Respiratory System and Skin Flashcards
Ventilation
Movement of air in and out of the lungs
Respiration
Exchange of gases between lungs and blood, or blood and tissue.
Conduction Zone
Parts of the body that only participate in ventilation.
Nose - nasal cavity - pharynx - larynx - trachea - bronchi - terminal bronchioles - respiratory bronchioles* - alveolar ducts* - alveoli*
Also part of the Respiratory zone
Respiratory Zone
Parts of the body that participate in gas exchange.
Respiratory bronchiole - Alveolar duct (walls consist of alveoli) - Alveolus
Alveoli are only one cell thick except where capillaries cross the surface.
Note, the respiratory bronchiole is identical to the terminal bronchioles except that it has some alveolar cells that permit gas exchange.
Alternate functions of the respiratory system
pH regulation.
Thermoregulation.
Protection from disease and particulate matter.
Hyperventilation
Results in an alkalinization of the blood, also known as respiratory alkalosis.
Hypoventilation
Results in an acidification of the blood also known as respiratory acidosis.
Larynx
Three functions:
1. Made entirely of cartilage and keeps the airway open
- Contains the epiglottis
- Contains the vocal cords
Trachea
Airway that must remain open for air flow.
Cartilage helps to maintain its structure.
Branches into two bronchi - also supported by cartilage. Bronchioles (1 mm) do not have any cartilage support but are made of smooth muscle.
Terminal Bronchioles
The walls here are too thick for gas exchange. No gas exchange occurs here.
Respiratory tract constitution
Epithelial cells cover from the nose all the way down into the bronchioles.
Specifically, COLUMNAR Epithelial cells. These cells are too thick to allow gas exchange though.
Goblet cells
Specialized epithelial columnar cells that secrete mucus.
The mucociliary escalator
Cilia on the apical surface of the respiratory tract constantly sweep mucus from goblet cells toward the pharynx, where mucus containing pathogens can be coughed out or swallowed.
Gas exchanging surface constitution
A thin, single layer of squamous epithelial tissue also referred to as SIMPLE SQUAMOUS EPITHELIUM.
Mucous cannot be on these surfaces, so alveolar macrophages patrol these surfaces.
Surfactant
A soapy substance that prevents collapse of alveoli. Reduces surface tension.
A mixture of phospholipids, proteins, and ions secreted by cells in the alveolar wall.
Types of Alveolar Cells
Type 1 Alveolar Cells - simple squamous epithelium that exhibit gas exchange
Type 2 Alveolar Cells - large fat cuboidal cells that secrete surfactant. Metabolically active with lots of mitochondria.
Inspiration
The active process driven by a contraction of the diaphragm that draws air in.
Expiration
The passive process driven by elastic recoil of the lungs that does not require muscle contraction.
Note, it can be active if abdominal muscles are used to expel air. Referred to as Forced Expiration.
Are the lungs directly connected to the chest cavity?
No.
Membranes (pleura) surrounding the lungs
Parietal Pleura - lines the inside of the chest cavity
Visceral Pleura - lines the surface of the lungs
Pressure in the pleural space, pleural pressure, is negative. Some fluid helps hold them together.
Diaphragm
Relaxed - dome shape
Contracted - flat
*intercostal muscles (between ribs) also contract during inspiration
Steps of inspiration
Diaphragm contracts
Volume of chest cavity expands
Pleural pressure decreases, becomes more negative
Lungs expand outward
Pressure in alveoli becomes negative
Air enters the lungs and the alveoli
Alveoli pressure at 0
At the end of expiration and right after inspiration before expiration.
Spirometry
The measurement of volume of air as it enters and exit the lungs at various stages of respiration.
Spirometer is a device used for measurement.
Tidal volume
The amount of air that moves in and out of the lungs during light breathing. About 10% of lung capacity. 0.5 L of 5 - 6L.
Expiratory Reserve Volume
Volume of air that can be expired after passive resting expiration.
Inspiratory Reserve Volume
The volume of air that can be inspired after relaxed inspiration.
Functional Residual Capacity
Volume of air left in the lungs after resting expiration.
