through in a single file
The exchange of O2 and CO2 takes place
through the capillary wall
RBC release the O2, it passes through the
wall and into surrounding tissue
The capillaries then pass their waste-rich
blood to the veins for transport back to the
heart
Venules
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Vessels that collect blood from capillaries
Carry blood that’s low in oxygen content
Join together to form veins
Spider veins- caused by
dilated venules
venule dilation is due to
valve damage
Veins
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Vessels that transport blood to the heart
Lie close to the surface
Thinner-walls and thus transport blood at a
lower pressure
More easily damaged
Have 3 layers: an outer tissue layer, a muscle
in the middle and a smooth inner layer of
epithelial cells
Veins cont.
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Receive blood from the capillaries after the
exchange of O2 and CO2 has taken place
Transport waste-rich blood back to the lungs and
heart
Important this waste-rich blood continues
moving in the right direction and not backwards
This is accomplished by valves inside the veins
Valves are like gates
Veins cont.
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Vein valves are necessary to keep blood
flowing toward the heart and allow blood to
flow against the force of gravity
Ex) blood flowing from the foot has to be able
to flow up the leg and to the heart
Vein valves provide footholds for the blood as
it climbs it way up
How is it that we can see our veins?
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the waste-rich blood is the deoxygenated form of
hemoglobin and makes the blood in veins appear
dark a deep red color
Vein walls are thin and waste-rich blood can be
seen through some body parts
LOOK at your wrist, ankles, hands inside elbow
You can probably see your veins carrying blood
back to your heart
*Your skin refracts light making the deep red look
a little blue
Functions of the Circulatory System
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It is an amazing highway that travels through your
entire body connecting all your body cells.
Transports materials such as nutrients, water, and
oxygen to your billions of body cells throughout your
body
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For example, glucose, a simple sugar used to produce ATP
Transport hormones - Numerous hormones that help
maintain constant internal conditions
Carries away wastes from cells such as carbon dioxide
Functions cont.
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Contains cells that fight infection
Helps stabilize the pH and ionic concentration
of the body fluids.
It helps maintain body temperature by
transporting heat.
The Veins and Arteries of the circulatory
system function to serve different areas in the
body and supply them with the circulation
they need to work properly and efficiently
A “Superhighway”
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The circulatory system consists of a lot of one
way streets.
The superhighways of the circulatory system
are the veins and arteries
Let’s take a look at each of these one way
streets that together form the superhighway of
our circulatory system
Systemic Circulation
It’s all throughout the body
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It’s a major part of the overall circulatory system.
Supplies nourishment to most of the tissue
throughout your body, (except the heart and lungs
they have their own systems)
The blood vessels (arteries, veins, and capillaries)
deliver oxygen and nutrients to the tissue.
The aorta carries and distributes oxygen rich blood
to all arteries.
Most major arteries branch off from the aorta
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During systemic circulation, blood passes through
the kidneys renal circulation
The kidneys filter much of the waste from the blood.
Blood also passes through the small intestine
portal circulation
The blood from the small intestine collects in the
portal vein which passes through the liver.
The liver filters sugars from the blood, storing them
for later.
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Superior vena cava- receives blood from the
head, neck, chest, shoulders and arms
Inferior vena cava- collects most of the venous
blood from organs below the diaphragm
Hepatic portal vein- collects blood from
visceral organs in the abdominopelvic cavity
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Delivers blood to capillary networks in the liver
Aorta
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The hearts main artery
Leaves the heart and heads toward the head via the
*aortic arch*
The arch turns into the *descending aorta* which
goes behind the heart and down the center of the
body distributing blood (aka-thoracic, abdominal)
inside layer is very smooth, allowing the blood to
flow quickly
outside layer is very strong, allowing the blood to
flow forcefully
Try this at home!
