Unit 5 - Breathing PART A & B Flashcards
What are the Respiratory System Main Functions?
- Respiration
- Homeostatic regulation of body pH
- Defends against microbes
- Metabolic functions - modifies arterial concentrations of
chemical messengers - Vocalization
- Sense of smell
Respiration 2 types
a. External respiration
b. Internal respiration
External respiration
involves exchange and transport of oxygen and carbon dioxide:
i. between lungs and atmosphere – involves PULMONARY
VENTILATION (inspiration and expiration)
ii. between alveoli and blood
iii. within the blood – transport from capillaries in the lungs to
capillaries in the systemic tissues and vice versa)
iv. between blood and cells
Internal respiration
= cellular respiration
i. Use of O2 by mitochondria in cells to produce ATP. CO2 is formed as a waste product of this process.
Homeostatic regulation of body pH
by retaining or releasing CO2 by decreasing or increasing respiratory rate.
↑ rate
– clears more CO2 and makes blood less acidic (more alkaline)
↓ rate
- allows CO2 to build up and makes blood more acidic.
Defends against microbes
- MUCOCILIARY ESCALATOR (mucus traps pathogens and beating cilia move the mucus toward the pharynx)
- resident alveolar macrophages phagocytize pathogens and debris in the alveoli.
Metabolic functions
modifies arterial concentrations of chemical messengers
removes and inactivates some messengers/enzymes
• E.g. ~30% of norepinephrine in venous blood is removed
in the lungs.
produces and activates others
• E.g. Angiotensin Converting Enzyme (ACE) produced in the lungs converts angiotensin I into angiotensin II (an important regulator of mean arterial pressure and water balance).
Vocalization
produced by moving air across the vocal cords in the larynx.
Sense of smell
requires inspiration so that scent molecules in the air can enter the nasal cavity and stimulate the olfactory receptors (free nerve endings) in the roof of the nasal cavity.
Respiratory System
consists of structures involved in ventilation of gas exchange
- CONDUCTING SYSTEMS of passages, or AIRWAYS…
- ALVEOLI (ALVEOLUS)…
- Bones & muscles of the thorax (chest cavity) & abdomen that assist in ventilation
Upper Respiratory Tract consists of the:
a. Nasal cavity
b. Mouth
c. Pharynx
d. Larynx
Nasal cavity
warms, humidifies, and filters (nasal hairs) air.
Mouth
alternative route for air entry from the atmosphere. Not as effective at warming/humidifying/filtering as breathing through the nose.
Pharynx
common passageway for food and air
Larynx
contains the vocal cords.
Lungs
- consist of light, spongy tissue whose volume is occupied mostly by air-filled spaces
Lungs
Located…
Located in thoracic cavity which is formed by the vertebral
column, rib cage and associated muscles including the muscles involved in breathing:
i. Diaphragm
ii. External intercostals
iii. Internal intercostals
iv. Sternocleidomastoids
v. Scalenes
Lungs
…associated muscles including the muscles involved in breathing:
i. Diaphragm
ii. External intercostals
iii. Internal intercostals
iv. Sternocleidomastoids
v. Scalenes
Lungs
Air enters the lungs via…
Air enters the lungs via the UPPER respiratory tract (mouth/nasal cavity, pharynx, larynx)) and the LOWER respiratory tract (trachea, bronchi, bronchioles)
Each lung is divided into lobes…
right lung 3 lobes, left lung 2 lobes.
Each lung is surrounded by…
a double layered membrane called the PLEURAL SAC.
Each lung is surrounded by a double layered membrane called the pleural sac. The two layers of the membrane are the:
i. visceral pleura
ii. Parietal pleura
Visceral pleura
INNER membrane attached to the SURFACE of the lung
Parietal pleura
OUTER membrane attached to the thoracic wall and diaphragm.
In between the two layers of the membrane (Visceral pleura & Parietal pleura) =
PLEURAL CAVITY, which is filled with a very thin layer of fluid that holds the visceral and parietal pleura close together (due to cohesive force of water molecules) and lubricates them during breathing
Pleural cavity
In between the two layers = pleural cavity, which is filled with a very thin layer of fluid that holds the visceral and parietal pleura close together (due to cohesive force of water molecules) and lubricates them during breathing.
Lower Respiratory tract
has ~ __ divisions of branches, starting with the…
23
trachea and ending at the alveoli.
(consists of: trachea, 2 primary bronchi, their branches, & the lungs)
Lower Respiratory tract
Each division of branches is…
narrower, thinner, shorter and more numerous than the one before it.
(therefore, TOTAL cross-sectional area INCREASES with each division of the airways)
Total cross-sectional area is ______ in the UPPER respiratory tract & greatest in the _______, analogous to the ______ in cross-sectional area that occurs from the aorta to the capillaries in the circulatory system
LOWEST
BRONCHIOLES
INCREASE
Velocity of air flow is ______ to total cross-sectional area of the airways
similar to the….
