Reviewer in Science

1. RESPIRATORY SYSTEM
The respiratory system allows gas exchange. It brings
oxygen into the body and expels carbon dioxide.
Respiration is the overall exchange of gases among the
atmosphere, the blood, and the cells.
Four Phases in Respiration
• Breathing
• External respiration
• Internal respiration
• Cellular respiration
Why is oxygen essential to life?
Oxygen serves as an essential element supporting life
and as an integral part of the atmosphere. Oxygen plays
a vital role in carrying out metabolic functions of cells; and
because of this,
a) its presence enables us to live.
b) It facilitates the breakdown of nutrients essential
for supporting growth and development.
THE CIRCULATORY SYSTEM
As the respiratory system initiates gas exchange within
the body, the circulatory system supplies oxygen to our
cells.
The pumping action of the heart and the network of
channels are responsible for carrying and distributing
nutrients, gases, hormones, antibodies, and many other
important substances that the body needs to live.
The rhythmic contraction and relaxation of the heart are
what produce the sound we all know as a heartbeat.
• Humans have a closed circulatory system, typical
of all vertebrates, in which blood is confined to
vessels and is distinct from the interstitial fluid.
• Materials are exchanged by diffusion between the
blood and the interstitial fluid bathing the cells.
Man's circulatory system consists of the following:
a) Heart- a pumping organ
b) Blood- circulating fluids
c) Blood Vessel- a system of tubes, or vessels
1) The Heart
➢ Cardiac muscle cells
➢ highly interconnected cells
➢ enclosed by a thin but strong sac (pericardium)
➢ four chambers: Right atrium, Right ventricle, Left
atrium, Left ventricle
Pathway of the Blood
✓ Superior Vena Cava
✓ Right Atrium
✓ Tricuspid Valve
✓ Right Ventricle
✓ Pulmonary Semilunar Valve
✓ Lungs
✓ Pulmonary Vein

2. ✓ Bicuspid Valve
✓ Left Ventricle
✓ Aortic Semilunar Valve
✓ Aorta
✓ To the body organs and cells
2) Blood Vessels
➢ The blood in the human body travels or is
transported through a system of tubes called
blood vessels.
➢ Transport blood from the heart
➢ Three types of blood vessels - arteries, veins, and
capillaries.
a) Arteries
➢ carries blood away from the heart and
generally transports oxygen-rich
(oxygenated/carbon dioxide-poor) blood
➢ Arteries branch into smaller branches called
arterioles before further branching out to
the tiniest blood vessels called capillaries
b) Capillaries
➢ connect arteries and veins.
➢ This is where the gas exchange between the
blood and the tissues takes place.
➢ Capillaries then merge into venules and
then into larger channels called veins.
c) Veins
➢ carry blood to the heart and generally
transport oxygen-poor (deoxygenated),
carbon dioxide-rich blood
Structure of Blood Vessel
3) Blood
➢ The amount of blood in the human body is
generally equivalent to 7 percent of body weight.
➢ Blood carries out all the important functions, like
transporting oxygen and nutrients.
➢ The blood plays three important roles,
transportation, protection, and regulation.
Functions Of The Blood
1. Transport of dissolved gases, nutrients,
hormones, and metabolic wastes.
2. Protection against toxins, pathogens, and blood
loss injuries.
3. Stabilization of body temperature.
4. Regulation of the pH through the blood buffering
system and electrolyte composition of interstitial
fluids throughout the body.
The Blood and Its Composition
The liquid part is the plasma with 3 types of cells
suspended in it: red blood cells, white blood cells, and
platelets.
Blood is composed mainly of:
a) Plasma - the yellowish liquid that is composed of
90% water that carries nutrients, hormones, and
other important substances.
b) Different blood cells:
o red blood cells
o white blood cells
o platelets
1) The Red Blood Cells (RBC)
➢ The red blood cells, also known as erythrocytes,
carry oxygen to the cells.
➢ After transporting oxygen to the cells, red blood
cells collect the waste gas (carbon dioxide, the
by-product of cellular respiration) and transport it
back to the lungs, where carbon dioxide is
expelled from the body as we exhale.
➢ Red blood cells are the most abundant of the
blood cells (around 5,000,000 red blood cells in a
drop of blood) and their lifespan is 120 days.
➢ The red blood cells are red in color because they
contain hemoglobin.
➢ Hemoglobin contains iron (Fe) making it an
excellent transporter of oxygen and carbon
dioxide.
➢ The long bones of your body, the spleen, and the
liver continually produce new red blood cells to
replace old worn-out cells.
2) The White Blood Cells (WBC)
➢ The white blood cells, also known as leukocytes,
battle infection, and attack and destroy germs or
foreign proteins that enter the body.

