RESPIRATORY SYSTEM
The respiratory system consists of those organs involved in gas exchange between
the external environment and the cardiovascular system. Respiration occurs on
several levels.
The breathing movements that move air into and out of the lungs can be clearly
seen. This is sometimes called external respiration or ventilation.
The movement of oxygen from the lungs into the blood and then to the cells and
tissues occurs at the microscopic level and is sometimes called internal respiration.
This delivers oxygen from the lungs to the body cells.
The final stage of the process – cellular respiraration uses oxygen to help provide
energy for the body and involves metabolic processes in the cells.
A.
Respiratory System
Identify on models or diagrams the structures listed below and state a function of
each:
Upper Respiratory Tract
Structure
Nasal Turbinates
Function
__warm and moisten air____
Pharynx
___joins nasal area and mouth to trachea and oesophagus –
contains nerve function to stimulate swallowing_______
Soft palate
___separates nasal passages from mouth - - enables
breathing to happen at same time as eating______
Epiglottis
_prevents food entering trachea__
Larynx
__allows air in and out of the trachea. Aids in coughing.
Contains vocal folds for noise production
Lower Respiratory Tract
trachea
transports air to lung from larynx__
bronchus
transports air from trachea to each lung_______
bronchiole
branches off bronchii, connects to alveoli__
hilus of lung
_where airways and blood vessels/nerves etc enter lung
diaphragm
_contracts to expand chest cavity
alveolar sac
_gas exchange of CO2 & O2
State the boundaries of the thoracic cavity and find them on a model (or diagram)
dorsally
_spine____________________________
laterally
_ribs_________________________________
caudally
_diaphragm___________________________________
cranially
_ribs and sternum_____________________________
ventrally
_sternum______________________________
the pleura is a thin membrane covering the walls of the thorax and the lungs. the
pleura that lines the thoracic cavity is the___parietal pleura
while the ____visceral pleura_______is the pleura that covers the lung. the
mediastinum is a double layer of pleura where the two sacs meet. It is made from
epithelial tissue
C.
Respiratory Physiology
Define the following
1. Respiration
exchange of gases between atmosphere, blood and cells____
2.
External respiration
exchange of co2 and o2 betweenblood and air in lungs
3.
Internal respiration -exchange of co2 and o2 between capillaries and body cells
4.
Cellular respiration oxidation of glucose within the body (the use of oxygen and
production of carbon dioxide within the cells)
5.
Ventilation
inflow and outflow of air to and from the lungs
Mechanics of ventilation
The process of taking air into the lungs is called ____inspiration, inhalation___ and
the process of expelling air is called __expiration, exhalation_
Using the model provided pull down on the rubber diaphragm. What happens to the
two balloons in the glass container and why?
When the rubber sheet is pulled down the balloons inflate.
This is because pulling down the rubber sheet creates more space inside the
container. The air in the container spreads out to fill the increased space. This means
the pressure around the balloons becomes lower than in the air above the opening.
So air is “sucked into the balloons.
Now release the rubber diaphragm and observe what happens in the balloons.
Explain what you see.
The balloons deflate.
This is because when the diaphragm moves up the space inside the container
reduces. The air is confined in a smaller space and the pressure around the balloons
increases, pushing air out of the balloons.
Now inflate the smaller balloons by applying positive pressure to the neck of the
glass “lung” apparatus. Can you think of a time when this method of inflation in an
animal might be useful?
Mouth to nose resuscitation
Explain the difference between negative and positive pressure as it pertains to
ventilation.
The contraction of the diaphragm and the intercostal muscles contracting and lifting
the ribcage up and out, and the diaphragm down. This creates less pressure inside
the lungs compared to outside, which makes air rush in to equalise this air pressure.
When they return to normal the pressure inside the thoracic cavity increases and air
is expelled.
B.
Dissection of Sheep Lungs (Pluck)
Identify the following structures:
Hilus of Lung
Diaphragm
Heart and Pericardium (if present)
Trachea
Visceral Pleura
Aorta
Left and Right Main Bronchi
Main Pulmonary Artery
Pulmonary Artery Branches
Parietal Pleura
Pulmonary Veins
1.
the cartilaginous rings in the trachea complete or incomplete?
Why is this important?
Incomplete. Allows flexibility of trachea and allows food to pass easily down the
oesophagus that sits dorsally to the trachea
2.
Cut into the trachea and observe the lining. Comment on how it feels:
_____slippery & slimy____________________
3.
What are the functions of the:
(a)
(b)
4.
goblet cells produce mucus
cilia
move mucus up the trachea___________
The mucous in the trachea is frothy. The froth is caused by detergent-like
surfactant produced in the lung. What is its function?
Keeps the airways moist and open (patent) Acts as a detergent and stops the
sides of the alveoli sticking together.
5.
Then using the vacuum pump, allow air to alternatively flow into and out of the
lung. Observe how the lung inflates. Does the lung inflate evenly or istages?
The lung inflates one lobe at a time.
6.
What happens when the pressure is released?
The lung deflates_______________________________
7.
What tissue in the lung allows this to happen?
__Elastic connective tissue__________________________
8.
Now sever one lung at the hilus. State which vessels (air, lymph and blood)
enter and leave the lung at this point.
____Air:
____Blood
Lymph:
Bronchi (primary)_________________________
Pulmonary artery, Pulmonary Vein ________
Lymph vessels
9.
Cut into the main bronchus and note how it divides in relationship to the lobes
of the lung. (Sheep lungs have bronchioles which branch off the main trachea
and bronchii – this is no the same as dogs and cats)
There is no question here.
10.
Open the bronchi out and attempt to follow the respiratory tree as far as
possible. How many divisions until there is no longer cartilage in the walls of
the airways?
__Can be up to 5 or 6 depending on the route you cut. ____
11.
How does gas exchange take place in the lung?
 The alveoli at the ends of the smallest bronchioles have walls made of
squamous epithelium that are 1 cell thick. Each alveolus is surrounded by a
network of very fine capillaries (also with walls only 1 cell thick)
 Inside the alveoli the air is 20% oxygen and 0.03% carbon dioxide
 The blood in the capillaries has very little oxygen (having delivered to the cells
of the body) and lots of CO2 (having picked it up as waste from body cells)
 Therefore Oxygen diffuses through the thin walls from the alveoli to the
capillaries and Carbon dioxide diffuses from the capillaries into the alveoli.
12.
Structure of the Lower Respiratory Tract
Label the following structures:
Trachea,
Bronchi (Primary & secondary)
Hilus of lung
Cartilage rings
Bronchioles
Lobe(s) of the lung
Hyoid Bone
Thyroid Cartilage
Cricoid Cartilage
This diagram is an extra.
Tracheal Cartilage
Trachea
Bronchi
terminal bronchiole
Lobe
lobe
Alveoli
13. The alveolar sacs are lined with the respiratory membrane where gas exchange
takes place. What type of epithelial tissue are the sacs made of?
______simple squamous________________________________
D.
1.
Give the normal respiration rate for:
(I)
(ii)
(iii)
2.
cat
__20 – 30 breaths per minute
dog
__10 – 30 breaths per minute
Horse __12 – 20 breaths per minute
Describe the route taken by an oxygen molecule from entry to the nose to exit
into the tissues of the kidney. Nares – nasal cavity
Pharynx, larynx, trachea, bronchus, bronchioles, alveoli, pulmonary capillaries,
pulmonary vein (**renal artery, renal capillaries, glomerulus) , left atrium, left
ventricle, aorta,
(**This part of sequence will make more sense when we have studied the renal
system.)