INVERSELY PROPORTIONAL
BF through diff. parts of the circulatory system, & means that the velocity of air flow is greatest in the upper airways & slowest in the terminal bronchioles
Lower Respiratory tract
Divided into
a. Conducting zone/Anatomical Dead Space
b. Respiratory zone
c. Respiratory membrane (0.2 – 0.5 µm thick)
Conducting zone/Anatomical Dead Space
i. trachea to primary bronchi, to secondary bronchi……etc. to bronchioles
ii. walls consist of cartilage, smooth muscle and elastic tissue (progressively less cartilage as you move closer to the bronchioles)
iii. Walls are lined by mucus-secreting ciliated epithelium – conditions the air by warming, humidifying, and filtering the air.
iv. Gases are transported in and out by bulk flow down pressure gradients (from areas of high pressure to areas of low pressure).
v. Total air volume in this area is ~ 150 mL – known as ANATOMICAL DEAD SPACE (becomes filled with air, but no gas exchange can take place here).
Mucus-secreting ciliated epithelium
conditions the air by warming, humidifying, and filtering the air.
(walls are lined by this)
Anatomical dead space
Total air volume in this area is ~ 150 mL – known as ANATOMICAL DEAD SPACE (becomes filled with air, but no gas exchange can take place here).
Bronchioles
within the lungs, the smallest bronchi branch to become BRONCHIOLES, small collapsible passageways with walls of smooth muscle
If you inspire 500 mL of air…
~150 ML of this will be lost to the anatomic dead space, and 350mL will reach the alveoli
Respiratory zone
Includes
Includes respiratory bronchioles, to alveolar ducts, to alveoli.
Respiratory zone
Walls are…
Walls are THIN and have NO cartilage and little (if any) smooth muscle. Walls of ALVEOLI have NO smooth muscle and are only ONE cell thick. Diameter of individual alveoli is ~0.25 mm.
Walls of alveoli have…
no smooth muscle and are only one cell thick.
Diameter of individual alveoli is…
~0.25 mm.
Respiratory zone
Provides
Provides huge, thin surface area, richly supplied with
capillaries to AID GAS EXCHANGE.
Respiratory zone
Elastin fibers between alveoli provide…
tensile strength and stretch/recoil properties - lungs can fill with air and stretch/expand).
Respiratory zone
Gasses move into alveoli by…
bulk flow and by diffusion. Alveoli are connected to one another by the PORES OF KOHN, which facilitate gas exchange between adjacent alveoli.
Pores of Kohn
Alveoli are connected to one another by the Pores of Kohn,
which facilitate gas exchange between adjacent alveoli.
Respiratory zone
At rest,…
post-inspiration air volume is ~3000 mL (it INCREASES when taking a deep breath, for example during exercise).
Respiratory membrane
(0.2 – 0.5 µm thick)
Site of gas exchange between lungs and blood
Respiratory membrane
is
3 layers (alveolar and capillary epithelia and their fused basement membrane):
Respiratory membrane
Wall of the alveolus made of 2 cell types:
1) Type 1 alveolar cells
2) Type II alveolar cells
Wall of the alveolus made of 2 cell types:
Type 1 alveolar cells
flattened (squamous) polyhedral cells that make up most of wall of alveolus; allow diffusion of gasses.
(v. thin so that gases can diffuse rapidly through them)
Resident ______ patrol the surface of Type-__ cells.
MACROPHAGES
1
Wall of the alveolus made of 2 cell types:
Type II alveolar cells
spherical cells
smaller, BUT thicker
Wall of the alveolus made of 2 cell types:
Type II alveolar cells
Spherical cells that:
secrete SURACTANT
reabsorb Na+ and H2O (prevents build up of water in alveoli)
- help minimize the amount of fluid present in the alveoli by transporting solutes, followed by water, out of the alveolar air space
Surfactant
chemical; mixes with the thin fluid lining of the alveoli to aid lungs as they expand during breathing
Respiratory membrane
3 things
i. Wall of the alveolus made of 2 cell types:
1) Type 1 alveolar cells
2) Type II alveolar cells
ii. Basement membrane
iii. Capillary wall – endothelium (flat simple squamous cells)
Basement membrane
in much of the exchange area; this layer fuses the alveolar epithelium to the capillary endothelium
Capillary wall
endothelium (flat simple squamous cells)
______ are the site of gas exchange (b/t themselves & the blood)
Alveoli
Thin walls of alveoli do NOT contain…
MUSCLE b/c muscle fibers would block rapid gas exchange
- therefore, lung tissue itself CANNOT contract
- however, CT b/t the alveolar epithelial cells contain many elastin & collagen fibers that create ELASTIC RECOIL when lung tissue is stretched
The proximity of capillary blood to alveolar air is essential for the…
RAPID exchange of gases
