BIOL-1507EL Lecture Notes - Lecture 24: Osmoregulation, Passive Transport, Ureter
27 Jun 2018
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Biology 2 - Day 24 2017.04.06
Human Respiratory System (continued)
-The trachea is divided into the two bronchi (single bronchus) that enter the right and
left lungs, each branches into a greater number of small passages called bronchioles
-The two bronchi resemble the trachea in structure, but as the bronchial tubes divided
and subdivided their walls become thinner and thinner, and rings of cartilage are no
longer present
-Each bronchiole terminates in an elongated space, enclosed by a multitude of air
pockets or sacs called alveoli, which makes up the lungs
Loading and Unloading of Oxygen and Carbon Dioxide
-The concentration of gasses, wether in air or dissolved in water, is measured as
partial pressure. At sea level, the atmosphere everts a total pressure of 76 mm Hg
-The partial pressure for oxygen is referred to as PO2 (approximately 160 mm Hg) and
for carbon dioxide, the partial pressure is referred to PCO2 (approximately 0.23 mm
Hg)
-A gas will always diffuse from a region of higher partial pressure to an area of lower
partial pressure
-blood arriving at a lung via the pulmonary artery, has a lower PO2 and higher PCO2
then the air in the alveoli
-As blood enters a capillary net around an alveolus, CO2 diffuses from the blood to the
air within the alveolus
-Oxygen in the air dissolved in the fluid that coats the epithelium and diffuses across
the surface into a capillary
-By the time the blood leaves the lungs in the pulmonary veins, its PO2 has been
raised and PCO2 has been lowered
-After returning to the heart, this blood pumped through the systemic circuit
-In the systemic capillaries, gradients of partial pressure favour the diffusion of oxygen
out of the blood, and CO2 into the blood
-This is because cellular respiration rapidly depletes the oxygen contents interstitials
fluid, and adds CO2 to the fluid (again by diffusion)
-After the blood unloads oxygem and loads CO2 it is returned to the heart by systemic
veins
-The blood is then pumped to the lungs again, where it exchanges gasses with air in
the alveoli
Regulating the Internal Environment (Ch. 50, Pg. 1235)
-… survive changes in their external environment by maintaining their internal
enviornment with ranges that can be tolerated by their cells, a condition known as
he..eostasis
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Document Summary
The trachea is divided into the two bronchi (single bronchus) that enter the right and left lungs, each branches into a greater number of small passages called bronchioles. The two bronchi resemble the trachea in structure, but as the bronchial tubes divided and subdivided their walls become thinner and thinner, and rings of cartilage are no longer present. Each bronchiole terminates in an elongated space, enclosed by a multitude of air pockets or sacs called alveoli, which makes up the lungs. Loading and unloading of oxygen and carbon dioxide. The concentration of gasses, wether in air or dissolved in water, is measured as partial pressure. At sea level, the atmosphere everts a total pressure of 76 mm hg. The partial pressure for oxygen is referred to as po2 (approximately 160 mm hg) and for carbon dioxide, the partial pressure is referred to pco2 (approximately 0. 23 mm.