3. ➢ There are about 7,000 WBCs per milliliter o and
this number can be used as an indicator of a
disease.
➢ During infection, the body produces more white
blood cells to help fight off the infection. Still, even
during an increased production of white blood
cells, it cannot outnumber the red blood cells.
3) Platelets
➢ also known as thrombocytes, help the blood clot,
thereby preventing bleeding when an artery or
vein is severed or broken
➢ The lifespan of a platelet is from five to nine days
only.
➢ A normal platelet count of a healthy individual is
from 150,000 to 450,000 per milliliter of blood.
Plasma
➢ Blood plasma is the pale, yellow fluid where the
blood cells are suspended.
➢ Plasma makes up more than half of the total
blood volume, roughly 55%.
➢ It consists mainly of water and also contains
dissolved constituents including proteins (such as
Albumin, Fibrinogen, and globulins) glucose,
clotting factors, electrolytes, and hormones.
➢ Plasma also contains carbon dioxide because it
is the main medium for the elimination of waste
products from our body cells. Plasma also plays
a very important role in osmosis, thereby
promoting the balance of electrolytes
➢ Blood serum is blood without the blood cells and
the factors.
The human blood groups include the ABO and Rh blood
groups (+ or -). The ABO blood groups are based on the
presence of antigen types A and B.
➢ When these antigens are absent in the blood, the
blood type is O.
➢ When both antigens are present the blood type
is AB.
Types of Body Circulation
1. Pulmonary circulation transports oxygen-
depleted blood from the heart to the lungs. Its
main function is to oxygenate the blood.
2. Systemic circulation carries oxygenated blood
from the heart to the organs and tissues. This
moves blood from the heart to all of the body
organs and tissues, except for the heart and
lungs, and back to the heart again.
QUESTION AND ANSWER
1) What is the function of the respiratory system?
GAS EXCHANGE
2) Where in the lungs does a gas exchange take
place? ALVEOLI
3) When the diaphragm contracts, ________
occurs. INHALATION
4) What are the two main branches from the
trachea? BRONCHI
5) What is the muscle below the lung that helps with
breathing? DIAPHRAGM
6) What is the small flap of tissue that covers the air-
only passage when we swallow? EPIGLOTTIS
7) What is the chamber behind the nose and mouth
that leads to the trachea? PHARYNX
8) What is the use of oxygen by the cells to release
energy from the food? CELLULAR
RESPIRATION
9) When you breathe in air, you bring oxygen into
your lungs and blow out what? CARBON
DIOXIDE
10) What happens when we exhale (breathe out)?
THE DIAPHRAGM RELAXES AND MOVES
UPWARDS
11) What type of blood vessel does the blood rich in
oxygen flow through? ARTERY

4. 12) What is the function of valves in the human
circulatory system? PREVENT THE
BACKWARD FLOW OF BLOOD
13) Jake cut his hand and was bleeding. Soon his
wound stopped bleeding, leaving a red lump on
the wound. What component of the blood helped
to stop the bleeding? PLATELETS
14) What is the TINY blood vessel that allows for
exchange between blood and cells in the tissue
in the body? CAPILLARY
15) How many chambers does the human heart
have? 4
16) The circulatory system is composed of what?
HEART, BLOOD, AND BLOOD VESSELS
17) Where does blood get oxygen from? LUNGS
18) Blood flows from the right atrium to the? RIGHT
VENTRICLE
19) What is the protein in red blood cell that carries
oxygen? HEMOGLOBIN
20) Through which path does blood typically flow
through the circulatory system? ARTERIES->
CAPILLARIES-> VEINS
Parts of the Circulatory System
Heart Blood Blood Vessels
pumping organ circulating fluids a system of
tubes, or
vessels