Lecture 16 Flashcards
To produce ATP, you need
Oxygen
Oxygen accounts for how much of the air that surrounds us?
~21% (1/5th)
How much air in a normal breath
500ml
When we inhale, oxygen gets into lungs, some o2 molecules in that air diffuse into blood passing through lungs, once in the blood, oxygen molecules do what
Enter RBC and bind to hemoglobin proteins (blood leaving lungs is now oxygenated)
Oxygenated blood from lungs returns where
To heart to be pumped out to rest of body
The process of cellular respiration produce what
Significant amount of carbon dioxyde as a waste product
Our cells constantly produce this bc of cellular respiration
CO2
The co2 produced by cell enters nearby blood vessel, transported back to heart,
Pumped out to lungs, diffuses out of blood and exhaled into atmosphere
Why is it important to get rid of co2
Bc reacts with water to create carbonic acid-> too much decreases pH and put in state of acidosis (potentially lead to death)
Respiratory syst main functions
- Provide oxygen to blood for transport in body
- Removes co2 from blood
Secondary respiratory syst functions
- Olfaction (olfactory receptors for smell)
- Speech (verbal communication)
- Helps control pH balance (breathing air)
- Excretion of some moisture/heat (water/temp regulation)
- Filters, warms and moistens air
Upper respiratory tract (nose) consists of
External visible and internal portion inside skull
Nose external portion lined with
Epithelium and hairs
Internal portion of nose contains
Tissues lined with mucous membrane containing ciliated epithelium
Role of internal portion tissue of nose
- Filters air
- Warming air
- Moistens air
- Detects smell
- Modify speech sounds
Air enters nostrils, dust trapped by hair, air flows over areas lined with highly folded/vascukarized muc membranes, blood in vessels warms air, mucus aids in moistening air/trapping dust, and cilia…
Moves dust and mucus DOWN to pharynx to be swallowed
How does nose detect smell
Olfactory receptors in nose connects to nervous system
Pharynx
- Passageway for food and air
- Resonating chamber for sounds
- Houses tonsils (lymphatic tissue for immune response)
Pharynx 3 subdivisions
- Nasopharynx
- Oropharynx
- Laryngopharynx
Nasopharynx
Upper part of pharynx lined with cilia that moves dust and mucus to mouth
Oropharynx
Middle part of pharynx, opens into mouth on one end, contains 2 pairs of tonsils
Laryngopharynx
Lowest part of pharynx, connects to esophagus and larynx
Larynx is a short tube of
Cartilage lined by mucous membrane and connects laryngopharynx eith trachea
Voice production mechanism (by larynx)
Vocal cords in larynx vibrate due to air from lungs blowing past, vibration creates sound
Ventral wall of larynx consists of
Thyroid cartilage (adam’s apple bc bigger in male bc of testosterone at puberty)
Dorsal from thryroid cartilage in larynx is
Epiglottis (cartilage covered in epithelium), prevents food from entering larynx from laryngopharynx
Food and liquid only go in esophagus or else
Chocking occurs (cough reflex)
Swallowing mechanism
Laryngopharynx and larynx rise -> elevation causes epiglottis to close over it
Trachea extends from
Larynx to primary bronchi
Function of trachae
Transport air to left and right bronchi
Trachea made of
Walls lined with ciliated epithilium and mucous-secreting cells, supported by cartilage
Tracheal cilia moves dust in what direction
UP toward pharynx
16-20 C shaped rings of cartilage in trachea open dorsally facing esophagus for it to
Expand during swallowing
How do trachea 16-20 rings remain open without collapsing
Cartilage provides rigidity necessary
What lines nasal cavity/superior portion of pharynx/trachea/bronchi/large bronchioles
Pseudostratified ciliated columnar epithilum
Cilia of epithelium in trachea does what
Sweep debris away from lungs and back in throat to be swallowed
R and L (primary) bronchi composition
Surrounded by cartilage rings and made of ciliated epithelium
Primary bronchi branch into secondary bronchi (one for each lobe) describe the lobes
Right lung has 3 lobes -> 3 sec bronchi
Left lung has 2 lobes -> 2 sec bronchi
Lobar bronchi divide into
