Anatomy of The Respiratory System

anatomy

How many pairs of ribs

12

What are costal cartilages?

‘bars’ of hyaline cartilage - lengthen ribs at anterior ends, medial extension to articulate with sternum

Ribs 1-7 are known as…

True ribs

Rib 1 features

• short

• curved

• flat

• no costal groove

• tubercule

Which ribs are false ribes? what defines them?

• ribs 8-10

• articulate posteriorly with vertebral column

• attach to rib 7 costal cartilage to form costal margin (don’t directly articulate with sternum)

Ribs 11-12 are… describe their features

• Floating ribs

• articulate posteriorly with vertebral column

• no costal cartilage

• no anterior articulation with costal cartilage or sternum

Features of typical ribs

• head

• neck

• tubercule

• curved

• body

• costal groove

Which ribs are typical ribs?

2-10

Which ribs are atypical?

1, 11, 12

Rib 11 features

• no neck

• no tubercule

• less curved then typical ribs

Rib 12 features

• no neck

• no tubercule

• less curved then typical ribs

• no costal groove

Function of costal groove

Intercostal veins and blood vessels run through

What is a supernumeracy rib? Risk associated?

• extra rib

• most likely to occur at cervical level (C7 at vertebra)

• Can cause compression of neurovascular structures

Label the thoracic vertebra

1. Vertebral body

2. Vertebral foramen

3. Spinous process

4. Transverse process

5. Inferior vertebral notch

6. Superior vertebral notch

7. Lamine

8. Superior articulator notch (articulation with other vertebrae)

9. Inferior articulator notch (articulation with other vertebrae)

10. Articulate facet (articulates with rib)

3 parts of the sternum

1. Manubrium

2. Body

3. Xiphoid process

1. Costovertebral joint - rib articulates with superior and inferior articulator facets

2. costo transverse joint - articulation of rib’s tubercule with articulator facet of the transverse process of the vertebra

3. costochondral - primary cartilagenous joint (costal cartilage-rib)

4. sternocostal joint - costal cartilage - sternum

Features of ribs from infants - 2

• almost horizontal (as in full inspiration position in adults)

Ribs from 2 years up & benefit?

Oblique - increases thoracic breathing

Ribs in old age

• lose elasticity (cartilage ossifies)

• thorax less involved in respiration (more work for diaphragm)

“Pump handle” breathing /A-P expansion

• sternum raises

• ribs elevate (oblique - horizontal)

• expansion (anterior - posterior diameter of thorax)

“Bucket handle” breathing/Lateral expansion

• movement of sternocostal joints & vertebral column

• rivs raise (oblique-horizontal)

• expansion (lateral diameter thorax)

Diaphragm at rest

Domed

Diaphragm on inhale/during inspiration

• Flattens

• Pulls down central tendon

• Increases vertical diameter of thoracic cavity

Where is diaphragm located?

Attached to costal margin, xiphoid process, vertebral column (at level T12 + L2)

Label

1. External intercostal muscle

2. Internal intercostal muscle

3. Innermost intercostal muscle

4. Nerve

5. Artery

6. Vein

7. Rib

(4,5,6 - neurovascular bundle - run in costal groove)

Primary muscle of inspiration?

Diaphragm

Right dome of diaphragm higher than left, why?

Liver

Other functions of diaphragm

• septum between thoracic cavity and abdominal cavity

• aids in increasing intra-abdominal pressure (facilitates defecation, micturition, parturition)

• Thoraco-abdominal pump - forcing blood to heart (vena cava)

Nerves supplying diaphragm?

C3, 4, 5 keeps the diaphragm alive - Phrenic nerve

Openings in diaphragm

• Caval opening (vena cava and branches of phrenic nerve)

• Oesophageal opening (Oesophagus and vagus nerve)

• Aortic opening -behind diaphragm (aorta and thoracic duct)

Role of external intercostal muscles?

Muscles of inspiration

Role of internal intercostal muscles?

Muscles of expiration

Role of innermost intercostal muscles

Stabilise chest wall

Accessory muscles - role in breathing?

Assist in deep inspiration or in respiratory distress

Name accessory muscles

1. Pectoralis major/minor

2. Serratus anterior

3. Sternocleidomastoid

4. Pectoralis minor

5. Latissimus dorsi

Muscles engaged in forced expiration?

• Intercostals

• Abdominal muscles

At vertebral level of T3…

Jugular notch

At vertebral level of T4/5…

Manubrial sternal joint/Sternal angle

At vertebral level of T9…

Xiphoid process

Vessels that supply the thorax?

• Subclavian artery

• Thoracic aorta

• Axiliary artery

Posterior intercostals 1 & 2 are supplied by…

Subclavian artery

Posterior intercostals 3 - 11 are supplied by…

Thoracic aorta

Anterior intercostals are supplied by…

Subclavian artery (branch called: Internal thoracic artery)

Each intercostal never is a branch of …

a spinal nerve (ventral raumus)

Pathway of the phrenic nerve?

Runs alongside the anterior scalene muscle

Mediastinum is

Large compartment of thoracic cavity, contains vital organs

Organs found in mediastinum:

• Heart

• Great vessels

• Pericardium

• Trachea

• Oesophagus

• Thymus

• Lymph nodes

What are the pleura?

