6.2 and 6.4 transport and respiration

6.2 The Blood System
Essential idea: The blood system continuously transports
substances to cells and simultaneously collects waste products.

Understandings
Statement Guidance
6.2 U.1 Arteries convey blood at high pressure from the ventricles to the tissues of the body
6.2 U.2 Arteries have muscle cells and elastic fibers in their walls
6.2 U.3 The muscle and elastic fibers assist in maintaining blood pressure between pump
cycles
6.2 U.4 Blood flows through tissues in capillaries. Capillaries have permeable walls that allow
exchange of materials between cells in the tissue and the blood in the capillary
6.2 U.5 Veins collect blood at low pressure from the tissues of the body and return it to the
atria of the heart.
6.2 U.6 Valves in veins and the heart ensure circulation of blood by preventing backflow.
6.2 U.7 There is a separate circulation for the lungs.
6.2 U.8 The heart beat is initiated by a group of specialized muscle cells in the right atrium
called the sinoatrial node
6.2 U.9 The sinoatrial node acts as a pacemaker.
6.2 U.10 The sinoatrial node sends out an electrical signal that stimulates contraction as it is
propagated through the walls of the atria and then the walls of the ventricles
6.2 U.11 The heart rate can be increased or decreased by impulses brought to the heart
through two nerves from the medulla of the brain.
6.2 U.12 Epinephrine increases the heart rate to prepare for vigorous physical activity

Applications and Skills
Statement Guidance
6.2 A.1 William Harvey’s discovery of the circulation of the blood with the
heart acting as the pump.
6.2 A.2 Pressure changes in the left atrium, left ventricle and aorta during
the cardiac cycle.
6.2 A.3 Causes and consequences of occlusion of the coronary arteries.
6.2 S.1 Identification of blood vessels as arteries, capillaries or veins from
the structure of their walls.
6.2 S.2 Recognition of the chambers and valves of the heart and the blood
vessels connected to it in dissected hearts or in diagrams of heart
structure.

What are the issues when
organizes become multicellular?
• Diffusion is not adequate for moving material
across more than 1 cell barrier

• Circulatory system solves this problem
– carries fluids & dissolved material throughout
body
– cells are never far from body fluid
– only a few cells away from blood
overcoming the limitations of diffusion

There are three main types of blood vessel:
Arteries carry high pressure blood away from the heart to tissues that need it
Capillaries are very small (< 10 μm diameter) and therefore can penetrate virtually every
tissue in the body. Blood moves slowly through them under low pressure providing
opportunities for the exchange of substances.
Veins carry the low pressure blood back to the heart using valves to ensure blood flows
in the correct direction.

6.2 U.1 Arteries convey blood at high pressure from the ventricles to the tissues of the body. AND
6.2 U.2 Arteries have muscle cells and elastic fibers in their walls. AND 6.2 U.3 The muscle and
elastic fibers assist in maintaining blood pressure between pump cycles
.
The structure of arteries• Thick muscular wall and fibrous
outer layer help the artery to
withstand high pressure
• Relatively (to the wall) small
lumen maintains high blood
pressure.
• Muscle contracts to decrease the
size of the lumen. This causes an
increase blood pressure and
therefore maintains high blood
pressure between the pulses of
high pressure blood travelling from
the heart
• Elastic fibers stretch to increase
the lumen with each pulse of
blood. After the pulse of blood
passes the fibers recoil decreasing
the lumen size and therefore
helping to maintain a high blood
pressure.

6.2 U.5 Veins collect blood at low pressure from the tissues of the body and return it to the atria of
the heart. AND 6.2 U.6 Valves in veins and the heart ensure circulation of blood by preventing
backflow.
https://commons.wikimedia.org/wiki/File:Venous_valve.svg
http://40.media.tumblr.com/tumblr_m0dwjt3WKQ1qzcf71o1_500.jpg
Because of the low pressure valves are
required to prevent back-flow of the blood
and therefore ensure that the blood moves
towards to heart.
The structure of veins
• Veins return blood to the heart for
re-circulation.
• The large lumen (compared to
arteries and the thickness of the
wall) means that the blood is under
low pressure.
• Because there is less pressure to
resist the walls of the veins are
thinner and less elastic than
arteries. They also contain less
muscle than the arteries.

