Human Biology (BIOL 104)
Talk Eight:
The Respiratory System
Chapter 10
And Drug Addiction
(Not in book)
The Respiratory System
• Works in conjunction with the Human
Cardiovascular System:
• For RESPIRATION to occur
• Breathing –air in and out of lungs
• External respiration –exchange of gasses between air
and the blood
• Internal respiration – exchange between blood and
tissue fluid
• Cellular respiration –production of ATP in cells
The Respiratory System
• Basic functions of the
respiratory system
• Breathing
• (Pulmonary Ventilation)
– movement of air in and out of
the lungs
• Inhalation (inspiration)
– draws gases into the lungs.
• Exhalation (expiration)
– forces gases out of the lungs.
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used with permission
The Respiratory System
– Gas Conditioning – as gases pass
through the nasal cavity and
paransal sinuses, inhaled air
becomes turbulent.
– The gases in the air are:
• warmed to body temperature
• humidified
• cleaned of particulate matter
– Gas Exchange - respiration
• Supplies body with oxygen
• Disposes of carbon dioxide
– Produces Sounds
– Protects respiratory surfaces
– Site for olfactory sensation
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used with permission
The Respiratory System
• Two parts:
• Upper Respiratory Tract
• Nasal Cavities
– Filter, warm and moisten
air
• Pharynx
– Connection to surrounding
regions
• Glottis
– Passage of air into
larynx
• Larynx
– Sound production
The Respiratory System
• Lower Respiratory Tract
• Trachea
– Passage of air to Bronchi
• Bronchi
– Passage of air to lungs
• Bronchioles
– Passage of air to each
alveolus
• Lungs
– Gas Exchange
The Larynx
• This serves as a passageway for
air between the pharynx and the
trachea.
• The larynx houses the vocal
cords
– Mucosal folds suspended by
elastic filaments stretched
across the glottis.
• Air moves through glottis
– vibration – sounds
• The trachea is a tube connecting
the larynx to the primary
bronchi.
The Trachea
• Windpipe – connects
larynx to primary
bronchi.
• Held open by cartilage
• Goblet cell
– Makes mucus
• Mucosa contains layer of
pseudostratified ciliated
epithelium
– Sweep dirt and excess
mucus upwards
Bronchi in the Conducting Zone
• Consists of:
– Respiratory muscles – diaphragm
and other muscles that promote
ventilation
– Respiratory zone – site of
external respiration – respiratory
bronchioles, alveolar ducts,
alveolar sacs, and alveoli.
– Conducting zones
• Provides rigid conduits for air
to reach the sites of gas
exchange
• Includes nose, nasal cavity,
pharynx, trachea
• Air passages undergo 23
orders of branching in the
lungs
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used with permission
Bronchi in the Conducting Zone
• Bronchial tree - extensively
branching respiratory
passageways
– Primary bronchi (main bronchi)
• Largest bronchi
• Right main bronchi - wider and
shorter than the left
– Secondary (lobar) bronchi
• Three on the right
• Two on the left
– Tertiary (segmental) bronchi branch into each lung segment
– Bronchioles - little bronchi, less
than 1 mm in diameter
– Terminal bronchioles - less than
0.5 mm in diameter
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used with permission
The Lungs
• These lie on either side of the
heart within the thoracic cavity.
• Total cross-sectional area of 50
– 70 meter squared (1 ½ Tennis
courts)
– Right lung has three lobes and
the left lung has two lobes.
• This allows room for the
heart
– Each lobe is divided into
lobules, further divided into
bronchioles serving many
alveoli.
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used with permission
The Lungs
•
Features of Alveoli
Alveoli cell types
– Type I cells site of gas exchange
– Type II cells - secrete surfactant
– Macrophages
•
•
•
Surrounded by basal laminae and elastic fibers
Interconnect by way of alveolar pores
Internal surfaces - site for free movement of alveolar macrophages
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The Respiratory System
• Bronchial “tree” and Associated
Pulmonary arteries
• A very complex network of
airways and blood vessels in the
lungs to support gas exchange.
• There are 300 million alveoli per
set of lungs.
• Each one is made up of squamous
epithelium and blood capillaries.
