The Respiratory System Flashcards
ventilation
the simple movement of air into and out of the lungs
respiration
the exchange of gases; either the lungs and the blood or the blood and the other tissues of the body
conduction zone
the parts of the respiratory system that participate only in ventilation
respiratory zone
parts of the respiratory system that participate in actual gas exchange
what are 3 roles other than respiration performed by the respiratory system?
1) pH regulation
2) thermoregulation (evaporative water loss and countercurrent exchange)
3) protection from disease and particulate matter (mucociliary escalator and alveolar macrophages)
hyperventilation
too much breathing, causes alkalinization of the blood (respiratory alkalosis)
hypoventilation
too little breathing, causes acidification of the blood (respiratory acidosis)
evaporative water loss
how breathing results in significant heat loss, liquid water absorbs heat as it changes into water vapour, and this heat is removed from the body during the process
pathway followed by inhaled air:
nose, nasal cavity, pharynx, larynx, trachea, bronchi, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveoli
what comprises the respiratory zone?
respiratory bronchioles, alveolar ducts, alveoli (involved in gas exchange)
nose
warming, humidifying, filtering inhaled air; nasal hairs and sticky mucus act as filters
nasal cavity
an open space within the nose
pharynx
the throat (common pathway for both air and food)
larynx
at the bottom of the throat/pharynx, made entirely of cartilage to keep the airway open, contains the epiglottis which seals the trachea during swallowing, contains the vocal cords
vocal cords
folds of tissue positioned to partially block the flow of air and vibrate, thereby producing sound
trachea
passageway which must remain open to permit air flow, rings of cartilage prevents its collapse
primary bronchi
one primary bronchi supplies each lung and branches repeatedly, collapse is prevented by small plates of cartilage
bronchioles
very small bronchi, contain no cartilage, walls made of smooth muscle which allows their diameters to be regulated to adjust airflow into the system
terminal bronchioles
the smallest and final branches of the conduction zone, very thick smooth muscles prevent diffusion of gases
alveolus
the actual structure across which gases diffuse, walls are only one cell thick
alveolar duct
the duct leading to the alveoli
respiratory bronchiole
a tube made of smooth muscle which has a few alveoli scattered in its walls, from which alveolar ducts branch off
what lines the respiratory tract
tall columnar epithelial cells that are too thick to assist in gas exchange
goblet cells
specialized epithelial cells along the respiratory tract that secrete a layer of sticky mucus
mucociliary escalator
cilia on apical surfaces of columnar epithelial cells in the upper respiratory tract which constantly sweep the layer of mucus toward the pharynx, where mucus containing pathogens and inhaled particles can be swallowed or coughed out
what kind of cells comprise gas-exchanging surfaces (i.e. terminal bronchioles, alveolar ducts, alveoli)?
a single layer of thin, delicate squamous epithelial cells, no mucus present, alveolar macrophages patrol the alveoli and protects from disease and inhaled particles
simple squamous epithelium
a single layer of squamous epithelial cells
surface tension
the tendency of water molecules to clump together, the force that causes wet hydrophilic surfaces to stick together in the presence of air
surfactant
soapy substance that coats the alveoli and reduces surface tension to prevent alveoli collapse, a complex mixture of phospholipids, proteins, and ions secreted by cells in the alveolar wall
pulmonary ventilation
the circulation of air into and out of the lungs to continually replace the gases in the alveoli with those in the atmosphere
inspiration
the drawing of air into the lungs; an active process driven by the contraction of the diaphragm which enlarges the chest cavity and draws air in
expiration
the movement of air out of the lungs; passive process driven by the elastic recoil of the lungs
each lung is surrounded by:
two membranes (pleura)
parietal pleura
membrane that lines the inside of the chest cavity
visceral pleura
membrane that lines the surface of the lines
pleural space
the narrow space between the two pleura, pressure in the pleural space is negative meaning that the two pleural membranes are drawn tightly together by a vacuum (thin layer of fluid)
diaphragm
a large skeletal muscle that is stretched below the ribs between the abdomen and the chest cavity, flattens when contracted
intercostal muscles
between the ribs, contract during inspiration and pulls ribs upward and further expands the chest cavity
forced expiration
an active process during exertion or forced exhalation that involves contraction of abdominal muscles to press upward on diaphragm, further shrinking the size of the lungs and forcing more air out
what are the steps in inspiration?
1) diaphragm contracts and flattens
2) chest cavity volume expands
3) pleural pressure decreases, becoming more negative
4) lungs expand outward
5) pressure in alveoli becomes negative
6) air enters the lungs and the alveoli
when is the alveolar pressure exactly zero/equal to atmospheric?
