2025 IQ2 & 3 BOOKLET 1 HETEROTROPHS MODULE 2 - ORGANISATION OF LIVING THINGS STUDENT BOOKLET

Heterotrophs - Nutrient and Gas Requirements and Transport Systems

Heterotrophs IQ2&3

• This booklet covers heterotrophs.
• There are separate booklets for autotrophs and a comparison between heterotrophs and autotrophs.

Learning Checklist

• Distinguish between autotrophs and heterotrophs.
• Identify nutrient and gas requirements of animals (linking to Module 1).
• Outline process and importance of Cellular Respiration (linking to Module 1).
• Define gas exchange and identify the organs and requirements for it to occur efficiently.
• Observe a lung dissection.
• Identify features of lung tissue in prepared slides.
• Outline the processes involved in gas exchange in mammals.
• Describe gas exchange systems in various animals: alveoli, gills, skin, spiracles.
• Compare gas exchange structures in mammals, frogs, fish, and insects.
• Define digestion in mammals as the breakdown of large, insoluble food molecules into small, water-soluble molecules for absorption into blood plasma.
• Compare physical and chemical digestion.
• Identify components and functions of the mammalian digestive system:
  • Mouth, Teeth, Saliva
  • Esophagus
  • Stomach
  • Pancreas
  • Liver
  • Caecum (herbivores)
  • Small intestines
  • Large intestines
  • Anus
• Describe the location and process of absorbing nutrients, minerals, and water, and the process for eliminating solid waste.
• Construct a flowchart to explain mammalian digestion: physical and chemical digestion, absorption, and elimination.
• Assess the effect of a digestive structure not performing its function (e.g., celiac disease).
• Describe structures in open circulatory systems (invertebrates) and their function.
• Describe structures in closed circulatory systems (vertebrates) and their function.
• Identify advantages and disadvantages of open and closed circulatory systems.
• Compare open and closed circulatory systems with examples.
• Identify the role of the Lymphatic system in mammals.
• Describe the structures and components of human cardiovascular transport systems:
  • Veins
  • Arteries
  • Capillaries
  • Heart
  • Valves
• Describe the structures and components for transport systems in two other animals (e.g., insects, fish, birds).
• Identify the components of blood and their functions.
• Draw labeled diagrams of veins, arteries, capillaries, blood, heart, and valves.
• Compare and contrast blood vessels.
• Identify the function of a range of organs and their nutrient and gas requirements (e.g., heart, lung).
• Compare the changes in the composition of the transport medium as it moves around the organisms.

Heterotrophs

• Heterotroph: organism that eats other plants or animals for energy and nutrients.
  • "Hetero" (Greek) = "other"
  • "Trophe" (Greek) = "nourishment"
• Organisms are categorized based on how they obtain energy and nutrients:
  • Autotrophs: producers that make their own food from raw materials and energy (e.g., plants, algae, some bacteria).
  • Heterotrophs: consumers that consume producers or other consumers (e.g., mammals, fungi, fish).
• All living organisms require inorganic and organic substances for efficient functioning.
• These nutrients:
  • Supply energy.
  • Provide raw materials for building cells and tissues.
• Organic nutrients:
  • Glucose
  • Amino acids
  • Fatty acids
  • Glycerol
  • Nucleotides
  • Vitamins
• Inorganic nutrients:
  • Minerals (phosphates, sodium ions, chloride ions)
  • Water
• Heterotrophs:
  • Take in all nutrients from external sources.
• Autotrophs:
  • Produce their own organic nutrients.
  • Obtain water, mineral ions, carbon dioxide, and oxygen from external sources.

Autotrophs and Heterotrophs

• Key Idea: Heterotrophs feed on other organisms for energy and carbon, while autotrophs use light or chemical energy to make their own food.
• Nutritional mode: how an organism obtains energy and carbon.
• Autotrophs ("self-feeders"):
  • Make food from simple inorganic substances using sunlight or chemical energy.
• Heterotrophs ("feeders on others"):
  • Feed on other organisms for energy.
  • Depend directly on other organisms (dead or alive) or their by-products (e.g., feces, cell walls, food stores).

