Post on 17-Feb-2016
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Define words for 33.3
Warm-Up
Ch. 33.3 – The Respiratory System
All cells require a constant supply of oxygen for cellular respiration.
Recall C6H12O6 + 6O2 --> 6H2O + 6CO2 + ATP
Respiration means the process of gas exchange between a body and the environment.
Human respiratory system picks up oxygen from the air we inhale and releases carbon dioxide into the air we exhale.
With each breath air fills our lungs and gas exchange occurs there.
The circulatory system links the gas exchange to the rest of our body.
Background Information
Structures of the Respiratory System
Consists of The noseThe pharynxThe tracheaThe bronchiThe lungs
Air must be filtered, moistened and warmed before entering the lungs
Hairs lining the entrance to the nasal cavity trap large particles
Incoming air is warmed in the inner nasal cavity and sinuses.
Mucus is produced that moistens the air and further filters.
The Nose
A cavity at the back of the mouth
Also called the throat
Serves as a passageway for both air and food
The Pharynx
After the pharynx air moves through the larynx to the trachea.
Contains two highly elastic folds of tissue known as the vocal cords.
These tissues give you the ability to produce sounds
When muscles pull the vocal cords together, the air moving between them causes the cords to vibrate and produce sounds.
The Larynx
Also known as the windpipe
When you shallow food or liquids, the epiglottis (a flap of tissue) covers the entrance to make the food or liquids go down the esophagus.
Lined with mucus that trap any inhaled particles.
Cilia lining the trachea sweep both the mucus and trapped particles upwards towards the pharynx. From there, the mucus and particles can be swallowed or spit
out This helps keep the lungs clean and open form the important
work of gas exchange.
The Trachea
Air then moves into the bronchi (singular: bronchus) – which are two large tubes in the chest cavity leading to each of the lungs.
The bronchus divides into smaller bronchi which then divides into the bronchioles (even smaller)
Bronchi and bronchioles are surrounded by smooth muscle tissue controlled by the autonomic nervous system As the muscles contract and relax, the size of the passageways
change.
Further divide until they reach the alveoli (singular: alveolus) Alveoli are grouped into clusters Surrounded by a delicate network of capillaries where the gas
exchange occurs.
The Lungs
Gas Exchange and Transport
Lungs contain about 150 million alveoliProvide an enormous surface area for gas
exchange
Oxygen and carbon dioxide are exchanged across the walls of the alveoli
Chemical properties of blood and red blood cells allow for efficient transport of gases throughout the body.
Background Information
Air enters alveoli where the oxygen dissolves in he moisture on their inner surface and then diffuses across the thin capillary walls.
At the same time, carbon dioxide is diffusing from the blood into the air.
Air being breathed contains 21% O2 and 0.04% CO2. Exhaled air contains less than 15% O2 and 4% CO2.
Lungs remove ~1/4 of the oxygen for the breathed air and increase the CO2 level by 100x.
Gas Exchange
Oxygen binds to the hemoglobin which transport it
Hemoglobin also increases the efficiency of gas exchange. Because hemoglobin actively binds to oxygen,
the oxygen is removed for the plasma and this maintains the concentration gradient towards the blood.
Increase the blood’s oxygen-carrying capacity more than 60 times
Transport
Carbon dioxide is transported by 3 ways1. Most enter the RBC and combine with H2O
to form carbonic acid.2. Some is dissolved in the plasma3. Binds to hemoglobin and proteins in the
plasma
This reverses the in the lungs, where the CO2 is released into the alveoli and exhaled.
Breathing
Muscles are not connected to the lungs to aid in breathing.
Forces that drives breathing is air pressure, the diaphragm and muscles associated with the ribs.
Movements of the diaphragm and rib cage change air pressure in the chest cavity during inhalation and exhalation.
Background Information
Lungs are in the pleural membranes (closed sacs) inside the chest cavity
At the bottom of the cavity is the diaphragm
When you inhale the diaphragm, contracts and flattens along with the muscle between the ribs contracting which raises the rib cage. Increases the volume of the chest cavity
The increased volume in turn creates a partial vacuum inside the cavity and atmospheric pressure causes air to fill the lungs
Inhalation
During ordinary breathing, this is usually passive.The rib cage and diaphragm relax; volume is
decreased in the chest cavity; atmospheric pressure causes the air to leave.
When you need additional force, the muscles between the ribs and abdominal muscles contract vigorously as the diaphragm relaxes.
This only works because the chest cavity is sealed.If the chest is punctured breathing is impossible.
Exhalation
You can control breathing whenever you want; however, the nervous system has final control over it
The medulla oblongata is the part of the brain stem where the breathing center is located.
Sensory neurons in or near the medulla and in large nearby blood vessels gather information on the CO2 levels in the blood and send that info to the medulla.When stimulated, the center sends nerve impulses to the
diagram and chest muscles to contractThe more CO2 the stronger the signals If the CO2 reaches critical levels, you cannot keep from
breathing.
Breathing and Homeostasis
How is inhalation different from exhalation?
What evidence supports the fact that breathing is not entirely under conscious control?
Warm-Up for 1/9/12
Smoking and the Respiratory System
3 most dangerous substances in tobacco smokeNicotine – an addictive stimulate that increase
heart rate and blood pressure
Carbon monoxide – a poisonous gas that blocks hemoglobin from binding with the blood
Tar – contains at least 60 cancer causing compounds
Effects on the Respiratory System
Also paralyzes cilia in the tracheaThis causes the inhaled particles to stick to the
walls of the respiratory tract or to enter the lungs
Mucus cannot be pushed upwards
Irritation occurs from the accumulated mucus and particles and a smoker’s cough is triggers in an attempt to clear the passageways
Causes the lining of the respiratory tract to swell which reduces airflow to the alveoli
Only 30% of male smokers live to age 80 while 55% of male nonsmokers do
Chronic Bronchitis bronchi become inflamed and clogged with
mucusTreatment control symptoms but there is no
cureDaily activities become difficult
Diseases Caused by Smoking
EmphysemaLoss of elasticity and eventual breakdown of
lung tissueMakes breathing difficultLeads to a lack of oxygen and a build up of
carbon dioxideNo cure but treatments include medication
Lung CancerParticularly deadly because by the time it is
usually detected the cancer has spreadFew people that are diagnosed live more than 5
years~87% of lung cancer deaths are due to
smoking
Child of smokers are twice as likely as children of nonsmokers to develop asthma or other respiratory problems
Smoking while pregnant places the baby at risk which can lead to lifelong problems
Quitting smoking improves the health of the smoker
Other Effects of Smoking