bio 30 respiration
what is the respiratory system
made up of a pair of lungs, a series of passageways into your body and respiratory surfaces for gas exchange. It is unique in that the internal organs that are part of this system- the lungs, are exposed to the external environment
what is breathing
the process by which oxygen in the air is brought into the lungs and into close contact with the blood. the blood absorbs the oxygen and carries it to all parts of the body. at the same time the blood gives up waste matter (co2) which is carried out of lungs with the air breathed out. involves inhalation and exhalation. net loss of co2, net gain o2
what is the first step of respiration
taking air into body through mouth/nose. air flows into the pharynx, passes the epiglottis, through the larynx and into the trachea
what is the nasal cavity (nose)
the usual entrance for outside air into the respiratory system. the nostrils lead to open spaces in the nose called nasal passages. the nasal passages serve as a moistener, filter, and to warm up the air before it reaches the lungs. cillia and mucus in it. there are capillaries under mucus membrane, blood in them helps warm the air
what are the sinuses
(frontal, maxillary, sphenoidal) are hollow spaces in bones of the head. small openings connect them to the nose. the functions they serve include regulating temp and humidity of air breathed in, lighten bone structure of head and allow for voice
what is the oral cavity
the mouth, enters during heavy exercize or when nasal passage is blocked.
what are the adenoids
lymph tissue at the top of the throat. when they enlarge and interfere with breathing, they may be removed. the lymph system, consisting of nodes and connecting vessels, carry fluid through the body. helps rid body of infection by filtering foreign matter and producing lymphocytes
what are the tonsils
lymph nodes in the wall of the throat (pharynx) that often become infected. also part of germ-fighting system of body
what is the pharynx
(throat) collects incoming air from the nose and mouth and passes it downward to the windpipe (trachea)
what is the epiglottis
flap of tissue that guards the entrance to the trachea (glottis). closing when anything is swallowed that should go into the esophagus and stomach
what is the larynx
(voice box) contains the vocal chords. when air leaves the pharynx it passes into the larynx. constructed mainly of cartilage. vocal chords are two pairs of membranes that stretch across inside of larynx. they vibrate as air is expired.
what is the trachea
(windpipe) main passage leading from pharynx to lungs. a tube approx 12cm in length and 2.5cm wide. kept open by rings of cartilage within its walls. covered with cillia and mucous membrane. cillia move mucus and trapped foreign material to pharynx. after that, they leave air passages and are normally swallowed. smoking stops cillia moving
what does the trachea divide into
two main bronchi- right bronchus and left bronchus, one for each lung, which subdivide into each lobe of lungs. these, in turn, subdivide further into bronchioles. bronchioles have a branching design
what are the lymph nodes
lymph nodes of the lungs are found against the walls of the bronchial tubes and trachea.
what are the ribs
bones supporting and protecting the chest cavity. move to a limited degree, helping lungs expand and contract
what are the lobes of the lungs
right lung is divided into 3 lobes. the left lung is divided into 2 lobes. each lobe is like a balloon, filled with spongy tissue. air moves in and out of lobes through a branch of bronchial tube
what are the pleura
two membranes, actually one continuous one folded back on itself, surround each lobe of the lungs and seperate lungs from chest wall. interpleural fluid is located between the two layers and reduces friction between lungs and chest cavity during breathing
what are the bronchial tubes lined with
cillia that carries mucus up and out of pharynx, where it is coughed up or swallowed.
what is the diaphragm
strong wall of muscle seperating chest/thoracic cavity from abdominal cavity. by moving downward, it creates suction in the chest to draw in air and expand the lungs. when relaxed, it is dome shaped bulging upward into chest cavity
what are the alveoli
tiny air sacs that are destination of air breathed in. each bronchiole ends in these tiny air chambers. lungs contain about 300mil alveoli. total surface would be 100m2, 40x surface of skin. the walls of the alveoli are the respiratory surface. they are thin, moist, and surrounded by capillaries- imbedded in walls of alveoli.
what do the capillaries in alveoli do
blood passes through them, brought by pulmonary artery and taken away by pulmonary vein to heart. while in capillaries, blood gives of co2 through capillary wall into alveoli and take up oxygen from air in alveoli.
what is respiration
gas exchange of co2 and o2 between an organism and the environment
three steps of respiration in humans
internal, external, cellular.