Distinguish between photoautotrophs, chemoautotrophs, and chemoheterotrophs:

• (a) Photoautotroph
  • Source of energy: Light
  • Source of carbon: Carbon dioxide
  • Examples: Green plants, cyanobacteria (Anabaena)
• (b) Chemoautotrophs
  • Source of energy: Inorganic compounds (e.g., elemental hydrogen)
  • Source of carbon: Carbon dioxide
  • Examples: Bacteria or archaea in hostile environments (geothermal/deep sea vents), e.g., Methanococcus (uses hydrogen to reduce CO_2 to methane).
• (c) Chemoheterotroph
  • Source of energy: Organic source of carbon and energy (usually glucose)
  • Source of carbon: Organic source of carbon and energy (usually glucose)

Three main nutritional modes of chemoheterotrophs:

• Many bacteria and protists (e.g., Paramecium) are heterotrophic.
• All fungi are chemoheterotrophs and most are decomposers (saprotrophs), obtaining nutrition from extracellular digestion of dead organic material.
• All animals are heterotrophs, relying on glucose (from plants, dead material, or other animals) for energy and carbon; holozoic nutrition is the main feeding mode of animals.

Difference between parasites and saprotrophs:

• Parasites live on or within a living host organism for part or all of their life (e.g. tapeworms).
• Saprotrophs obtain nutrition from extracellular digestion of dead organic material (decomposers).

Autotrophs vs. Heterotrophs

• Autotrophs make their own organic molecules by photosynthesis, while heterotrophs cannot.
• Photosynthesis: converts water and carbon dioxide into glucose and oxygen using sunlight energy.
• Autotrophs manufacture energy from the sun; heterotrophs rely on other organisms for energy.
• Autotrophs have chloroplasts with chlorophyll, capturing sunlight energy for photosynthesis; heterotrophs lack chloroplasts.

Cellular Respiration in Autotrophs and Heterotrophs

• Cellular respiration: an essential process in both plants and animals (Module 1).
• Releases energy stored in glucose to make ATP (adenosine triphosphate), which powers cellular work.
• Cellular respiration equation: C6H{12}O6 + 6O2 \rightarrow 6CO2 + 6H2O + \text{Chemical Energy (in ATP)}
• In plants and animals, Cellular Respiration occurs in the mitochondria.

Gas Exchange in Heterotrophs - Lesson 1

• Gaseous exchange:
  • Occurs in all animals.
  • Involves movement of gases between internal and external environments by diffusion across cell membranes.
  • Gases required for cell functioning move into the cells.
  • Waste gases diffuse out.
• Oxygen:
  • Essential for cellular respiration to release energy from nutrients.
• Carbon dioxide:
  • Produced during cellular respiration.
  • Must be removed as it is toxic in high concentrations, changing cell pH and interfering with enzyme functioning.
• Respiratory system:
  • Enables gas exchange between organism and environment.
  • Contains organs made of specialized tissues.
  • Examples: lungs (mammals), gills (fish), tracheal system (insects).
• Microscopic organisms:
  • Gas exchange occurs by diffusion across cell membrane.
• Larger terrestrial animals:
  • Gas exchange system is internal to prevent dehydration of gas exchange surfaces.
• All gaseous exchange structures share common characteristics for efficient functioning:
  • Large surface area: enhanced by folding, branching, or flattening for faster diffusion.
  • Moist, thin surface: ensures gases dissolve for easier diffusion; thinness decreases travel distance.
  • Close proximity to efficient transport system: transports gases to and from all cells.
  • Concentration gradient: higher concentration of required gas on one side of the membrane to maintain diffusion.

1. Gas exchange: the movement of gases between the internal and external environments by diffusion across cell membranes.
2. Gas taken into cells: Oxygen
   Waste gas removed from cells: Carbon dioxide
3. Cells need to remove wastes to prevent toxicity and interference with enzyme functioning.
4. Animal respiratory systems are not all the same; they vary based on the animal and its environment.
5. Gaseous exchange structures share common characteristics to ensure efficient functioning and maximum exchange of gases.

