Download CF and Respiratory System File

Topic 2: Genes and
Health
Introduction
• Read pages 54 and 55 in your textbook.
• Changes in DNA can result in genetic disease.
• Symptoms of cystic fibrosis.
• Extending on knowledge of structure of lungs and gas
exchange, surface area to volume ratios.
• Cell membrane structure
• Movement of substances across a membrane.
• Genes coding for proteins.
• How faults arise in the cell surface membranes of a person
with cystic fibrosis (CF).
• Genetic screening and gene therapy.
• Ethical issues raised by new technologies.
Activity 2.1 After the Funeral
• Symptoms
• Treatments
• Causes
• Issues raised
Cystic Fibrosis and the
Respiratory system
Specification- topic 2
• 6 Describe the properties of gas exchange surfaces in living
organisms (large surface area to volume ratio, thickness of
surface, difference in concentration) and explain how the
structure of the mammalian lung is adapted for rapid gaseous
exchange.
• 17 Explain how the expression of a gene mutation in people
with cystic fibrosis impairs the functioning of the gaseous
exchange,
Read page 56 and then (without
your book) try to annotate the
two diagrams below-naming
the structures and describing
their functions
Turn to the activity
Respiratory System
and label the diagramdo as homework if
there is less time.
Respiratory System
1. Describe the pressure changes in the lungs during inhalation.
decrease and then increase
2. Explain how these pressure changes are brought about.
•
•
•
•
•
•
• Diana
• Invites
• Richard
• Very
• Politely
• Accepts
Diaphragm contracts and goes down,
(external) intercostals contract pulling
rib cage upwards and outwards,
volume in thorax increases,
pressure in thorax decreases,
air flows in from high to low pressure, so pressure in lungs increases
3. Describe the pressure changes in the lungs during exhalation.
•
increases and then decreases
4. Explain how these pressure changes are brought about.
• Diana
• Invites
• Richard
• Very
• Politely
• Accepts
• diaphragm relaxes and goes up,
• (external )intercostals relax pulling
• rib cage downwards and inwards,
• volume in thorax decreases,
• pressure in thorax increases,
• air flows out from high to low pressure so pressure in lungs
decreases
5. Explain the advantage to the body of elastic walls of the alveoli.
•
Recoil can help to push air out during exhalation
Tissues and Epithelial cells
• Read page 57- «Did you know?»
• What is meant by the term tissue? Give examples.
– cells with similar structure
–Working together for one function
–E.g. Muscle, epithelial tissue
• Describe function and structure of epithelial tissue–Function: Line cavities, outer surfaces, tubes and
organs
–Structure:
• Cells «sit» on a basement membrane
• free surface is exposed to air or a liquid
Activity Tissues and epithelial cells
Structure
• Tissues are groups of cells with a common _____________
and
Function
______________.
Different types of tissues have different
structures that are especially suited to their functions. The term
tissue is from a Latin word meaning "weave."
• Tissues are classified into four main categories: epithelial tissue,
connective tissue, nervous tissue, and ______________
tissue.
muscle
These are present to some extent in all but the simplest animals;
the following survey emphasizes the tissues of vertebrates.
Epithelial Tissue
• Occurring in sheets of tightly packed cells, epithelial tissue covers
Cavities
the outside of the body and lines organs and ______________
within the body. The cells of an epithelium are closely joined, with
little material between them. This tight packing enables the
epithelium to function as a barrier protecting against mechanical
injury, invasive microorganisms, and fluid loss. The free surface of
air
liquid
the epithelium is exposed to ___________
or ______________.
Epithelial Cells
Which description matches which picture?
• Simple squamous epithelia,
which are thin and leaky, function
in the exchange of material by
diffusion. These epithelia line
blood vessels and the air sacs of
the lungs.
• The intestines are lined with
simple columnar epithelia that
secrete digestive juices and
absorb nutrients
• Cuboidal cells specialized for
secretion make up the epithelia
of kidney tubules and many
glands including salivary glands.
