Transcript File

DO NOW 4/14
PSYCHE (SYE kee) n.
• the human soul; the mind
• The study of poetry often helps students to
examine their own PSYCHE.
• Because the inmate was so hardened in crime, it
was difficult to imagine that he possessed a
PSYCHE.
• A true appreciation for classical literature
engages one’s PSYCHE.
CHAPTER 10: GAS
EXCHANGE
GAS EXCHANGE
• Human gas exchange
system links circulatory
system w/ atmosphere
• Clean and warm entering air
• Maximize surface area for
diffusion of oxygen and carbon
dioxide
• Minimize distance for diffusion
• Maintain adequate gradients
for diffusion
GAS EXCHANGE
• Need oxygen for respiration
• Multicellular organisms have gas exchange surface
where external oxygen can diffuse into body, and
carbon dioxide can diffuse out
• In humans: alveoli (found in lungs, total surface area over
70m sq)
LUNGS
• Found in thoracic (chest) cavity surrounded by
pleural membranes, which enclose an airtight
pleural space (aka pleural cavity)
• pleural space contains small amount of fluid to
reduce friction during ventilation
TRACHEA, BRONCHI, BRONCHIOLES
• Leading from the throat to the lungs is the trachea,
and at the base are two bronchi (singular:
bronchus) which then subdivide several times into
even smaller bronchioles
TRACHEA, BRONCHI, BRONCHIOLES
• Cartilage in the trachea and
bronchi keep airways open
and air resistance low, and
prevents them from
collapsing or bursting as air
pressure changes during
breathing
• Trachea: regular
C-shaped cartilage
rings
• Bronchi: irregular
blocks of cartilage
BRONCHIOLES
• Surrounded by smooth muscle which contract/relax
to adjust diameter of airways
• Relax= greater diameter, more air
• Possible b/c no cartilage
WARMING AND CLEANING THE AIR
• As air flows through nose and trachea, it is warmed
and moistened by evaporation from the lining to
protect lungs from drying out (desiccation)
• Small hairs inside nose and mucosal membranes
trap suspended particles (dust, pollen, bacteria,
viruses)
MUCUS
• In trachea and bronchi, goblet cells of the ciliated
epithelium produce mucus, a slimy solution of
mucin, which is composed of glycoproteins with
many carbohydrate chains that make them sticky
MUCUS
• Also made by mucous glands beneath the
epithelium
• Some chemical pollutants, like sulfur dioxide and
nitrogen dioxide, can dissolve into mucus and
irritate the airways
MUCUS
• Beneath goblet cells are ciliated cells that carry
mucus upwards towards the larynx, where it is
(usually) swallowed so pathogens can be destroyed
by the acid in our stomachs
MACROPHAGES
• Phagocytic white blood cells patrol the surfaces of
the airways scavenging small particles like bacteria
and fine dust
ALVEOLI
• Terminal end of bronchioles. Have very thin lining of
epithelial tissues (single cell thick) and are
surrounded by capillaries carrying deoxygenated
blood
• Thinness of barriers ensures fast diffusion
• Walls contains elastic fibers which can stretch and
recoil during breathing
ALVEOLI
• Oxygen moves into bloods via
partial pressure differences
between alveoli (high) and
capillaries (low)
• Carbon dioxide moves from high
in capillaries to low in alveoli
• Blood is constantly moving so
pressure gradient is maintained