Unit 11 Gas Exchange in Humans Flashcards
Describe the features of gas exchange surfaces
in humans, limited to:
large surface area, thin
surface, good blood supply and good ventilation
with air
How does ventilation happen?
The diaphragm, a sheet of muscle that separates the thorax (chest) from abdomen
The intercostal muscles that lie between the ribs
Explain: role of the ribs, the internal and
external intercostal muscles & the diaphragm
in
producing volume and pressure changes in the thorax leading to the ventilation of the lungs
Explain INHALATION
Internal intercostal muscles [RELAX] and external intercostal muscles [CONTRACT], pulling your ribs [UP AND OUT].
Diaphragm also [CONTRACTS] and [FLATTENS]
Volume of thorax [INCREASES].
Air pressure in thorax [DECREASES, CREATING A NEGATIVE PRESSURE]
Air [ENTERS] the lungs to equilibrate pressure
EXHALATION
INTERNAL intercostal muscles → CONTRACT
EXTERNAL → RELAX
Pulling ribs → DOWN AND IN
Diaphragm → RELAXES AND MOVES UP
Volume of thorax DECREASES
Air pressure in thorax INCREASES, creating a POSITIVE PRESSURE
Air EXITS the lungs to equilibrate pressures
- muscles contracting/relaxing
- how it affects thorax volume (increase/decrease)
- how it affects air pressure in thorax compared to atmosphere (larger = lower pressure)
- if air moves in/out of lungs to equilibrate pressures
so
contract/relax?
thorax volume?
air pressure?
in/out?
Identify in diagrams and images the following
parts of the breathing system: lungs, diaphragm,
ribs, intercostal muscles, larynx, trachea, bronchi,
bronchioles, alveoli and associated capillaries, internal and external intercostal muscles
Explain the link between physical activity and
the rate and depth of breathing in terms of:
an increased carbon dioxide concentration in the
blood,
which is detected by the brain, leading to an increased rate and greater depth of breathing
Exercise increases …
➡ the frequency & depth of breathing
because?
because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed)
to keep up with the energy demand
If they cannot meet the energy demand…
What happens then?
then they will also respire anaerobically, producing lactic acid
After exercise has finished, the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions
can only be removed by…
combining it with oxygen - this is known as ‘repaying the oxygen debt’
can be tested by…
seeing how long it takes after exercise for the breathing rate and depth to return to normal -
the longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid
Investigating the Effects of Physical Activity on Breathing
How?
investigated by counting the breaths taken during one minute at rest and measuring average chest expansion over 5 breaths using a tape measure held around the chest
Exercise for a set time (at least 3 minutes)
Immediately after exercising, count the breaths taken in one minute and measure the average chest expansion over 5 breaths
Following exercise, the number of breaths per minute will have increased and the chest expansion will also have increased
Mechanism for increasing breathing during exercise
rate of respiration increases in _____ cells when __________
rate of respiration increases in muscle cells, when exercising heavily
In terms of respiration, what is CO2?
___ levels increase in muscle cells?
CO2 is a product of aerobic respiration, so CO2 levels increase in the muscle cells
What does CO2 then do?
Blood becomes more ____
This CO2 diffuses out of the cells into the blood plasma
CO2 in solution causes a slight drop in pH so the blood becomes slightly more acidic
blood flows around the circulatory system and passes to the brain where the increased carbon dioxide levels are detected by chemoreceptors in the brain,
which are?
Chemoreceptors: cells that detect chemical changes in the body
They can detect changes in blood gas levels, as well as changes in pH
The chemoreceptors are located in the medulla oblongata of the brain
brain sends nerve impulses to the ______ to _____ the rate and depth of muscle contraction
diaphragm and the intercostal muscles
increase
conclusion
rate of inspiration increases, along with the the volume of air moved in and out with each breath
result overall
which support?
result is greater absorption of oxygen and removal rate of carbon dioxide
This supports the increased rate of respiration in the exercising muscle cells
role of goblet cells, mucus and
ciliated cells in protecting the breathing system
from pathogens and particles
- goblet cells (look like goblet cups)
Goblet cells in the lung epithelium
- produce and secrete MUCUS. They are named such as they look a bit like cups
- mucus
traps bacteria, viruses & any other particles that enter our lungs
- cilia (at the top, the finger-like projections)
cilia are the small hairs on the surface of epithelial cells
they push mucus & other small particles towards the nose and throat
trachea is made up of…
rings of cartilage
helps to keep trachea from collapsing
Oxygen will pass…
down the trachea
through left and right bronchus
through the bronchioles within each lung
alveoli is the site of gas exchange with bloodstream
alveoli - specialised for maximising rate of diffusion [FOUR THINGS]
→ oxygen makes its way to special bundles of air sacs called alveoli.
maximise rate of diffusion by:
→ 1. covered in capillaries, reducing diffusion distance
2nd thing
→ 2. alveoli only 1 cell thick, reducing diffusion distance
3rd
→ 3. Large surface area in contact between capillaries and alveoli
4th
→ 4. Blood is flowing through capillaries, maintaining concentration gradients
Laws of diffusion
The movement of the oxygen from the blood to the cells also follows the law of diffusion
→ It is highly concentrated within the blood [coming from lungs]
→ Meanwhile the concentration is low within the cell
→ So oxygen passes into the body cells
Larynx in the lungs
The larynx functions as a lid to stop your food going down your trachea when swallowing
Inspired vs expired air
Water vapour concentration is also _____ in EXHALED air compared to inhaled
HIGHER
Gas - oxygen (5, higher inspi.)
