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

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

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

The heart

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

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

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

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

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.

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

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

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

Multiple-choice quiz

Heart dissection

The Lungs

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

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

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

Comparing respiratory systems

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

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

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

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

The digestive system

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

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

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

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

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

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

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

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

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)

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

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

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

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)

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

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

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

Comparing digestive systems

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

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