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Lie down on your back
Look down at your abdomen
Sometimes when you look at your abdomen
pulsates with each heart beat
DON”T WORRY! This is normal
This pulsation is the aorta throbbing with each
heart beat
Pulmonary Circulation
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movement of blood from the heart, to the lungs, and back to
the heart again
The heart is divided into 4 chambers, 2 associated with each
circuit:
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R. Atrium- receives blood from the systemic body circuit
R. Ventricle- discharges it into the pulmonary (lungs) circuit
L. Atrium- collects blood from the pulmonary circuit
L. Ventricle- ejects blood to the systemic circuit
When the heart beats, the two ventricles contract at the same
time, ejecting equal volumes of blood
The two atria are separated by the interatrial septum (WALL)
The two ventricles are divided by the interventricular septum
(WALL)
Blood Flow Through the Heart
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The veins bring waste-rich blood back to the heart
Blood travels from the right atrium into the right ventricle
through a broad opening called the Tricuspid valve
Papillary muscles on the inner surface and anchor the valves
to the heart (tricuspid and mitral valves)
The right ventricle fills and then contracts, pushing the blood
into the pulmonary trunk, which is guarded by the semilunar
valve
From the trunk, blood flows in to the left and right pulmonary
arteries
These arteries branch repeatedly with in the lungs
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This supplies the capillaries, where the exchange of
carbon dioxide and oxygen takes place
Blood collects into the left and right pulmonary veins
These veins return and empty into the left atrium
Like the right atrium, there is a valve bicuspid or mitral
valve
Blood flows from the left atrium, through the mitral
valve and into the L. ventricle
Blood leaves the L. ventricle passing through the aortic
semilunar valve and into the body via the ascending
aorta
Pulmonary Circulation cont.
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The one-way valves are important for preventing any
backward flow of blood
The circulatory system is a network of one-way
streets. If blood started flowing the wrong way, the
blood gases (oxygen and carbon dioxide) might mix,
causing a serious threat to your body
You can use a stethoscope to hear pulmonary
circulation
The two sounds you hear, "lub" and "dub," are the
ventricles contracting and the valves closing.
Pulmonary Circulation cont.
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The SA node (sinoatrial or sinus node) is the heart's
natural pacemaker
consists of a cluster of cells that are situated in the
upper part of the wall of the right atrium (right upper
chamber)
electrical impulses are generated there
If these impulses cannot be created on their own, an
artificial pacemaker for the heart can be inserted
The electrical signal moves from cell to cell down
through the heart until it reaches the AV node
Pulmonary Circulation cont.
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Atrioventricular node (AV): is an electrical relay
station between the atria (the upper) and the
ventricles (the lower chambers of the heart).
Serves as a gate to slow electrical currents
Electrical signals from the atria must pass through
the AV node to reach the ventricles.
controls heart rate
generates electrical impulses and conducts them
throughout the muscle of the heart, stimulating the
heart to contract and pump blood.
Component of the Blood
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What makes up our blood?
Red Blood Cells (RBC)
White Blood Cells (WBC)
Platelets
Plasma
RBC, WBC and Platelets are made by bone
marrow (a soft tissue inside our bones)
Red Blood Cells (erythrocytes)
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Carry O2 and CO2
Pick up O2 in the lungs and transport it to cells
Gathers CO2 (waste from working cells) and
transports it to the lungs where it gets exhaled
(breathe out)
There are about 5,000,000 RBC in ONE drop of
blood
White Blood Cells (leukocytes)
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Help fight off germs by attacking and
destroying them as they enter the body
When you have an infection, your body will
produce more WBC to help fight it
If our WBC cells need a little help with a lg.
scale infection, the Doctor will prescribe an
antibiotic to help
There are ~10,000 WBC in ONE drop of
blood
Platelets (thrombocytes)
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Blood cells that help stop bleeding
When we cut ourselves, we’ve broken a blood
vessel and blood leaks out
Platelets start sticking to the opening of the
broken vessels to plug up the holes
As platelets stick, they attract more platelets,
fibers and other blood cells
When the bleeding stops scabs
There are ~250,000 platelets in ONE drop of
blood
Plasma
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Liquid part of the blood
~ ½ of our blood is plasma
Carries blood cells throughout the body
Made in the liver
ONE drop of blood contains a half a drop of
plasma
The Heart
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The heart is an amazing organ.
It is the main component of the circulatory
system
It beats about 3 Billion times during an avg.
lifetime
It is a muscle about the size of your fist
Located in center of your chest slightly to the
left
Heart Rate
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Usually it is calculated as the number of contractions
(heart beats) of the heart in one minute and
expressed as "beats per minute" (bpm).
When resting, the average adult human heart beats at
about 70 bpm (males) and 75 bpm (females)
The infant/neonatal rate of heartbeat is around 130150 bpm, the toddler's about 100–130 bpm, the older
child's about 90–110 bpm, and the adolescent's about
80–100 bpm.