Tertiary bronchi, then bronchioles, then terminal bronchioles
As bronchi get smaller, cartilage rings become plates and smooth muscle nb in tube increases. Eventually,
Bronchi subdivide in very small bronchioles -> lack cartilage. Those subdivide and terminate on alveolar sacs (consist of many alveoli)
Alveolus is
Functional unit of lung where gas exchange is performed between air and blood
Air from terminal bronchiole subdivides into
A few respiratory bronchioles
Each respiratory bronchioles bring air to
Alveolar sac via alveolar ducts (consists of several alveoli)
Each alveolus is surrounded by its own____ which allows ____
Capillary bed, gas exchange across thin alveolar walls
The walls of alveolus is
Extremely thin to enable gas exchange
O2 and co2 cross plasma membrane(cells) of alveolar walls and cells of capillaries by
Simple diffusion
Each alveolus consists of
- Pneumocytes type I
- Pneumocytes type II
- Alveolar macrophages
- Extensive network of pulmonary capillaries
Pneumocytes type I/alveolar cells
For gas exchange, thin squamous epithelial cells, line alveolar wall
Pneumocytes type II/surfactant-secreting cells
Secrete surfactant (alveolar fluid) -> contains phospholipids and prots. Coats thin layer of water that lines inside of alveoli.
Water is absolutely necessary for gas exchange bc
Gases must dissolve in fluid before diffuse across membrane
Surfactant prevents what by reducing formation of H-bonds between h2o molecules
Alveolar collapse and lowers energy needed to inflate lungs during respiration
Alveolar macrophages
From immune system, phagocytes moving around inside alveoli to remove dust and debris from them
Around each alveolus is
And extensive network of pulmonary capillaries
What is surfactant
Mixture of proteins and phospholipids that type II alveolar cells form
Functions of surfactant
- Reding surface tension
- Keeping alveoli open
- Modulating immune response
Surfactant reduces surface tension
Prevents alveolar collapse at end of exhalation
Surfactant keeps alveoli open
Keeps alveoli dry, clean, open
Surfactant modulates immune response
Interacts and kills pathogens/prevents their spread
Respiratory membrane size
Very thin, 0,5 um thick, ~1/16 diameter of RBC for rapid diffusion of gases
Respiratory membrane kocation
From alveolar space to blood plasma
4 layers of respiratory membrane
- Type I alveolar cells (type II and associated macrophages) -> alveolar wall
- Epithelial basement membrane (underlies alveolar wall)
- Capillary basement membrane (often fused to epithelial basement)
- Capillary endothelium
A basement membrane is a
Layer of connective tissue
Right lung has a greater
Volume than left lung (10% bigger)
Left lung has indentation called
Cardiac notch, on medial surface for apex of heart
Lobes if lungs are separated by
Fissures
Oblique fissures in left lung
Divides it into superior and inferior lobes
Oblique and horizontal fissures divide right lung into
Superior, middle and inferior lobes
Each lung is surrounded by
Double-layered pleural membranes
Outer layer of pleural membrane
Parietal pleural: lines ribcage,attach to wall of thoracic cavity and diaphragm to cover diaphragm upper surface
Inner layer of pleural membranes
Visceral pleura: attached to/covers lungs
In between double-layered pleural membranes
Pleural cavity (contains fluid secreted by membranes)
Function of fluid in pleural cavity
Reduce friction between membranes during breathing
What is respiratory distress syndrome (RDS)
Breathing disorder in premature newborns where alveoli doesn’t remain open bc lack of surfactant
RDS surface tension of alveolar fluid greatly increased so
Many alveoli collapse at end of exhalation. Great effort is needed at next inhalation to reopen it
The more premature newborn, the more risk of
RDS
Symptoms of RDS
Laboured and irregular breathing, nostrils flaring while inhaling, grunting while exhaling, blue skin color
In mild RDS, supplemental o2 administered through
Oxygen hood or tube in nose
In severe RDS, O2 administered in
Continuous positive airway pressure through tubes in nostrils or face mask, surfactant administered directly to lungs
