Physiology: lecture 9 - respiratory system

• What is respiration?

• Name the 2 types

• Process of gas exchange

• Internal & External respiration

• What is internal respiration also known as?

• What is internal respiration the process of?

• where does internal respiration exchange occur between? (what 2 structures)
  
  

• Cellular respiration

• Making ATP

• Blood and tissue

• # of processes make up external respiration?

• the processes of external respiration?
  
  

• 3 processes

• Pulmonary ventilation, Exchange between lungs and blood, Transportation in blood

What is the main function ?

Respiration

What are the other functions besides respiration?

Regulating blood pH, Enabling vocalization, Defense against pathogens, Providing route for water & heat loss, Enhance venous return, Activating certain plasma proteins

What are the 3 primary components of anatomy?

1. Upper airways

2. Respiratory tract

3. Structures of the thoracic cavity

What does the upper airways consist of? (4 structures)

Air passages of the head and neck, Nasal cavities, Oral cavity, Pharynx

What is the pharynx?

Tube serving as a common passageway for food & air

• What is the respiratory tract?

• How many functional components does the respiratory tract have?

• What are they?
  
  

• All passageways leading from pharynx to lungs

• 2 functional components

• Conducting zone & respiratory zone

(what part & function)

• What is the conducting zone?

• What is the respiratory zone?
  

• Upper part; conducts air from larynx to lungs

• Lowermost part; Contains sites for gas exchange in lungs

• What is the conducting zone? (structure wise)

• How much air does the conducting zone hold?

• conduction zone is also called what? (aka)
  
  

• Tubes carrying air from outside to alveoli

• 150 ml

• respiratory dead zone

What are the characteristics of respiratory dead space? (2 of them)

No gas exchange, Relatively thick wall

What does the conducting zone do to air? (3 things)

Condition, Clean, and Humidify air

What two cells line the conducting zone?

1. Goblet cells

2. Ciliated cells

• What do goblet cells do?

• What do ciliated cells do?
  
  

• Secretes mucus & traps foreign particles

• Keeps airways clean by moving mucus up to be swallowed

What three tubes make up the conducting zone?

Trachea, Bronchi, Bronchioles

What are the tubes of the conducting zone lined with?

Smooth muscle

What does smooth muscle in the conducting zone allow?

Bronchodilation and bronchoconstriction

What are the tubes of the conducting zone ringed with?

Cartilage

• What does cartilage do for the tubes?

• When does cartilage disappear?
  
  

• Holds tubes open

• when bronchi become bronchioles

• What is the respiratory zone?

• the three main structures of the respiratory zone?
  
  

• Site of gas exchange in the lungs

• Respiratory bronchioles, Alveolar sacs, Alveoli

What do respiratory bronchioles connect to?

Terminal bronchioles from conducting zone

• What are alveolar sacs?

• How many alveoli are there?
  
  

• Clusters of alveoli

• 300,000,000

What is the primary structure for gas exchange?

Alveoli

• What can some alveoli do?

• How do alveoli connect to other alveoli?
  
  

• Open off respiratory bronchioles

• By alveolar pores

How many types of cells are found in each alveoli?

3

What are the 3 types of cells in each alveoli?

Type 1 alveolar cells, Type II alveolar cells, Alveolar macrophages

• What do Type 1 alveolar cells do?

• What do Type II alveolar cells produce?
  
  

• Structural cells and help with diffusion

• Surfactant

• What does surfactant do?

• What do alveolar macrophages do?
  
  

• Prevents alveolar collapse

• Phagocytize foreign particles and pathogens

What structures protect the lungs? (5 of them)

Rib cage, Sternum, Thoracic vertebrae, Associated muscles and connective tissue

What are the muscles of the thoracic cavity? (3 of em)

Internal intercostals, External intercostals, Diaphragm

What does the diaphragm do?

Seals off the thoracic cavity from the abdominal cavity

What is the thoracic cavity to all these structures?

Airtight from all these structures

What drives pulmonary ventilation?

