RESPIRATORY SYSTEM

RESPIRATORY SYSTEM

Consists of nose, pharynx, larynx, trachea, bronchi, and lungs.

Functional Division of the Respi System

•  divided into the conducting zone and respiratory zone.

Structural division of the respi system

• divided into the upper and lower respiratory system

Upper respiratory system

Nose, nasal cavity, pharynx, and associated structures

Lower respiratory system

larynx, trachea, bronchi, lungs

Conducting zone

• Consists of a series of interconnecting cavities and tubes both outside and within the lungs. 

• These include the nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles;

• their function is to filter, warm, and moisten air and conduct it into the lungs.

Respiratory Zone

• Consists of tubes and tissues within the lungs where gas exchange occurs. 

• These include the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, and are the main sites of gas exchange between air and blood

• Provides for gas exchange: intake of O2 for delivery to body cells and removal of CO2 produced by body cells

• Helps regulate blood pH

• Contains receptors for the sense of smell, filters inspired air, produces vocal sounds (phonation), and excretes small amounts of water and heat.

What are the functions of the respiratory system?

Nose

• Consists of a visible external portion and an internal portion inside the skull called the nasal cavity.

• The external nose is the portion of the nose visible on the face and consists of a supporting framework of bone and hyaline cartilage covered with muscle and skin and lined by a mucous membrane.

Pharynx

• Throat

• Funnel-shaped tube that starts at the internal nares and extends to the level of the cricoid cartilage, the most inferior cartilage of the larynx

Larynx

• Voice box

• Short passageway that connects the laryngopharynx with the trachea. 

• It lies in the midline of the neck anterior to the esophagus and the fourth through sixth cervical vertebrae

Trachea

• Located anterior to the esophagus and extends from the larynx to the superior border of the fifth thoracic vertebra

• Divides into right and left primary bronchi

Bronchi

• Superior border of 5th thoracic vertebra

• Divides into right and left primary bronchus

• Divides into lobar bronchi

• Continues to branch into the segmental bronchi

• Divides into bronchioles then into terminal bronchioles

Alveoli

• Cup-shaped out-pouching lined by simple squamous epithelium and supported by a thin elastic basement membrane

• An alveolar sac consists of two or more alveoli that share a common opening

1. Pulmonary ventilation

2. External (pulmonary) respiration

3. Internal (tissue) respiration

What are the basic steps of respiration?

Pulmonary ventilation

• Moving air in and out of lungs

External (pulmonary) respiration

• Gas exchange between alveoli and blood

• Pulmonary capillary blood gains O2 and loses CO2.

Internal (tissue) respiration

• Gas exchange between blood and cells

• Blood loses O2 and gains CO2

Inhalation

• Inspiration/ Breathing in

• For air to flow into the lungs, the pressure inside the alveoli must become lower than the atmospheric pressure.

• Increases size of lungs

• Primary: Diaphragm, External Intercostal

• Accessory: Scalenes, SCM, Upper Trapezius, Pectoralis Major/Minor 

Exhalation

• Expiration/ Breathing out

• The pressure in the lungs is greater than the pressure of the atmosphere

• Normal exhalation during quiet breathing, unlike inhalation, is a process because no muscular contractions are involved

• Results from elastic recoil of the chest wall and lungs

• Primary: Passive recoil

Accessory: Abdominalis, Internal intercostals

THORACIC CAGE MECHANISM

• Movement of the ribcage

Pump Handle Motion

• Sternum and Ribs 1-6

• Superior/anterior (inhalation)

• Inferior/posterior (exhalation)

Bucket Handle Motion:

 Ribs 7-10

• lateral/superior (inhalation)

• medial/inferior (exhalation)

Caliper motion

Ribs 8-12

• lateral (inhalation)

• medial (exhalation)

1. surface tension of alveolar fluid

2. compliance of the lungs

3. airway resistance

What are the factors affecting pulmonary ventilation?

Surface tension of Alveolar Fluid

• Coats the luminal surface of alveoli and exerts a force known as surface tension.

Compliance of the Lungs

• How much effort is required to stretch the lungs and chest wall 

• High = expand easily

• Low = resist expansion

Airway Resistance

Rate of airflow through the airways depends on both the pressure difference and the resistance

Tidal Volume

• Volume of air inspired or expired with each normal breath

• about 500 milliliters in the adult male

Inspiratory reserve volume

• extra volume of air that can be inspired over and above the normal tidal volume when the person inspires with full force; 

• about 3000 ml

Expiratory reserve volume

• Maximum extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration; 

• about 1100 ml

Residual volume

• volume of air remaining in the lungs after the most forceful expiration

• about 1200 ml

Inspiratory capacity

• Amount of air a person can breathe in, beginning at the normal expiratory level and distending the lungs to the maximum amount

• about 3500 ml

Functional residual capacity

•  Air that remains in the lungs at the end of normal expiration

• about 2300 ml

Vital Capacity

• Maximum amount of air a person can expel from the lungs after first filling the lungs to their maximum extent and then expiring to the maximum extent

• about 4600 ml

Total lung capacity

• maximum volume to which the lungs can be expanded with the greatest possible effort

• about 5800 ml

Pleural pressure

• “Intrapleural pressure”

• the pressure of the fluid in the thin space between the lung pleura and the chest wall pleura. 