at the end of a resting expiration and just after inspiration before expiration
spirometry
the measurement of the volume of air entering or exiting the lungs at the various stages of ventilation
spirometer
a device used to measure volume of air entering or exiting the lungs
tidal volume (TV)
the amount of air that moves in and out of the lungs with normal light breathing
expiratory reserve volume (ERV)
the volume of air that can be expired after a passive resting expiration
inspiratory reserve volume (IRV)
the volume of air that can be inspired after a relaxing inspiration
functional residual capacity (FRC)
the volume of air left in the lungs after a resting expiration
inspiratory capacity (IC)
the maximal volume of air which can be inhaled after a resting expiration
residual volume (RV)
the amount of air that remains in the lungs after the strongest possible expiration
vital capacity (VC)
the maximum amount of air that can be forced out of the lungs after first taking the deepest possible breath
total lung capacity (TLC)
the vital capacity plus the residual volume
deoxygenated blood is carried toward the lungs by the pulmonary arteries which branch into:
networks of pulmonary capillaries/alveolar capillaries which surrounds alveolus and have extremely thin walls which permit diffusion of gases between blood and alveolus
pulmonary edema
fluid in the lungs resulting from increased blood pressure
how does the lymphatic system help to prevent pulmonary edema?
by carrying interstitial fluid out of the lungs
partial pressure
the contribution of each individual gas to the total pressure
Henry’s Law
the amount of gas that will dissolve into liquid is dependent on the partial pressure of that gas as well as the solubility of that gas in the liquid
according to Henry’s law, how does one find the concentration of a gas in the bloodstream?
the product of partial pressure of gas in the air above the fluid and the solubility of the gas in that liquid
what is the driving force for the exchange of gases in the lungs?
the difference in partial pressures between the alveolar air and the blood
respiratory membrane
three barriers to diffusion of gas from air to blood: first pass alveolar epithelium, interstitial liquid, capillary endothelium
type II alveolar cell
produces surfactant
respiratory control center
in the medulla of the brain stem, controls breathing (involuntary process)
what stimuli affects ventilation rate?
mechanical and chemical stimuli
what are the principal chemical stimuli that affect ventilation rate?
increased partial pressure of carbon dioxide, decreased pH, and decreased partial pressure of oxygen (secondary regulator)
peripheral chemoreceptors
located in the aorta and carotid arteries, monitor the partial pressure of carbon dioxide, pH, and partial pressure of oxygen
central chemoreceptors
found in the medullary respiratory control center, monitor partial pressure of carbon dioxide and pH of the cerebrospinal fluid
what are mechanical stimuli that affect ventilation rate?
physical stretching of the lungs and irritants
mechanical stretching of lung tissues stimulates:
stretch receptors that inhibit further excitatory signals from the respiratory center to the muscles involved in inspiration
bronchoconstriction
contraction of this smooth muscle
irritation of the inner lining of the lung stimulates:
irritant receptors and reflexive contraction of bronchial smooth muscle to prevent irritants from continuing to enter the passageways
bronchoconstriction is determined by which nerves?
parasympathetic nerves that release Ach
histamine causes:
bronchoconstriction (released during an allergy attack), opposed by epinephrine
bronchodilation
smooth muscles in airways relax
irritant receptors in the lung
trigger coughing and/or bronchoconstriction when an irritating chemical is detected
stretch of lung is detected by:
stretch receptors in lung to inhibit inspiration
increased partial pressure of carbon dioxide is detected by:
peripheral chemoreceptors and medullary respiratory centre
decreased pH is detected by:
peripheral chemoreceptors and medullary respiratory center to increase respiratory rate
decreased partial pressure of oxygen is detected by:
peripheral chemoreceptors to increase respiratory rate
epidermis
the outermost layer of the skin
dermis
deeper connective tissue underneath epidermis
hypodermis/subcutaneous tissue
adipose tissue underneath dermis, protective, insulating layer
the epidermis is composed of:
stratified layers of squamous epithelial cells that are constantly sloughed off and replenished by mitosis of cells at the deepest part of the epidermis (stratum basale)
stratum basale
deepest layer of epidermis, right above dermis
if cells in the epidermis die, they become:
keratinized: filled with a thick coating of the tough, hydrophobic protein keratin which helps make skin waterproof
melanin
a brown pigment produced by specialized cells (melanocytes) in the epidermis that helps absorb ultraviolet light to prevent damage to underlying tissues
dermis consists of:
various cell types embedded in a connective tissue matrix, blood vessels that nourish both the dermis and the epidermis, sensory receptors, sudoriferous glands, sebaceous glands, and hair follicles
sudoriferous glands
sweat glands
sebaceous glands
oil glands
hairs consist of:
dead epithelial cells bound tightly together
some specialized regions of skin contain:
ceruminous (wax glands) such as the external ear canal
sweat glands are responsive to:
aldosterone (high levels=sodium reabsorption so sweat does not waste salt)
homeotherms
body temperature is relatively constant
how do humans generate heat?
by metabolic processes and muscle contraction
chemical thermogenesis/nonshivering thermogenesis:
some homeotherms maintain their temperature by burning special fat (brown adipose tissue)
what are four strategies for keeping warm:
1) contraction of skeletal muscle
2) skin insulates us to conserve heat generated by metabolism
3) heat loss by conduction is minimized by constriction of blood vessels in the dermis (cutaneous vasoconstriction)
4) clothing/blankets
cutaneous vasoconstriction
constriction of blood vessels in the dermis
what are mechanisms for dissipating excess heat?
1) sweating (allows heat loss by evaporation)
2) dilation of blood vessels in the dermis (cutaneous vasodilation) which results in heat loss by conduction or convection when air blows past the skin
cutaneous vasodilation
dilation of blood vessels in the dermis