Pressure gradients

• What happens during inspiration?

• What happens during expiration?
  
  

• Pressure in lungs less than atmospheric pressure

• Pressure in lungs greater than atmospheric pressure

• What is atmospheric pressure (Patm) at sea level?

• How are all other lung pressures expressed?

• What is atmospheric pressure set to?
  
  
  

• 760 mm Hg

• Relative to atmospheric pressure

• Patm = 0 mm Hg

• What is a pneumothorax?

• What are the types of pneumothorax? (2 of them)
  
  

• Collapsed or punctured lung

• Spontaneous or traumatic

What happens in a pneumothorax?

Air leaks into the space between lung & chest wall

Why does the lung collapse in a pneumothorax?

Increased pressure in thoracic cavity

• What is intra-alveolar pressure (Palv)?

• What is Palv during inspiration?

• What is Palv during expiration?
  
  
  

• Air pressure in alveoli

• Negative

• Positive

• What creates pressure gradients? (2 structures)

• What is resistance (R) mostly determined by?
  
  

• Diaphragm and intercostals

• Diameter of the alveoli

What type of muscle is the diaphragm?

Sheet-like skeletal muscle

• What happens to the diaphragm during expiration?

• What happens to the diaphragm during inspiration?
  
  

• Relaxed; Dome shaped w/ small thoracic cavity

• Contraction; Flattened w/ large thoracic cavity

What happens to inspiratory muscles to inhale?

Contract

What are the primary inspiratory muscles?

Diaphragm & external intercostals

What does contraction of inspiratory muscles result in?

Increased volume of thoracic cavity, Negative Palv

• What kind of process is expiration during relaxed breathing?

• What happens during active/heavy breathing expiration?
  
  

• Passive process

• Internal intercostals contract

What happens to fresh air as it enters the lungs?

Fresh air mixes with residual air

• What is anatomical dead space?

• How much is anatomical dead space?
  
  

• Air in conduction zone does not participate in gas exchange

• ~150 mL

• What is tidal volume (VT)?

• How much is tidal volume?
  
  

• Volume of air that moves into and out of the lungs during a single, unforced breath

• ~500 mL

• What is inspiratory reserve volume (IRV)?

• How much is inspiratory reserve volume?
  
  

• Maximum volume of air that can be inspired from the end of a normal inspiration
  

• ~3000 mL

• What is expiratory reserve volume (ERV)?

• How much is expiratory reserve volume?
  
  

• Maximum volume of air that can be expired from the end of a normal expiration
  

• ~1000 mL

• What is Vital Capacity (VC)?

• How much is vital capacity?
  
  

• Maximum volume of air that can be expired following a maximum inspiration
  

• ~4500 mL

How do O2 and CO2 move between alveolar air and blood?

Via diffusion across a concentration gradient

• What is the concentration relationship for O2?

• What is the concentration relationship for CO2?
  
  

• Alveolar O2 concentration > blood O2

• Blood CO2 concentration > alveolar CO2

What do rates of diffusion depend on? (3 of them)

Steepness of gradient, Surface area, Permeability

What happens with steeper gradients?

They result in faster diffusion

• What provides lots of surface area?

• What are cell membranes permeable to?
  
  

• Alveoli provides lots of surface area

• O2 and CO2

How is oxygen carried in the blood?

Bound to hemoglobin (Hb)

• How many O2 molecules does each Hb bind?

• What law does O2 binding to Hb follow?
  
  

• 4 O2 molecules in a rapid and reversible process

• Law of mass action

• What happens with more oxygen according to the law of mass action?

• How else is oxygen transported?
  
  

• More oxygen than more binding to Hb

• in the fluid plasma (~1.5%)

• What does low PO2 promote?

• What happens at capillaries?
  
  

• Release of O2 from Hb

• PO2 > tissues

• What is arterial blood?

• What is Hb saturation in arterial blood?

• How many binding sites of Hb are occupied in arterial blood?
  
