Human systems 1: respiratory structures

external respiration

gas exchange between the air in lungs and the blood in the capillaries

internal respiration

gas exchange between the blood and body cells

cellular respiration

the use of oxygen to metabolize glucose and produce ATP and waste gases: carbon dioxide and water vapour

Respiratory system overview

The respiratory system consists of all the organs tissues and structures that work together to exchange matter and energy with the atmosphere

Nasal passages entrance

Nostrils form the entrance to the nasal passages at the beginning of the respiratory tract pathway air takes

Nasal passages function

Mucous and tiny hairs called cilia line the nasal cavity filtering the air by trapping foreign particles while warming and moistening it

Pharynx location and role

The pharynx is located at the back of the oral cavity and below the nasal cavity just above the entrances to the trachea and esophagus and acts as a crossroads for air and food

Air movement into pharynx

Air moves from the nasal cavity or from the oral cavity into the pharynx

Epiglottis structure and function

The epiglottis is a flap of elastic cartilage at the entrance to the larynx that stays open during breathing but closes during swallowing to seal off the trachea and direct food or drink into the esophagus

Larynx location and nickname

Air from the pharynx passes into the larynx located at the top of the trachea also called the voice box

Larynx structure

The larynx is made of cartilage tissues and muscles and contains two vocal folds that control pitch and volume of sound by changing tension

Adams apple function

Thick cartilage called the Adams apple protects the larynx

Trachea definition

The trachea also called the windpipe carries air from the larynx to the bronchi

Trachea structure

The trachea is lined with cilia and mucous producing cells to filter foreign matter and supported by strong flexible C shaped rings of cartilage with muscle and connective tissue in its walls

Bronchi branches

The trachea branches into the left and right bronchus each leading to a lung

Bronchi structure and infection

Bronchi walls contain cartilage bands and smooth muscle support inflammation in the bronchi is called bronchitis

Bronchioles structure

Bronchioles are small passageways branching from bronchi less than 1 mm in diameter lacking cartilage rings but containing muscle tissue

Bronchiole control

The nervous and endocrine systems control bronchiole diameter causing dilation during exercise or fight or flight response and constriction during irritants stress or asthma

Bronchioles infection

An infection in the bronchioles is called bronchiolitis

Alveoli definition

The alveoli are tiny air sacs at the ends of bronchioles where gas exchange occurs

Alveoli structure and function

Each alveolus is wrapped in a capillary bed and gas exchange occurs across thin membranes driven by concentration gradients oxygen diffuses into blood while carbon dioxide diffuses into alveoli

Alveoli breathing cycle

Alveoli inflate during inhalation and collapse during exhalation with a lipoprotein lining preventing alveolar walls from sticking together

Alveoli adaptations

Gas exchange is efficient because alveolar walls are thin alveoli are small in diameter around 0.1 mm there are about 50 million alveoli per lung and their bulbous shape maximizes surface area

Diaphragm definition

The diaphragm is a dome shaped muscle separating the thoracic chest cavity from the abdominal cavity controlling breathing

Diaphragm contraction

When the diaphragm contracts and moves downward thoracic volume increases air pressure decreases and air rushes into the lungs

Diaphragm relaxation

When the diaphragm relaxes and moves upward thoracic volume decreases air pressure increases and air rushes out of the lungs

Intercostal muscles role

Intercostal muscles between ribs assist breathing by moving the rib cage

Intercostal contraction

When intercostals contract the rib cage moves upward and outward increasing thoracic volume decreasing air pressure and pulling air into the lungs

Intercostal relaxation

When intercostals relax the rib cage moves downward and inward decreasing thoracic volume increasing air pressure and forcing air out of the lungs

Pleural membranes definition

The pleural membranes are thin coverings on the surface of the lungs and lining of the chest cavity that adhere together so lung volume changes with chest cavity volume

Pleural membranes fluid

A thin fluid between pleural membranes reduces friction during breathing