• Veins carry blood back to the heart. Have thin walls containing valves to prevent
the back flow of blood, due to the lower pressure of blood in the veins.
• Pressure in veins is low, so veins depend on nearby muscular contractions to move
blood along.
6.2.U5 Veins collect blood at low pressure from the tissues of the body and return it to the atria of
the heart. AND 6.2.U6 Valves in veins and the heart ensure circulation of blood by preventing
backflow.

6.2 U.4 Blood flows through tissues in capillaries. Capillaries have permeable walls that
allow exchange of materials between cells in the tissue and the blood in the capillary.
The structure of capillaries
• Capillaries are the smallest blood vessels and are adapted
for the exchange of substances to and from the blood.
• This enables tissues to gain nutrients and molecules such as
oxygen and to rid themselves of waste material.
• Capillaries also allow substances to enter and leave the
organism, e.g. gas exchange of oxygen and carbon dioxide in
the lungs.
Due the the massive number of
capillaries present and the small
lumen the surface area available for
the exchange of substances is very
large.

6.2 S.1 Identification of blood vessels as arteries, capillaries or veins from the structure
of their walls.
a
b
c
d
https://www.ouhsc.edu/histology/Text%20Sections/Cardiovascular.html
Identify the labelled structures using your understanding of blood vessels.

https://www.ouhsc.edu/histology/Text%20Sections/Cardiovascular.html
Identify the labelled structures using your understanding of blood vessels.
6.2 S.1 Identification of blood vessels as arteries, capillaries or veins from the structure
of their walls.

Nature of Science: Theories are regarded as uncertain - William Harvey overturned
theories developed by the ancient Greek philosopher Galen on movement of blood in the
body. (1.9)
Remember a theories are by definition the best accepted explanations and predictions of natural
phenomena. Although they are usually thoroughly tested based on evidence and reason theories
theories are the only the current best accepted explanation. Theories if successfully questioned can be
modified or even rejected/falsified if a better explanation arises.
Theories of blood movement around the body
• Galen (129 - c216) Blood was not seen to
circulate but rather to slowly ebb and
flow. Using elusive attractive powers.
• Ibn-al-Nafiz (1300) first challenger to Galen
idea of blood movement
• William Harvey (1578 - 1657) published “De
Motu Cordis” in 1628. Even then it took
many years for his theory of systemic
circulation (similar to modern accepted
theory) to succeed Galen’s.

Path of blood through the heart
• Deoxygenated blood return to the
heart to right atrium from the body
• The Right Atrium, receives "used
blood" from the body. Blood will be
pushed through the tricuspid valve to
the
• Right Ventricle, the chamber which
will pump to the lungs through the
pulmonic valve to the
• Pulmonary Arteries, providing
blood to both lungs. Blood is
circulated through the lungs where
carbon dioxide is removed and
oxygen added. It returns through the
Systemic Circuit.

Path of blood through the heart
• Oxygenated blood enters the Left
Atrium from the lungs
• Pulmonary Veins, empty into the
Left Atrium.
• From the Left Atrium, a chamber
which will push the Mitral Valve
open. Blood then passes into the
• Left Ventricle. Although it doesn't
always look like it in drawings done
from this angle, this is the largest
and most important chamber in the
heart. It pumps to the rest of the
body. As it pumps, the pressure will
close the mitral valve and open the
aortic valve, with blood passing
through to the Pulmonary Circuit

6.2.S.2 Recognition of the chambers and valves of the heart and the blood vessels connected to it
in dissected hearts or in diagrams of heart structure
a. Atria: thin-walled
upper chambers which
collect blood returning
to the heart
Part of the Heart
b. Ventricles: thick,
muscular lower
chambers which pump
blood to the lungs and
other body tissue.
c. Septum (wall): separate the
right and left sides of heart to
prevent mixing of oxygenated
and deoxygenated blood.

