Chapter 4 - gas exchange and excretion Flashcards
What is gas exchange in humans
The take in of oxygen and the removal of carbon dioxide
Where does gas exchange occur in humans
- In humans, gas exchange occurs in the alveoli in the lungs
- Gas exchange occurs via diffusion
What parts are used to move air in the alveoli
They move alongthe trachea and the bronchi and bronchioles
How does deoxygenated blood move to the alveoli
It moves along capillaries that branch from the pulmonary artery
How does oxygenated blood move from the alveoli
Along the capillaries that join up to the pulmonary vein
How does oxygen diffuse from the alveoli to the blood
- Capillaries lie close to the walls of the alveoli
- oxygen diffuses form the air inside the alveoli into the capillaries
- this occurs because the concentration of oxygen is higher inside the air in the alveoli than in the deoxygenated blood
- Hence there is a diffusion gradient for oxygen, from the alveoli to the blood
Why does carbon dioxide diffuse from the blood into the air inside the alveoli
- Because the concentration of carbon dioxide is higher in the deoxygenated blood than in the air inside the alveoli
- Thereofre, there is a diffusion gradient for carbon dioxide, from the blood into the alveoli
Which features allow maximum gas exchange to occur
Large surface area - faster diffusion
Thin walls - short diffusion distance
Good ventilation with air - so diffusion gradients are maintained
Good blood supply - To maintain a high concentration gradient so diffusion occurs faster
Describe the diagram of gas exchange
Why are the alveoli kept moist
To stop them from drying out
Label this
What is the role of the ribs
Its a bone structure that protect vital organs
What is the role of interocstal muscles
Muscles between ribs which control their movement causing inhalation and exhalation
What is the role of the diaphram
Sheet of connective tissue and muscle at the bottom of the thorax that helps change the volume of the htorax to allow inhalation and exhalation
What is the role of the trachea
It is a windpipe that connects the lungs with the mouth and nose
Role of the larynx
The voice box; when air passes across the larynx a sound is made
What is the role in bronchi
large tubes branching of the trachea with one bronchus for each lung
Role of the bronchioles
Bronchi split to form bronchioles in the lungs which connect to alveoli
What is the role of alveoli
They are tiny air sacs where gas exchange takes place
Features of the trachea and their functions
Rings of cartilidge surround the trachea to provide support for the airways and to keep them open during breathing
What are goblet cells
Cells that secrete mucus
What are cilia cells
Cells covered in tiny hairs called cilia
- They are used to beat and push mucus out of the lungs into the throat
How does cilia and mucus work together
- Bacteria and small particles in the air are trapped in the sticky mucus
- The cilia wave in unison, pushing the mucus up towards the back of the throat where it is swallowed
- This prevents bacteria and small particles entering the lungs and causing infection
What is the definition of a breathing movement
The movement of air in and out of the lungs
What happens in inspiration (muscles)
- Muscles in the diaphragm contract, pulling the diaphragm upwards
- The external intercostal muscles contract pulling the ribs upwards
- These increase the volume in the thorax
- pressure in the thorax decreases
- air from the outside of the body flows down the trachea into the thorax, from higher pressure outside the thorax to lower pressure inside
What happens in expiration (muscles)
- The muscles in the diaphragm relax, pulling it up
- The external intercostal muscles relax, allowing the ribs to move down
- These decrease the volume of the thorax
- The pressure of the htorax increases
- Air from inside the body flows out of the thorax up the trachea, from higher pressure to lower pressure inside the thorax to the lower pressure region inside it.