The pulse is the most commonly used method of
measuring the heart rate
Blood Pressure (BP)
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What Is Blood Pressure?
BP is the force of the blood pushing against the walls
of the arteries.
Each time the heart beats (about 60–70 times a
minute at rest), it pumps out blood into the arteries
Your BP is at its highest when the heart beats,
pumping the blood systolic pressure
When the heart is at rest, between beats, your blood
pressure falls diastolic pressure
BP
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Blood pressure is always given as these two
numbers, the systolic and diastolic pressures –
both are important
The systolic pressure is the top number and
the diastolic is the bottom, such as 120/80
mmHg (measured in millimeters of mercury)
If your blood pressure is 120/80, you say that
it is "120 over 80."
BP
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Blood pressure changes during the day
It’s lowest as you sleep and rises when you
get up
It rises when you are excited, nervous, or
active
For most waking hours, it should stay pretty
much the same when you’re standing or
sitting still
High Blood Pressure
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If one or both numbers are usually high, you
have high BP
A BP of 140/90mmHg is considered high BP
Uncontrolled high BP is dangerous and can
lead to stroke, heart failure, heart attack,
kidney failure or blindness
High BP is called the Silent Killer b/c there
are usually no signs or symptoms
BP Table
Systolic (top
number)
Diastolic (bottom
number)
Less than 120
Less than 80
120–139
80–89
Stage 1
140–159
90–99
Stage 2
160 or higher
100 or higher
Category
Normal
Prehypertension
High blood
pressure
Coronary Artery Disease
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an obstruction of the coronary (heart) arteries
Strenuous activity causes the heart to work
harder to supply oxygen-rich blood.
The constrictions in coronary arteries prevent
the heart from receiving the necessary amount
This insufficient supply of blood to the heart
muscle results in oxygen deprivation, a
condition called myocardial (heart) ischemia.
Congestive Heart Failure (CHF)
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occurs when weak heart function is accompanied by
a build up of fluids in the body
blood flow slows, decreasing the amount of blood
pumped from the heart.
Blood returning to the heart backs up in the veins
and forces fluid into surrounding tissues (often the
feet and legs) to swelledema
edema can spread to other parts of the body,
including vital organs, such as the lungs, which can
be life-threatening
~400,000 Americans are diagnosed with CHF each
year
Heart Attack
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myocardial infarction
occurs when the blood supply (via coronary arteries) to
part of the heart muscle is severely reduced or stopped
Usually caused by the buildup of plaque (deposits of fatlike substances)
The plaque can eventually burst, tear or rupture, creating
a "snag" where a blood clot forms and blocks the
artery heart attack
If the blood supply is cut off for more than a few
minutes, muscle cells suffer, they can be permanently
injured and die
This can kill or disable someone, depending on how
much heart muscle is damaged
Anemia
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a deficiency of red blood cells or the hemoglobin
molecules within them
Oxygen has trouble getting where to it needs to
hemoglobin is not accessible
the blood struggles to bring oxygen molecules to
tissues for energy in the body
can be very serious because the human body
depends on oxygen to survive.
Symptoms: Weakness, fatigue
High Cholesterol
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What Is Cholesterol?
Cholesterol is a waxy, fat-like substance that is
found in all cells
Your body needs some cholesterol to work the right
way and it makes all the cholesterol it needs on its
own
Found in some of the foods you eat.
Body uses cholesterol to make hormones, vitamin D,
and substances that help you digest foods.
High Cholesterol
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Blood is watery, and cholesterol is fatty, therefore,
just like oil and water, the two do not mixplaque
Cholesterol is carried in small packages to the
bloodstream called lipoproteins
The small packages are made of fat (lipid) on the
inside and proteins on the outside.
Two kinds of lipoproteins carry cholesterol
throughout your body. It’s important to have healthy
levels of both:
Lipoproteins
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Low-density (LDL) sometimes called bad
cholesterol
High LDL cholesterol leads to a buildup of
cholesterol in arteries increases your chances of
having heart disease
High-density (HDL) sometimes called good
cholesterol
HDL carries cholesterol from other parts of your
body back to your liver, where it is removed from
the body
The higher your HDL cholesterol level, the lower
your chance of getting heart disease.