or breathing, gas exchange, cellular, where internal and external are part of gas exchange.
lung and heart activity in a day
in 1 day, 8000-9000L of breathed in air meet 8000-10000L of blood pumped in by heart through pulmonary artery. lungs relieve blood of waste and return an oxygen-rich stream of blood to heart through pulmonary vein
what is gas exchange
process of transferring o2 from air into body and co2 from blood out of body. takes place at a respiratory surface- a boundary between external environment and interior of body
how do gases cross respiratory surface
diffusion- movement of a substance from area of high conc to low conc. single-cell organisms exchange gas directly across membrane, but size is limited. animals that lack specialized exchange surfaces (flat bodies) are best for gas exchange, but are small
gas exchange large animals
cant maintain diffusion across outer surface. developed variety of respiratory surfaces that increase area for exchange.
what is a respiratory surface covered in
thin moist epithelial cells that allow oxygen and co2 exchange. those gases can only cross cell membranes when dissolved in h2o or aqueous solution
conditions necessary for gas exchange across a membrane
- concentration gradient
- large surface area
- thin permeable surface
- moist exchange surface
what is external respiration
exchange of gases across the respiratory surface between air sacs (alveoli) in the lungs and the blood.
what is internal respiration
exchange of gases between the blood and individual cells in the tissues
what is cellular respiration
use of oxygen to break down glucose and produce energy in cell. this occurs in mitochondria of cells. series of chem reactions that convert energy of food to energy used for cells. carbohydrates as glucose are best
respiratory system functions other than gas exchange
- warm/cool air to proper body temp
- moisturize inhaled air for necessary humidity
- protect body from harmful substances through cough etc
respiratory system sequence
nose
pharynx
larynx
trachea
bronchi
bronchioles
alveoli
capillaries
rbcs
diaphragm
why is the forcing of air into and out of lungs by breathing movements necessary
to increase exchange of gases with the environment. diffusion of o2 from external atmosphere into nose, through respiratory system to alveoli would be too slow to supply an organism with enough o2 and ridding of co2.
voluntary and involuntary breathing
involuntary- ordinarily, without thinking. continue when unconcious. necessary bc body doesnt store o2, and momentary stopping can be lethal.
voluntary- possible for short time, i.e. holding breath, but involuntary soon takes control
what are the two processes of breathing
inspiration and expiration. largely controlled by diaphragm, large muscle seperating thoracic cavity from abdominal cavity, and intercostal muscles
what is inspiration
diaphragm contracts and flattens. intercostal muscles act in unison with diaphragm, attached to 12 pairs of ribs encircling thorax. when diaphragm contracts, rib muscles contract, moving up and forward
how does inspiration increase volume of chest cavity
as thorax expands, pleura moves outward and downward with them, causing lungs to expand. increase of volume lowers air pressure in alveoli to below atmospheric pressure (create vacuum). bc of diffusion, air rushes through resp tract into alveoli- negative pressure breathing
what is expiration
reversing steps of inhalation. when diaphragm relaxes, it assumes maximum curvature and pushes up. at same time, intercostal muscles relas, ribs move down and back. both movements push against pleura. chest cavity decreases in size, air pressure in lungs rises above external air- forcing air out of lungs
homeostasis in body
ability to adjust and maintain levels of o2 and co2
what are the muscles to breathe stimulated by
diaphragm and intercostal muscles are stimulated by impulses from the brain.
what maintains homeostasis in body
system of brain, nerves, lungs, muscles makes negative feedback mechanism that keep homeostasis
what is the respiratory center
located in the medulla oblongata of the brain (at back), connected to respiratory muscles (diaphragm and intercostal muscles) by motor neurons. a set of sensory neurons conducts impulses from lungs to respiratory center
sensory neurons in inspiration and expiration
inspiration- resp center sends nervous impulse to resp muscles, they contract, inflates lungs, which initiate impulses in sensory neurons that extend from lungs to brain, inhibit breathing center which stops sending impulses to resp muscles.
expiration- no longer stimulated, muscles relax, and lungs deflate. lungs stop stimulating sensory neurons which then stop sending impulses to resp center. no longer inhibited, resp center sends out nere impulse, process repeats
aorta and carotid arteries direction
aorta - left ventricle - body
carotid arteries - brain
what happens when co2 is dissolved in blood
reacts with water to form carbonic acid, which ionizes to form a bicarbonate ion and a hydrogen ion.