Case Study: Gaseous Exchange in Mammals

• Human respiratory system structure:
  • Tube-like passages decreasing in size towards air sacs.
  • Air enters through nose or mouth, passes through pharynx and larynx, travels down trachea (cartilage rings for strength).
  • Trachea divides into two bronchi (smaller than trachea), each leading to a lung.
  • Bronchi branch into smaller bronchioles, ending in clusters of microscopic air sacs called alveoli.
• Terrestrial animals:
  • Respiratory systems are internal to reduce water loss from respiratory surface.
• Alveoli:
  • Gaseous exchange surfaces in the lungs.
  • Thin-walled air sacs connected to external environment, surrounded by tiny thin-walled blood vessels (capillaries).
  • MASTER gaseous exchange surface.
• Alveoli features for efficient gas exchange:
  • Increased surface area: ~300 million microscopic alveoli supplied by 280 million capillaries.
  • Thin lining: single layer of flattened cells for efficient diffusion.
  • Moist surface: air inside saturated with water vapor; mucus-lined epithelium reduces water evaporation; ensures gases diffuse in dissolved form.
  • Close contact with blood capillaries: ensures all alveoli are close to blood.
• Gas movement:
  • Occurs by diffusion across a concentration gradient.
  • Inhaled air: ~20% oxygen, 0.04% carbon dioxide.
  • Exhaled air: ~15% oxygen, 4% carbon dioxide.
  • Oxygen: higher concentration in alveolar air than bloodstream, diffuses into bloodstream.
  • Carbon dioxide: higher concentration in bloodstream, diffuses into alveolar air to be exhaled.

*Fill in the blanks to the flow diagram for the passage of air into the respiratory system: Breathed in nose Pharynx Larynx Trachea bronchus Bronchioles alevoli
*Respiratory systems of animals internal? to reduce the loss of water from the respiratory surface
*Identify the name of the gaseous exchange structure in the lungs: alveoli

9. Blood that flows to the lungs has a high concentration of carbon dioxide and a low concentration of oxygen, blood that flows away from the lungs has a high concentration of oxygen and a low concentration of carbon dioxide.
10. Features that make alveoli efficient gas exchange structures:
    • High surface area
    • Thin lining (single layer of flattened cells)
    • Moist surface
    • Close contact with blood capillaries

Respiratory System

Body Part and Function

1. Nose: Filters, warms, and moistens air.

2. Pharynx: Passageway for air and food.

3. Epiglottis: Prevents food from entering the trachea.

4. Larynx: Voice box; produces sound.

5. Vocal Chords: Vibrate to produce sound.

6. Trachea: Windpipe; carries air to the lungs.

7. Bronchi tree: Branches that carry air to the lungs.

8. Bronchioles: Smaller branches that carry air to the alveoli.

9. Lungs: Organs where gas exchange occurs.

10. Alveoli: Air sacs where oxygen and carbon dioxide are exchanged.

11. Diaphragm: Muscle that helps with breathing.

12. What Gas Exchange is: The process by which oxygen is brought into the body, carbon dioxide is released

13. Organ where gas exchange occurs in the different organisms below:
    Mammal (Polar bear): lungs
    Fish (Shark): gills
    Mexican Salamander: skin
    Insect (Locus): spiracles
    Amphibian (Poison Dart Frog): skin and lungs

14. Requirements for efficient gas exchange

    • Large surface area
    • Moist surface
    • Thin membrane
    • Close proximity to blood supply

Gas exchange in mammals: Labelling the Alveoli

The alveoli allow for efficient gas exchange to occur in mammals due to its:

• Large surface area
• Thin lining (single layer of flattened cells)
• Moist surface
• Close contact with blood capillaries

Graph Trends

a) Gas exchange starts off exponentially increasing fast, then decreasing slightly slower
b) Gas Exchange is the process by which oxygen is brought into the body, carbon dioxide is released

Human Respiratory System - Activities

• Activity 1: Labeling the diagram of the human respiratory system using the terms provided.
  • Key structures: nasal cavity, mouth, pharynx, larynx, trachea, left and right bronchus, bronchiole, alveoli, lungs, diaphragm.
• Activity 2: Modeling the action of the diaphragm.
  • When the bottom balloon/rubber glove is pulled down, the internal balloon expands, and when it's pushed up, the internal balloon deflates.
  • The diaphragm's movement controls inhalation (contraction, moves down, increases chest cavity size) and exhalation (relaxation, moves up, reduces chest cavity size).
• Activity 3: Comparing composition of inhaled and exhaled gases.
  • Oxygen: Inhaled gas (21%) > Exhaled gas (17%)
  • Carbon dioxide: Inhaled gas (0.04%) < Exhaled gas (4%)
  • Nitrogen: remains the same (78%)
  • Other gases: remains the same (0.9%)
• Activity 4: Gas exchange by diffusion.
  • Carbon dioxide diffuses out of the blood because its concentration is higher in the blood than in the alveoli.
  • Oxygen diffuses into the blood from the alveoli because its concentration is higher in the alveoli than in the blood.
  • Having many small alveoli increases the surface area to volume ratio, aiding the rate of diffusion compared to having two large air sacs.
• Activity 5: Differentiating cellular respiration and the respiratory system.
  • The respiratory system aids cellular respiration by providing oxygen and removing carbon dioxide.
  • Alternative name for the respiratory system: gas exchange system