  
  

• Blood leaving the lungs

• 97.5% saturated

• All 4 binding sites of Hb are occupied

• What is Hb saturation in blood leaving systemic capillaries?

• What happens to most O2 in blood leaving systemic capillaries?

• How many binding sites of Hb are occupied in blood leaving systemic capillaries?
  
  
  

• 75% saturated

• Most O2 is not exchanged but reserved

• Only 3 binding sites of Hb are occupied

What does the plateau of the oxyhemoglobin dissociation curve represent?

Safety margin

What does the steep part of the curve represent?

Storehouse of readily available O2 during exercise or emergency

What happens if cells use more O2?

More O2 will be delivered

What binds with Hb during CO poisoning?

Carbon Monoxide (CO)

What is CO's binding to Hb in direct competition with?

O2

What is Hb's affinity for CO compared to O2?

Much higher affinity for CO than for O2

• How much greater is Hb's affinity for CO?

• What happens when CO binds with Hb?

• What can result from CO binding with Hb?
  
  
  

• 200-300x greater than O2

• does not release (locked)

• Can be lethal

In how many forms is CO2 transported in blood?

3 forms

• What percent of CO2 is dissolved in plasma?

• What percent of CO2 is chemically bound to Hb?

• What percent of CO2 is bicarbonate ion in plasma?
  
  
  

• ~7%

• ~20%

• ~70%

What does CO2 combine with in RBCs?

H2O to form carbonic acid

What does carbonic acid quickly dissociate into?

H+ and bicarbonate ions

Why do RBCs form bicarbonate fast?

bc of carbonic anhydrase

• What splits carbonic acid at the lungs?

• What does splitting carbonic acid release?
  
  

• Carbonic anhydrase

• CO2 and water

Where does CO2 diffuse to at the lungs?

From the blood into the alveoli

• What does this system do to blood pH changes?

• What is the normal pH range?
  
  

• Resists blood pH changes

• 7.35 – 7.45

What happens if H+ in blood begins to rise?

Excess H+ is removed by combining with bicarbonate ions

What happens if H+ begins to drop?

Carbonic acid dissociates, releasing H+

Where does direct/indirect control of ventilation come from?

Chemoreceptors

What do chemoreceptors have direct contact with?

Arterial blood

• What changes are the primary stimuli for changes in ventilation under normal conditions?

• What do chemoreceptors respond mainly to?
  
  

• Changes in arterial PCO2

• Changes to blood pH

• What may changes to blood pH come from?

• How important are O2 levels for regulation of respiration?
  
  

• CO2 or other sources like lactic acid

• Not very important

When are receptors sensitive to O2?

Only sensitive when it drops to very low levels

What does quiet breathing require?

Only inspiratory muscle contraction

• What signals the diaphragm?

• What signals the intercostal muscles?
  
  

• Phrenic nerve

• Intercostal nerves

What type of muscles are respiratory muscles?

Skeletal muscles

What contains the respiratory centers?

The brainstem

• How many classes of neurons are there?

• What are the classes of neurons?
  
  

• 2 classes of neurons

• Inspiratory neurons, Expiratory neurons

• When do inspiratory neurons depolarize?

• When do expiratory neurons depolarize?
  
  

• During inspiration

• During expiration

• Where in the brainstem are the respiratory centers located?

• How many centers are located on each side?
  
  

• In the medulla

• 2 centers

• What is the Ventral respiratory group (VRG)?

• What is the Dorsal respiratory group (DRG)?
  
  

• Both neuron classes

• Only inspiratory

• What is smoker's cough?

• What causes smoker's cough?

• What does smoker's cough do to lungs?
  
  
  

• A persistent, often phlegm-filled cough

• Toxins in tobacco and vape smoke

• Damages lungs and can paralyze cilia

• What are glass lungs?

• What causes glass lungs?
  
  

• Hazy, grey patches on a CT scan indicating inflammation, fluid, or damage

• Caused by E-cigarettes or Vaping-Associated Lung Injury (EVALI)