Blood
Introduction
Blood, a type of connective tissue,
is a complex mixture of cells,
chemicals, and fluid.
Blood transports substances
throughout the body, and helps to
maintain a stable internal
environment.
The blood includes red blood cells,
white blood cells, platelets, and
plasma.
Red Blood Cells
Red blood cells (erythrocytes) are
biconcave disks that contain one-third
oxygen-carrying hemoglobin by volume.
When oxygen combines with
hemoglobin bright red oxyhemoglobin
results.
Deoxygenated blood (deoxyhemoglobin)
is darker.
RBCs discard their nuclei during
development and so cannot reproduce
or produce proteins.
Figure
RBC Production, Control &
Counts
Red blood cell production occurs in
the red bone marrow after birth.
The average life span of a red blood
cell is 120 days.
The number of RBCs is a measure
of the blood’s oxygen-carrying
capacity.
Dietary Factors Affecting RBC
Production
Vitamins B12 and folic acid are
needed for DNA synthesis, so they
are necessary for the reproduction
of all body cells
Iron is needed for hemoglobin
synthesis.
A deficiency in red blood cells or
quantity of hemoglobin results in
anemia.
White Blood Cells
White blood cells (leukocytes) help
defend the body against disease.
Five types of WBCs are in circulating
blood and are distinguished by size,
granular appearance of the
cytoplasm, shape of the nucleus,
and staining characteristics.
The types of WBCs are the granular
neutrophils, eosinophils, and
basophils, and the agranular
monocytes and lymphocytes.
Functions of White Blood Cells
Neutrophils and monocytes are
phagocytic, with monocytes engulfing the
larger particles.
Eosinophils moderate allergic reactions as
well as defend against parasitic infections.
Basophils migrate to damaged tissues and
release histamine to promote
inflammation and heparin to inhibit blood
clotting.
Lymphocytes are the major players in
specific immune reactions and some
produce antibodies.
White Blood Cell Counts
A differential WBC count can help
pinpoint the nature of an illness,
indicating whether it is caused by
bacteria or viruses.
Leukocytosis occurs after an
infection when excess numbers of
leukocytes are present; leukopenia
occurs from a variety of conditions,
including AIDS.
Blood Plateletes
Platelets help repair damaged
blood vessels by adhering to their
broken edges.
Blood Plasma
Plasma is the clear, straw-colored
fluid portion of the blood.
Plasma is mostly water but
contains a variety of substances.
Plasma functions to transport
nutrients and gases, regulate
fluid and electrolyte balance, and
maintain a favorable pH.
Blood Plasma – Gases & Nutrients
The most important blood gases
are oxygen and carbon dioxide.
The plasma nutrients include amino
acids, monosaccharides,
nucleotides, and lipids.
Plasma Electrolytes
Plasma electrolytes are absorbed
by the intestine or are by-products
of cellular metabolism.
They include sodium, potassium,
calcium, magnesium, chloride,
bicarbonate, phosphate, and
sulfate ions.
Some of these ions are important
in maintaining osmotic pressure
and pH of the plasma.
Hemostasis
Hemostasis refers to the stoppage
of bleeding.
Following injury to a vessel,
three steps occur in hemostasis:
blood vessel spasm, platelet plug
formation, and blood
coagulation.
Figure
Blood Coagulation
Once a blood clot forms, it
promotes still more clotting
through a positive feedback
system.
After a clot forms, fibroblasts
invade the area and produce fibers
throughout the clots.
A clot that forms abnormally in a
vessel is a thrombus; if it
dislodges, it is an embolus.
Blood Groups and Transfusions
After mixed success with
transfusions, scientists determined
that blood was of different types
and only certain combinations
were compatible.
Antigens and Antibodies
Clumping of red blood cells following
transfusion is called agglutination.
Agglutination is due to the interaction
of proteins on the surfaces of red
blood cells (antigens) with certain
antibodies carried in the plasma.
Only a few of the antigens on red
blood cells produce transfusion
reactions.
These include the ABO group and
Rh group.
ABO Blood Group
Type A blood has A antigens on red
blood cells and anti-B antibodies in the
plasma.
Type B blood has B antigens on red
blood cells and anti-A antibodies in the
plasma.
Type AB blood has both A and B
antigens, but no antibodies in the
plasma.
Type O blood has neither antigen, but
both types of antibodies in the plasma.
ABO Blood Group Cont.
Adverse transfusion reactions are
avoided by preventing the mixing
of blood that contains matching
antigens and antibodies.
Adverse reactions are due to the
agglutination of red blood cells.
Figure
Rh Blood Group
The Rh factor was named after the
rhesus monkey.