• Gas exchange occurs: O2 diffuses
across the alveolar wall and
enters blood – CO2 goes in other
direction.
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used with permission
Alveoli- site of gas exchange
•
External respiration refers to gas
exchange between air in the alveoli and
blood in the pulmonary capillaries.
•
Blood entering the pulmonary capillaries
has a HIGHER partial pressure of CO2
than atmospheric air.
•
CO2 diffuses out of the blood into the
lungs.
•
Carried in blood plasma as bicarbonate
ions (HC03 ions)
•
Blood entering the pulmonary capillaries
has a LOWER partial pressure of O2 than
the avlvoli.
•
O2 diffuses into plasma and then red
blood cells
•
Binds with hemoglobin – forms
oxyhemoglobin
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used with permission
Alveoli- site of gas exchange
•
Internal respiration - gas exchange
between the blood in systemic capillaries
and the tissue fluid.
•
O2 diffuses out of the blood into the
tissue because the partial pressure of O2
in tissue fluid is LOWER than that of
blood.
•
O2 leaves hemoglobin and enters tissue
fluid
•
CO2 diffuses into the blood from the
tissue because the partial pressure of
CO2 in tissue fluid is HIGHER than that
of blood
•
CO2 combines with H20 – forms carbonic
acid. Some binds to hemoglobin – forms
carbaminohemoglobin
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used with permission
Pulmonary Ventilation (breathing)
• Inspiration: due to
contraction of:
– diaphragm
– intercostal muscles (both
external & internal, costal
nerves)
– Expanding the thorax reduces
pressure within the lungs (you
don’t “suck in air”…you
“vacuum” it)
• Expiration: relaxation of
muscles
– Recoil of elastic fibers in
tissue
– Allows costovertebral joint to
return to original position
• As lungs constrict,
surfactant prevents alveolar
collapse
Mechanism of Breathing
• Respiratory Volumes
– Tidal volume is the amount of air
that moves in and out with each
breath.
– Vital capacity is the maximum
amount of air that can be moved
out in a single breath.
• Inspiration can be increased
by expanding the chest
(inspiratory reserve volume).
– Residual volume is the air
remaining in the lungs after deep
exhalation.
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used with permission
Breathing at High Altitude
•
At sea level, because air is
compressible, the weight of all that air
above us compresses the air around us,
making it denser.
• As you go up a mountain, the air
becomes less compressed and is
therefore thinner.
• The important effect of this decrease
in pressure is this:
– in a given volume of air, there are
fewer molecules present. This is
really just another way of saying that
the pressure is lower (this is called
Boyle's law).
This bottle was photographed at
3600m (left) then again at sea level
(right)
Breathing at High Altitude
• The percentage of those molecules
that are oxygen is exactly the same:
21%.
• The problem is that there are fewer
molecules of everything present,
including oxygen.
• So although the percentage of oxygen
in the atmosphere is the same, the
thinner air means there is less oxygen
to breathe.
This bottle was photographed at
3600m (left) then again at sea level
(right)
Breathing at High Altitude
• The function of the lungs is to expose
blood to fresh air, and breathing faster
essentially increases the flow of fresh
air past the blood.
• This means that whenever an oxygen
molecule is taken away by the blood, it is
quickly replaced by another one.
• Carbon dioxide (CO2) is constantly
produced by the body and the lungs
remove it by allowing it to diffuse into
the fresh air in the lungs.
• Increasing the flow of fresh air through
the lungs, by hyperventilating, increases
the rate at which CO2 is lost.
Breathing at High Altitude
•
Because CO2 is an acid gas, losing more of it
from the blood leaves the blood relatively
alkaline.
•
At altitudes up to about 6000m, the kidneys
correct the alkalinity of the blood over a few
days by removing alkali (in the form of
bicarbonate ions, HCO3) from the blood.
•
When the blood passing through an area of
lung isn’t picking up enough oxygen, the blood
vessels carrying that blood tighten, so
that less deoxygenated blood can get
through the lungs.
•
This is called hypoxic pulmonary
vasoconstriction.
– means that less deoxygenated blood gets
through, so there is more oxygen in the
mixture of blood leaving the lungs.