In inspiration and expiration, what are the internal and external intercostal muscles
Antagnostic, they do the opposite
What is the gas composition of inspired air
- Oxygen - 21%
- Carbon dioxide - 0.04%
- Water vapour - variable
What is the compositon of expired air
- Oxygen - 16%
- Carbon dioxide - 4%
- Water vapour - high
How does nitrogen compare from inspired ot expired air
Stays at 78%
Describe and make a diagram for a test to show more CO2 is present in expired air
- When we breath in the air is drawn through boiling tube A
- Breath out, air drawn through boiling tube B
- Limewater in A remains clear, boiling tube B turns cloudy
- Shows the CO2 is more present in expiration
What happens to the rate and depth of breathing within heavy excercise
Breathing is faster and deeper - so you can get more air to your working muscles, and remove the co2 they produce during excercise
What happens when there is a higher carbon dioxide concentration in the blood
- The carbon dioxide concentration stimulates recpetor cells in the brain
- The brain sends impulses to the muscles of the lungs to contract faster and more strongly
- This causes the depth and frequency of breathing to increase
What is the energy from respiration used for
- Muscle contraction
- Building protein molecules
- cell division
- sending electrical impulses
- keeping body tempurature constant
- active transport of substances
Definition of aerobic respiration
The chemical reactions in cells that use oxygen to break down nutrient molecules to release energy
What does respiration involve
The action of enzymes in cells
Describe an experiment to investigate the uptake of oxygen in aerobic respiration
- As the organisms anaerobically respire, they take in oxygen and give out carbon dioxide
- the carbon dioxide is absorbed by soda lime
- the volume of air therefore decreases in the syringe barrel
- this causes the drop of liquid to move along the capillary tube towards the organisms
- The fatser the rate of respiration, the faster the drop moves along the capillary tube
Definition of anaerobic respiration
The chemical reactions in cells that break dwon nutrient molecules to release energy without using oxygen
What are the two word equations for anaerboic respiration
- Glucose –> Lactic acid
- Glucose –> Alchahol and carbon dioxide
What is the balanced equation for anaerobic respiration
C6H12O6 —> 2C2H5OH + 2CO2
What is an oxygen debt and how does it occur
- When a person does vigorous excercise, contracting muscles use oxygen to release energy in aerobic respiration
- The extra oxygen isn’t enough to allow the muscles to release all of the energy, therefore the muscles use anaerobic respiration to top up the energy release
- Lactic acid produced builds up in muscle cells, diffuses into the blood, and is transported to the liver, faster heart rate speeds this up
- Liver cells break down the lactic aicd by combining it with oxygen, this occurs for some time after the excercise, this is oxygen debt
- *
Where is carbon dioxide excreted from?
The lungs
Where is urea produced and excreted
It is produced in the liver and excreted through the kidneys
Where are excess salts and water excreted from
The kidneys
What is the volume and concentration of urine produced by the kidneys affected by
- How much liquid you have drunk; the more water you take in the more urine
- How hot is it, or how much excercise you do; the hotter you are, the more water you lose in sweat, the less water will be in your urine
What is the liquid produced by the liver, and how does it get to where it is stored
Urine is produced in the liver and flows down two ureters, is stored in the bladder, and leaves the body through the urethra
What are the roles of the liver
- (think nitrogen)
- When protein in foods is digested to amino acids, the amino acids are transported to the liver in the blood in the heptic vein
- In the liver - some of the amino acids are built into proteins, such as plasma protein fibrinogen
- In the liver - the excess amino acids are broken down to urea by deamination
What is the definition of deamination
The removal of the nitrogen-containing part of amino acids to form urea
Why must urea be removed
Urea is toxic and too much accumulated would harm the cells in the body
Which part of the kidneys produce urine
Nephrons - tiny little tubules
Identify - the kidney, ureter, bladder and urethra
Why must excretion take place
To get rid of toxic chemicals like urea and carbon dioxide
Label the kidney tubule
What is dialysis
The passing of a person’s blood through a machine in which the blood is spearated from dialysis fluid by a partially permeable membrane
What does dialysis fluid contain and why are their concentrations ideal?
- It contains water, salts and glucose
- The concentration is ideal as it is the same as human blood
- The dialysis fluid does not contain urea
Dialysis - what happens as blood flows through the machine
- Urea in the blood diffuses from the blood into the dialysis fluid, down its concentration gradient via the membrane
- Glucose either diffuses into or out of the blood, depending if its concentration is higher or lower than the dialysis fluid
- water moves by osmosis either in or out of the blood, depending if the water potential is higher or lower than in the dialysis fluid
Disadvantages of dialysis
- Expensive
- Highly trained proffessionals can only use it properly
- the person must be linked up to the machine regularily for several hours at a time
- the
in between treatments the concentration of urea and other toxic substances may damage body tissue
What is the alternative to dialysis
A kidney transplant -
- However kidneys are in short supply
- Even if the cell types are a good match, the person recieving the kidney will need to take immunodepressant drugs for the rest of his life, leaving them vulnerable to infectious disease