6.2.S2 Recognition of the chambers and valves of the heart and the blood vessels connected to it in
dissected hearts or in diagrams of heart structure
1. Tricuspid valve /AV valve
Valves of the Heart
2. Pulmonary valve
4. Bicuspid
valve / AV
valve
3. Aortic valve

6.2 S2 Recognition of the chambers and valves of the heart and the blood vessels connected to it in
dissected hearts or in diagrams of heart structure.
Label the heart diagram

6.2.S2 Recognition of the chambers and valves of the heart and the blood vessels connected to it in
dissected hearts or in diagrams of heart structure.
Label the heart diagram
Now try to label this heart: http://sciencelearn.org.nz/Contexts/See-through-Body/Sci-Media/Animation/Label-
the-heart
bicuspid valve

Pulse
• When you take your pulse, you feel (or hear) two changes in pressure.
• The first sound is the closing of the AV’s (systolic pressure), the “lub”
sound the heart makes. The 2nd sound is the closing of the SV’s
(diastolic pressure), the “dub” sound.
6.2 U.8 The heart beat is initiated by a group of specialized muscle cells in the right atrium called the sinoatrial node.
6.2 U.10 The sinoatrial node sends out an electrical signal that stimulates contraction as it is propagated through the walls
of the atria and then the walls of the ventricles.

Control of the Heart Beat
• Beating is due to myogenic muscle.
Meaning it is the origin of contraction
in the heart and is not controlled
externally
• The hearts pacemaker (Sinoatrial
Node/SA node) which controls the
rate of heartbeats is made up of this
muscle.
• Large groups of these cell cause the
atria to contract.
• The contraction cause a signal to a
group of nerve cells causing the
ventricles to contract at the
atrioventricular node/AV node.

The control of heart rhythm

The interrelationship of blood flow
velocity, cross-sectional area of
blood vessels, and blood pressure

6.2 U.11 The heart rate can be increased or decreased by impulses brought to the heart through
two nerves from the medulla of the brain.
6.2 U.12 Epinephrine increases the heart rate to prepare for vigorous physical activity.
• Controlled by the autonomic
nervous system response to
changing body conditions by
speeding up or lowing down
breathing
• When the level of CO2 are low
chemical receptors in the
Medulla sends a signal to the
Vagus nerve which decreases
heart rate.
• When the level of CO2 high
Accelerator nerve which
increase heart rate.
Medulla
Vagus Nerve
Accelerator Nerve
SA Node

6.2 U.11 The heart rate can be increased or decreased by impulses brought to the heart
6.2 U.12 Epinephrine increases the heart rate to prepare for vigorous physical activity.
Hormonal Control of Heart Rate
• Epinephrine, more commonly known
as adrenaline, is a hormone secreted by
the medulla of the adrenal glands
• Released into the bloodstream,
epinephrine causes an increase in heart
rate, muscle strength, blood pressure, and
sugar metabolism.

How does the Heart work?
blood from the
body
blood from
the lungs
The heart beat begins when the
heart muscles relax and blood
flows into the atria.
STEP ONE

The atria then contract and
the valves open to allow blood
into the ventricles.
STEP TWO

The valves close to stop blood
flowing backwards.
The ventricles contract forcing
the blood to the aorta and out of the
heart.
At the same time, the atria are
relaxing and once again filling with
blood.
The cycle then repeats itself.
STEP THREE

6.2 A.2 Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle.
The Cardiac Cycle
1. Right Atria & Ventricles relax and
blood flows into the heart from
the veins.
2. AV valve open, Right Atria
contacts and Ventricle relaxes,
blood moves into the ventricle.
3. Pulmonary valve opens, Right
Ventricle contracts, blood flows to
the lungs.
4. Blood flows from the lung into
the left Atria AV valve opens,
blood flows into the Left
Ventricle.
5. Left Atria contracts blood flows
into Left Ventricle.
6. Aortic valve opens, Left Ventricle
contracts blood flows into the
arteries.