If the Rh factor surface protein is
present on red blood cells, the blood is
Rh positive; otherwise it is Rh negative.
There are no corresponding antibodies
in the plasma unless a person with Rh-
negative blood is transfused with Rh-
positive blood; the person will then
develop antibodies for the Rh factor.
Erythroblastosis fetalis develops in Rh-
positive fetuses of Rh-negative mothers
but can now be prevented.
Figure
Cardiovascular System
Introduction
The cardiovascular system consists of
the heart, and vessels, arteries,
capillaries and veins.
A functional cardiovascular system is
vital for supplying oxygen and nutrients
to tissues and removing wastes from
them.
Structure of the Heart
The heart is a hollow, cone-shaped,
muscular pump within the thoracic
cavity.
Size and Location of the Heart
The average adult heart is 14 cm long
and 9 cm wide.
The heart lies in the mediastinum
under the sternum; its apex extends
to the fifth intercostal space.
The pericardium encloses the heart.
Figure
Wall of the Heart
The wall of the heart is composed of three
distinct layers.
The outermost layer, the epicardium, is made
up of connective tissue and epithelium; it
houses capillaries along with coronary arteries.
It is the same as the visceral pericardium.
The middle layer called myocardium consists of
cardiac muscle and is the thickest layer of the
heart wall.
The inner endocardium is smooth and is made
up of connective tissue and epithelium, and is
continuous with the endothelium of major
vessels joining the heart.
Figure
Heart Chambers and Valves
The heart has four internal chambers:
two atria on top and two ventricles
below.
Atria receive blood returning to the
heart and have thin walls and ear-like
auricles projecting from their exterior.
The thick-muscled ventricles pump
blood to the body.
Heart Chambers and Valves cont.
A septum divides the atrium and ventricle on
each side. Each also has an atrioventricular
(A-V) valve to ensure one way flow of blood.
The right A-V valve (tricuspid) and left A-V
valve (bicuspid or mitral valve) have cusps
to which chordae tendinae attach.
Chordae tendinae are, in turn, attached to
papillary muscles in the inner heart wall
that contract during ventricular contraction
to prevent the backflow of blood through
the A-V valves.
Heart Chambers and Valves
cont.
The superior and inferior vena cavae
bring de-oxygenated blood from the
body to the right atrium.
The right ventricle has a thinner wall
than does the left ventricle because it
must pump blood only as far as the
lungs, compared to the left ventricle
pumping to the entire body.
Heart Chambers and Valves
cont.
At the base of the pulmonary trunk
leading to the lungs is the pulmonary
valve, which prevents a return flow of
blood to the ventricle.
The left atrium receives blood from four
pulmonary veins.
The left ventricle pumps blood into the
entire body through the aorta, guarded
by the aortic valve that prevents
backflow of blood into the ventricle.
Figure
Figure
Path of Blood through the Heart
Blood low in oxygen returns to the right
atrium via the venae cavae and
coronary sinus.
The right atrium contracts, forcing
blood through the tricuspid valve into
the right ventricle.
Path of Blood through the Heart
The right ventricle contracts, closing the
tricuspid valve, and forcing blood
through the pulmonary valve into the
pulmonary trunk and arteries.
The pulmonary arteries carry blood to
the lungs where it can rid itself of
excess carbon dioxide and pick up a
new supply of oxygen.
Path of Blood through the Heart
Freshly oxygenated blood is returned to
the left atrium of the heart through the
pulmonary veins.
The left atrium contracts, forcing blood
through the left bicuspid valve into the
left ventricle.
The left ventricle contracts, closing the
bicuspid valve and forcing open the
aortic valve as blood enters the aorta
for distribution to the body.
Figure
Blood Supply to the Heart
The first branches off of the aorta,
which carry freshly oxygenated blood,
are the right and left coronary arteries
that feed the heart muscle itself.
Branches of the coronary arteries feed
many capillaries of the myocardium.
Blood Supply to the Heart cont.
The heart muscle requires a continuous
supply of freshly oxygenated blood, so
smaller branches of arteries often have
anastomoses as alternate pathways for
blood, should one pathway become
blocked.
Cardiac veins drain blood from the heart
muscle and carry it to the coronary
sinus, which empties into the right
atrium.
Figure
Figure
Heart Actions
The cardiac cycle consists of the atria
beating in unison (atrial systole)
followed by the contraction of both
ventricles, (ventricular systole) then the
entire heart relaxes for a brief moment
(diastole).
Cardiac Cycle
During the cardiac cycle, pressure
within the heart chambers rises and
falls with the contraction and relaxation
of atria and ventricles.