Non-respiratory Air Movements
• Coughing: deep inspiration, closure of the glottis,
followed by strong expulsion that forces open the
glottis
•
• Sneeze: = air exits via nasal cavity rather than oral
cavity
• Yawn: = deep inspiration, pause, sudden expiration
• Laugh: = deep inspiration followed by sudden & rapid
expirations
• Crying: is very similar, but glottis remains open the
entire time…why you often choke when you cry
• Hiccup: = spastic diaphragm contractions
Drugs and addiction
Important
but NOT in book
Drugs and addiction
• Drug addiction is a condition
characterized by compulsive drug
intake, craving and seeking, despite
negative consequences associated
with drug use.
• The activity of any drug varies with
dose
– The amount of the drug taken
over time
• The amount of a drug taken to be
toxic or lethal depends upon the
chemical structure of the drug
– Also body size and other
physiological variables
From Wikimedia Commons, a freely licensed
media file repository
How drugs enter the body
• In the US, most drugs are
inhaled and quickly enter the
blood system and affect the
brain.
• However, it is important to
remember that the most
popular drug in the US is
caffeine!
• The second is alcohol!
• It is important to remember
what is a drug!
From Wikimedia Commons, a freely licensed
media file repository
Drugs and addiction
• Although
being
addicted
implies drug dependence, it is
possible to be dependent on a
drug without being addicted.
• People that take drugs to
treat diseases and disorders,
which interfere with their
ability to function, may
experience improvement of
their condition.
From Wikimedia Commons, a freely licensed
media file repository
How drugs enter the body
• The way in which a drug enters
the body often affects its
resulting concentration in body
tissues.
• Example: Cocaine
– A product of the coca plant –
grows in the high Andes
• Cocaine exists in many forms that
differ in both conc of the drug and
its molecular form.
• Coca leaves are chewed by South
American Indians
– Concentrations absorbed by
the gut are low.
From Wikimedia Commons, a freely licensed
media file repository
How drugs enter the body
• By contrast:
• When cocaine is purified into a
powder and sniffed the rate and
concentration of absorption is
increased many times.
– Cocaine is sometimes further
purified into crack
• Whether cocaine is sniffed or
smoked, it is inhaled not as a gas,
but as small particles
• For these chemicals to be
absorbed they must first adhere
to lung tissue.
Copyright ©The McGraw-Hill Companies;
used with permission
How drugs enter the body
• Other drugs are
injected into the body.
• Can be injected into
veins, or under the skin
• Continued uses always
leads to infection and
amputation of damaged
tissue.
From Wikimedia Commons, a freely licensed
media file repository
How drugs enter the body
• Chemicals can be highly
concentrated within a particle
• Thus these particles cause
substantial damage to lung
tissue
• Sniffing cocaine powder also
causes substantial damage to
cells in the nasal passage and
rot a person nose
• Can also eat away at the roof of
the mouth.
From Wikimedia Commons, a freely
licensed media file repository
Addiction
• Addiction has been defined as
– “Compulsive physiological and psychological need for a
substance”
• This implies there is both a biological basis and a
mental basis for addiction.
• However, as all brain function is biochemically
based, the distinction between physiological and
psychological addiction is becoming blurred.
Addiction
•
Ventral tegmental area (VTA)
– Thought to be positive enforcement
area (pleasure center).
– Experiments on rats and rhesus
monkeys have show that both would
rather electrically stimulate this area
of the brain than eat – even if near to
starvation
•
Nucleus accumbens (NA)
– joined to the VTA by synaptic
connections
– Interprets the stimulation signal from
the VTA
Addiction
• Frontal cortex (FC)
– Play a part in impulse control,
judgment, language production,
working memory, motor function,
problem solving, sexual behavior,
socialization and spontaneity.
– Assist in planning, coordinating,
controlling and executing
behavior.
– This is why behavioral
changes occur which are
hard to break.
Addiction
• So these positive
reinforcement areas are
affected by drugs
• Amphetamines indirectly
stimulate the neurons of
the VTA
– Used as a treatment for
depression
• Cocaine acts on the brain
cells of the VTA that
secrete dopamine
– Produces euphoria.
Addiction
• Opiates, marijuana, caffeine,
and alcohol all produce VTA
self-reinforcing effects.