1. (from cellular respiration)
co2 + h2o - h2co3
h2o in blood plasma, carbonic acid is weak
2.
h2co3 - hco3 + h+
h+ concentration rises, ph lowers, more acidic but still close to neutral
respiratory center in brain detection and effect
detects the higher h+ concentration
two things detected- h+ in the brain, o2 in aorta and carotid arteries.
result- depth and rate of breathing increase
how does normal breathing maintain oxygen and carbon dioxide balance in the body?
Normal breathing supplies enough O₂ to meet the body's needs and removes CO₂ as fast as it is formed. However, if CO₂ accumulates in the blood or O₂ levels drop, breathing rate and/or depth increase
is the body more sensitive to changes in CO₂ or O₂ levels?
The body is more sensitive to CO₂ concentration in the blood than O₂ concentration. A rise in CO₂ triggers an increase in breathing rate faster than a drop in O₂.
what controls the breathing rate in the body?
The breathing rate is mainly controlled by the respiratory center in the brain, which monitors CO₂ levels in the blood.
what monitors O₂ levels in the blood?
O₂ levels are monitored by chemoreceptors located in the aorta and carotid arteries. These neurons detect changes in O₂ concentration and stimulate the respiratory center when levels fall.
what happens when CO₂ levels in the blood rise?
- More CO₂ in the blood leads to higher H⁺ (hydrogen ion) concentration, making the blood more acidic.
- The respiratory center in the brain detects the change and sends impulses to the respiratory muscles.
- breathing rate increases
what stimulates breathing more: dissolved CO₂ or H⁺ concentration?
The high concentration of H⁺ in the blood, rather than the dissolved CO₂ gas itself, stimulates the respiratory center to increase breathing rate.
How does the body respond to low O₂ levels?
Neurons with chemoreceptors in the aorta and carotid arteries detect low O₂ levels. monitor blood continuously, when o2 falls, stimulate resp center in brain
co2 negative feedback mechanism
cause: exercise (more cellular respiration)
change: h+ and co2 increase, blood ph lowers
receptor: chemoreceptors for h+ ions
control center: respiratory center
effector: increase stimulation rate of respiratory muscles
change: breathing rate and depth increase, co2 is released
normal condition: h+, co2, and blood ph return to normal
o2 negative feedback mechanism
cause: exercise (more cellular respiration)
change: o2 decreases
receptor: chemoreceptors in aorta and carotid arteries
control center: respiratory center
effector: rate of stimulation of respiratory muscles increases
change: increase in rate and depth of breathing, more breaths in
normal condition: return o2 levels to normal
vital capicity
maximum amount of air a person can forcibly exhale after the largest possible inhalation of air. measured as the sum of three volumes of air:
tidal volume + inspiratory reserve + expiratory reserve
tidal volume
amount of air inhaled or exhaled during normal, quiet breathing
inspiratory reserve
amount of air that can be forcefully inhaled after normal inhalation
expiratory reserve
amount of air that can be forcibly exhaled after normal exhalation
defense mechanisms (5)
coughing- reflex after irritation of throat, trachea, lungs, pleural membrane. rapid contraction of chest and diaphragm muscles, epiglottis closes and suddenly opens
sneezing- irritation of lining of nasal cavity. air taken by normal breathing is interrupted, heart stops momentarily
hiccupping- after vagus nerve is stimulated. involuntary contraction of diaphragm forcing air out of lungs
yawning- psychological and physical reactions- involuntary stretching of mouth and intake of air- body requires o2
snoring- result of vibrations of soft palate while sleeping
how is the concentration gradient maintained in breathing
continuous supply of high co2 blood, low in o2.
how does oxygen diffuse in gas exchange
from alveoli into capillaries
how does carbon dioxide diffuse gas exchange
from capillaries into the alveoli to be expelled
what is breathing caused by
contraction or relaxation of respiratory muscles, controlled by neves.
contract- upon stimulation or a signal "message," motor neurons on, firing
relax- removal of stimulation or a signal "no message," motor neurons off, not firing
sensory neurons
activated by some form of stimulation ex. light, pressure, stretching
detecting or stimulated: on
not: off