Identify the epithelium found in the airways
of the lungs.
FEATURES OF GAS EXCHANGE SURFACES
Read pages 58-59 “Key Biological Principle”, answer Q 2.3- Q 2.13 and pages 60-61, and
complete the table below using in addition your knowledge from GCSE. Items in red are not
explicitly mentioned-they are necessary but do NOT affect the rate of gas exchange. Items in
black affect the rate of gas exchange.
Ameoba
Gas exchange
surface
Steepness of the
Concentration
gradient
____________
Moist exchange
surface
Permeability
___________ of
exchange
surface*
outer cell membrane
Oxygen is constantly
used by aerobic
respiration and CO2
is constantly being
produced
Lives in an aquatic
environment
Cell surface
membrane is
permeable to gases
Human
Alveoli
Ventilation brings in fresh air raising the
concentration of O2 in the alveoli and removes the
alveolar air thus reducing the concentration of CO2 in
the alveoli.
The transport system (blood capillaries) transports 02
away (reducing the concentration of 02 in blood) and
CO2 is brought to the lung capillaries from the
respiring cells maintaining a high concentration in the
blood there.
In which direction and how do the gases move?
Lungs are deep within the bodyreducing water loss- maintaining a
humid environment in the lungs
Alveoli walls are permeable to gases
Surface area
___________
area across
which it occurs
Small unicellular
organisms have a
large outer
surface area to
volume ratio
Multicellular organisms have a smaller
outer surface area to volume ratio- the
numerous alveoli in the lungs provides a
surface area which is about 100m2
Q2.3-2.13
Lung surfactant prevents the alveoli
from collapsing and sticking to each
other(it reduces the surface tension)
Diffusion
distancethickness of the
surface
Gas exchange
surface is simply the
cell membrane.
In unicellular
organisms the
distance to the
center of the cell is
very small
Alveolar wall is composed of squamus
epithelial cells sitting on a basement
membrane. This tissue is one cell thick
and the cells are very thin.
The blood capillaries lie very close to
the alveoli
The capillary wall is one cell thick and
composed of very thin endothelium
cells
Turn back to the activity Respiratory Systems and answer #
6-10 using pages 56-61
6.
Name and identify where the following epithelial
tissues can be founda. ciliated columnar epithelium
b. squamous epithelium
7. What is the role of mucus in the lungs of humans?
•
pathogens, dust, smoke particles stick to the mucus.
• Mucus is moved away to the back of your throat by beating of
cilia. This is swallowed.
• Acid in stomach kills most pathogens
8. Describe the mucus in a patient with CF
thicker and stickier than in anyone else
9. Describe the effects of this type of mucus?
a. Gas Exchange:
a. mucus is too sticky to be moved by the cilia so this blocks
smaller bronchioles completely, reducing the number of
alveoli and therefore the surface area available for gas
exchange,
b. air can’t be breathed out effectively so alveoli are
overinflated and can lose elasticity
b. Immune System-
a. mucus is too sticky to be moved by the cilia so there is a build up
of pathogens so greater chance of infection.
b. Anaerobic pathogens thrive due to lack of oxygen in the mucus
c. White blood cells in the mucus die and make the mucus even
stickier.
d. Eventually there can be damage to the structures in the gas
exchange system.
10. Why is CF mucus so sticky? (see page 62)
it contains less water than normal due to faulty transport protein in
the membrane.
Turn to Histology of the Lungs, following the directions to label the
parts of the lung as seen down a light microscope.
Activity 2.4 The Structure of
Alveoli
• Complete this activity looking down the microscope at preprepared slides of lung tissue.
Specification- topic 2
• 6 Describe the properties of gas exchange surfaces in living
organisms (large surface area to volume ratio, thickness of
surface, difference in concentration) and explain how the
structure of the mammalian lung is adapted for rapid gaseous
exchange.
• 17 Explain how the expression of a gene mutation in people
with cystic fibrosis impairs the functioning of the gaseous
exchange,