Inspiratory Capacity
Maximum volume of air that can be inspired after relaxed exhalation.
Residual Volume
Amount of air remaining in the lungs after the strongest possible expiration.
Vital Capacity
The maximum amount of air that can be forced out of the lungs after the deepest possible breath.
Total Lung Capacity
RV + VC
Pulmonary Circulation
The Pulmonary artery takes deoxygenated blood from the heart to the lungs. It eventually branches into many different alveolar capillaries.
*Note that lungs are supplied with lymphatic vessels as well.
Pulmonary edema
Can occur if left ventricle pressure is too high, forcing pressure to increase in alveolar capillaries, which can cause fluid to secrete into surrounding lung tissue.
The lymphatic system can help by carrying interstitial fluid out of the lungs.
Surface area of the lungs
Very high, around that size of a tennis court.
Henry’s Law
The amount of a gas that will dissolve into a liquid is dependent upon the partial pressure of the gas and its solubility in the liquid.
[Dissolved O2] = P(O2) x S(O2)
Note: gases are less soluble as temperature increases
What is the driving force for the exchange of gases between alveolar air and blood in the lungs?
Partial pressure between the alveolar air and the blood.
Respiratory Membrane
The three layers that gases must diffuse through to reach the blood stream.
Alveolar epithelium, interstitial fluid, and the capillary endothelium
Because this membrane is so thin, equilibration of partial pressures occurs rapidly
Respiratory control center
Regulated by the medulla in the brain stem.
Ventilation Rate Modulation
Dictated by assessment of 3 factors:
Partial pressure CO2
pH
Partial pressure O2 (to a lesser degree)
Peripheral chemoreceptors
Located in the Aorta and carotid arteries and monitor all three factors affecting ventilation rate.
Central Chemoreceptors
Found in the medullary respiratory control centre and monitor the partial pressure of CO2 and pH of the CSF.
Constriction/Dilation of Bronchi and bronchioles
Bronchoconstriction
Bronchodilation
Bronchoconstriction occurs as a result of ACh release from the parasympathetic system. Usually it is a response to an irritant in the lungs.
Ex. During an allergy attack, mast cells release histamine that causes bronchioconstriction. Epinephrine causes the smooth muscle to relax in the lungs.
People with Asthma use inhalers that have epinephrine, anti-histamines and anticholinergics.
Mechanical Stimuli that affect ventilation rate
Irritants
Physical stretching of the lungs - stretching activates stretch receptors that inhibt anymore excitatory signals from respiratory center.
Irritant Receptors
In the lungs, tigger coughing and bronchoconstriction when irritants are detected (ex. smoke)
Role of the skin
Protect from pathogens
Prevent excessive evaporation
Regulate body temperature
Layers of the skin
Epidermis
Dermis
Subcutaneous tissue (hypodermis), protective insulating layer of fat.
Epidermis
Composed of stratified squamous epithelium.
Cells are constantly sluffed off and replaced by mitosis at the deepest layer: Stratum Basale.
Basically surface skin is dead
Stratified squamous epithelium cells are
Keratinized
Also contain melanin (produced by melanocytes)
Dermis
Various cell types in a connective tissue matrix.
Contains blood vessels that provide the epidermis and dermis.
Sensory receptors: touch, pressure, pain.
Sudoriferous (sweat) glands
Sebaceous (oil) glands
Hair follicles -
Some specialized areas contain ceruminous glands (wax) glands
Homeotherms
Humans have a relatively constant body temperature.
Maintained by metabolism and muscle contraction.
Some other animals can use brown adipose tissue to produce energy, and this is known as chemical thermogenesis or non-shivering thermoregulation; however, humans do not use this to a considerable degree.
Four methods to manage cold temperatures for the human body
- Contraction of skeletal muscles
- Skin provides insulation to heat produced via metabolism
- Constriction of blood vessels in the dermis. Cutaneous vasoconstriction. Sympathetic nervous system.
- Protective layers like clothing.
Note that thyroid hormone, although it can increase the metabolic rate, is not considered an effective thermoregulator as it can take weeks to take effect.
4.
Expelling excess heat
- Sweating
- Vasodilation