6.2 A.2 Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle.
The Cardiac Cycle
Ventricular Pressure
1. Ventricular pressure increases
as ventricle contracts. This
forces blood into the aorta,
increasing aortic pressure.
2. (a) Shows the increase in atrial
pressure due to atrial
contraction.
3. Shows increase in atrial
pressure due to the inflow of
blood from the veins (following
systole).
Ventricular Volume
4. Increase as atrial contraction
forces blood into the ventricle
5. Decrease as ventricular
contraction forces blood into
the aorta
6. Increases as blood returns to
the heart following systole.
Click on the
hyperlink

6.2 A3 Causes and consequences of occlusion of the coronary arteries.
6.3 A1 Causes and consequences of blood clot formation in coronary
Arteriosclerosis
• Hardening and thickening of the walls of
the arteries.
• The condition can occur because of fatty
deposits on the inner lining of arteries
(atherosclerosis).
• Calcification of the wall of the arteries, or
thickening of the muscular wall of the
arteries from chronically elevated blood
pressure occurs.
• As the deposits of fat and plaque begin to
build the lumen of the arteries become
reduced. If the plaque frees itself from the
wall a blood clot may form. This may lead
to coronary thrombosis (reduced blood
flow to the heart).
• When coronary arteries that supply blood
to the heart muscle are effected a shortage
of oxygen delivered to the heart itself may
lead to a heart attack.
Coronary arteries supply heart
muscles with oxygen and nutrients

6.2 A3 Causes and consequences of occlusion of the coronary arteries.
6.3 A1 Causes and consequences of blood clot formation in coronary
Risk Factors in Coronary Heart Disease
Factor Causes
Genetics Family history of high cholesterol/blood
pressure
Age Older people have a greater risk due to
a loss in elasticity in arteries
Sex Males have a greater risk then females
Diet Increases in fat intake lead to higher
levels of cholesterol and increase
formation of plaque
Exercise A lack of exercise increase risk. This is
due to a weakening of circulation
Obesity Increase in blood pressure which leads
to increase plaque formation in the
arteries
Stress Stress has been linked to increased
levels of the hormone Cortisol. Which
has been show leads to a increase
likelihood of atherosclerosis

Essential idea: The lungs are actively ventilated to ensure that gas exchange can occur
passively.
6.4 Gas exchange

Understandings
Statement Guidance
6.4 U.1
Ventilation maintains concentration gradients of
oxygen and carbon dioxide between air in alveoli
and blood flowing in adjacent capillaries.
6.4 U.2
Type I pneumocytes are extremely thin alveolar
cells that are adapted to carry out gas
exchange.
6.4 U.3
Type II pneumocytes secrete a solution
containing surfactant that creates a moist
surface inside the alveoli to prevent the sides of
the alveolus adhering to each other by reducing
surface tension.
6.4 U.4
Air is carried to the lungs in the trachea and
bronchi and then to the alveoli in bronchioles.
Students should be able to draw a diagram to
show the structure of an alveolus and an
adjacent capillary.
6.4 U.5
Muscle contractions cause the pressure changes
inside the thorax that force air in and out of the
lungs to ventilate them.
6.4 U.6
Different muscles are required for inspiration
and expiration because muscles only do work
when they contract.

Applications and Skills
Statement Guidance
6.4 A.1 Causes and consequences of lung cancer.
6.4 A.2 Causes and consequences of emphysema.
6.4 A.3 External and internal intercostal muscles, and
diaphragm and abdominal muscles as examples
of antagonistic muscle action.
6.4 S.1 Monitoring of ventilation in humans at rest and
after mild and vigorous exercise. (Practical 6)
Ventilation can either be monitored by simple
observation and simple apparatus or by data
logging with a spirometer or chest belt and
pressure meter. Ventilation rate and tidal
volume should be measured, but the terms
vital capacity and residual volume are not
expected.

What is respiration?
• External respiration -
exchange of O2 & CO2
between respiratory surfaces
& the blood [breathing].
• Internal respiration -
exchange of O2 & CO2
between the blood & cells.
• Cellular respiration -
process by which cells use O2
to produce ATP.
Gas Exchange in Animals
Why do organisms need a respiratory system?

CO2
CO2
O2
O2Bloodstream
Muscle cells carrying out
Cellular Respiration
Breathing
Glucose + O2
CO2 + H2O + ATP
Lungs
What is the relationship between
respiration and cellular respiration?

