Topic 2: Genes and Health

Topics covered 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.

CF is a recessive genetic condition affecting most critically the lungs, but also the pancreas, liver, and intestine. What causes CF? genetic mutation, DNA replication, protein synthesis. Symptoms: lungs and surface area, cell membranes, enzymes, digestive system. Ethical issues What is Cystic Fibrosis

Tissues and Epithelial cells What is meant by the term tissue?- – cells with similar structure – Working together for one function – E.g. Muscle, epithelial tissue 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

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.

Activity 2.3cTissues and epithelial cells Tissues are groups of cells with a common _____________ and ______________. 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. 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 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 the epithelium is exposed to ___________ or ______________. Structure Function muscle epithelial tissue airliquid

Cystic Fibrosis and the Respiratory system

Annotate the two diagrams below-naming the structures and describing their functions

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

FEATURES OF GAS EXCHANGE SURFACES How do these organisms ensure the most efficient gas exchange in each of these areas? Pages 58-59, answer Q 2.3- Q 2.13 AmeobaHuman Gas exchange surface Steepness of the ____________ Moist exchange surface ___________ of exchange surface* Oxygen is constantly used by aerobic respiration and CO2 is constantly being produced Ventilation brings in fresh air with a higher O2 concentration and removes the air which has a higher CO2 concentration The transport system (blood capillaries) transport 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. outer cell membrane Alveoli Lives in an aquatic environment Lungs are deep within the body- reducing water loss- maintaining a humid environment in the lungs Cell surface membrane is permeable to gases Alveoli walls are permeable to gases

___________ area across which it occurs Diffusion distance- thickness of the surface i 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 Q Lung surfactant prevents the alveoli from collapsing and sticky to each other(it reduces the surface tension) 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

6. Name and identify where the following epithelial tissues can be found- a.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 thick and sticky

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? 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 pre- prepared slides of lung tissue.