Year 11 Biology 2023

​The respiratory system allows us to take in oxygen and remove carbon dioxide.

 

This is essential, as all cells need oxygen in order to function. As a byproduct of cellular processes, cells produce carbon dioxide, which must be removed or else it becomes toxic within the body.

​Comparing respiration to breathing.

Respiration is a series of chemical reactions that cells perform in order to produce energy from nutrients (food).

​Breathing is the physical act of moving air into and out of our bodies, by inflating and deflating our lungs.

Multiple Choice

Recall the primary function of the respiratory system.

• To facilitate the exchange of carbon dioxide and oxygen between the environment and our bodies

• To expel wastes from our body

• To ensure each cell receives enough oxygen

• To maintain the body's optimal pH

Multiple Choice

State which of these is the waste gas that is expelled from the body during exhalation.

• Carbon

• Carbon Dioxide

• Sulfur Dioxide

• Carbon Monoxide

Multiple Choice

State which of these is the main gas that is inhaled into the body during inhalation.

• Carbon Monoxide

• Oxygen

• Carbon

• Carbon Dioxide

​The bronchi

 

Right before the lungs, the trachea splits in two, forming two bronchi (singular="bronchus"). The bronchi go into a lung each.

​ Within the lungs, the bronchi split into many smaller and smaller branches, known as bronchioles.

 

This can be thought of like an upside-down tree.

​The alveoli

At the very end of each bronchiole are bunches of little air sacs (like bunches of grapes) called alveoli (singular= "alveolus"). The alveoli are the place where gas exchange occurs.

​Gas exchange

 

Gas exchange is where oxygen that we have breathed in is moved into the bloodstream for cells to take up, and where carbon dioxide shifts from the bloodstream into the lungs, so that it can be breathed out.

 

Alveoli are very thin and moist, so that oxygen and carbon dioxide can quickly and easily move through them, into or out of the blood.

Multiple Choice

Identify what structure is indicated by the blue arrow in the picture above.

• Alveoli

• Bronchi

• Lungs

• Vocal Cords

Multiple Choice

Identify the structure that is shown in the picture above.

• Alveoli

• Bronchi

• Trachea

• Abdomen

Open Ended

Recall the main role of the respiratory system.

Explain why it is so important.

Open Ended

Explain the difference between respiration and breathing.

Open Ended

Given what you know about the anatomy of the respiratory system, explain how people can make milk or spaghetti come out of their nose when they sneeze.

​At the very end of each bronchiole are bunches of little air sacs (like bunches of grapes) called alveoli (singular= "alveolus").

The alveoli are the place where gas exchange occurs.

​Gas exchange is where oxygen that we breathe in is moved into the bloodstream for cells to take up and carbon dioxide is removed from the bloodstream into the lungs, so that it can be breathed out.

​Alveoli are very thin, so that oxygen and carbon dioxide can quickly and easily move through them, into or out of the blood. They are also moist and have transport systems which maintain the concentration gradients, allowing efficient diffusion.

​Oxygen that we breathe in, eventually makes it to the end respiratory system structure: the alveoli.

 

Once you have breathed in and oxygen has reached your alveoli, oxygen then diffuses into red blood cells in capillaries (blood vessels) that surround the alveoli. These red blood cells deliver the oxygen throughout your body. There is an extensive capillary network surrounding the alveoli to speed up gas exchange.

​How is gas exchange so efficient?

 

To speed up the diffusion (form of movement) of oxygen, the membrane of an alveolus is moist and very thin - only one cell thick! It also is divided into alveoli to produce a huge surface area. The total area of the lungs for gas exchange is roughly the size of a tennis court!

 

The membrane between the alveolus and capillary is called the respiratory surface.

 

Once the oxygen reaches the tissue cells where it is needed, it is released from the red blood cells and travels through the thin capillary walls to the tissue cells by diffusion.

​Movement of carbon dioxide.

Carbon dioxide in the bloodstream diffuses in the opposite direction to oxygen, entering the alveoli to travel through the respiratory system, where it is exhaled.

 

Too much carbon dioxide is toxic for our body. This is the primary reason why we dispose of it!

