Respiratory System

Unit 3 - Prep for Final Exam

What are the five vital functions of the human respiratory system?

1) ventilation (which is the physical movement of air in and out of lungs) and gas exchange (called “respiration”)

2) filtering air, warming air, and humidifying air

3) sound production

4) airway protection

5) sense of smell

What mechanisms are included in the upper respiratory tract?

nasal cavity

oral cavity

pharynx

larynx (point of division between upper and lower tracts)

What mechanisms are included in the lower respiratory tract?

trachea

bronchi

lungs

Components of the Lower Respiratory Tract (also called the “breathing pump”)

The pulmonary apparatus - made up of the lower airways and the lungs

The chest wall - made up of the rib cage, diaphragm, abdominal wall, and abdominal content

Components of LOWER AIRWAYS ( a part of the lower resp. tract)

The Trachea - ‘c’ shaped cartilages, inferior to the larynx, trachea extends into bronchial tubes (into lungs), within lungs the bronchi tubes extend into low bar bronchi (develops into 20 generational branches of bronchi tubes)

The Bronchi - are made of cartilage, smaller divisions of bronchi are called “bronchioles”

Bronchioles - lack the cartilage of trachea and bronchi so they are less rigid, made up of smooth muscle instead, bronchioles eventually lead to alveoli

The Lungs - porous and spongy, contain many elastic fibers (so that the alveoli can stretch during inhalation and exhalation), have 5 lobes ( 3 on the right, 2 on the left), left lung is smaller than the right to accommodate for the heart, lungs are covered by visceral pleura ( a membrane)(outer most wall of the lungs - a hard material), parietal pleura (inner most chest wall)(makes contact with lungs)(thin membrane)

Pleura and pleura fluid - essential for respiration, reduces friction as pleura moves past one another, critical for pleural linkage (allows entire chest cavity to move as one)

Alveoli - -tiny air sacs at the very end of bronchioles where gas exchange takes place (300 million), also made of elastic fibers to expand and contract, inside alveoli is filled with lipids and proteins (surfactant - lowers surface tension for easier breathing), alveoli are wrapped in mesh of pulmonary capillaries, gas moves into the blood via pulmonary capillaries

Internal and External Respiration - the exchange of oxygen and carbon dioxide between tissue capillaries and tissue cells

Internal Respiration - exchange at the tissue level

External Respiration - exchange at the blood level

Pulmonary apparatus

comprised of lower airways and lungs

components of the CHEST WALL

Rib Cage - the skeletal portion of the chest wall, protects lungs and heart, part of the thoracic vertebrae, 12 total pairs of ribs (1st 7 pairs are “true” ribs, lower 3 pairs are “false” ribs, and bottom 2 pairs are floating ribs)

Sternum - protects middle of chest, positioned above the heart, made of 3 parts (manubrium, body, and xiphoid process)(manubrium - connects 1st and 2nd rib pairs, blade - connects 3-7 pairs)

Diaphragm - a muscle between the thorax and abdomen, left side sits lower than right to accommodate heart

Abdominal wall - oblong shape with 15 vertebrae (lumbar and sacrumal region), includes muscle and connective tissue, contains and protects organs, maintains anatomical position

Abdominal content - stomach, intestines, etc., involved in digestion, suspended by “suction force” (breathing muscles pull upward creating low pressure to hold abdominal content up)

Pulmonary apparatus and chest wall as a unit

*pleural linkage allows pulmonary apparatus and chest wall to operate as a unit

• allows for effortless breathing

• like 2 people leaning outward holding hands = comprise

• lungs pulled in by chest wall, lungs stretched out, chest wall compressed

Filter in Respiratory system

• mucus filters dust

• cilia moves in wave-like pattern to activate filtration

Humidification

• to prevent hoarse speech

• humid, warm air allows for smooth movement of vocal folds

Force in the respiratory system

• passive forces

• active forces

Passive forces

• spring-like behavior (effected by surface tension of alveoli, gravity, and natural recoil of muscles)

Active Forces

• actions of muscles (muscles in chest wall, diaphragm, and abdominal wall)

Inspiratory muscles (part of the function of respiratory musculature)

• muscles that expand the rib cage during inspiration with resultant airflow into lungs

• include the diaphragm and rib cage wall

• within the rib cage wall is external intercostals sternocleidomastoid, and scalenes

Expiratory muscles

• muscles that compress rib cage and abdomen to expel air

• includes the rib cage wall (the internal intercostals) and abdominal wall (rectus abdominis, external oblique, internal oblique, and transversus abdominis)

Diaphragm - 3 components:

• sternal

• costal

• vertebral

The Sternal - origin in lower and back border of xiphoid process, insertion at central tendon (the point of attachment where muscles move - the central tendon contracts and moves diaphragm down/flattens, course is superior and medial

The Coastal division (bottom of ribs) - origin at low border and inferior surface of ribs 7-12, insertion at central tendon, course is superior and medial

The Vertebral division - origin at upper lumbar vertebrae, insertion at central tendon, course is superior and medial

3 major openings into diaphragm

1) aortic hiatus - opening for the aorta

2) esophageal hiatus - where digestive tract passes

3) Foramen vena cava - where largest vein passes

• all 3 allow for major vessels, nerves, and esophageal tube to pass through muscular wall without keeping diaphragm from breathing

• the diaphragm is primary muscle for inhalation

• during contraction, central tendon pulls down and forward and the lower 6 ribs elevate to allow lung expansion

Rib Cage Wall of inspiratory muscles

• external intercostals - 11 connected muscles that fill the outer portion of the rib interspaces (between each rib; 12 ribs; 11 spaces)

  • each muscles connects from bottom border of upper rib all the way to top border of inferior rib

    these muscles pull the ribs up and out to make room for air

• Sternocleidomastoid - origin at sternum and clavicle, insertion at skull behind the ear

  • this muscles pulls up on the sternum, clavicle and ribs

• Scalenes - elevate top 2 ribs for inspiration

  • Anterior Scalene - origin at C3-C6, insertion at inner border of top of 1st rib, elevates the 1st rib

  • Medius Scalene - origin at C2-C7, insertion at 1st rib, elevates 1st rib

  • Posterior Scalene - origin at C5-C7, insertion at outer surface of 2nd rib, elevates 2nd ib

Accessory inspiratory muscles

• Pectoralis major

• Pectoralis minor

• Subclavius

• Serratus anterior

• Serratus posterior superior

• Lateral iliocostalis cervicis

• Lateral iliocostalis thoracis

• Levatores costarum

• all aforementioned muscles of the rib cage wall function to ASSIST IN BREATHING, PROTECT ORGANS, and MAINTAIN THORACIS STABILITY