Respiration
• (Breathing) provides for the exchange of
O2 and CO2 between an organism and its
environment

All respiratory surfaces MUST
be:
• moist
• thin
• large enough to meet
metabolic needs of
organism
Challenges:
Aquatic organisms -
H2O contains only 1/30
of the O2 present in air.
Terrestrial organisms -
must prevent
desiccation of
respiratory surface.
Types of Respiratory Surfaces

Structure of the ventilation system
a) Trachea
b) Cartilage ring support
c) Bronchi (plural) Bronchus
(single)
d) Lung
e) Heart
f) Sternum
g) Rib cage
h) Bronchioles
j) Alveoli
k) Diaphragm
6.4 U.4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in
bronchioles. (Page 78)

Can you use the diagram to produce a flow chart to show the passage of air into the lungs?

Review: 6.2 U.11 The heart rate can be increased or decreased by impulses brought to the heart
• Controlled by the autonomic
nervous system response to
changing body conditions by
speeding up or lowing down
breathing
• When the level of CO2 are low
Vagus nerve which decreases
heart rate.
• When the level of CO2 high
Accelerator nerve which
increase heart rate.
Medulla
Vagus Nerve
Accelerator Nerve
SA Node

6.4 A.3 External and internal intercostal muscles, and diaphragm and abdominal
muscles as examples of antagonistic muscle action. (Page 78)
• The medulla oblongata is
involved in regulating many of the
bodily processes that are
controlled automatically like blood
pressure, heart rate and
RESPIRATION.
• The medulla oblongata detects
carbon dioxide (CO2) and Oxygen
(O2) levels in the bloodstream and
determines what changes need to
happen in the body.
• It can then
send nerve impulses muscles in
the ribs and diaphragm, letting
them know that they need to
either step up their game, or slow
down a bit.

Ventilation: for gas
exchange
• The flow of air in and out of the
alveoli is called ventilation and has
two stages: inspiration (or
inhalation) which increases the
concentration and expiration (or
exhalation) which removes CO2.
• For gas exchange to be efficient,
high concentration gradients must
be maintained in the alveoli.
• Lungs are not muscular and cannot
ventilate themselves, but instead
the whole thorax moves and
changes size, due to the action of
two sets of muscles: the intercostal
muscles and the diaphragm
6.4 U.1 Ventilation maintains concentration gradients of oxygen and carbon dioxide
between air in alveoli and blood flowing in adjacent capillaries. (Page 78)
Alveoli (air sac)

Ventilation of the lungs:
Inhale
• External intercostal muscles
contract, moving ribs up and
out
• Diaphragm contracts,
fattening and moving down
• Increased volume in thorax
lowering pressure
• Air flows into the lungs to
balance the pressure change
decrease in pressure
(draws air inwards)
6.4 A.3 External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic
muscle action. AND 6.4 U.5 Muscle contractions cause the pressure changes inside the thorax that force air in and out of
the lungs to ventilate them.
(Page 78)

Ventilation of the lungs:
Exhale:
• Internal intercostal muscles
contract, moving ribcage down
and in
• Abdominal muscles contract
pushing the diaphragm up into
a dome shape
• Decrease in volume of thorax
increasing air pressure
• Air flows out from the lungs
increase in pressure
(pushes air outwards)
(Page 78)

Negative pressure breathing
(Page 78)

Gas Exchange
This is the diffusion of gases (oxygen
and carbon dioxide) There are two
sites for gas exchange
A. Alveoli: Oxygen diffuses
into the blood from the alveoli
and carbon dioxide diffuses
from the blood into the alveoli
B. Tissues: Oxygen diffuses
from blood into the cells and
carbon dioxide diffuses from
cells to the blood
6.4 U.1 Ventilation maintains concentration gradients of oxygen and carbon dioxide
between air in alveoli and blood flowing in adjacent capillaries. (Page 78)

6.4 U.2 Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange. AND
(Page 79)

6.4 U.3 Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the
alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension. (Page 79)

