A&P test 3

What is the major function of the respiratory system?

Respiration

• Supply body’s tissues with oxygen

• Remove CO2 from body

What are the 3 secondary functions of the respiratory system?

• Allows for speech (nasal cavity serves as a resonance chamber for sound)

• Sense of smell

• Immune system (mucus)

What are the four processes of respiration?

• Pulmonary ventilation

• External respiration

• Internal respiration

• Transport

Pulmonary ventilation

Bulk movement of air in and out of lungs

What must occur for pulmonary ventilation to occur?

A change in pressure

External respiration

• breathing/gas exchange

• the process where O2 diffuses from the lungs into the blood and CO2 diffuses from the blood into the lungs

Transport

the movement of oxygen and carbon dioxide within the body, primarily through the bloodstream, to facilitate gas exchange between the lungs and tissue

Internal respiration

the exchange of gases (oxygen and carbon dioxide) between the blood and the body's tissues

Conducting Zone vs Respiratory Zone

Conducting zone: pipes that supply air; NO gas exchange

Respiratory zone: location where gas exchange occurs

4 functions of the nasal cavity

• Moistens air

  • Adds H2O to the air by the epithelial cells secreting H2O

• Smell (olfactory receptors)

• Resonance chamber for sound

• Mucus, nose hairs, and cilia on cells will help filter and clear air that will help destroy viruses

What is the pharynx?

Throat (muscular tube) that serves as a passageway for air and food

Where is the larynx located?

At the top of the trachea

3 functions of the larynx

• Prevents food from going down trachea

  • Epiglottis

• Responsible for voice production

  • Vocal chords made of bands of cartilage

• Aids in breathing

Glottis function

Traps air in lungs

• Example: lifting up something heavy and you intake air and hold it and clench your core — this helps during lifting something

Laryngitis

Swelling of larynx

• can be caused by excessive use of vocal chords or from infection

1

Lumen of trachea

2

Trachealis muscle

3

Espophagus

4

Mucosa

What is the mucosal layer of the trachea?

Ciliated epithelial cells that use a “sweeping” motion to move gunk out of our lungs

• long-term smoking causes peristalsis of the ciliated mucosal cells

5

Submucosa

What is the submucosal layer of the trachea?

Contains glands that secrete mucus that aid in protection

6

Serous mucous gland in submucosa

7

Hyaline cartilage

What is hyaline cartilage in the trachea?

Rings of cartilage that covers and protects the front of the trachea

8

Adventitia

What is the adventitia of the trachea?

Outer layer of connective tissue

What are the 5 parts of the conducting zone?

1. Larynx

2. trachea

3. Bronchi (1, 2, 3, smaller)

4. Bronchioles

5. Terminal bronchioles

Deeper into the conducting zone, the inner diameter…

Decreases

Deeper into the conducting zone, the # of ciliated cells… because…

Decreases because in smaller tubes the cilia could block them

Deeper into the conducting zone, the # of goblet cells…because…

Decrease because they secrete mucus, which will cause clogging in the smaller tubes

Deeper into the conducting zone, the amount of cartilage…because…

Decreases because protection isn’t needed that far down

Deeper into the conducting zone, smooth muscle…

Increases — regulates diameter of tube

What are respiratory bronchioles made of?

Alveoli

Why is it important to have many alveoli?

More alveoli creates more surface area, allowing for increased gas exchange

• Increased SA = more capillaries for more gas exchange

What do capillaries on the outside of alveoli allow for?

Allows for O2 and CO2 exchange

What are the three factors that make gas exchange so efficient?

1. Huge surface area — many alveoli

2. Vast blood supply — many capillaries

3. Thin respiratory membrane

Type I cell (pneumocyte I) function

facilitate gas exchange in the lungs by forming the thin air-blood barrier in the alveoli

Type II cell (pneumocyte II) function

Secretes surfactant

Function of surfactant

• helps the lungs stay inflated by reducing surface tension

• secretes a protein/lipid mix to prevent alveoli collapsing in on each other

Surface tension

Attraction of liquid molecules to one another at a gas-liquid interface

• produces surface tension

• Water attracts water by hydrogen bonds

• Results in the alveoli pulling together

T/F: The respiratory zone has abundant amounts of mucus

producing cells

False

As you move deeper into the conducting zone the amount of smooth muscle

a. Increases

b. Decreases

c. Does not change

a - increases

The type of alveolar cell that prevents the formation of hydrogen bonding of water molecules on the alveolar surface are

a. macrophages

b. Type 1 pneumocytes

c. Type 2 pneumocytes

c. Type 2 pneumocytes

What are the membrane layers of the lungs (external to internal)?

