Anatomy & Physiology - The Respiratory System

These flashcards cover key vocabulary and concepts from SLT7002 Lecture 4 on the Respiratory System, aiding in exam preparation.

Trachea

Also known as the windpipe, it is a singular tube supported by C-shaped rings of cartilage.

Diaphragm

The primary muscle of respiration that separates the thoracic cavity from the abdominal cavity.

Bronchial Tubes

Branches of the trachea that continue to divide until they reach microscopic size, made of smooth muscle.

Surfactant

A fluid that lines alveoli, preventing them from collapsing (atelectasis) by reducing surface tension.

Develops at 24-34 weeks gestation so may be given artifically to premature babies

Pleura

Membranes that surround the lungs allow for frictionless movement and provide a protective layer.

Enables muscles to act on the lungs without damaging the tissue

Subglottic Pressure

Pressure generated beneath the vocal folds, necessary for phonation.

Vital Capacity (VC)

The maximal volume of air that can be moved in and out of the lungs.

Tidal Volume (TV)

The amount of air exchanged during a normal respiratory cycle.

VC = TV+IRV+ERV

Inspiratory Reserve Volume (IRV)

The amount of air that can be inhaled beyond the tidal volume.

Approx 3300ml

Expiratory Reserve Volume (ERV)

The largest volume of air that can be exhaled during maximal expiration.

The volume of air that can be exhaled after a normal tidal expiration.

Approx 1000-2000ml

Neurological Control of Breathing

Breathing is controlled by both the brainstem (automatic control) and the cerebral cortex (voluntary control).

Aspiration Pneumonia

An infection caused by the presence of foreign material in the lungs, leading to inflammation.

COPD (Chronic Obstructive Pulmonary Disease)

A combination of chronic bronchitis and emphysema characterized by airflow limitation.

Asthma

A condition where bronchial tubes become inflamed and narrow, resulting in difficulty breathing.

Laryngomalacia

A condition in infants where the airway is floppy leading to stridor; may resolve on its own.

Tracheotomy

A surgical procedure involving an incision in the neck to create an opening in the trachea.

Mechanical Ventilation

A method to mechanically assist or replace spontaneous breathing.

Vagus Nerve

Cranial nerve responsible for motor and sensory functions of the larynx.

Phrenic Nerve

Nerve arising from C3-C5 that controls the diaphragm.

Cervical Vertebrae

The first seven vertebrae in the neck labeled C1 through C7, including the atlas and axis.

Lung Function in Infants

Infants have a higher breathing rate, smaller lung size, and flexible ribcage.

Oxygen Saturation

Measurement of how much oxygen is bound to hemoglobin in blood, measured in %.

Boyle’s Law

Assuming temperature is kept constant, volume and pressure will be inversely related to each other. 

e.g. if volume increases, pressure will decrease proportionally 

According to Boyle’s Law, what happens when we inhale (4 stages)

1. The diaphragm contracts (moves down) and intercostal muscles lift the ribcage.

2. This makes the thoracic cavity bigger → lung volume increases.

3. According to Boyle’s Law: when volume ↑, pressure ↓.

4. So, pressure inside the lungs becomes lower than atmospheric pressure → air flows into the lungs.

According to Boyle’s Law, what happens when we exhale (4 stages)

1.  The diaphragm relaxes (moves up) and ribcage falls.

2. This makes the thoracic cavity smaller → lung volume decreases.

3. According to Boyle’s Law: when volume ↓, pressure ↑.

4. So, pressure inside the lungs becomes higher than atmospheric pressure → air is pushed out of the lungs

How is air exchange calculated?

TV x breaths per minute

How many breaths per minute to adults take on average?

12-18

How does air that comes into the lungs provide oxygen to the body?

Oxygen is diffused into the capillaries via alveolar cells. It then binds to haemoglobin in red blood cells and is transported around the body to tissues. The reverse happens when expelling carbon dioxide.

Oxygen saturation

The percentage of oxygen bound to haemoglobin in the blood. Normal range - 95-100%

Intercostal muscles

Muscles located between the ribs that assist with breathing by expanding and contracting the thoracic cavity.

External vs internal intercostal muscles

Contraction of external aid in inhalation by elevating the ribs, while contracting internal facilitate exhalation by depressing the ribs.

Lungs

Primary organ involved in respiration. Made of spongy, pourous tissue. Right is slightly larger than the left due to the heart occupying more space on the left side.

What structure controls automatic (involuntary breathing)

Brainstem

What structure controls voluntary breathing

Cerebral cortex

Nerves: specifically the phrenic nerve and vagus nerve

Inspiratory Capacity (IC)

The maximum volume of air that can be inhaled after a normal tidal expiration

(TV+IRV)

Functional Residual Volume (FRC)

The volume of air remaining in the lungs after a normal tidal expiration,

Residual Volume (RV)

The amount of air left in the lungs after a maximal exhalation. Cannot be be measured.

Total Lung Capacity (TLC)

The maximum volume of air the lungs can hold, including all respiratory volumes.

Vegetative breathing

the automatic process of breathing that occurs at rest, controlled by the brainstem, without conscious effort.

Suck - swallow - breathe patterns 

1 suck: 1 swallow: 1 breath 

Established around 36 weeks gestation

Ration decreases with age (3:1 at 1 month)

Obligate Nasal Breathers

Infants are primarily dependent on nasal breathing for respiration. Allows them to continually breathe whilst feeding and minimizes the risk of aspiration.

This is due to the veloepiglottic seal where the tip of the epiglottis connects with the soft palate, creating a "seal" or continuous airway from the nose to the lungs.