Respiratory system Flashcards
Diffusion
The difference in concentrations on the two sides of the membranes and the relative solubilities in the membrane
Fick’s Law of Diffusion
the rate of diffusion increases with surface area, decrease distance or the increase of the pressure difference
Gill filament
Consists of lamellae
lamellae
thin membranous plates that project into water flow
water flows past lamellae only
Countercurrent flow
within each lamella, blood flows opposite to direction of water movement
Benefits of countercurrent flow
maximizes oxygenation of blood
increases pressure difference
what are the most efficient of all respiratory organs
fish gills
amphibian respiration
many use cutaneous respiration for gas exchange
Terrestrial arthropods respiratory structures
air ducts called trachea, which branch into small tracheoles
Tracheoles
in direct contact with individual cells
Spiracles
Openings in the exoskeleton that can be opened or closed by valves
Amphibian Lungs
Positive Pressure Breathing
Air is forced into the lungs
Exhalation is completed by elastic response of the lungs
Bird Lungs
Multiple air sacs improve efficiency
Air moves in a single direction over lung surfaces
Mammal Lungs
Negative Pressure Breathing
Diaphragm contracts and intercostal muscles expand chest
Alveoli
sites of gas exchange in mammalian lungs
Path of air in mammalian lungs
passes through larynx, glottis, and trachea. Then bifurcates into right and left bronchi which enter each lung and further subdivide into bronchioles
What are alveoli surrounded by
an extensive capillary network
Partial pressures
based on the percent of the gas in dry air
Partial Pressure of N2 at 1.0 atm
600.6 mmHg
Partial Pressure O2 at 1.0 atm
159.2 mmHg
Partial Pressure CO2 at 1.0 atm
0.2 mmHg
what is the atmospheric pressure at 6000 m
380 mmHg
What is gas exchange driven by
differences in partial pressures
Blood returning from systemic circulation, depleted in oxygen, has a partial pressure of
40 mm Hg
Partial pressure of oxygen in the alveoli
105 mm Hg
Blood leaving the lungs has a partial pressure of
100 mm Hg
Outside of each lung is covered by
visceral pleural membrane
Inner wall of thoracic cavity is lined with
parietal pleural membrane
Pleural cavity
space between parietal and visceral membranes
small and filled with fluid
causes 2 membranes to adhere
Lungs move with thoracic cavity
What happens during inhalation
thoracic volume increases through contraction of two muscle sets
two muscle sets contracted during inhalation
external intercostal and diaphragm
Contraction of external intercostal muscles
expands rib cage
Contraction of the diaphragm
expands the volume of thorax and lungs
Inhalation causes ____ pressure which draws air into the lungs
negative
What structures have elasticity in inhalation
thorax and lungs
Tension in thorax and lungs is released by
the relaxation of the external intercostal muscles and diaphragm.
Produces unforced exhalation
Unforced exhalation
allows thorax and lungs to recoil
Chronic Obstructive pulmonary disease (COPD)
Refers to any disorder that obstructs airflow on a long term basis
Asthma
Allergen triggers the release of histamine, causing intense constriction of the bronchi and sometimes suffocation
COPD symptoms
Alveolar walls break down and lung exhibits larger but fewer alveoli
Lungs become less elastic
People expend 3 to 4 times the normal amount of energy just to breathe
Causes of COPD
smoking (largest cause)
Air pollution
Indoor cook stoves
Lung Cancer
Accounts for more deaths than any other form of cancer
caused by smoking
Chance of recovery from metastasized lung cancer
3% of patients surviving 5 years after diagnosis
Respiratory Pigments
proteins that transport oxygen, greatly increase the amount of oxygen that blood can carry
Arthropods, Vulcan, and mollusk oxygen-binding component
hemocyanin with copper
Hemocyanin
not bound to cells, but is directly suspended in the hemolymph
Vertebrate oxygen-binding component
hemoglobin contained within erythrocytes
Hemoglobin
consists of four polypeptide chains: two alpha and two beta
Chains in hemoglobin
Each chain is associated with a heme group
Heme group
Each heme group has a central iron atom that can bind a molecule of O2
Oxyhemoglobin
when hemoglobin loads up with oxygen in the lungs, it forms oxyhemoglobin
Deoxyhemoglobin
some molecules lose O2 as blood passes through capillaries, forming deoxyhemoglobin
How saturated is hemoglobin at a blood Po2 of 100 mm Hg
97% saturated
When blood returns to the lungs, it leaves the majority of the oxygen
in the blood as a reserve
The reserve
enables the blood to supply body’s oxygen needs during exertion
Hemoglobin’s affinity for oxygen is affected by
pH and temperature
Bohr shift
Increased CO2 in blood increases H+
Lower pH reduces hemoglobin’s affinity for O2
Results in a shift of oxyhemoglobin dissociation curve to the right
Facilitates oxygen unloading
What else does hemoglobin help transport?
CO2
20% of Co2 is transported by hemoglobin
CO2 diffuses into the blood and is transported either in
blood plasma, bound to hemoglobin, or as bicarbonate ions.