1. Parietal membrane (connected to the chest wall)

2. Pleural cavity (between parietal and visceral membranes; interpleural pressure)

3. Visceral membrane (contact with the external surface of the lungs)

What are the 3 types of pressure in the lungs?

1. Intrapleural pressure

2. Intrapulmonary/intra-alveolar pressure

3. Trans pulmonary pressure

Interpleural pressure

Pressure in the pleural cavity of the lungs

• Always negative pressure

• Pressure that prevents lungs from collapsing in or pushing out

• Fluctuates with breathing

Intrapulmonary (intra-alveolar) pressure (IAP)

• The pressure of air within the alveoli of the lungs

• Right after inhalation, but before exhalation

• Fluctuate with breathing — contracting diaphragm

Why does contracting the diaphragm cause a change in intra-alveolar pressure?

• Diaphragm contracting makes the size of the lungs bigger. If the size of your lungs becomes bigger, pressure is going to decrease (lower pressure in lungs than outside of lungs)

• When your relax your diaphragm and your lungs get smaller, the pressure increases and is higher than outside of lungs

Trans pulmonary pressure

Difference between intra-alveolar pressure and intrapleural pressure

• will always be positive because subtracting a negative number (intrapleural pressure is always negative) makes a positive number

• The larger your inhalation is, the higher the transpulmonary pressure is

• Indication of how much air we have intaken

To pull air into our lungs, we need to ____ IAP because…

To pull air into our lungs, we need to decrease IAP because pressure drives flow

What will IAP always return to?

0 mm Hg (relative to ATM)

• equalizes with pressure of atmosphere (P_atm)

How is negative intrapleural pressure established?

• Anatomy — parietal membrane, visceral membrane, and pleural cavity (fluid filled)

• Natural tendencies for…

  • Chest wall to recoil outward

  • Lungs to recoil inward

Pneumothorax

Loss of negative intrapleural pressure

• usually due to trauma

What are the 2 phases of ventilation?

Inspiration: gases flow into lungs

Expiration: gases exit lungs

Volume changes lead to _____ changes, which leads to…

Volume changes lead to pressure changes, which leads to gas flows to equalize pressure

Boyles law

Pressure varies inversely of volume

• inhalation (more air) = decreased pressure (because larger cavity)

Sequence of events for inspiration (5)

1. Inspiratory muscles contract (diaphragm descends and rib cage rises)

2. Thoracic cavity volume increases

3. Lungs stretch; Intrapulmonary volume increases

4. Intrapulmonary pressure drops (to -1 mm Hg)

5. Air flows into lungs down its pressure gradient until intrapulmonary pressure is 0 (equal to P_atm)

Sequence of events for expiration (5)

1. Inspiratory muscles relax (diaphragm rises and rib cage descends due to recoil of costal cartilages)

2. Thoracic cavity volume decreases

3. Elastic lungs recoil passively; Intrapulmonary volume decreases

4. Intrapulmonary pressure rises (to +1 mm Hg)

5. Air flows out of lungs down its pressure gradient until intrapulmonary pressure is 0 (equal to P_atm)

What does a graph for the intra-alveolar pressure look like? Why does it look like that? What about breath volume?

The IAP is curved like that because the alveoli will change their size before intaking/expelling air

Relationship (equation) between flow (F), pressure (P), and resistance (R)

Flow has an inverse relationship with resistance

How does ΔP change (via physical mechanisms)?

ΔP changes due to respiratory muscles changing lung size

How does resistance change?

Decrease in flow (rate of which air goes into/leaves the lungs) and/or ΔP

Is bronchiolar smooth muscle wired to the PNS or ANS?

PNS

Bronchoconstriction vs bronchodilation

Bronchoconstriction: contraction of smooth muscles in bronchi, making the airway smaller

Bronchodilation: dilation of smooth muscles in bronchi, making the airway larger

What 2 controls impact the contractile states of bronchiolar smooth muscle?

Extrinsic controls

Intrinsic controls

Extrinsic vs Intrinsic controls

Extrinsic — whole body control (nervous system)

Intrinsic — local control/autoregulation

Extrinsic control factors (2)

• SNS

• Hormones

Intrinsic control factors (2)

• CO2

• Histamine

What two factors cause bronchodilation?

