Download Circulatory System and Blood

Main Structures of the Circulatory System
1. The heart
2. Blood vessels
3. Blood
Blood vessels found in glands.
Functions of the Circulatory System
 Transport gases- oxygen from the lungs to cells
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around the body and carbon dioxide from the cells to
the lungs.
Transport nutrients (sugars, calcium).
Transport wastes from cells to organs that are
capable of breaking wastes down (liver, kidneys)
Blood contains white blood cells that fight infection.
Maintains the pH levels and ionic concentration of
fluids in the body.
Helps maintain body temperature
The Heart
The heart is a hollow organ about the size of a
clenched fist. It is made almost entirely of muscle.
As the heart pumps blood, it creates a pressurized
system that forces blood to travel through the
blood vessels throughout your body, and back to
the heart again, thus circulation!
Your heart pumps more than 6,000 Liters a day!
(Equivalent to 1600 gallons of blood a day).
The Heart
The heart has two layers:
1. The outer layer of the heart is a protective film
called pericardium.
(peri means outer)
2. The inner layer of the
heart is known as
myocardium.
(myo means muscle)
Heart Chambers
The Human heart has 4 chambers, as follows:
 the right ventricle
 the left ventricle
 the right atrium
 the left atrium.
Atria pump blood into
the heart.
Ventricles pump blood
out of the heart.
*Notice the sides of the heart are reversed. Think of yourself as the doctor, and the
heart you are looking at as the patient’s. Your rights and lefts would be switched.
Heart Valves
Blood is pumped through the chambers, aided by
four heart valves. The valves open and close to
allow the blood to flow in only one direction.
The function of the heart valves is to act as a oneway door to prevent the backflow of blood.
Heart Valves
 The tricuspid valve is between the right atrium and right
ventricle.
 The pulmonary valve is between the right ventricle and the
pulmonary artery.
 The mitral valve is between the left atrium and left ventricle.
 The aortic valve is between the left ventricle and the aorta.
Each valve has a set of flaps (also called leaflets or cusps). When
working properly, the heart valves open and close fully.
The average person’s heart beats about 70 times per
minute- the more “fit” you are, the less your heart
beats.
The heart’s pacemaker is an electrical signal called an
SA node (sinoatrial node). It is located in the right
atrium. The SA node is a bundle of nerve cells that
control the hearts muscle contractions in an orderly
manner by triggering electricity!
The Heart
Aorta
Superior Vena Cava
Pulmonary Artery
Pulmonary Veins
Pulmonary Veins
Left
atrium
Right
atrium
Mitral Valve
Tricuspid valve
Right
ventricle
Inferior vena cava
Left
ventricle
Label the
remaining
parts of
the heart!
BLOOD VESSELS
There are 3 types of blood vessels:
1. Arteries
2. Capillaries
3. Veins
Arteries
 Arteries are blood vessels made of
smooth muscle that carry blood away
from the heart.
 This definition suggests that all arteries
carry oxygenated blood- which is true for
all except the pulmonary arteries.
Arteries con’t
Some major arteries you may have heard
of before:
 Femoral artery
 Carotid artery
 Abdominal artery
 Coronary artery
Major arteries the biggest ones of all, but
still very thin (less than 1 mm in
diameter).
Arteries get smaller as they approach the
tiniest blood vessels, the capillaries.
These smaller versions of arteries are
known as arterioles.
Veins
Veins are blood vessels made of smooth muscle
that carry blood towards the heart. All veins in
your body, except the pulmonary veins carry
deoxygenated blood. Veins have valves to ensure
that there is no backflow of blood as the blood
works its way up to the heart.
Valve
Varicose veins are veins that
have faulty valves. They are
common in older people, when
valves may not work as well.
This causes the veins to swell.
Capillaries
Capillaries are the tiniest blood vessels. Capillaries
deliver oxygen and nutrients to cells as well as take
waste from cells. Therefore, they can carry
oxygenated or deoxygenated blood.
They are found between arteries and veins.
Blood Vessel Network
Direction of Blood Flow
The direction of blood flow is very specific. Deoxygenated
blood (blood that contains carbon dioxide) travels
differently from oxygenated blood as there are different
destinations.
The lungs work very closely with the circulatory system to
release CO2 and gain oxygen.
Direction of Blood Flow: Oxygenated blood
The following sequence is the path that oxygenated
blood will travel through the different parts of the
body:
a. Capillaries within the lungs 
b. Pulmonary vein 
The ONLY vein that carries oxygenated blood!
c. Left atrium 
d. Left ventricle 
e. Aorta 
f. Arteries 
Blood becomes oxygenated
when oxygen diffuses across
the alveolar membrane into the
capillaries of the lungs.

h. Cells (ALL cells need O2 to survive!)
g. Capillaries in the body tissues
Direction of Blood Flow: Deoxygenated Blood
Once blood reaches the cells, red blood cells drop off oxygen,
and pick up carbon dioxide, becoming deoxygenated. The
following sequence is the path of deoxygenated blood
throughout the body:
a. Cells 
b. Capillaries 
c. Veins 
d. Vena cava 
Blood becomes deoxygenated when
the oxygen diffuses from your blood
to your cells, and carbon dioxide
(celluar waste) diffused to the blood.
e. Right atrium 
f. Right ventricle 
g. Pulmonary artery 
The ONLY artery that carries deoxygenated blood!
h. Capillaries within the Lungs.