2 double lined sacs, contain the lungs, located in thoracic cavity

Purpose of serous fluid

prevents friction during breathing

Where is serous fluid produced?

mesothelial cells in pleural cavity

What is the hilum of the lung?

entrance of the lung - for blood, oxygen

Label

Thoracic aorta

Label

1. Midaxillary line

2. Posterior axillary line

3. Anterior axillary line

Name and explain

Dermatomes

Areas of skin that connect to a specific nerve root from the spine. Info travels through nerve to and from brain

Label thoracic cavity

1. cervical pleura

2. visceral pleura

3. costal part

4. mediastinal part

5. diaphragmatic part

6. parietal pleura

7. visceral pleura

8. pleural cavity

9. thoracic wall

10. lung

11. diaphragm

Label lungs

1. Larynx

2. Trachea

3. Left bronchus

4. Right bronchus

5. Alveoli (clusters)

6. Bronchioles

Function of trachea

Transports air to lungs

Structure of bronchi…

• Trachea bifurcates into 2 branches (R&L) to enter into lungs

• Main bronchus splits into lobar bronchi:

• Right bronchus (3) - supply 3 lobes of lung

• Left bronchus (2) - supply 2 lobes of lung

• Lobar bronchi splits into segmental bronchi

What happens in the lungs?

Air transported to alveoli for gaseous exchange

In the alveoli…

Gaseous exchange occurs

Label lower respiratory tract

1. Thyroid gland

2. Hyoid bone

3. Thyroid cartilage

4. Cricoid cartilage

5. Sternal notch

6. Trachea

Alveoli terminate into…

Alveolar sacs

Function of surfactant

Prevents alveolar walls from collapsing and sticking together

3 major types of cell in alveolar wall

1. Phagocyte

2. Type II cells

3. Alveolar macrophages

Pulmonary surfactant is produced by

epithelial type II cells

Functions of pulmonary surfactant:

• Lowers surface tension at the air/liquid interface within the alveoli

• Stabilises alveoli - prevents them from collapsing during inhalation

• Increases lung compliance (easier to expand)

Alveoli are covered by…

Pulmonary capillaries

Pores of Kohn are…

Small holes in the walls of adjoining alveoli (alveolar septa) for movement of alveolar liquid, surfactant, macrophages

Canals of Lambert

connections in the lungs between some bronchioles and their adjacent alveoli - facilitate collateral movement of gases

Which lung? Label.

Right lung

1. Horizontal fissure

2. Oblique fissure

3. Apex

4. Superior lobe

5. Middle lobe

6. Inferior lobe

7. Base

Which lung? Label.

Left lung

1. Apex

2. Superior lobe

3. Cardiac notch

4. Inferior lobe

5. Base

6. Oblique fissure

& Lingula describes projection in upper lobe - homologue of middle lobe (right lung)

Lungs are covered by a double layered sac called…

the pleural membrane

Layers of the pleural membrane:

• Outer layer: Parietal layer

• Inner layer: Visceral layer

• Space between: Pleural cavity - pleural fluid/lubricant

Respiration involves…

The exchange of oxygen and carbon dioxide between organism and external environment (involves respiratory and circulatory systems)

Conducting zone involves:

• Larynx - terminal bronchioles

• Air: larynx to lungs (no gas exchange)

• air is filtered, warmed, moistened

• involved in phonation

Respiratory zone involves:

• respiratory bronchioles - alveolar sacs

• contains sites of gaseous exchange

Alveolar pores are…

means of collateral ventilation - in the case of partial deflation, some ventilation

Type I alveolar cells

• cover 95% of alveolus surface

• physical support for alveoli

• fast gaseous exchange

Type II alveolar cells are…

• 5% of alveolar wall surface area

• Produce pulmonary surfactant

• repair alveolar wall - replace damaged type I/II

Components of thoracic wall

• spinal column

• ribs

• sternum

• intercostal muscles

During inspiration…

• Alveolar pressure < atmospheric pressure

• air from external environment flows into lungs to balance pressure

• movement stops when pressure stabilises

• At rest alveolar pressure = atmospheric pressure

During expiration…

• alveolar pressure > atmospheric pressure

• air flows out of lungs to balance pressure

• when pressure stabilises, air stops flowing out

• At rest alveolar pressure = atmospheric pressure

Alveolar pressure =

760mmHg

Atmospheric pressure =

760mmHg

True or false: Lungs are active

False. Movement of air is regulated by volume/pressure

Lung volume depends on:

1. Transpulmonary pressure - between the inside and outside of the lungs

2. ‘Stretchability’ of the lungs

What is transpulmonary pressure?

pressure difference between the inside and the outside of the lung

Transpulmonary pressure =

alveoli pressure - intrapleural pressure

At rest, alveoli pressure is…

0mmHg

At rest, intrapleural pressure =

-4mmHg

At rest, transpulmonary pressure =

4mmHg

Chest wall pressure =

intrapleural pressure - atmospheric pressure

At rest, chest wall pressure =

-4mmHg

What causes negative value for resting chest wall pressure?

Natural tendency for chest wall to spring forward (musculoskeletal anatomy); neg. pressure required to reduce chest cavity volume

What causes changes to transpulmonary pressure?

Contractions of respiratory muscles (change in volume) - changes in chest wall pressure = changes to transpulmonary pressure

Residual volume (RV) describes:

Amount of air remaining in lungs after maximum exhalation

Functional residual capacity (FRC) describes

Amount of air remaining in lungs after normal exhalation

Expiratory reserve volume (ERV)

Amount of air in excess of tidal expiration that can be exhaled with maximum effort

Tidal Volume (TV)

Amount of air that can be inhaled/exhaled in one breath