Multiple Choice

Recall two important features of the alveolar wall for gas exchange to occur.

• It is thick and dry

• It is thin and moist

Multiple Choice

Look at the following depiction of gas exchange in the alveoli.

Recall what the blue arrows must represent.

• Movement of oxygen

• Movement of carbon dioxide

Multiple Choice

Look at the following depiction of gas exchange in the alveoli.

Recall what the red arrows must represent.

• Movement of oxygen

• Movement of carbon dioxide

Multiple Choice

Recall what the respiratory surface is.

• The external surface of the lungs

• A flat space for people to breathe on

• The place where respiration happens

• The membrane between the alveoli and capillaries

Drag and Drop

Select the correct words and drag them to the spaces below:



Oxygen diffuses from the ​

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to the ​​

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.

Drag these tiles and drop them in the correct blank above

alveoli

capillaries

Drag and Drop

Select the correct words and drag them to the spaces below:



Carbon dioxide diffuses from the ​​

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to the ​

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.

Drag these tiles and drop them in the correct blank above

capillaries

alveoli

Open Ended

Explain the relationships between alveoli, oxygen and carbon dioxide.

Multiple Choice

Recall if the following is true or false.

"We inhale and exhale nitrogen gas, into our lungs."

• True

• False

Multiple Choice

In inhaled air, recall if there is a higher concentration of carbon dioxide or oxygen.

• Carbon dioxide

• Oxygen

Multiple Choice

Recall if there is a higher concentration of carbon dioxide in inhaled or exhaled air.

• Inhaled

• Exhaled

Open Ended

Discuss why alveoli are shaped like they are: sac-like structures, similar to grapes.

Open Ended

Using your knowledge of movement of materials between capillaries and tissues in the body, predict the relative concentrations of oxygen, carbon dioxide and nutrients in the capillaries and tissue fluid in your muscles.

​How do alveoli speed up gas exchange?

 

To speed up gas exchange, the lungs are divided into millions of tiny sacs called alveoli, which increases the surface area. The membrane of each alveolus is very thin and moist. There is a huge capillary network surrounding the alveoli.

 

This means the gas can dissolve and diffuse through into the blood faster.

​Why are fish specially adapted for gas exchange?

 

Whilst the air contains about 20% oxygen, water contains a much lower percentage of dissolved oxygen, typically less than 1%. Because of the low oxygen levels, animals that live in the water have to be adapted to extract the oxygen from the water.

Fish gain their oxygen and remove carbon dioxide by swallowing water into their mouths, then passing the water over structures called gills.

 

The gills are found in the gill chamber, which is covered by a gill cover or operculum.

 

As the mouth opens, the gill cover closes and water enters the mouth. Then, as the mouth closes, the gill cover opens, which pushes water from the mouth over the gills.

 

Each gill is made of filaments, which have extensions called lamellae. The filaments are arranged in 2 rows called a gill arch.

 

Each gill is surrounded by a dense network of capillaries. All these features provide a large surface area for gas exchange.

​Fish gills use countercurrent oxygen exchange to maximize the amount of oxygen that their blood can pick up.

 

They achieve this by maximizing the amount of time their blood is exposed to water that has a higher oxygen level, even as the blood takes on more oxygen.

 

Countercurrent oxygen exchange means the blood flows through the gills in the opposite direction as the water flowing over the gills.

 

This flow pattern ensures that as the blood progresses through the gills and gains oxygen from the water, it encounters increasingly fresh water with a higher oxygen concentration that is able to continuously offload oxygen into the blood.

Multiple Choice

Recall if oxygen level in water is higher or lower than in air.

• Lower

• Higher

Multiple Choice

Recall what structure in fish is adapted for gas exchange.

• Gills

• Tail

• Scales

• Fins

Multiple Choice

Recall if gills have a large or small surface area.

• Small

• Large

Multiple Choice

Recall which of the following structures are part of the gills.

