Respiratory system

5 functions of respiratory system

1. Provides a large SA for the exchange of gases
2. Movement of air in and out of lungs (breathing)
3. Protection (moist, warm, cilia to prevent debris entering the lungs)
4. Sound production (larynx/voice box)
5. Sensations to the nervous system/brain (smell)

Respite track

nose/nasal cavity → pharynx → larynx → trachea → primary bronchus → secondary bronchus → tertiary bronchus → bronchioles → alveoli

breathing

* Breathing is a mechanical act to pulls air in/out of the lungs by changing the volume in the lung
* Also called ventilation
* When volume changes, the pressure in the lungs also changes (has an inverse relationship) volume increases - pressure decreases


* At rest, inspiration actively pulls air into the lungs (diaphragm & external intercostals used to breathe in)
* During exercise, inspiration and expiration actively pull and push air in/out of lungs

inhalation

1. Diaphragm and external intercostals muscles __**contract**__ 
2. As the outside of the lungs are attached to the diaphragm & chest wall by the plural membranes and pleural fluid, when the diaphragm & chest moves, so too do the lungs


1. The diaphragm changes from a __**dome**__ shape to a __**flat**__ shape, __**pulling**__ the base of the lungs __downwards__
2. Rib cage moves __up__ and __out__ 
3. This __**increases**__ lung volume
4. This causes a __**drop**__ in lung pressure (there is __more__ space and no change in the number of particles within the lung cavity) relative to the pressure outside the body
5. Air will naturally move from an area of higher pressure to lower pressure
6. This causes air to be __**drawn**__ __**/pulled into**__ the **lung** space
7. Once the air reaches the alveoli, the difference in concentration of gases between the blood vessels and the alveoli cause oxygen to diffuse into the blood and carbon dioxide to diffuse into the alveolar air space

Exhalation

1. Diaphragm and external intercostals muscles __**relax**__ 
2. As the outside of the lungs are attached to the diaphragm & chest wall by the plural membranes and pleural fluid, when the diaphragm & chest moves, so too do the lungs


1. The diaphragm changes from a __**flat**__ shape to a __**dome**__ shape, __**pushing**__ the base of the lungs __upwards__
2. Rib cage moves __down__ and __in__
3. This __**decreases**__ lung volume
4. This causes an __**increase**__ in lung pressure (there is __less__ space and no change in the number of particles within the lung cavity) relative to the pressure outside the body
5. Air will always naturally move from an area of higher pressure to lower pressure
6. This causes air to be __**pushed**__ __**out**__ of the **lung** space
7. Air rich in carbon dioxide and low in oxygen is removed from the body

gases are transferred across alvioli membranes if:

* the concentration gradient is maintained
* continual movement of air in and out of the lungs (breathing)
* continual flow of blood through the capillaries that surround the alveoli

nasal cavity

* Highly convoluted inner surface - increase SA
* Dense capillary network helps to warm & humidify incoming air
* Cells have hair and mucus to filter and trap debris & dirt in the incoming air
* Lots of smell receptors
* Resonates sound to enhance those produced by larynx

pharynx

* From back of nasal cavity to top of trachea 
* Common space for air and food
* Epiglottis (a flap of elastic cartilage) prevents food entering trachea (i.e., always open and when you swallow food, it closes over the larynx)

larynx

* Made of cartilage (Adam’s apple) with membranes stretched across them that contain vocal cords (elastic ligaments) which vibrate to produce sound
* Air flows through the central space (glottis)
* Muscles are attached to the cartilage
* when relaxed there is no sound
* when contract the glottis is narrowed, and air causes the cords to vibrate
* Volume: force of vibration
* Pitch: changing tension in cords (tight = high pitch)

trachea

* C-shaped bands of cartilage - means it is flexible but stays open regardless of pressure change
* Ciliated mucous membrane
* mucus to trap debris
* cilia beat to push mucus & trapped debris upwards to be swallowed

bronchi

* C-shaped cartilage to keep them open, increasingly spread out
* Cilia & mucus
* Primary (each lung) --> secondary (each lobe of lung) --> tertiary (bronchioles)

Bronchioles

* Fine tubes made of smooth muscle & elastic with **no** cartilage or cilia
* Controls air flow into alveoli (asthma affects these)
* Terminal bronchioles

Alveoli

* Air sacs that occur in clusters, make up most of the lung
* Cells are 1 cell thick and moist
* Dense capillary network surrounds each one
* Site of gas exchange

repiration circulation

the alveoli are well supplied with capillaries that have low concern of oxygen meaning the the high concentration of oxygen in the alveoli causes it to diffuse through the thin membrane and into the blood. the blood then travels to the heart where is is pushed around the body oxygenating cells as CO2 diffuses into the blood due to the concentration gradient. the deoxygenated blood that now has a high concentration in CO2 travels back to the alvioli where it diffuses through the capillary into the alveoli to be exhaled.

deamination

aminon acid + oxygen = amonium + CO2

creation of urea

energy + CO2 + ammonium = urea + water

renal capsule

filter blood from the capillaries of glomerulus

formation of filtrate in the glomerulus capsule

PCT and LOH

passive readsorption of bicarb ions, potassium and chloride. active reasdorption of glucose and sodium. passive adsorption of water through osmosis