1. Heart Lungs Digestive System
From Cells to Systems
Heart
Lungs
Digestive System

2. Cells and their Functions
Multi-cellular organisms contain specialised cells with different structure and function
Complete the Cut and Paste activity on Specialised Cells

3. Cells to Systems
In multicellular organisms, cells work together in small groups called tissue which have similar structures and functions
Eg: muscle tissue, nerve tissue, skin tissue
An organ is made up of different tissues working together to perform a particular function
Eg: heart, lung, stomach, brain
A system is made up of a group of organs that work together to perform a particular function
Eg: digestive system, circulatory system

4. The heart

5. The Circulatory System
The body’s own transport system that carries substances around the body.
Which organs are involved in this system?
heart
blood vessels
blood

6. The Circulatory System
The circulatory system carries two types of blood:
oxygen-rich blood
oxygen-poor blood
blood travelling
to the body cells
high oxygen content
low carbon dioxide content
blood travelling
away from the body cells
low oxygen content
high carbon dioxide content

7. The Heart
The organ at the centre of the circulatory system. It pumps blood around the body.

8. The Chambers of the Heart
Each section of the heart is called a chamber. There are 4.
An upper chamber is called an atrium (plural atria).
A lower chamber is called a ventricle.
right
atrium
left
atrium
right
ventricle
left
ventricle

9. The Chambers of the Heart
The chambers of the heart have different functions.
Pulmonary artery - blood to the lungs
Aorta - blood to
the body
Pulmonary vein - blood from the lungs
Superior Vena Cava - blood from the body
The atria collect blood that enters the heart.
The ventricles pump blood out of the heart.

10. Heart valves
Blood always flows in the same direction as it moves through the heart during each circulation of the body.
The chambers of the heart are separated by valves which prevent blood from flowing in the wrong direction.
Pulmonary Valve - valve leading out of
right ventricle
Aortic Valve - valve leading out of
left ventricle
Tricuspid Valve - valve between
right atrium and right ventricle
Mitral Valve - valve between
left atrium and left ventricle

11. The Heart right side of the heart oxygen-rich blood left side
The inside of the heart is divided into two sections so that the two types of blood (oxygen-rich and oxygen-poor)
are kept apart.
right side
of the heart
oxygen-rich
blood
left side
of the heart
oxygen-poor
blood

12. The Heart and Lungs lungs lungs body’s cells
Blood is pumped around the body by the heart.
It takes about 30 seconds for blood to go once around the body.
The left side of the heart pumps oxygen-rich blood to the rest of the body.
Blood picks up carbon dioxide from the body’s cells.
This oxygen-poor blood then travels back to the right side of the heart.
Next, the right side of the heart pumps oxygen-poor blood to the lungs.
In the lungs the blood gets rid of the waste carbon dioxide and collects more oxygen.
The oxygen-rich blood then returns to the left side of the heart.
lungs
lungs
body’s
cells

13. Multiple-choice quiz

14. Heart dissection

22. The Lungs

23. The Lungs Major part of the respiratory system
Main function is to transport oxygen from the atmosphere into the bloodstream and to release CO2 from the bloodstream into the atmosphere
They are a large organ because they need a large surface area to exchange gasses
This occurs in specialised cells that form millions of tiny, highly specialised thin walled air sacs called alveoli

24. Exchanging Gasses
Air travels down the trachea (windpipe) and divides into 2 main branches (bronchi)
Air then continues to subdivide into the bronchioles until it reaches the alveoli where gas exchange occurs

25. Respiration
A series of chemical changes taking place in cells to release energy
In animals, this means we take in air and extract oxygen from it
Oxygen passes into the bloodstream to be distributed throughout the body
The walls of the alveoli and blood capillaries are only 1 cell thick

26. Comparing respiratory systems

27. Mammals Get oxygen from the air Gas exchange occurs in the lungs
Air has a high O2 concentration
It is easier to ventilate
Gas exchange occurs in the lungs
Bidirectional airways
Air goes in and out the same way
With each breath, not all the old air makes it out which means not all the air coming in is new. Therefore you don’t get the maximum O2 possible out of the air
Mucus in the trachea helps keep the gas exchange surface area moist

28. Fish Get oxygen from the water Gas exchange occurs in the gills
Water has a low O2 concentration
It is harder to ventilate
Gas exchange occurs in the gills
Unidirectional airways
Water (oxygen) comes in through the mouth and is pushed out through the gills via a special flap called the operculum
The blood flows in the opposite direction to the water, so the O2 diffuses from the water directly into the bloodstream whilst the CO2 diffuses into the water
The gas exchange surface area is kept moist by the water they live in