Oxygen Dissociation Curve

• Plots the proportion of hemoglobin saturated with oxygen against the level (partial pressure) of oxygen.
• Explains why hemoglobin picks up oxygen at the lungs and drops it off at the tissues.
• At high O2 levels: hemoglobin binds to oxygen to form oxyhemoglobin (blood is fully saturated).
• At low O2 levels: oxyhemoglobin releases oxygen to form hemoglobin.

Gas Exchange Systems and Environment - Lesson 2

• Key Idea: Animal gas exchange systems are suited to the animal's environment, body form, and metabolic needs.
• Cellular respiration and gas exchange are linked.
  • Cellular respiration takes place in the mitochondria of every cell, breaking down glucose to provide energy as ATP.
  • This creates demand for oxygen and a need to eliminate carbon dioxide.
  • These gases are delivered and removed via diffusion across gas exchange surfaces.
• Gas exchange: the process by which gases enter and leave the body by diffusion across gas exchange surfaces.
  • Effective gas exchange surfaces are thin with a high surface area and are moist because gases must dissolve before diffusing across.
  • In animals with gas exchange systems, the gas exchange surfaces lie close to capillary networks.
  • Effective gas exchange relies on maintaining a concentration gradient for gas diffusion.
• Purpose of gas exchange: to meet the demands of aerobic metabolism by exchanging gases with the environment (oxygen delivery and carbon dioxide removal).
• Gases are exchanged with the environment by diffusion across gas exchange surfaces.
• Gradients for diffusion are maintained in a simple organism by the high surface area to volume ratio.
• Gradients for diffusion are maintained in an organism with a gas exchange system Oxygen is transported away from the gas exchange surface by the blood, reducing its concentration relative to the environmental side of the gas exchange surface. CO₂ is transported to the gas exchange surface, increasing its concentration relative to the environmental side of the membrane.

*Gas exchange systems and environment
*Two reasons why most animals require specialised gas exchange structures and systems: Larger or more complex animals have specialised systems to supply the oxygen to support their metabolic activities. The type of environment presents different gas exchange challenges to animals.
*Three ways the gas exchange surfaces of air breathers are kept moist:
-internal lungs within the body protecting from the dry environment

• mucus
  -water vapour produced by metabolism
  Gills would not work in a terrestrial environment:In air, gas exchange surfaces will dry out
  Why do animals have to ventilate their gas exchange surfaces: Exchange rates for the diffusion of gases are maintained by ventilation of the gas exchange surface.(breathing in and out)
  Difficulty associated with gas exchange
  (a) In air: gas exchange surfaces will dry out
  (b) In water: the oxygen content is much lower than in air.

Comparing Respiratory Systems in Different Animals

• Aquatic animals:
  • Gases have low solubility in water, so concentration in water is much lower than in air.
  • Gas exchange structures (gills) extract maximum possible oxygen from water.
  • Water flows in one direction over the gills, entering as the fish opens its mouth while swimming, leaving through gill slits.
  • Gaseous exchange takes place as water flows over the gills.
• Insects:
  • Terrestrial habitat challenges insects to reduce water loss from internal respiratory surfaces.
  • Insects take in and expel air through spiracles (breathing pores) with valves regulating their opening and closing.
  • Little or no gaseous exchange occurs through their body coverings.
  • Insects lack lungs or blood capillaries; use a simpler system for gas exchange due to their small size.
  • Air enters spiracles, drawn into branching air tubes called tracheal tubes (kept open by chitin rings).
  • Tracheae branch into smaller tubules called tracheoles, creating large surface area for gaseous exchange.
  • Tracheoles bring air directly to cells; no blood or capillaries involved in gas transport.
  • Ends of tracheoles filled with watery fluid where gases dissolve.
  • Oxygen dissolves in fluid, diffuses into cells; carbon dioxide diffuses out of cells into tracheoles.
  • Spiracle opening/closing controls respiration rate; muscular movements of thorax and abdomen (during movement/flight) help ventilate the tracheal system.