… And the cycle repeats (circulates) when oxygen diffuses
into the capillaries at the lungs!
The heart is a double pump!
This is because one half of the heart (the right ventricle) sends blood through the lungs;
and the other half of the heart (the left ventricle) sends blood through the body.
The right ventricle contains deoxygenated blood
and the left ventricle contains oxygenated blood.
Diffusion of Oxygen and Carbon Dioxide
across the Alveoli
The lungs contain tiny
structures called alveoli
(singular: alveolus).
Diffusion of
O2
Alveoli is where gas
exchange occurs.
Oxygen enters the
alveolus and then
diffuses into the blood
stream. Carbon dioxide
takes the opposite route.
Diffusion of
CO2
The Heart Song
Blood Pressure (BP)
When you go to the doctor they take your
BP. You’ve probably heard something
like “120 over 80! Excellent!” And you’ve
probably just smiled and nodded
Sphygmomanometer
What do those numbers mean?
When your heart is beating, it is contracting and relaxing. This
creates two different pressures, one will be higher than the
other.
Systolic pressure- the pressure measured on your blood vessels
during heartbeats (contractions).
Diastolic pressure- the pressure measured on your blood vessels
between heartbeats (relaxed).
Systolic
BP is measured in milimeters of mercury
mm/Hg
Diastolic
(mmHg), the SI unit for fluid pressure.
Common Term
Scientific Term
Red Blood Cell
Erythrocyte
White Blood Cell
Leukocyte
Platelets
Thrombocytes
Functions of Blood:
1) Transportation:
o oxygen & carbon dioxide
o nutrients
o waste products (metabolic wastes, excessive water,
& ions)
2) Regulation - hormones & heat (to regulate body
temperature)
3) Protection - clotting mechanism protects against
blood loss & leukocytes provide immunity against
many disease-causing agents
What is blood made of?
Components of Blood - average adult has about 5
liters
1) Formed Elements
o Red blood cells (or erythrocytes)
o White blood cells (or leucocytes)
o Platelets (or thrombocytes)
Formed elements account for 45% of the total
volume of blood, most of which is erythrocytes.
Components of Blood
2) Plasma= water + dissolved solutes , accounts for
55% of the total volume of blood.
Red blood cell, platelet, white blood cell.
Red Blood Cells
(or erythrocytes)
1 - biconcave discs
2 - lack a nucleus & cannot reproduce
(average lifespan = about 120 days)
3 - transport hemoglobin (each RBC has about
280 million hemoglobin molecules)
4 - Typical concentration is 4-6 million per cubic mm
5 - contain carbonic anhydrase (critical for transport of
carbon dioxide)
How do we know percentages?
A centrifuge is a device that rotates materials at a
very high speed to separate solids and liquids.
Hemoglobin
 composed of globin (made up of 4
highly folded polypeptide chains)
+ 4 heme groups (with iron)
 each molecule can carry 4
molecules of oxygen
• called oxyhemoglobin when carrying oxygen &
called reduced hemoglobin when not carrying
oxygen
• can also combine with carbon dioxide & helps
transport carbon dioxide from the tissues to the
lungs
White blood cells (or leucocytes or leukocytes):
 have nuclei & do not contain hemoglobin
 typical concentration is 5,000 - 9,000 per cubic
millimeter
 Types of WBCs:
o Granular white blood cells include:
 neutrophils (50 - 70% of WBCs)
 eosinophils (1 - 4%)
 basophils (less than 1%)
o Agranular (or non-granular) white blood cells
include:
 lymphocytes (25 - 40%)
 monocytes (2 - 8%)
White Blood Cells
Platelets (or thrombocytes)
1 - formed in the bone marrow (from
cells called megakaryocytes)
2 - have no nucleus, but can secrete
a variety of substances & can also
contract (because they contain
actin & myosin)
3 - normal concentration in the blood
is about 250,000 per cubic
millimeter
4 - remain functional for about 7 - 10
days (after which they are removed
from the blood
5- play an important role in
hemostasis (preventing blood loss)
Plasma Components:
1 - Water - serves as transport medium; carries heat
2 - Proteins
 Albumins
 Globulins
 Fibrinogen
o important in clotting
Recall that your blood is
mostly plasma (55%).
Plasma is mostly water.
Plasma continued
3 - Inorganic constituents (1% of plasma) - e.g.,
sodium, chloride, potassium, & calcium
4 - Nutrients - glucose, amino acids, lipids & vitamins
5 - Waste products - e.g., nitrogenous wastes like urea
6 - Dissolved gases - oxygen & carbon dioxide
7 - Hormones
Hemostasis - prevention of blood loss from broken
vessel.
Hemostasis results in a clot- formed primarily of fibrin threads
but also including blood cells & platelets. Fibrin is a protein
that your body builds in response to blood loss.
Blood clots in the right places prevent the loss of
blood from ruptured vessels, but in the wrong
place can cause problems such as a stroke.