When the atria fill, pressure in the atria
is greater than that of the ventricles,
which forces the A-V valves open.
Pressure inside atria rises further as
they contract, forcing the remaining
blood into the ventricles.
Cardiac Cycle cont.
When ventricles contract, pressure
inside them increases sharply, causing
A-V valves to close and the aortic and
pulmonary valves to open.
As the ventricles contract, papillary
muscles contract, pulling on chordae
tendinae and preventing the backflow
of blood through the A-V valves.
Heart Sounds
Heart sounds are due to vibrations in
heart tissues as blood rapidly changes
velocity within the heart.
Heart sounds can be described as a
"lubb-dupp" sound.
The first sound (lubb) occurs as
ventricles contract and A-V valves are
closing.
The second sound (dupp) occurs as
ventricles relax and aortic and
pulmonary valves are closing.
Blood Vessels
The blood vessels (arteries, arterioles,
capillaries, venules, and veins) form a
closed tube that carries blood away
from the heart, to the cells, and back
again.
Arteries and Arterioles
Arteries are strong, elastic vessels
adapted for carrying high-pressure blood.
Arteries become smaller as they divide
and give rise to arterioles.
The wall of an artery consists of smooth
muscle and connective tissue.
Arteries are capable of vasoconstriction as
directed by the sympathetic impulses;
when impulses are inhibited, vasodilation
results.
Figure
Capillaries
Capillaries are the smallest vessels,
consisting only of a layer of
endothelium through which substances
are exchanged with tissue cells.
Capillary permeability varies from one
tissue to the next, generally with more
permeability in the liver, intestines, and
certain glands, and less in muscle and
considerably less in the brain (blood-
brain barrier).
Capillaries cont.
The pattern of capillary density also varies
from one body part to the next.
Areas with a great deal of metabolic
activity (leg muscles, for example) have
higher densities of capillaries.
Precapillary sphincters can regulate the
amount of blood entering a capillary bed
and are controlled by oxygen concentration
in the area.
If blood is needed elsewhere in the body,
the capillary beds in less important areas
are shut down.
Figure
Venules and Veins
Venules leading from capillaries merge to
form veins that return blood to the heart.
Veins have the same three layers as
arteries have and have a flap-like valve
inside to prevent backflow of blood.
Veins are thinner and less muscular
than arteries; they do not carry high-
pressure blood.
Veins also function as blood reservoirs.
Blood Pressure
Blood pressure is the force of blood
against the inner walls of blood vessels
anywhere in the cardiovascular system,
although the term "blood pressure“
usually refers to arterial pressure.
Arterial Blood Pressure
Arterial blood pressure rises and falls
following a pattern established by the
cardiac cycle.
During ventricular contraction, arterial
pressure is at its highest (systolic
pressure).
When ventricles are relaxing, arterial
pressure is at its lowest (diastolic
pressure).
The surge of blood that occurs with
ventricular contraction can be felt at certain
points in the body as a pulse.
Factors that Influence Arterial BP
Arterial pressure depends on heart
action, blood volume, resistance to
flow, and blood viscosity.
Heart Action
Heart action is dependent upon
stroke volume and heart rate
(together called cardiac output); if
cardiac output increases, so does
blood pressure.
Factors that Influence Arterial BP
cont.
Blood Volume
Blood pressure is normally directly
proportional to the volume of blood within
the cardiovascular system.
Blood volume varies with age, body size, and
gender.
Peripheral Resistance
Friction between blood and the walls of blood
vessels is a force called peripheral resistance.
As peripheral resistance increases, such as
during sympathetic constriction of blood
vessels, blood pressure increases.
Factors that Influence Arterial BP
cont.
Blood Viscosity
The greater the viscosity (ease of flow)
of blood, the greater its resistance to
flowing, and the greater the blood
pressure.
Venous Blood Flow
Blood flow through the venous system is
only partially the result of heart action and
instead also depends on skeletal muscle
contraction, breathing movements, and
vasoconstriction of veins.
Contractions of skeletal muscle squeeze
blood back up veins one valve at a time.
Differences in thoracic and abdominal
pressures draw blood back up the veins.
Figure
Paths of Circulation
The body's blood vessels can be divided
into a pulmonary circuit, including
vessels carrying blood to the lungs and
back, and a systemic circuit made up of
vessels carrying blood from the heart to
the rest of the body and back.
Pulmonary & Systemic Circuit
The pulmonary circuit is made up of
vessels that convey blood from the right
ventricle to the pulmonary arteries to the
lungs, alveolar capillaries, and
pulmonary veins leading from the lungs
to the left atrium.