LINK BACK TO:
inspired:
expired:
back to RESPIRATION QUESTION
inspired: 21%
expired: 16%
Gas: CO2 [3.96%, more exp.]
bc CO2 product of respiration
inspired: 0.04%
expired: 4%
Gas: Nitrogen [THE SAME]
inspired: 78%
expired: 78%
Gas: WATER VAPOUR
insp. = less
inspired: LESS
expired: MORE.
Conclusions about effect of exercise on heart and lungs
When we exercise:
Our rate of breathing increases AND the tidal volume (air in and out per breath).
- to maintain high concentrations of oxygen and low concentrations of carbon dioxide in alveoli,
maintaining the steep concentration gradients between blood and alveoli.
What do our hearts do?
Our heart pumps faster.
- to transport oxygen and glucose to body cells faster and to transport carbon dioxide in to alveoli faster to maintain the high rates of respiration.
After starting physical activity the concentration of CO2 in blood increases.
Explain how effect on breathing is coordinated [3]
📌 stimulus is CO2
📌 [increasing level of] CO2 detected by the brain
📌 by a receptor
[📌 brain sends impulses to (intercostal) muscles]
Explain function of ciliated cells & goblet cells in trachea
goblet cells produce mucus [1]
mucus traps dirt and pathogens [1]
cilia beat [1]
to move fluid out of airway [1]
Gas exchange occurs at the alveoli.
Describe how oxygen molecules move from alveoli into blood [3]
📌 diffusion
📌 across semi-permeable cell membranes
📌 high concentration to low concentration
[📌 O2 is dissolved]
During inspiration, air moves from the atmosphere into the lungs
Describe the mechanism of inspiration
📌 external intercostal muscles contract
📌 internal intercostal muscles relax
📌 lifts ribs upwards
📌 diaphragm contracts
📌 diaphragm flattens
📌 volume of thorax increases
📌 pressure in thorax decreases
📌 air flows in DOWN A PRESSURE GRADIENT
role in inspiration
ribs
move up to + increase volume/decrease pressure
/ prevent collapse of thoracic cavity or lungs
intercostal muscle
contracts + to move ribcage up / to increase volume of chest cavity
diaphragm
contracts/moves downwards + to increase volume of chest cavity
Explain how these cells help to keep the bronchus free from dust and bacteria. [4]
cilia beat
- to move mucus out (of bronchus);
production + of mucus;
mucus is sticky ;
- to trap bacteria;
Describe how the actions of these cells would be affected by one named
compound of tobacco smoke.
nicotine
cilia + become paralysed/stop working;
OVERVIEW of structures in lungs
❗ structure that makes sounds - A larynx
❗ bone that provides protection for the lungs - E rib;
❗ airway that allows passage of air only into the right lung - J bronchus ;
❗ airway that allows passage of air into both lungs - B trachea ;
❗ contracts to increase the volume of the thorax - F/G (F) diaphragm/(G) external
intercostal muscle ;
❗ muscle that contracts to lower the ribcage - K internal intercostal muscles ;
❗ site of gas exchange M alveoli ;
The gas exchange system contains cartilage.
Describe the function of cartilage in the gas exchange system [2]
keeps airways and trachea open;
allows (free flow of) air into (the lungs) and flexibility when bent or swallowing
Use the results in Fig. 2.1 to describe how the pattern of breathing during the match is different from the pattern of breathing before the match starts. [3]
DEEPER BREATHING during match
slower breathing rate before match ; ora
during the match breaths are different from each other ; ora
pressure (in lungs) increases during the match ;
Carbon dioxide is excreted from the body through the lungs.
(i) Explain why this process is termed excretion.
(CO2) is metabolic /AW, waste ;
(CO2) is toxic ;
Name the part of the blood in which most carbon dioxide is transported.
plasma
Carbon dioxide moves from the blood capillaries into the alveoli by diffusion.
Explain why the rate of diffusion of carbon dioxide increases during exercise. [2]
more, (aerobic) respiration ;
steeper concentration gradient ;
Explain the effect of strenuous physical activity on the pH of the blood. [3]
any 3 from:
pH decreases;
increased rate of aerobic respiration;
more carbon dioxide (into blood plasma);
anaerobic respiration occurs (during strenuous exercise);
lactic acid produced;