6.4 U.2 Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange. AND
6.4 U.3 Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the
alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension. (Page 79)
Edited from: https://beyondthedish.files.wordpress.com/2011/11/gas-barrier-small.jpg
http://neurobio.drexelmed.edu/education/pil/microanatomy/Cases/01_Quintana/4_Epithelium/Images/alveolarepithelium.jpg
Connective
tissue
Type II pneumocytes
• Secrete fluid to moisten the inner
surface of the alveolus
• Fluid aids diffusion of gases
• Fluid contains surfactant to prevent the
walls sticking together – maintains the
lumen
Alveoli walls and gas exchange
Type I pneumocytes
• A single layer of cells form the
walls of an alveolus
• Extremely thin – short
diffusion distance
• Permeable – aids diffusion

Emphysema
• Disease caused by smoking,
lung infections or air pollution.
All of which cause an
inflammatory response in the
lungs.
• Protease is released by
leukocytes (white blood cells)
and inflamed lung tissue. The
protease breaks down the
connective tissue such as
elastin, of the lungs. This
results in the destruction of
small airways and alveoli. This
results in the formation of large
air pockets and the breakdown
of capillaries
• The disease creates a reduction
in surface area gas exchange
which results shortness of
breath, difficulty in breathing,
and decreased lung capacity.
• Emphysema is a progressive
disease with no known cures.
There are treatments that can
help you manage the disease
6.4 A.2 Causes and consequences of emphysema. (page 79)
Symptoms include:
• Difficulty breathing
• Cough
• Loss of appetite
• Weight loss

Review: 1.6 and U.6 Mutagens, oncogenes and metastasis are involved in the development of
primary and secondary tumors.
Tumors are abnormal growth of tissue that develop at any stage of life in any part
of the body. A cancer is a malignant tumour and is named after the part of the
body where the cancer (primary tumour) first develops. Use the links to find out:
• most common types of cancer
• what causes cancer and associated risk factors
• how cancer can be treated
http://youtu.be/8BJ8_5Gyhg8
http://www.cancerresearchuk.org/cancer-
info/cancerandresearch/all-about-cancer/what-is-cancer/
What causes
cancer?

6.4 A.1 Causes and consequences of lung cancer. (Page 78)
“Lung cancer is the leading cause of death from cancer in the U.S.”
http://www.cancer.gov/types/lung
Lung cancer is cancer that starts in the windpipe (trachea),
the main airway (bronchus) or the lung tissue.
By far the biggest cause of lung cancer is smoking. It causes more
than 8 out of 10 cases (86%) including a small proportion caused by
exposure to second hand smoke in non smokers (passive smoking).
Some other things increase lung cancer
risk by a small amount:
• Exposure to radon (a radioactive) gas
• Air pollution
• Previous lung disease
• A family history of lung cancer
• Past cancer treatment
• Previous smoking related cancers
• Lowered immunity
The symptoms of lung cancer may include:
• Being short of breath
• Having a cough most of the time
• Coughing up phlegm with blood
• An ache or pain in the chest or shoulder
• Loss of appetite
• Tiredness/fatigue
• Losing weight
Like most cancers lung cancer, if untreated, will end with
death. Because detection of lung cancer is difficult it is often
only diagnosed in the later stages. As a consequence only
10% of those diagnosed will survive for 5 years.
Source: http://www.cancerresearchuk.org/about-cancer/type/lung-cancer/
http://spacecoastdaily.com/wp-content/uploads/2014/01/Cigarette-Smoking-is-Mainly-Causes-of-Lung-Cancer.jpg

6.4 S.1 Monitoring of ventilation in humans at rest and after mild and vigorous exercise. (Practical 6)
Monitoring ventilation
https://commons.wikimedia.org/wiki/File:DoingSpirometry.JPG
https://en.wikipedia.org/wiki/File:Lungvolumes_Updated.png
Independent variable: the intensity of
exercise
Dependent variable: What measure(s) are
you using for ventilation?
What type of exercise? For how long?
How will you make sure that individuals
exercise similarly?
Frequency of breaths? Spirometer data
showing tidal volumes?
Ethical and safety concerns: how are you making sure
that the experiment is safe? Are participants aware of
the risks? Are you seeking written permission from
participants?
: design an investigation, collect and analyze the data
Controlled variables: what are the key factors
that need to be measured and kept constant
to ensure a fair test?
Data analysis: you should be calculating a rate.
For example the count of breaths or tidal
volume per unit time (s or min)

Bibliography / Acknowledgments

6.2 and 6.4 transport and respiration

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