• Drugs of abuse take over the
neuronal circuitry involved in
motivation and reward, leading
to altered engagement of
learning processes.
• Because of this, drug-associated
cues can trigger cravings as well
as unconcious or compulsive
drug-seeking behavior, with the
sense that voluntary control
over drug use is lost.
Addiction
• The stages of problematic use could be defined as
Pre-occupation/anticipation, binge/intoxication &
withdrawal/negative effect
• As drugs activate neuronal pathways in the brain
we effectivly learn to use them, these pathways in
the brain not only get 'laid down' stronger and
stronger with sucessive use but also activate
faster
– the quicker the effect or 'high' the stronger this
dysfunctional learning.
Addiction
• Objects, people or places also seem to to be
strongly associated with the drug experience,
making them 'Triggers' to 'Cravings'
– increase the chances of further use.
• Animal studies have shown drug availabilty over and
above the actual effects of the substance) are
associated with stimuli, exposure to objects
associated with use trigger the release of
adrenaline (Fight or flight)
– this excitation can be perceived as a 'need' to use.
Addiction
• Users in addictive
drugs in the US in 1991
• The top three are
widely not considered
drugs by most of the
population
• All of these three
produce addictive
behavior.
METH
• Methamphetamine or “Meth”, a derivative of
amphetamine is an extremely powerful stimulant
that affects the central nervous system.
• Developed in 1919 by Japanese pharmacologist.
• Although its initial uses were for medical purposes,
its ability to increase energy and to enable users to
function without sleep made it attractive for
military purposes during World War II.
METH
• Meth has undergone both legal and illegal uses in
the United States.
– As early as the 1930s it was used therapeutically to
treat asthma and epileptic seizures
– In the 1950s it was given to housewives to cope with
bordem and depression
– During the 1970s meth was a primary appetite
suppressant in prescription diet pills.
• The illicit demand for meth resulted in forged
prescriptions, theft and a black market.
METH labs
• How is Meth Made?
– ephedrine reduction.
• In this process, ephedrine or
psuedoephedrine are
chemically extract from over
the counter cold medicines.
• Red phosphorous (match tips),
iodine (table salt), acetone
(nail varnish remover), and
sulphuric acid (car battery)
are all that is required.
METH labs
• Lastly, drain cleaner,
camping fuel and paint
thinner are used to dry out
the drug into a powder.
• Clandestine labs are often
simple, crude and consist of
common household items.
• Meth can be cooked in
basements, old buildings,
motel rooms, camping
trailers and moving vehicles.
From Wikimedia Commons, a freely licensed media file repository
How to tell if Someone is on or
has been using Meth
• Meth affects nerve endings
throughout a user's body.
• Many people feel a sensation of
small bugs, known as "Meth
Mites", moving right under their
skin.
• They scratch, pick and dig the
spots, trying to relieve the
itching.
• The Meth Mites and the
scratching result in sores and
serious infections.
From Wikimedia Commons, a freely licensed
media file repository
How to tell if Someone is on or has
been using Meth
• The heated substance, when
fully aspirated, swirls
through the users' teeth
and gums, inevitably leading
to sores which never heal Meth Mouth
• Tooth enamel wears away
quickly as entire rows of
teeth dissolve to the gum
line.
• Collects in the nasal
passages which drain in the
back of the throat,
effectively corroding your
entire face.
From Wikimedia Commons, a freely licensed
media file repository
How to tell if Someone is on or has
been using Meth
• Chronic meth users are
typically gaunt, maintain
poor hygiene.
• Lose interesting in eating
– Digestive system shuts down
due to chemicals used to make
meth
• Kidney and liver shut down
– Due to all the toxic chemicals
• Skin scratched off,
infections
• Blindness.
From Wikimedia Commons, a freely licensed
media file repository
Environmental Damage
• Each pound of meth produced leaves behind
five-seven pounds of toxic waste.
• Toxic byproduct is often poured down drains or
directly into the ground, creating long term
hazards.
• Mobile labs and meth lab dump-sites are found
threaten our state’s natural resources.
• Clean-up costs range from $5,000 to
$50,000..5,000-$50,000