Respiratory Surfaces

• Respiratory systems facilitate exchange of materials between internal and external environments.
• Individual cells obtain energy through respiration.
• Aerobic respiration: organic molecules (e.g., glucose) + oxygen -> energy + carbon dioxide + water.
• 'Gas exchange': movement of oxygen and carbon dioxide in different directions across a membrane.
• For respiration to occur, organisms need to supply oxygen to cells and remove carbon dioxide.
• Respiratory surfaces require several features:
  • Moist surface: allows oxygen and carbon dioxide to dissolve for diffusion.
  • Large surface area: allows maximum diffusion.
  • Rich blood supply: removes oxygen and absorbs more oxygen.
  • Thin: reduces diffusion distance.

*Mammalian Respiratory System:
* Lungs and passages involved with the intake, expulsion, and exchange of oxygen and carbon dioxide.
* Air enters the nostrils, travels to the pharynx and then to the trachea
* epiglottis prevents food entering the trachea.
* The trachea splits into two bronchi, which each enter a lung and branch into smaller tubes called bronchioles. Bronchioles end in air sacs called alveoli
* oxygen diffuses across the wall of the alveoli into the blood in the capillary and carbon dioxide diffuses out of the bloodstream into the alveoli
* In capillary oxygen attaches to haemoglobin of a red blood cell, forming oxyhaemoglobin, and is transported to the heart in the pulmonary vein
Fish:
* respiratory surface of fish needs to be more efficient than the respiratory surface of humans as there is less oxygen in water than in air and diffusion is slower in liquids than in air.
* respiratory organs the gills. Most fish have 4 gill arches on either side of the head and each arch has two rows of gill filaments.
* flow of blood in the capillaries is in the opposite direction to the flow of water. called a countercurrent arrangement. increases efficiency so that up to 96% of oxygen can be obtained from the water that passes over the gills.
Insects:
* have an exoskeleton made of chitin that is often coated in a thin layer of wax. is impermeable and does not allow gas exchange, and thus insects need a system to allow gases in and out of their body.
* called a tracheal system and consists of holes called spiracles that form a row along both sides of their body. spiracles connect to a series of tubes, called tracheae, which can be strengthened with chitin
* movement of air in and out of the spiracles is by diffusion, however, some insects use a rhythmic pumping movement of the abdomen to increase air movement and flight insects often use the movement of their flight muscles to aid ventilation of their tracheal system.
Frogs
* the skin of many amphibians is used as a respiratory surface
* have very simple sac-like lungs which are connected to the buccal cavity.

necessary characteristics of a respiratory surface

• Moist
• Large surface area
• Rich blood supply
• Thin

Passage of Air in the Human Body Flowchart

Nostrils → Pharynx → Trachea → Bronchi → Bronchioles → Alveoli

Why does the respiratory surface in fish need to be more efficient in fish than in humans? There is less oxygen in water than in air and diffusion is slower in liquids than in air

Respiratory surface in fish - Gills

Countercurrent Arrangement in Fish flow of blood in the capillaries is in the opposite direction to the flow of water

*Why do insects need a respiratory system? Their exoskeleton is impermeable to gasses

Movement of Air into Insects Flowchart

Spiracles → Tracheae → Tracheoles → Body Cells

How do some insects increase the flow of air in their tracheal system? By the rhythmic pumping movement of the abdomen*

Gas exchange frogs occurs in: Skin and sac like lungs

10. The efficiency of the fish respiratory system needs to be higher due to the lower concentrations of gases dissolved in water compared to air/ Fish can also use counter current exchange mechanism to maximise efficiency

Gill filament shape to help with O2 absorption

a) They increase the surface area for diffusion and increases amount of O2 able to be absorbed
b) The structure collapses and this is why they need water, the gills collapses on each other in attempt to maintain structure of the gills and also to allow absorption
c) Add numbers and arrows to add the following labels to the correct locations on this fish:

1. Water enters the fish -mouth-
2. Water is pumped across .the gills
3. Oxygen diffuses into capillaries -gills-
4. Carbon dioxide diffuses out of capillaries
5. Water exits the fish -operculum-

a) water temperature and the number of times a goldfish opens its mouth: -Inversely proportional increases decreases- Openings per minute
b)There may be more oxygen more opens
c) A student collected this data-Unreliable

True or False - Insect Tracheae

a) False
b) True
c) False
d) True
e) True
f) True
g) True

Respiratory Surfaces of Different Organisms

Mammalian Digestion - Lesson 3

• Heterotrophs ingest complex foodstuffs broken down by the digestive system into simpler molecules for absorption into the bloodstream.
• Digestion is the breaking down of large and complex food particles into much smaller and simpler particles.
• There are two types of digestion: mechanical and chemical.
• The overall aim of digestion is to break down the particles into substances that are small enough to be absorbed through the intestinal walls into the bloodstream.

Mechanical Digestion

• Involves physical breakdown of food particles.
• Begins in the mouth with teeth breaking food into smaller pieces by cutting, tearing, chewing, and grinding.
• Churning motion of the stomach continues the process.
• Increases surface area for enzymes to act on in chemical digestion.

Chemical Digestion

• Involves using digestive enzymes to chemically break down large, complex molecules into smaller, simpler forms.
• Examples of simple substances from complex:
  • Glucose from complex carbohydrates
  • Amino acids from proteins
  • Glycerol and fatty acids from lipids
  • Nucleotides from nucleic acids

Pathway of the Digestive System

• Mouth
  • Mechanical digestion begins.
  • Teeth break food into smaller pieces, increasing surface area.
  • Salivary amylase is released, beginning the chemical breakdown of starch into maltose.
  • Food is chewed and mixed with saliva to form a bolus.
  • The esophagus is used to swallow the bolus
• Oesophagus
  • Bolus travels down the soft-walled, muscle-ringed tube to the stomach.
  • The epiglottis closes over the trachea to prevent food entry into the respiratory system.
  • Peristalsis (muscular contractions) moves the bolus.
  • Chemical digestion of starch continues.
• Stomach
  • Narrow openings at entry and exit controlled by circular sphincter muscles.
  • Relaxation and contraction of stomach walls continue mechanical digestion.
  • Bolus breaks up and combines with gastric juices to form chyme.
  • Gastric juices contain water, hydrochloric acid, pepsinogen, and pepsin.
  • Acid causes the pH of the stomach interior to be 2.0–3.0.
  • Mucus lining prevents acid from ‘eating away’ the stomach walls.
  • Pepsinogen is converted into active pepsin in the acidic environment, beginning the chemical breakdown of proteins into peptides.
  • Pepsin also breaks down nucleic acids into nucleotides.
  • Chyme remains in the stomach for about 6 hours.
• The small intestine The chyme from the stomach enters the small intestine gradually through a small muscular opening, the pyloric sphincter
  • Highly folded small intestine ~7m long
    *Stimulates hormone release releases pancreatic juices
  • Pancreatic juices secreted by the pancreas and contain a mixture
    ** digestive enzymes amylase, trypsin and lipase
    ** The bicarbonate ions act to neutralise the acidic chyme from the stomach.

**Amylase continues the chemical breakdown of carbohydrates

*Trypsin continues the chemical breakdown of proteins .
*Bile released with presence of lipids in the chyme, is produced by the liver and is stored in the gall bladder

• Bile detergent - Breaks down(emulsifies) fats into smaller pieces drops Increases surface area enzyme lipase to chemically break the lipids into fatty acid and glycerol molecules
  *Food enters the rest of the small intestine - absorbs digestion products.Absorption

ABSORPTION IN SMALL ISNTINE

• absorption of substances mostly occurs in the small intestine.
• Some substances, such as alcohol and drugs, are absorbed quickly in the stomach. *The products of digestion, amino acids, glucose, fatty acids and glycerol in transport systems
  • diffusion or active transport through tiny projections Villi tiny projections, - increase surface area for efficient absorption-Walls are moist and are one cell thick-. They have a rich blood supply tiny capillaries wrapped around a lacteal. Lacteals are connected to another transport system in the body - lymphatic system
  • Glucose and amino acids are absorbed into the capillaries, while fatty acids and glycerol move into the lacteal.
    *Some water absorption will also occur here.

