Applied Medical Science Exam 3 Flashcards
What does the transesophogeal ridge develop into?
The Tracheoesophageal Ridge Forms a Septum to
Separate the Trachea and Esophagus
What does the respiratory diverticulum develop into?
The respiratory diverticulum lengthens to form the trachea and
then divides to form two lung buds
What do the long buds develop into?
These buds divide into three branches on the right and two on the left, reflecting the number of lobes of the respective lungs on those sides
Types of alveolar cells
Type 1
Type 2
16% of alveolar cells are present at birth; remainder develop for
10 years
Type 1 Alveolar cells
Gas Exchange
Type 2 Alveolar cells
(6.5-7 months) = secrete surfactant =
reduces surface tension in the alveoli so they can remain open
during breathing. If not for surfactant, alveoli would collapse.
Pleura of lungs
Visceral pleura covers the lungs directly
Parietal pleura forms the lung cavity
Both are formed from the lateral plate of the mesoderm
3 domains of life
Bacteria
archaea
Eukarya
Domian bacteria
Usually single‐celled. Majority have cell wall with peptidoglycan. Most lack a membrane‐bound nucleus. Ubiquitous and some live in extreme environments. Cyanobacteria produce significant amounts of oxygen.
Domain Eukarya
Protists—generally larger than Bacteria and Archaea.
• Algae—photosynthetic.
• Protozoa—may be motile, “hunters, grazers”.
• Slime molds—two life cycle stages.
• Water molds—devastating disease in plants.
Fungi.
• Yeast—unicellular.
• Molds and mushrooms—multicellular.
Domain Archaea
Distinguished from Bacteria by unique rRNA gene sequences. Lack peptidoglycan in cell walls. Have unique membrane lipids. Some have unusual metabolic characteristics. Many live in extreme environments.
Spontaneous generation.
• Idea that living organisms can develop from nonliving or decomposing matter
Francesco Redi (1626 to 1697). • Discredited spontaneous generation.
Louis Pasteur - swan neck flasks
Gram negative
Gram negative ‐ peptidoglycan cell wall, surrounded by
an outer membrane containing lipopolysaccharide.
Gram negative ‐ three principal layers in the envelope;
the outer membrane, the peptidoglycan cell wall, and
the cytoplasmic or inner membrane
.
Gram positive
Gram‐positive ‐ lack an outer membrane, surrounded by layers of peptidoglycan many times thicker than is found in the Gram‐negatives
In Gram positives ‐ threading through these layers of
peptidoglycan are long polymers called teichoic acids
Chemotaxis
• Move toward chemical attractants such as nutrients, away
from harmful substances.
• Move in response to temperature, light, oxygen, osmotic
pressure, and gravity.
Gram stain reactions in cell wall
Gram stain reaction due to nature of cell wall.
Shrinkage of the pores of peptidoglycan layer of Gram‐
positive cells.
• Constriction prevents loss of crystal violet during
decolorization step.
Thinner peptidoglycan layer and larger pores of Gram‐
negative bacteria do not prevent loss of crystal violet.
• Alcohol may also remove/extract some lipids from outer layer of Gram‐negative cell wall, making crystal violet dye removal easier.
Steps of gram stain
Add crystal violet stain over the fixed culture. Let stand for 10 to 60 seconds; Rinse
Add the iodine solution on the smear, . Let stand for 10 to 60 seconds. Rinse
Add a few drops of alcohol, Rinse it off with water after 5 seconds.
Counterstain with basic fuchsin solution for 40 to 60 seconds, Rinse
Flagellar Movement
Flagellum rotates like a
• Very rapid rotation up to
1100 revolutions/sec.
• In general, counterclockwise
(CCW) rotation causes
forward motion (run).
• In general, clockwise rotation
(CW) disrupts run causing
cell to stop and tumble.
Chlamydia
Elementary body (EB) attaches to host cell.
- Reticulate body (RB) reproduction by binary fission.
- Differentiate back into EB, lyses cell.
Releases EB’s
Cycle repeats
Chlamydia Metabolism information
Cannot catabolize carbohydrates.
Cannot synthesize ATP or NAD+
. • Import up from host.
• Do have genes for substrate-level phosphorylation, electrontransport, and oxidative phosphorylation.
RBs have biosynthetic capabilities when supplied
precursors from host; can synthesize some amino acids.
EBs seem to be dormant forms.
Spirochete diseases.
Lyme disease
syphilis
Mycobacterium cell walls
Outer membrane contains mycolic acids
linked to peptidoglycan by arabinogalactan, a
polysaccharide.
- Cell walls very hydrophobic.
- Impenetrable by antibiotics.
Basic fuchsin dye not removed by acid
alcohol treatment.
• non-acid-fast bacteria easily decolorize
on the addition of the acid-alcohol and
take up the counterstain dye of
methylene blue and appear blue.
This technique identifies Mycobacterium
tuberculosis and Mycobacterium leprae
Mycobacterium types
M. bovis. • Tuberculosis in cattle, other ruminants, and
primates.
M. tuberculosis. • Tuberculosis in humans.
M. leprae. • Leprosy.
M. avium complex (MAC).
• Various diseases.
Streptomycetales
Provide us with antibiotics
Bifidobacteriales
Pathogens and Probiotics
Bacillus
Produce the antibiotics bacitracin, gramicidin, and polymyxin.
B. cereus—food poisoning.
B. anthracis—anthrax.
B. thuringiensis and B. sphaericus—used as insecticide
Three Groups of Streptococci
Pyogenic (pus producing) streptococci.
• For example, S. pyogenes—streptococcal sore
throat, acute glomerulonephritis, and rheumatic
fever.
Oral streptococci.
• For example, S. mutans—dental caries.
Other streptococci.
• For example, S. pneumoniae—pneumonia and otitis
media.
Prion diseases
TSE
Bovine spongeform
Kuru
Creutzfeld Jakob
Prions
Abnormaly folded proteins
Protists
Flagellated
lack mitochondria
some have mitosomes
Protozoa—wide
distribution in nature;
single-celled eukaryotic
chemoorganotrophs.
Naegleria fowleri
Protozoan
Amebic Meningoencephalitis
Muscosal Membranes: Ears,
Eyes, Nose, Genitals
