3.1 Exchange and Transport Flashcards
What do larger organisms have in terms of gaseous exchange ?
Larger organisms have developed a range of different adaptations to increase this ratio at exchange surfaces.
What is the SA:V ratio in smaller and larger cells ?
-Smaller cells have a larger SA:V ratio.
-Larger cells have a smaller SA:V ratio.
What does the alveoli in the lungs have in terms of SA:V ratio ?
Alveoli significantly increase the SA:V ratio, which allows for more effective exchange of oxygen and carbon dioxide between alveoli and capillaries.
What is the gaseous exchange like in a root hair cell ?
Root hair cells increase the surface area of the cell, which increases the rate of absorbance of nutrients.
What is the trachea ?
windpipe.
What is the trachea surrounded by and what is its function ?
Trachea is surrounded by 16-20 rings of hyaline cartilage. This tissue provides support to prevent the organ from collapsing.
Why are rings of cartilage c-shaped ?
Allows the trachea to expand when larger volume of air is needed.
What are ligaments and their function ?
Ligaments connect rings and smooth muscle known as trachealis muscle that bridges gap between ends of cartilage rings.
What is the trachea lined with ?
Lined with ciliated epithelium, which is quantified to shape and specific arrangement of layers of cells.
What does the trachea branch into ?
4th thoracic vertebrae (T4), trachea branches into left and right bronchi (primary bronchi. These enter the lungs at the hilum and branch into secondary bronchi and then tertiary bronchi.
What are goblet cells and what is their function ?
Goblet cells are located between ciliated psuedostratified columnar epithelium and they release mucus. Cilia then waft pathogens caught in the mucus back up to the mouth. Then swallowed and killed by HCL in the stomach.
Where are the lungs located ?
Lungs are located in the thoracic cavity.
Which lung is anatomically larger ?
Right lung contains 3 lobes where as the left lobe only has 2 lobes.
What happens to airways when bronchi divide into secondary and tertiary bronchi ?
The airways get narrower
What does the tertiary bronchi divide into ?
4th, 5th and 6th order. Once they are too narrow to be supported by cartilage, they have become bronchioles.
Why are bronchioles different to bronchi ?
Structurally different as bronchioles as walls do not have hyaline cartilage and rely on elastic fibres that are attached to lung tissues for support.
What do bronchioles divide into ?
They divide into terminally bronchioles then respiratory bronchioles, which is the start of the respiratory zone where air is delivered into the alveoli.
How does the epithelium in the bronchioles change ?
Starts as simple ciliated psuedostartified columnar epithelium then turns into simple cuboidal epithelium as the size decreases.
What is the average size of surface area of alveoli ?
70 m2
What is alveoli lined with ?
Lined with simple squamous epithelium consisting of single layers of flattened cells, which reduces diffusion distance. This is a moist lining that can dissolve gases.
What is each lung enclosed within ?
Each lung is enclosed within a pleural sac that contains pleural fluid to allow inner and outer walls to slide over each other during breathing with little friction.
What is the diaphragm innervated by ?
The diaphragm is exclusively innervated by the phrenic nerve, where it is under autonomic control.
What are the 3 main openings in the diaphragm ?
Vena cava
aorta
oesophagus
What is the first step in inhalation (stimulation causes movement) ?
First the phrenic nerve is stimulated, which causes the diaphragm contracts and moves in the inferior direction.
What are intercostal muscles ?
Muscles between ribs and lungs.
What are external intercostal muscles ?
Responsible for elevation of ribs and bending them more open through contraction.