• This is normally a slight suction, which means a slightly negative pressure. 

• The normal pleural pressure at the beginning of inspiration is about -5 centimeters of water,which is the amount of suction required to hold the lungs open to their resting level.

Alveolar pressure

• Intrapulmonic pressure”

• the pressure of the air inside the lung alveoli.

• When the glottis is open and no air is flowing into or out of the lungs, the pressures in all parts of the respiratory tree, all the way to the alveoli, are equal to atmospheric pressure, which is considered to be zero reference pressure in the airways that is, 0 centimeters water pressure.

Transpulmonary pressure

• the difference between the alveolar pressure and the pleural pressure

•  measure of the elastic forces in the lungs that tend to collapse the lungs at each instant of respiration, called the recoil pressure.

OXYGEN TRANSPORT

Transported from the lungs to peripheral tissues by the hemoglobin that is densely packed in our red blood cells.

RELATIONSHIP BETWEEN HEMOGLOBIN AND O2 PARTIAL PRESSURE

• The more oxygen partial pressure (PO2), the more oxygen combines with Hemoglobin (Hb). 

Dissolved CO2

The smallest percentage about 7% is dissolved in blood plasma. On reaching the lungs, it diffuses into alveolar air and is exhaled.

Carbamino compounds

• A somewhat higher percentage, about 23%, combines with the amino groups of amino acids and proteins in the blood to form carbamino compounds

Bicarbonate ions

• The greatest percentage of CO2– about 70%- is transported in blood plasma as bicarbonate ions. 

• CO2 diffuses into systemic capillaries and enters red blood cells, it reacts with water in the presence of the enzyme carbonic anhydrase to form carbonic acid, which dissociates into H+ and HCO3

Dorsal root ganglion

•  previously known as “inspiratory area”

  • For inspiration

  • Location: Dorsal Medulla (Nucleus Tractus Solitarius)

  • Responsible for inspiratory ramp signal

    • 2 seconds on 

    • 3 seconds off

Ventral root ganglion

• formerly known as “expiratory area”

  • for expiration and inspiration, but its mainly for expiration

  • Location: Ventrolateral Medulla

PONTINE RESPIRATORY GROUP

• Pneumotaxic center

• Apneustic Center

Pneumotaxic center

• limits inspiration by switching off the inspiratory ramp signal

• Location: Upper  pons

• Controls rate and depth of breathing

• Controls inspiratory time

Apneustic Center

• Prolongs inspiration by preventing the switching off the inspiratory ramp signal

• Location: Lower pons

Limbic system stimulation

• anticipation of activity or emotional anxiety may stimulate the limbic system, which then sends excitatory input to the DRG, increasing the rate and depth of breathing

Temperature

• Body ____ ↑ = Rate of breathing ↑

• Body _____ ↓ = Rate of breathing ↓

•  A sudden cold stimulus causes temporary apnea, an absence of breathing.

Pain

• A sudden, severe ___ brings about brief apnea, but prolonged somatic___ increases breathing rate.

•  Visceral ___ may slow the rate of breathing

Stretching the anal sphincter muscle

Increases the breathing rate and is sometimes used to stimulate respiration in a newborn baby or a person who has stopped breathing.

Irritation of airways

Physical or chemical irritation of the pharynx or larynx brings about an immediate cessation of breathing followed by coughing or sneezing.

Blood pressure

• The carotid and aortic baroreceptors that detect changes in blood pressure have a small effect on breathing. 

• A sudden rise in _______ decreases the breathing rate, and a drop in _________ increases the breathing rate.

Chest symmetry- Upper lobes

• Thumbs: sternal notch

• Fingers: Above the clavicle

Chest symmetry- Right Middle Lobe and Lingula

• Thumbs: Xiphoid process

• FIngers: Lateral ribs

Chest symmetry- lower lobes

• Thumbs: Lower thoracic spine

• Fingers: Lateral ribs

HEART RATE

• Resting _____= lowest amount of blood you need because you’re not exercising

• normally 60-100 bpm

BLOOD PRESSURE

• Measurement of pressure in an artery at the peak of systole and during diastole and is measured in mmHg

• Normal: 120/80 mmHg

PULSE RATE

• Number of heartbeats per minute.

• Resting pulse rate = 60-80bpm

RESPIRATORY RATE

• Number of breaths per minute

• Number of movements indicative of inspiration and expiration per unit time

• Count the number of themes the chest rises or falls per minute