• Gill arch

• Filaments

• Lamellae

• All answers are correct

Drag and Drop

Select the correct words and drag them to the spaces below:



Fish gills use ​

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oxygen exchange to ​

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the amount of oxygen that their blood can pick up. They achieve this by maximising the amount of time their ​

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is exposed to water that has a higher oxygen level, even as the blood takes on more oxygen. Countercurrent oxygen exchange means the blood flows through the gills in the ​

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direction as the water flowing over the ​

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Drag these tiles and drop them in the correct blank above

countercurrent

maximise

blood

opposite

gills

Open Ended

Discuss what features fish gills and human alveoli have in common. 

Hint: think about gas exchange.

​The circulatory system acts to connect all the systems within the body.

 

It is comprised of the heart, blood vessels and blood.

 

It transports oxygen from the respiratory system and products of the digestive system to cells requiring energy. It also removes waste products from cells and delivers them to the lungs and kidneys to be excreted.

Multiple Choice

Recall the primary function of the circulatory system.

• To give us a pulse

• To make patterns on our body out of veins

• To keep wastes in circulation, so that they poison your cells

• To transport food and oxygen to all cells of the body

​The largest part of the circulatory system are the blood vessels.

 

Blood vessels are like highways, linking all the different parts of your body together.

 

They carry blood throughout your body. The three main blood vessels you will learn about are:

1. Arteries

2. Veins

3. Capillaries

​The Heart

 

The heart is like a big motor, powering the movement of traffic along the blood vessel highways. It is made of muscle and pumps continuously (yes, even when you sleep) to keep your blood moving.

The traffic on the highways of the circulatory system is the blood.

The blood is a fluid that contains many blood cells which carry food, oxygen and nutrients to where they're needed in the body. It also takes waste products like carbon dioxide away from the organs that produce them.

Multiple Choice

Recall what fluid contains cells that transport food and oxygen around the body.

• Bile

• Blood

• Gastric juice

• Saliva

Multiple Choice

Recall the name of the organ that pumps blood around the body.

• Heart

• Lungs

• Blood vessels

• Liver

Multiple Choice

Recall the name of the transport channels or highways of the circulatory system.

• Blood vessels

• Lungs

• Blood

• Heart

Drag and Drop

The vessels that transport blood from one part of the body to another are known as ​

Placeholder

. Blood is important, because it contains ​

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that carry food and oxygen to all the cells of our body, allowing them to survive. THe organ that keeps all of the blood moving is the ​

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.

Drag these tiles and drop them in the correct blank above

blood vessels

cells

heart

Open Ended

In your own words, explain each of the components that make up the circulatory system and describe what they all work together to do.

The circulatory system is made up of...

They work together to...

​The heart is the motor of the circulatory system.

 

The heart muscle contracts and pumps deoxygenated blood (low in oxygen from cell usage) directly into the lungs where it becomes oxygenated (oxygen-rich), before returning to the heart to be transported throughout the body.

​Without the heart, our blood would be immobile and the cells in our body wouldn't be able to get enough oxygen and nutrients to survive.

 

The heart is the driving force of the entire circulatory system.

The heart is a muscle which acts as a pump. It is approximately the size of your fist and is located slightly to the left of the middle of your chest.

​Have you noticed you don't have to make your heart beat?

 

The heart beats without having to be told to. This is because the heart has a natural pacemaker, called the sinoatrial node.

 

This controls heart rate by sending electrical signals through the heart muscle, making the heart contract and pump blood throughout the body.

​The heart consists of four different chambers along with the blood vessels entering and leaving the heart.

 

The figure shows the structure of the heart. Note how there are two atriums and two valves.

​The two atria sit at the top of the heart, while the two ventricles sit underneath them. The atria are relatively thin walled while the ventricles have very thick, muscular walls.

 

​The heart has two separate sides, each with two chambers, giving four chambers in total.

 

The sides of the heart are the left and the right side. These are divided by a thick, muscular wall called a septum.

 

The left side is shown in red and the right is blue.

​On each side of the heart, there are two chambers. These are called an atrium and a ventricle.  

Both the left and right atria (singular: atrium) are the receiving chambers of the heart.

 

Blood coming into the heart from veins in the body or lungs enters in the left or right atrium.

Once blood enters the heart in either of the atria, it is then pushed into the ventricle on the same side of the heart as the atrium it came from.

