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Pop Quiz
• What produces mucus, HCl and pepsinogen
in the stomach?
• List a water soluable vitamin
• What is a ruminant stomach?
Respiratory System
Review
• Cellular
respiration: obtain
glucose and
oxygen, get rid of
wastes and carbon
dioxide
Review
• Cellular respiration: Exchange occurs in the
mitochondria
Gas exchange: breathing, gas transport,
servicing cells
Gas exchange
• Breathing involves inhaling O2 and exhaling
CO2
• Transport involves diffusion, hemoglobin,
and occurs in RBC’s
• Blood supplies every cell with O2 and picks
up waste CO2
CO2 and O2 are exchanged over moist body surfaces
CO2 and O2 are exchanged over
moist body surfaces
• Surfaces must be thin and extensive
• Gasses dissolve in water before the diffuse
in or out of cells
• Fish have gills that project from the body,
worms exchange across the skin, insects
have trachea, terrestrial vertebrates have
lungs
Gills achieve gas exchange in aquatic
environments
Gills achieve Gas exchange in aquatic
environments
Gills
• Advantage: - Gills are always wet
• Disadvantage:O2 is less abundant in water
• Inhale - close opercula and expand mouth;
exhale open opercula and flush water over
the gills with the mouth closed
• Gas is exchanged across the gill filaments
and lamellae then into capillaries
Countercurrent exchange
Countercurrent exchange
Countercurrent exchange
• Found in many animal systems
– thermoregulation, and in the kidney
• The transfer of a substance flowing in one
direction to another moving in the opposite
direction
• Efficient - gill can remove 80 % of O2
Insect tracheal system
Insect tracheal system
• Air contains more O2 than water, air is
easier to move,terrestrial vertebrates use
less energy in ventilating their respiratory
surfaces
• Tracheae branch extensively, bringing air
directly to cells
• Air sacs pumped by muscles move air in
and out
Insect tracheal system
• System consists of:
–
–
–
–
Spiracles (openings)
Tracheae (branched tubes)
Tracheoles (fluid filled and reach all cells)
Airsacs (enlarged chambers that work like
bellows)
Terrestrial vertebrates: lungs
Figure 42.23c Alveoli
Terrestrial vertebrates: lungs
• Restricted to one part of the body, circulatory
system required to transport gasses to/from the
cells
• Human respiratory system:
– Nasal cavity (filters, warms, humidifies an d senses
odors)
– Pharynx (conducts air and food)
– Larynx/ vocal cords (muscular cords which can be
tensed or stretched to generate sound as air rushes by)
– Trachea (windpipe)
Terrestrial vertebrates: lungs
• Lungs
– Bronchi (forked tubes leading to the lungs)
– Bronchioles (smallest tubes leading to the alveoli- site
of gas exchange)
• Diaphragm (muscular, moves air in/out of lungs)
• Breathing
Smoking and lung function
• Normal function:
– Mucus and cilia trap and move
pollutants and sweep them out of the
respiratory system
– Macrophages kill bacteria
• Tobacco smoke
– irritates epithelial cells
– Destroys cilia and macrophages
– Toxins reach the alveoli, coughing
results
– Emphysema - brittle alveoli that
eventually rupture
– Smoking leads to cardiovascular
disease
Respiratory diseases
• Upper respiratory system infection – viral infection - inflammation of mucus membranes.
• Lung Cancer
– Linked to smoking.
• Pneumonia
– Viruses, fungi or bacteria in the alveoli. Fluid in the lungs prevents
gas exchange there.
• Tuberculosis
– Caused by Tubercle bacilli Symptoms: cough fever weight loss
infection. Nodules and scars form preventing normal alveoli
function.
• Pulmonary embolism
Breathing
fig 22.8A
Breathing ventilates the lungs
• Inhalation
– Ribcage expands, diaphragm contracts, chest
expands - lungs increase in size - air flows into
the alveoli from higher pressure outside.
• Exhalation
– Rib and diaphragm muscles relax- chest
contracts, lungs decrease in size -air forced out.
Birds have highly efficient, flow
through lungs (fig 22.8B)
Birds have highly efficient, flow
through lungs
• One - way air flow through the lungs
• Air sacs ventilate respiratory surface in the
lungs
• Inhalation- posterior sacs fill with fresh airanterior sacs fill with stale air
• Exhalation - both sacs deflate forcing air
into the lungs and out of the system
• No alveoli, parallel tubes, countercurrent
exchanger, 5% more efficient than
mammalian lung
Control over breathing
CO2
Carbonic acid
Lowered blood pH
Medulla increases
respiratory rate
Control over breathing
• Autonomic control centers in the brain
regulate breathing
• It ensures coordination between the
circulatory and respiratory systems
• Breathing control centers monitor pH, CO2,
and remote sensors monitor O2 in the blood.
• Control centers signal rib muscles and
diaphragm to alter breathing rate
• CO2 is the major signal controlling the
respiratory rate
Transport of
gases
in the body
Transport of gases
in the body
• Blood transports the respiratory gases,
hemoglobin carries the oxygen
• Heart has 2 pumps
– One pumps O2 poor blood to the lungs
– One pumps O2 rich blood to the body
• O2 dissolves poorly in fluids, hemoglobin in
RBC’s increases ability of cells to carry O2
Hemoglobin
Hemoglobin
• Transports both O2 and CO2
• Helps to buffer the blood by carrying CO2
• HCO3- generated can bind H+ and keep
blood pH stable
• Reverse process occurs in the lung, so CO2
is given off
Hemoglobin
•
•
•
•
•
A multipurpose molecule
Transports oxygen
Transports carbon dioxide
Buffers the blood
Tissue cells- forms carbonic acid,
bicarbonate, and H+
• Lungs - the reverse reaction occurs - off
loading carbon dioxide to the alveoli
Fetal respiration
Fetal respiration
• Fetus is in the amniotic fluid
• Capillaries from the fetus (umbilical cord)
and the uterus combine to form the placenta
• Countercurrent exchange occurs between
the capillaries of the fetus and the mother
• Fetal hemoglobin attracts O2 better than
maternal hemoglobin
• Placental transfer stops at birth - the
umbilical cord is cut - respiratory center is
stimulated from decreased blood pH
Pop Quiz!
• Write the chemical reaction for generating
bicarbonate from carbon dioxide
• State one reason that a bird lung is more efficient
than a mammalian lung
Review
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Cellular respiration vs. breathing
Respiratory surfaces
Lungs, gills, bird lungs, epithelial exchange
Respiratory illnesses
Anatomy of the system
Transport of gases
Fetal circulation