29. Insects Get oxygen from the air Do not have lungs or a bloodstream
Unidirectional airways
They have openings in their exoskeleton called spiracles where oxygen enters
These open up into a network of tubes called tracheae
These branch into smaller and smaller tubes, ending in sacs which directly ventilate the tissues
There is water in the sacs to keep the gas exchange surface area moist

30. Amphibians
Have two forms of respiration: bidirectional (same as mammals) and cutaneous
Cutaneous involves breathing through the skin (which is why they live near water and have moist skin)
This takes longer than diffusion in the lungs
The top layer of their skin is thin to allow diffusion
Deeper layers of skin have capillary networks for the O2 to reach the bloodstream

31. The digestive system

32. The Digestive System
The digestive system is used for breaking down food into nutrients
These pass into the circulatory system and are taken to where they are needed in the body

33. The Digestive System
The only visible parts of the digestive system are the entry and exit points (mouth and anus)
Stretched out the digestive system is a 9m tube
It is extremely folded and passes through many organs

34. Physical vs Chemical Digestion
Physical Digestion: changing the shape of the food
Chemical: breaking down the food to release nutrients

35. Stages to Food Processing
Ingestion: taking in food
Digestion: breaking down food into nutrients
Absorption: taking in nutrients by cells
Egestion: removing any leftover wastes

36. Mouth Begins when food enters the mouth
It is physically broken down by the teeth
It is begun to be chemically broken down by amylase, an enzyme in saliva that breaks down carbohydrates

37. Mouth to Pharynx
The tongue moves the food around until it forms a ball called a bolus
The bolus is passed to the pharynx (throat) and the epiglottis makes sure the bolus passes into the esophagus and not down the windpipe

38. Peristalsis The bolus passes down the esophagus by peristalsis
A wave of muscular contractions that push the bolus down towards the stomach

39. Into the Stomach
To enter the stomach, the bolus must pass through the lower esophageal sphincter
A tight muscle that keeps stomach acid out of the esophagus

40. The Stomach Contains folds called rugae
A big muscular pouch which churns the bolus (physical digestion) and mixes it with gastric juice, a mixture of:
Stomach acid: kills off any invading bacteria or viruses
Mucus: protects the lining of the stomach from being eaten away by the acid.
Enzymes: break down proteins and lipids (chemical digestion)

41. Absorption in the Stomach
Some medicines (eg. aspirin), water and alcohol are all absorbed through the stomach
The digested bolus is now called chyme and it leaves the stomach by passing through the pyloric sphincter

42. Into the Small Intestine
The majority of absorption occurs here
The liver and pancreas help the small intestine to maximize absorption
The small intestine is broken down into three parts

43. Duodenum Receives chyme from the stomach
Bile breaks down fats (stored in the gall bladder)
Pancreatic juice reduces the acidity of the chyme.

44. Jejunum Where majority of absorption takes place
Lined with tiny fingerlike projections called villi (increase surface area for absorbing nutrients)
Each villi has microvilli (further increase surface area for absorption)

45. Ileum Last and longest portion of small intestine
Has fewer villi and basically compacts the leftovers to pass through the caecum into the large intestine

46. Into the Large Intestine
Also known as the colon
Used to absorb water from the waste material leftover
Produces vitamin K and some B vitamins using the helpful bacteria that live here

47. The Large Intestine
All leftover waste is compacted and stored at the end of the large intestine called the rectum
When full, the anal sphincter loosens and the waste (feces) passes out of the body through the anus

48. Comparing digestive systems

49. Carnivores A much simpler system as meat is easily digested
Only have one stomach
Strong, sharp teeth to make it easier to tear apart meat
Minimal to no salivary enzymes to break down food so it does not spend long in the mouth
They can eat a lot and digest it over a few days
They cannot break down cellulose, such as the yellow casing of corn kernels, which is why they come out whole in the faeces

50. Herbivores Plant material is difficult to digest
The digestive tract is longer as their diet is high in fibre which is difficult to digest
The intestine is 27 times longer than the animal!!
Some have one stomach and a large caecum with billions of bacteria to help digestion (horse, rabbit, gorilla)
Others have multiple, complex stomachs each with a different role in digesting the plant material (cows, goat, camel, sheep)
Flat, wide teeth to grind the plant material