ANAT - 8.2 - lower resp

What is the pleura and what are the 2 layers of the pleura?

The pleura is a serous membrane around the lungs.

Layers:

1) Visceral pleura: This layer sticks directly onto the lung and covers lung surface.

2) Parietal: This layer lines the chest wall, diaphragm and Mediastinum (heart area) [so the thoracic cavity]

Parts of the Parietal Pleura

1) Cervical pleura: Top part near neck/cervical vertebrae.

2) Costal pleura: Lines ribs/chest wall. (note: costal means ribs)

3) Mediastinal pleura: Near the heart/mediastinum.

4) Diaphragmatic pleura: covers diaphragm

Nerve Supply Difference btw visceral and parietal pleura:

Visceral Pleura: Has autonomic nerve supply

• means dull ache, poorly localised, hard to tell where pain is

Parietal Pleura: Has somatic nerve supply

• means sharp pain, well localised, can tell where pain is

What is the hillium of the lung?

Hillium is the “doorway” of the lung.

Things entering/exiting:

• Bronchi

• Pulmonary arteries

• Pulmonary veins

• Nerves

• Lymphatics

Note: At the hilum, parietal pleura becomes visceral pleura to form a single, continuous, closed sac surrounding each lung,

Where is the pleural cavity situated and what does it do?

Pleural cavity is a tiny gap situated between visceral and parietal pleura. It contains serous fluid.

Functions:

• As lungs expand and move, it allows layers to glide smoothly w/o damage from rubbing. - reduces friction

• The fluid makes the layers stick together slightly. - creates surface tension

Natural Forces in the Chest relating to lungs and chest wall

• Lungs naturally want to recoil inward

• Chest wall naturally wants to spring outward

The pleura and pleural cavity keep them coupled together so lungs don’t recoil inward.

What does Pneumothorax mean and how do Drs fix it?

If a rib pierces the pleura, Air enters pleural cavity, Surface tension is lost and lung collapses (bcs it wants to recoil inwards naturally). This condition is called Pneumothorax.

To fix it, Drs insert a tube to remove trapped air above the rib, as veins, nerves and arteries live under each rib.

What are the 2 types of pleural recesses (extra spaces) that lungs can use to expand during deep breaths?

1) Costodiaphragmatic recess: Situated btw ribs and diaphragm. Its big and clinically important, as fluid/blood can collect in recesses due to gravity. Doctors listen here with stethoscope.

2) Costomediastinal recess: Near front of chest beside mediastinum.

Apex and Base of lung

Apex = top, which actually extends above the clavicle.

Base = bottom of lung which rests on diaphragm

Lobes of the Lungs

RIGHT LUNG has:

• Superior lobe

• Middle lobe

• Inferior lobe

LEFT LUNG has:

• Superior lobe

• Inferior lobe

What are the 2 different fissures of the lung?

Oblique fissure: present in both lungs

Horizontal fissure: Only present in right lung

Why are lungs different sizes?

• Right lung is Shorter & Wider/larger, because liver pushes it upward.

• Left lung is smaller/narrower, because heart takes up space.

What is the cardiac notch?

Indentation in left lung caused by heart.

What is the Lingula?

It’s the small tongue-like part of left lung. Acts like the “middle lobe equivalent.”

What are the 3 lung surfaces?

1) Costal surface - touches ribs

2) Mediastinal surface- touches mediastinum/heart

3) Diaphragmatic surface - touches diaphragm

What are the 3 Borders of Lung?

• Anterior border

• Posterior border

• Inferior border

Listening to the Lungs:

From the BACK:

• You mainly hear superior + inferior lobes

From the front/side:

• Middle lobe is best heard:

Mediastinal Surface Impressions

Right lung impressions

• Heart

• Superior vena cava

• Azygos vein

• Oesophagus

Left lung impressions

• Heart

• Arch of aorta

• Descending aorta

• Oesophagus

Where is the pulmonary ligamnet located and what’s its role?

Its an extension below the hillum (lung door). It allows Flexion and extension.

Bronchi, pulmomary arteries and plumonary vein arrangement in Hillum:

• Bronchi usually posterior (back)

• Pulmonary arteries usually anterior to bronchi (in front of bronchi)

• Pulmonary veins usually anterior + inferior (front and bottom)

What are the highest structures of the right and left hillums?

• Right Hillum: Highest structure = bronchus

• Left Hillum: Highest structure = pulmonary arteries

What is the trachea and where is it located (relative to oesophagus)?

Trachea is a tube carrying air. It’s located anterior to (in front of) oesophagus.

Why does trachea have C shaped cartilage instead of full circles?

Because oesophagus behind it needs room to expand when swallowing food.

What is the Carina and where exactly is it located?

The Carina is where trachea splits into left + right bronchi.

It occurs around T4/T5 and the sternal angle.

What’s the clinical importance of carina?

Lymph nodes below it can enlarge from cancer.This may push carina sideways.

How’s the Right main bronchus different to the left one?

It’s wider, shorter and more vertical. So inhaled objects usually enter the right lung. (This is called aspiration)

3 levels of Bronchial branching:

1) Main (Primary) bronchi: Come off trachea.

2) Lobar (Secondary) bronchi: 2 R, 3 L - Go to lobes.

3) Segmental (Tertiary) bronchi: Supply bronchopulmonary segments.

How many Supply bronchopulmonary segments are there per lung and what does each contain?

• About 10 per lung

Each contains:

• Own bronchus

• Own artery

• Own vein

Conducting vs Respiratory Zones

Conducting zone: Air passage only. NO gas exchange. Contains cartilage. (ex//trachea and bronchi)

Respiratory zone: Gas exchange occurs. NO cartilage. (ex//Respiratory bronchioles & Alveoli)

Cartilage Trend

As branches get smaller:

• Cartilage decreases

• Smooth muscle increases

This allows bronchioles to constrict and dilate.

How does asthma occur?

Bronchioles constrict too much. Air can’t move properly. Because respiratory bronchioles lack cartilage, they can narrow a lot.

What do alveoli look like & what happens there?

• Tiny grape/raspberry-like sacs.

• Gas exchange happens at alveoli

What triggers coughing?

Conducting airways contain mucus & cillia. They trap particles and move them upward.

The Sympathetic causes:

• Bronchodilation

• Reduced mucus

The Parasympathetic (Vagus nerve) causes:

• Bronchoconstriction

• Increased mucus

Which nervess supply the costal, mediastinul and diaphragmatic pleura?

• costal = Intercostal nerves

• Mediastina = phrenic

• Diaphragmatic = phrenic

The Plumonary trunk leaves a certain heart chamber and splits into 2 things. What’s the heart chmaber and what’s the 2 things it splits into.

It leaves the right ventricle and splits into right pulmonary artery and left pulmonary artery. Being pulmonary, these carry deoxy blood.

Do pulmonary arteries return oxy.deoxy blood to which chamber?

Return oxy blood to Left atrium.

Bronchial Circulation

Bronchial arteries supply oxygenated blood to lung tissue itself.

How do the functions of pulmonary arteries and bronchial arteries differ?

• Pulmonary arteries are for gas exchange

• Bronchial arteries are for feeding lung tissue

What is the Ligamentum Arteriosum?

It’s a remnant from fetal circulation. It Connected pulmonary trunk to aorta before birth.

Relo btw Macrophages + Carbon

Macrophages “eat” inhaled carbon particles. Carbon stays trapped inside them.

Lung Appearance differences btw Healthy/rural lungs, City lungs and Smoke lungs:

1) Healthy/rural lungs: Lighter in colour

2) City lungs: Darker from pollution.

3) Smoker lungs: very black