LIVER

*Digested food goes to liver
*Center of Metabolism
*Keeps balance of sugars, glycogen, proteins.
*detoxifies blood.
LARGE INTISTINE
-undigested moves from material small intestine,
substances - salts and dietary fiber
material compacting into a more solid substance. into bloodstream
*colon and the rectum -absorb the water
*faeces- moved into the rectum by peristalsis eliminated, from the body through the anus
*PRODUCTS
*Can be built by body into new material /source of energy

Human Digestive System

Salivary enzymes begin carbohydrate digestion and break up food particles. Mouth Directs food into the stomach to prevent choking Epiglottis Moistens and lubricates food. The enzyme amylase digests carbohydrates-saliva-Esophagus-Carries food down from the mouth to the stomach liver The largest organ inside the body. Makes bile (fluid that helps break down fats and gets rid of wastes in the body); changes food into energy; and clears alcohol, some medicines, and poisons from the blood.-liver Stores vitamins and iron. Destroys old blood cells-Stores the bile made in the liver, then empties it into the small intestine to help digest fats gallbladder Secretes gastric juice and hydrochloric acid, and activates enzymes., continues to breakdown food and kill off any pathogens-Stomach Stores and churns food. Enzyme pepsin digests protein-stomach small int Digests protein, fats and carbohydrates. - small intLarge Bacteria metabolism plus nutrient and excess water absorption. Surface is covered in villi for greater absorption -small intestine *makes enzymes for digestion, and bicarbonate to neutralize stomach acid Pancreas makes the hormone Insulin ,which helps the body turn food into energy,and regulates blood sugar levels. pancreas makes vitamins Large A pouch attached to the first part of the large intestine. No one knows its function-appendixAnus The lower end of the large intestine, leading to the anus-forms and stores feces Stores and expels faeces -anus *

Function table Mammalian

|Organ |Function |
|:-----------------|
| Mouth | digestion |
|Osephagus|bolus to stomach|
|Stomach |break down||liver|makes bile|
|Gallbadder|stores bile|
|Pancreas |nuetralize|, makes enzymes|
|,Small intestin| Absorb|large intest|water and excretet|
anus|excrete food|

MECHANCIAL VS CHEMICAL DIGESTION

MECHANICAL is breaking food phsyical
CHEMICAL is breaking food by chemical reactions

WHAT IS mechanical vs chemical
physical without the involvement of any chemicals

-the chewing of food food mastication
Major-gastroilithes ratite bird ,crocodyles
teeth teeth ginding using parts to
What is CheMical Digest
Mechanically broken down food particles long and complex molecules.
These have to be simplified using chemical digestion in order for
enzymes Mainly ,protease,amylase.

Similarities
Both of these
both digestion processes begin in the mouth.

DIFFERENCE betwwen CHEMCAL VS MECHANICAL
mechanical digestion is the process of breaking foods into small pieces by mechanical digestion is the process of breaking foods into small pieces by chewing, grinding, swallowing and muscular movements chewmcial digestion is the process of breaking foods in the mouth, stomach, and intestines through the use of acids and enzymes

*Physical vs chemical exam.
Mechanical- physical chemcial digestion vs use enzyme to break down.
**

Digestive System - Lesson 4

• The human digestive system (gut) is a tubular tract with a complex series of organs and glands that process food.
• Organs of the digestive tract:
  • Carry out the physical and chemical breakdown (digestion) of food
  • Absorb nutrients
  • Eliminate undigested material efficiently
• The gut is essentially outside the body, having contact only with the cells lining the tract.
• Several accessory organs and glands lie external to the digestive tract, secreting enzyme-rich fluids to aid digestion.

Diagram

• Salivary glands: produce lubricating secretions with α-amylase, which begins starch digestion.
  In the stomach, gastric glands
• contain parietal cells, which produce hydrochloric acid, and chief cells, which produce a protein-digesting enzyme.
• Oesophagus
• Gall bladder
• Liver
• Stomach
• Pancreas
• Large intestine
  Cells lining the walls on the
  small intestine (the intestinal
  epithelium) have microscopic
  extensions of the plasma
  membrane called microvilli.
  These form a brush border that
  increases the surface area for
  absorption of food molecules.
  *Function of villi formed? : -increases the surface area
  What is the purpose of microvilli?:increase surface area food absorbed faster
  *The smooth muscle surrounding the intestine-peristalsis.