Respiratory System Flashcards
What is respiration?
Exchange of oxygen and
carbon dioxide between an
organism and the external
environment (external
respiration
How is oxygen utilised?
By cells in metabolism - internal respiration; cellular respiration
Describe the structure/anatomy of the upper respiratory tract.
- The nose and nasal sinuses
- The nasopharynx
- The pharynx
- The larynx
Describe the structure/anaotmy of the lower respiratory tract.
- The trachea
- The bronchi
- The bronchioles
- The lungs
State the functions of the respiratory system.
- Gaseous exchange: absorption of oxygen and
excretion of carbon dioxide - Olfaction: by specialist nerve endings in the nasal
cavity and transmitted to the brain via the first cranial
nerve (olfactory) - Speech: via the vocal cords in the larynx
- Homeostasis: via the oxygen and carbon dioxide
exchange - Protection: via the immune system and mucus
production
Describe the structure of the nose.
- Lined by epithelial cells with tiny hairs which filter incoming air
- The epithelial cells secrete a sticky fluid to trap dust and bacteria to prevent them entering the lungs
- In the nose air is warmed and filtered
- It is the organ of smell
Describe the structure of the nasopharynx.
- Lies behind the nose. Continue to warm air
- At the back of the nasopharynx are the adenoids which are made up
of dense lymphoid tissue and fight infections - The Eustachian tubes connect the nasopharynx to the middle ear and have a key role in equalising pressure in the ear to atmospheric pressure
Describe the structure of the pharynx.
- This is a large and muscular tube which lies behind the mouth and between
the nasopharynx and larynx - It serves as both an air and food passage
- At the back are the tonsils which are made up of dense lymphoid tissue
- Continue the process of warming inspired air
Describe the structure of the larynx.
- This is the short passage which connects the pharynx to the trachea
- It has rigid walls and contains the vocal cords
- When air passes over them it creates sound
- The opening from the pharynx to the larynx is called the glottis
- During the act of swallowing food this is covered and
closed by the epiglottis to prevent choking
Describe the structure of the trachea.
- This is a tube-like structure which extends from the larynx to the upper chest
- It is made of 20 ‘C’ shaped rings of cartilage and smooth muscle
- The ‘C’ shape of the cartilages allows expansion of the oesophagus when a
bolus of food is swallowed - They also ensure the patency of the airway
Describe the structure of the bronchi.
- The trachea divides to form two bronchi which are similar in structure to the trachea
- They are lined with ciliated epithelial cells which secrete mucus and saline
- The mucus traps solid particles and the cilia move them outwards so that
they can be expelled by coughing
Describe the model of saline secretion by airway epithelial cells.
- NKCC brings Cl- into epithelial cells from ECF
- Apical anion channels, including CFTR, allow Cl- to enter the lumen
- Na+ goes from ECF to lumen by the paracellular pathway, drawn by the electrochemical gradient
- NaCl movement from ECF to lumen creates a conc. gradient so water follows into the lumen
State how the bronchioles subdivide.
- The bronchi subdivide into bronchioles which again subdivide finally leading to
the air filled sacks called the alveoli
Describe the walls of the bronchioles.
Cartilage is absent
from the more terminal bronchioles whose walls contain more smooth muscle
Describe how the bronchi and bronchioles are innervated by the autonomic nervous system.
- muscarinic cholinergic receptors M3 cause bronchoconstriction,
- β2 adreno-receptors medicate bronchodilation