The systemic circuit includes the aorta
and its branches leading to all body
tissues as well as the system of veins
returning blood to the right atrium.
Arterial System
The aorta is the body's largest artery.
Principal Branches of the Aorta
The branches of the ascending aorta are the
right and left coronary arteries that lead to
heart muscle.
Principal branches of the aortic arch include
the brachiocephalic, left common carotid, and
left subclavian arteries.
The descending aorta (thoracic aorta) gives
rise to many small arteries to the thoracic wall
and thoracic viscera.
The abdominal aorta gives off the following
branches: celiac, superior mesenteric,
suprarenal, renal, gonadal, inferior mesenteric,
and common iliac arteries.
Figure
Figure
Figure
Figure
Venous System
Veins return blood to the heart after the
exchange of substances has occurred in
the tissues.
Characteristics of Venous Pathways
Larger veins parallel the courses of
arteries and are named accordingly;
smaller veins take irregular pathways
and are unnamed
Characteristics of Venous Pathways
Veins from the head and upper torso
drain into the superior vena cava.
Veins from the lower body drain into
the inferior vena cava.
The vena cavae merge to join the right
atrium.
Figure
Figure
Figure
Respiratory System
Introduction
A. The respiratory system consists of tubes that
filter incoming air and transport it into the
microscopic alveoli where gases are
exchanged.
B. The entire process of exchanging gases
between the atmosphere and body cells is
called respiration and consists of the
following: ventilation, gas exchange between
blood and lungs, gas transport in the
bloodstream, gas exchange between the
blood and body cells, and cellular respiration.
I. Organs of the Respiratory System
A. The organs of the respiratory tract can
be divided into two groups: the upper
respiratory tract (nose, nasal cavity,
sinuses, and pharynx), and the lower
respiratory tract (larynx, trachea,
bronchial tree, and lungs).
B. The nose is supported by bone and
cartilage, provides an entrance for air
in which air is filtered by coarse hairs
inside the nostrils.
Figure
Nasal Cavity
C. Nasal Cavity
1. The nasal cavity is a space posterior to the
nose that is divided medially by the nasal
septum.
2. Nasal conchae divide the cavity into
passageways that are lined with mucous
membrane, and help increase the surface
area available to warm and filter incoming
air.
3. Particles trapped in the mucus are carried to
the pharynx by ciliary action, swallowed, and
carried to the stomach where gastric juice
destroys any microorganisms in the mucus.
Paranasal Sinuses
D. Paranasal
1. Sinuses are air-filled spaces within the
maxillary, frontal, ethmoid, and
sphenoid bones of the skull.
2. These spaces open to the nasal cavity
and are lined with mucus membrane
that is continuous with that lining the
nasal cavity.
3. The sinuses reduce the weight of the
skull and serve as a resonant chamber
to affect the quality of the voice.
Pharynx
E. Pharynx
1. The pharynx is a common
passageway for air and food.
2. The pharynx aids in producing
sounds for speech.
Figure
Larynx
F. Larynx
1. The larynx is an enlargement in the
airway superior to the trachea and
inferior to the pharynx.
2. It helps keep particles from entering
the trachea and also houses the vocal
cords.
3. The larynx is composed of a
framework of muscles and cartilage
bound by elastic tissue.
Larynx Cont.
4. Inside the larynx, two pairs of folds of
muscle and connective tissue covered
with mucous membrane make up the
vocal cords.
a. The upper pair- false vocal cords
b. The lower pair- true vocal cords
c. Changing tension on the vocal cords
controls pitch, while increasing the
loudness depends upon increasing the
force of air vibrating the vocal cords.
Larynx Cont.
5. During normal breathing, the vocal
cords are relaxed and the glottis is a
triangular slit.
6. During swallowing, the false vocal
cords and epiglottis close off the
glottis.
Figure
Trachea
G. Trachea
1. The trachea extends downward
anterior to the esophagus and into the
thoracic cavity, where it splits into
right and left bronchi.
2. The inner wall of the trachea is lined
with ciliated mucous membrane with
many goblet cells that serve to trap
incoming particles.
3. The tracheal wall is supported by 20
incomplete cartilaginous rings.
Bronchial Tree
H. Bronchial Tree
1. The bronchial tree consists of branched tubes
leading from the trachea to the alveoli.
2. The bronchial tree begins with the two primary
bronchi, each leading to a lung.
3. The branches of the bronchial tree from the
trachea are right and left primary bronchi; these
further subdivide until bronchioles give rise to
alveolar ducts which terminate in alveoli.
4. It is through the thin epithelial cells of the
alveoli that gas exchange between the blood
and air occurs.
Figure
Figure
Lungs
I. Lungs
1. The right and left soft, spongy, cone-
shaped lungs are separated medially
by the mediastinum and are enclosed
by the diaphragm and thoracic cage.
2. The bronchus and large blood vessels
enter each lung.
3. A layer of serous membrane, the
visceral pleura, folds back to form the
parietal pleura.
Lungs cont.
4. The visceral pleura is attached to the
lung, and the parietal pleura lines the
thoracic cavity; serous fluid lubricates
the “pleura cavity” between these two
membranes.
5. The right lung has three lobes, the left
has two.
6. Each lobe is composed of lobules that
contain air passages, alveoli, nerves,
blood vessels, lymphatic vessels, and
connective tissues.
II. Breathing Mechanism
A. Ventilation (breathing), the movement
of air in and out of the lungs, is
composed of inspiration and expiration.
Figure
III. Control of Breathing
A. Normal breathing is a rhythmic, involuntary
act even though the muscles are under
voluntary control.
B. Respiratory Center
1. Groups of neurons in the brain stem
comprise the respiratory center, which
controls breathing by causing inspiration
and expiration and by adjusting the rate
and depth of breathing.
2. The components of the respiratory center
include the rhythmicity center of the
medulla and the pneumotaxic area of the
pons.
Respiratory Center Cont.
3. The medullary rhythmicity center includes
two groups of neurons: the dorsal
respiratory group and the ventral respiratory
group.
a. The dorsal respiratory group is
responsible for the basic rhythm of
breathing.
b. The ventral respiratory group is active
when more forceful breathing is required.
4. Neurons in the pneumotaxic area control the
rate of breathing.
Factors Affecting Breathing
C. Factors Affecting Breathing
1. Chemicals, lung tissue stretching, and
emotional state affect breathing.
2. Chemosensitive areas (central
chemoreceptors) are associated with the
respiratory center and are sensitive to
changes in the blood concentration of carbon
dioxide and hydrogen ions.
a. If either carbon dioxide or hydrogen ion
concentrations rise, the central
chemoreceptors signal the respiratory
center, and breathing rate increases.
Factors Affecting Breathing Cont.
3. Peripheral chemoreceptors in the carotid
sinuses and aortic arch sense changes in
blood oxygen concentration, transmit
impulses to the respiratory center, and
breathing rate and tidal volume increase.
4. An inflation reflex, triggered by stretch
receptors in the visceral pleura, bronchioles,
and alveoli, helps to prevent overinflation of
the lungs during forceful breathing.
5. Hyperventilation lowers the amount of
carbon dioxide in the blood.
IV. Alveolar Gas Exchanges
A. The alveoli are the only sites of gas
exchange between the atmosphere
and the blood.
B. Alveoli
1. The alveoli are tiny sacs clustered at
the distal ends of the alveolar ducts.
Respiratory Membrane
C. Respiratory Membrane
1. The respiratory membrane consists
of the epithelial cells of the alveolus,
the endothelial cells of the capillary,
and the two fused basement
membranes of these layers.
2. Gas exchange occurs across this
respiratory membrane.
Figure
Diffusion across the Respiratory
Membrane
D. Diffusion across the Respiratory
Membrane
1. Gases diffuse from areas of higher
pressure to areas of lower pressure.
2. In a mixture of gases, each gas
accounts for a portion of the total
pressure; the amount of pressure each
gas exerts is equal to its partial
pressure.
Diffusion across the Respiratory
Membrane Cont.
3. When the partial pressure of oxygen is
higher in the alveolar air than it is in the
capillary blood, oxygen will diffuse into the
blood.
4. When the partial pressure of carbon
dioxide is greater in the blood than in the
alveolar air, carbon dioxide will diffuse out
of the blood and into the alveolus.
5. A number of factors favor increased
diffusion; more surface area, shorter
distance, greater solubility of gases, and a
steeper partial pressure gradient.
V. Gas Transport
A. Gases are transported in association
with molecules in the blood or
dissolved in the plasma.
Oxygen Transport
B. Oxygen Transport
1. Over 98% of oxygen is carried in the
blood bound to hemoglobin of red
blood cells, producing
oxyhemoglobin.
2. Oxyhemoglobin is unstable in areas
where the concentration of oxygen is
low, and gives up its oxygen
molecules in those areas.
Oxygen Transport cont.
3. More oxygen is released as the blood
concentration of carbon dioxide
increases, as the blood becomes
more acidic, and as blood
temperature increases.
4. A deficiency of oxygen reaching the
tissues is called hypoxia and has a
variety of causes.
Figure