Transcript Human Respiratory System Hanes Magnet School 7 Grade Science

Human Respiratory System
Hanes Magnet School
7th Grade Science
Mr. Bombick
Human Respiratory Tract Outline
• Anatomy of the Respiratory Tract
(both Upper and Lower Tracts)
• Control of Breathing
• Physiology of Breathing
• Measurements of Human
Breathing
• Homeostatic Mechanisms of the
Respiratory System
• Diseases of the Respiratory Tract
Respiratory Tract-Anatomy
• The respiratory tract can be
divided into two major parts, the
upper and lower respiratory tract
• The upper respiratory tract
consists of the nose and the
pharynx
• The lower respiratory tract
consists of the trachea and the
lungs
Events in the Upper Respiratory Tract
The nose and pharynx make up the upper respiratory
tract. The upper respiratory tract has several
important functions which include the filtering of air,
the warming of the air, and humidifying the air before
the air reaches the lower respiratory tract.
Nose hairs help filter out particulates from the air to
prevent them from getting into the lower airways.
Tissues lining the nasal cavity contain many small
blood vessels which help to warm the air. These
tissues also secrete mucous which further helps filter
the air. Many of the cells that line the nasal cavity
also contain cilia which can transport the mucous
containing the dust and particulates to the back of
the nasal cavity to be coughed out or swallowed and
digested in the stomach.
The air finally flows into the region of the larynx.
Upper Respiratory Tract-Anatomy
Lower Respiratory Tract-Larynx
The larynx contains two major parts; the vocal
cords and the epiglottis. The epiglottis is a flap of
cartilage that helps prevent food from going into
the lower respiratory tract. Stimulation of the
larynx by ingested food also initiates a type of
coughing or gag reflex to help prevent food from
getting into the lower respiratory tract. A person
can choke on food if the epiglottis fails to close the
opening of the trachea.
The vocal cords consists of two folds of connective
tissue that becomes stretched and vibrated when
air passes through. The length of the vocal cords
determines the pitch of the sound and the volume
of sound is dependent on the intensity of
expiration. Sound is only produced when air is
passing through the cords. The production of sound
can definitely be under voluntary control.
Lower Respiratory Tract-Continued
• The trachea is the major airway from
the larynx to the two bronchi
• The trachea is surrounded by
cartilaginous rings that help maintain
the tubular shape
• Two bronchi branch off of the trachea
• The bronchi go into the lungs and start
to branch into smaller tubes called
bronchioles
• The terminal parts of the smallest
bronchioles create the alveolar sacs
where gas exchange occurs
Lower Respiratory Tract-Anatomy
Control of Breathing
Breathing is an automatic and rhythmic
action produced by bundles of neurons in
the pons and medulla of the hind brain.
These bundles of neurons direct muscles
that form the walls of the thorax and
abdomen and produce differences in
pressure that move air into and out of the
lungs. The respiratory rhythm and the
length of each phase of respiration are set
by alternating stimulatory and inhibitory
actions of the neurons in the brain stem.
Respiratory Physiology
As the diaphragm moves down and the rib
cage moves up and out, the lungs expand.
During inspiration, the expansion of the lungs
causes the pressure in the lungs (and alveoli)
to become slightly negative relative to
atmospheric pressure (creation of a vacuum).
As a result, air moves from an area of higher
pressure (the air) to an area of lower
pressure (our lungs & alveoli). During
expiration, the respiration muscles relax &
lung volume decreases. This causes pressure
in the lungs (and alveoli) to become slight
positive relative to atmospheric pressure. As
a result, air leaves the lungs.
Respiratory Physiology (cont.)
Respiratory Physiology (cont.)
The Respiratory System
The exchange of gases (O2 & CO2) between
the alveoli & the blood occurs by simple
diffusion: O2 diffusing from the alveoli into
the blood & CO2 from the blood into the
alveoli. Diffusion requires a concentration
gradient. So, the concentration (or pressure)
of O2 in the alveoli must be kept at a higher
level than in the blood & the concentration
(or pressure) of CO2 in the alveoli must be
kept at a lower lever than in the blood. We
do this, of course, by breathing continuously bringing fresh air (with lots of
O2 & little CO2) into the lungs & the alveoli.
Show Two Video Clips
Breathing Measurements
Breathing measurements are obtained using a plethysmograph
Breathing Measurements (cont.)
• VC = vital capacity—The amount of air
that can be forced out of the lungs
after a maximal inspiration (4.6/3.6
liters)
• VT = Tidal volume—The amount of air
breathed in or out during normal
respiration (0.5/0.39 liters)
• TLC = Total lung capacity—The volume
of air contained in the lung at the end of
maximal inspiration; The total volume of
the lung (6.0/4.7 liters)
• RV = Residual volume—The amount of air
that stays in the lungs after maximal
expiration (1.2/0.93 liters)
Homeostasis of Respiration
• Central chemoreceptors of the
central nervous system are sensitive
to pH in the blood (increased CO2 in
the blood means more acidic
conditions and therefore, lower pH)
and adjust breathing rate
accordingly
• Peripheral chemoreceptors detect
variations of the oxygen in the
arterial blood, in addition to
detecting arterial CO2 and pH
(decrease in pH increases breathing
rate)
Homeostasis of Respiration (cont.)
• Mechanoreceptors are located in the airways and
lung lining to control reflex reactions that prevent
over inflation of the lungs. Other upper airway
mechanoreceptors control responses as coughing,
sneezing, closure of the glottis, and hiccups. A
spinal cord reflex is responsible for activation of
respiratory muscles for a gasping response,
hypoventilation, and increases in breathing
frequency and volume.
• In addition, respiration can be affected by
conditions such as emotional state (limbic system)
or temperature (hypothalamus).
• Voluntary control of respiration originates from
the cerebral cortex although chemoreceptors are
capable of overriding conscious control.
Respiratory Pathologies
• Cancers of the Respiratory System
(include all structures of the respiratory
system)
• COPD (Chronic Obstructive Pulmonary
Disease) includes chronic bronchitis and
emphysema
• Cystic Fibrosis
• Variety of infections (viral, bacterial,
protists, helminthes, nematodes, fungi,
etc.)
• Asthma
Emphysema
Normal Lung
Emphysema
Lung Cancer
Cystic Fibrosis