M9S1 Respiratory Overview And Function

Question 1

Respiratory system overview

Answer 1

-facilitates breathing and allow body to acquire oxygen, a molecule necessary for metabolic function and cell survival, from the air
-made up of many organs contributing to the condition of air to and from the lungs, as well as gas exchange within the lungs

Question 2

Breathing involved 2 cyclic phases

Answer 2

1. Inspiration (inhalation): draws oxygen rich air into the lungs
2. Expiration (exhalation): forces oxygen poor air out of lungs

Question 3

Functions of the respiratory system

Answer 3

-not only provides structures for mechanical breathing (inspiration and expiration) but contributes to functional mechanisms of respiratory and immunity

Gas exchange
-involves movement of gases across membranes
-external respiration refer to exchange of gases between the air and body. Inspired oxygen (O2) moves across the cellular membranes of the alveolus of the lung and its associated capillaries into the blood, while waste, carbon dioxide (CO2) moves in the opposite direction and out of body through expiration
-internal respiration similar mechanism that exchanges gases (O2 and CO2) between blood and cells of body

Gas conditioning
-gases enter lungs need to be conditioned or warmed or cleansed to prevent damage to lungs
-occurs in nasal cavities and paranasal sinuses where air swirled around to become warmed and humidified
-inhaled afire is cleansed of particulate matter through contact with mucosal lining of respiratory epithelium.

Sound production
-ex singing or speech
-occurs by forceful expiration of air through the vocal cords in larynx, causing them to vibrate
-different tensions of vocal cords produce different sounds with help from teeth, lips, tongue

Olfaction
-olfactory epithelium covers top of nasal cavity
-receptors for the sense of smell located within this epithelium
-when air inhaled into nasal cavity, airborne molecules dissolve in mucus which lines the cavity and stimulates the receptors
-signals from the receptors travel to brain through olfactory nerve (CN I) resulting in sense of smell

Defense
-many airborne molecules and microbes that can cause disease so respiratory system has line of defence against these molecules that can cause infection
-coarse hairs of nostrils, the ciliated cells of respiratory epithelium, and mucus lining help to trap particles and microorganism from entering the nose and respiratory system
*refer to goodnotes

Question 4

Respiratory tract epithelium (RTE)

Answer 4

-plays a large role in dense of the system and lines most of the surfaces from the nasal cavity down to the terminal bronchi

Pseudostratified ciliated columnar epithelium
-means all cells are attached to basal lamina but only some reach surface
-apical surface covered in cilia to provide increased surface area for conditioning air (filtering, humidifying, moistening)
-cilia also trap inhaled particles and microorganisms caught in mucus and sweep the back up respiratory tract and out through the nose and mouth

Goblet mucus cells
-found interspersed throughout Pseudostratified epithelium
-produce mucus, causing them, to stain lightly in histological image
-mucus forms protective layer over epithelium and traps particulate matter or microorganisms that may be inhaled
-provides moisture to humidify air before reaches lungs

Question 5

Regions of the respiratory system

Answer 5

-made of many structures that differ in contribution to flow of air to and from lungs
-structures can be divided into 2 regions: conducting portion and respiratory portion

Conducting portion:
-functions to transfer or “conduct” inhaled air from the outside world to lung tissue
-portion also conductors air from lungs to outside world
-where humidification and trapping of debris occur
-no oxygen is absorbed into blood in this region as walls of organs too thick
-structures of conducting portion include:
Nose and nasal cavity
Paranasal sinuses
Pharynx
Larynx
Trachea
Primary, secondary and tertiary bronchi
Terminal bronchioles

Respiratory portion
-functions to transfer gases between lungs and pulmonary capillaries
-pulmonary capillaries are terminal structures within lungs that have walls thin enough to facilitate movement of gases from air to blood and vice versa
Structures that make up respiratory portion:
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli