ANSC 300 Respiratory System

Functions of the Respiratory Tract

1. Exchange of gases

2. Respiratory pump

3. Regulation of body pH

4. Protection from inhaled pathogens/foreign objects

5. Vocalization

6. Water & heat exchange

   • inhale: warm/humidified

   • exhale: cool/water

Ventilation and Respiration are Not the Same Thing.

True

Ventilation

mechanics of breathing

Respiration

exchange of gases between and animal and its environment

Upper Respiratory Tract

• nasal cavity

• pharynx

• larynx

Lower Respiratory Tract

• trachea

• primary bronchi

• lungs

Concha

mucosa-covered turbinate bones

Epiglottis & Vocal Chords

• epiglottis: prevents the entrance of food into the trachea

• phonation: sound production

• located in the upper respiratory tract: larynx

Trachea

cartilage rings incomplete

Bronchi Split into ______ ______

primary bronchi

Bronchioles

smallest airway division

Alveoli

• single layer of epithelium

• key site of gas exchange = smallest functioning unit of the respiratory tract

• Type 1: Gas Echange

• Type 2: Secrete Surfactant

Each Branch of the Airway is Called a ________

generation

Why does the Cross-Sectional Area (CSA) Increase with each Generation?

1. Decreased Velocity = better exchange at capillaries

2. Decreased Pressure = protects small vessels

3. Increased Surface Area = increased efficiency of diffusion

4. Increased Volume Capacity = stabilized blood flow

The Number of Lobes can Vary By Species

L = 2

R = 3/4

Thoracic Cavity

• lungs and heart

• the pleura lines the chambers

  • visceral: inner layer, moves with the lungs during breathing

  • parietal: outer layer, lines the inside of the chest wall

• Mediastinal Space: the space between pleural cavities

Pleura

• allow for almost friction free movement of the lungs

• made of connective tissue

• 25-30 mL in a 70 kg man

• important for “sticking” the lungs to the thoracic cavity

Respiratory Cycle

• includes 1 inhale and 1 exhale

• actuated by vacuum

• Inspiration

  • pressure drops

  • muscle contraction

    • intercostals, 25-40%

    • diaphragm, 60-75%

• Expiration

  • typically passive

  • active expiration: during exercise or forced breathing

During INSPIRATION, the Volume of the Thoracic Cavity (and Thus the Lungs) will Decrease.

False

Boyle’s Law

states that the pressure of a gas is inversely proportional to its volume

Dead Space Ventilation

occurs when there is no gas exchange of O2 and CO2 across a membrane

• anatomical dead space: nose, pharynx, trachea, bronchioles

• functional dead space: alveoli

Respiratory Frequency

• body size

• age

• exercise

• excitement

• environmental temperature

• health status

• pregnancy

• filling of GI tract

***Cows have a high range of bmp at rest***

Lung Capacity

is the sum of 2 or more lung volumes

Air

is a mixture of gases; we use partial pressures when talking about O2 and CO2

Fick’s Law

• gases diffuses down a concentration gradient

• important for understanding how CO2 and O2 diffuse through the body

CO2 is _____ _____ ______ in Water than O2.

20x more soluble

Hemoglobin carries ____

O2

• oxyhemoglobin (HbO2)

O2 Carrying Capacity with Hb

200 mL O2/L Blood

O2 Carry Capacity without Hb

3 mL O2/L Blood

Oxyhemoglobin Dissociation Curve

shows the saturation of hemoglobin with O2

• PO2 40 mm Hg = 72% saturation

What are the 3 Ways CO2 is Transported?

1. Dissolved in plasma (7%)

2. Converted to bicarbonate (70%)

3. Bound to hemoglobin (23%)

Carbon Dioxide Transport

from tissues and get removed at the lungs

Oxygen → Carbon Dioxide

Neutral & Humoral Controls Over Breathing

• Carotid Receptors: primary chemoreceptors; highly sensitive to changes in oxygen concentration

• Aortic Receptors: less sensitive; detect changes in more stuff than carotid receptors

Respiratory Clearance

• the removal of harmful particles that been inhaled

• Deposition affected by:

  • inertia: large particles like pollen tend to get stuck in the nose and throat when airflow changes direction quickly

  • sedimentation: medium-sized particles settle out due to gravity, usually in the bronchi and bronchioles

  • brownian motion: tiniest particles move randomly and can reach the deepest part of the lungs (alveoli)

• Upper Resp. Clearance: moving mucous blanket

• Alveolar Clearance:

  • phagocytosis → macrophages

  • dissolve

  • transported to lymph

  • sequestered