• Extrinsic: SNS activation causes release of epinephrine

• Intrinsic: CO2 increase

What two factors cause bronchoconstriction?

• Extrinsic: PNS activation causes release of acetecholine

• Intrinsic: increase in histamine release (from cells in lungs)

Bronchodilation control factors (extrinsic control) (2)

• SNS activation (i.e., bear chasing you)

• Extrinsic hormone release

How does extrinsic hormone release occur with bronchodilation?

SNS activation acts on the adrenal gland to release epinephrine, while goes to the bronchioles and causes bronchodilation

Bronchoconstriction control factors (extrinsic control) (1)

• Regulated by PNS activation

  • PNS innervates bronchiolar smooth muscle, causing bronchoconstriction

Acute asthma cause

Caused by spastic contractions of bronchiolar smooth muscle

Triggers for asthma (3)

• Cold air

• Allergens

• Sickness

3 methods to help with asthma

• Inhaler

• Flo-vent

• Medications that are acetecholine inhibitors

How does an inhaler work?

It contains albuterol, which is a Beta2 agonist, acting like epinephrine to bind to Beta2 receptors. This results in SNS activation, and therefore bronchodilation

Chronic obstructive pulmonary disease (COPD)

Long lasting airway obstruction

Examples of COPD (2)

• Chronic bronchitis

• Emphyzema

What are COPDs usually caused by?

Smoking and airborne pollution + toxins

The pressure that is always less than atmospheric pressure is:

a. Intrapulomonary or Intra-alveolar pressure

b. Intrapleural pressure

c. Transpulmonary pressure

b. Intrapleural pressure — always negative

Inhaling a beta 2 agonist would result in:

a. Bronchodilation

b. Bronchoconstriction

a. Bronchodilation — acts like epinephrine

Inhaling an acetylcholine antagonist would result in:

a. Broncho-dilation

b. Broncho-constriction

c. No change

a. Bronchodilation

• Ach antagonists inhibit the action of Ach, resulting in bronchodilation (since Ach causes bronchoconstriction)

Tidal volume

Volume of air that you breathe in during one respiratory cycle

Minute ventilation

• Total air moved into and out of your lungs over a minute

• Tidal volume x respiratory rate = minute ventilation

Respiratory rate

Number of breaths per minute

Anatomic dead space

• Dead space in the conducting zone

  • Air in these tubes are not involved in respiration

• Respiration is NOT happening in the dead space

Alveolar ventilation

The volume of air that reaches the alveoli in the lungs for gas exchange per minute

External respiration location

occurs at alveoli

Internal respiration location

Occurs at the level of the cells and tissues

Gases diffuse ____ their own ____ ____

Gases diffuse down their own pressure gradient

Capillaries around alveoli have a ___ O2 gradient, and a ___ CO2 gradient. This means that O2 will ____ the alveolar capillaries, and CO2 will ___ the alveolar capillaries.

Capillaries around alveoli have a low O2 gradient, and a high CO2 gradient. This means that O2 will enter the alveolar capillaries, and CO2 will exit the alveolar capillaries.

At sea level, ATM pressure is 760 mm Hg . At the top of Mt. Everest, ATM pressure is only 250 mm Hg. Given that the air in both places is 21% oxygen, what is the partial pressure of oxygen at the top of Mt. Everest?

250 × 0.21 = 52.2

Henry’s Law

Describes how much gas will dissolve in a liquid

3 features of Henry’s law

• Each gas dissolves in proportion to its partial pressure

• At equilibrium, partial pressures in gas and liquid phases will be equal

• Amount of each gas that dissolves depends on solubility of the molecule

Is CO2 or O2 more soluble in blood? Why is this and what does this mean?

• CO2

• CO2 interacts more with water than O2 does, making it more soluble in blood

• Means that CO2 doesn’t need as much of a pressure gradient (in alveoli) to make the CO2 leave the capillaries

  • Easier for CO2 to go from gas to liquid, and visa versa

SLIDES 9-11 — RESPIRATORY SYSTEM, LECTURE B (watch video)!

What 3 factors make external respiration very efficient?

1. Many capillaries surrounding alveoli

2. Thin respiratory membrane

3. Vast surface area because of alveolar number and shape