 

Each atrium is separated from its ventricle by a valve. This prevents blood flowing backwards through the heart. The ventricles contract to pump blood into the arteries, to travel to either the lungs or around the body.

Multiple Choice

Recall what a receiving chamber of the heart is called.

• The atrium

• The ventricle

• The septum

• The sinoatrial node

Multiple Choice

Each atrium is separated from its ventricle by a valve.

Recall the function of the valve.

• Prevents blood flowing backward through the heart

• To keep the four chambers of the heart separate

• No real significance

Multiple Choice

Recall which structure within the heart contracts to push blood into the arteries.

• The atrium

• The veins

• The ventricles

• The valves

​Our heart circulates our blood to two places:

1. The lungs, to receive oxygen (become oxygenated).

2. The body, where cells can use the oxygen (become deoxygenated).

​All throughout the circulatory system, nutrients and wastes, such as carbon dioxide produced in cellular respiration, are transported via the blood.

​Below are two visual representations of the circulatory system and the pathway blood takes from start to finish.

​From the body, deoxygenated blood enters the heart through two big veins: the superior and inferior vena cava. They both empty into the right atrium. When the right atrium contracts, blood is pushed into the right ventricle.

 

The right ventricle then contracts, sending the blood into the pulmonary artery, where it heads to the lungs to become oxygenated. Once blood has passed through the lungs, it enters the pulmonary vein. This drains into the left atrium.

​When the left atrium contracts, blood is pumped into the left ventricle.

The left ventricle then contracts and ejects blood into the aorta, the largest artery in our body!

The aorta then splits into smaller arteries, supplying all of our cells with oxygenated blood. Once the cells have used up the oxygen they need from the blood, it then enters the veins.

 

The blood from the veins (blood vessels that carry blood back to heart), eventually drain into the superior or inferior vena cava, to repeat its journey through the heart again!

​Arteries take blood away from the heart

 

Each time your heart beats, blood is forced into large arteries. Arteries are blood vessels that carry blood away from the heart to other tissues.

 

A trick to remembering: Arteries carry blood Away from the heart. Veins carry blood into the heart.

​Arterioles

 

From the large arteries, blood starts its one-way journey around the body, moving into smaller and smaller arteries, eventually moving into the arterioles.

 

Arterioles are small branches of arteries that lead into capillaries.

The microscopic capillaries serve as the location for the exchange of gases and nutrients between blood and tissue cells.

 

Capillaries are the alleyways that extend and branch into every tissue of your body, ensuring that every cell has a blood supply. In the capillary beds in your lungs, your cells pickup oxygen and nutrients and drop off carbon dioxide and wastes.

​Veins

 

After leaving the capillary beds, blood starts its trip back to the heart by first entering venules, which are groups of capillaries that unite to become small vessels that drain the capillary bed.

 

These small vessels in turn empty into larger vessels called veins.

Veins are blood vessels that carry blood toward the heart from various tissues.

 

One-way flaps, called valves, in your veins keep blood flowing in the right direction.

 

Remember, veins have valves.

Open Ended

What are the names of the 3 major blood vessels of the human body?

Multiple Choice

Recall which blood vessel serves as the location for the exchange of gases and nutrients between blood and tissue cells.

• Arteries

• Capillaries

• Veins

Multiple Choice

Do the arteries carry blood towards or away from the heart.

• Toward

• Away

Multiple Choice

Do the veins carry blood towards or away from the heart.

• Away

• Toward

​Blood Vessel Summary

​	​Arteries	​Capillaries	​Veins
​Wall thickness	​Thick	​Thin	​Very thin (one cell)
​Direction of blood flow	​Away from the heart	​Towards the heart	​From the artery to vein
​Pressure	​High	​Low	​Varies
​Blood oxygen content	​Oxygenated	​Deoxygenated	​Varies
​Other features	​N/A	​Valves	​Small holes

Dropdown

For fast and efficient transport of blood throughout the body, mammals have a complex network of arteries and veins, which house the blood as it travels through the body.



Select the correct words to fill in the blanks below:



A vein is a vessel that ​

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and an artery is a vessel that ​

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.



The blood that a vein carries is ​

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, while the blood that an artery carries is ​

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, except the pulmonary vessels.