Download The parts of the alimentary canal in sequence

1. The parts of the alimentary canal in sequence.
i.
Starts from mouth, oesophagus, stomach, duodenum, jejunum, ileum, caecum & appendix,
ascending/transverse/descending colon, rectum and ends at anus.
2. Explain the function of the alimentary canal?
i.
It is a muscular tube that runs through the body. At parts along its length it is lined with glands
and villi for digestion of food and absorption of digestive products.
ii.
It is the site of ingestion via the mouth, mechanical/physical digestion, chemical digestion and
absorption of products into the transport system. These processes facilitate the use/metabolism
of food through the liver a process called Assimilation.
iii.
Ingested food that cannot be digested by the body is egested at the end of the alimentary canal/
anus.
3. Discuss the process ingestion.
i.
It is the action of taking food into the mouth to START the process of digestion to facilitate
swallowing.
4. How does food move along the length of the alimentary canal?
i.
The muscular walls of the alimentary canal contract before and relax after the food ball/bolus in a
wave like action pushing it forward. This wave like action pushing the food is called peristalsis.
5. Where does digestion begin? And explain how this occurs?
i.
In the mouth.
i. The teeth masticate food/ mechanically break it up.
ii. the tongue mixes and moves food bolus down the oesophagus
iii. The salivary glands secrete salivary amylase that starts the chemical digestion of starch to
maltose and lubricates bolus.
6. Explain how the mouth is adapted to the process of mechanical digestion.
i.
Incisor - one pair of 4 chisel shaped teeth evenly at the front upper and lower jaw that is used to
cut food.
ii.
Canines - 2 pairs of pointed teeth between upper and lower jaw on either side of the incisors used
to tear or rip food apart.
iii.
Premolars and Molars - 8 & 12 divided evenly between upper and lower jaw following the canines
towards the back of each side of the jaws used for crushing and grinding food.
7. Draw and label an incisor.
8. How do the teeth set differ between mammals that are herbivores, carnivores and omnivores?
i.
Herbivores - have incisors and crown shaped premolars and molars.
ii.
Omnivores - have all four types of teeth.
iii.
Carnivores - have all four types of teeth except the premolars and molars are more canine shaped.
9. Match the labels to their description and/function
i.
1. Enamel, 2. Dentine, 3. Pulp cavity, 4. Tough fibres, 5.cement
ii.
1. Hardest substance of the human body as a coating over teeth used in mastication of food.
2. Living bone like layer that supports the enamel layer
3. Containing blood supply (nutrient and waste movement) and nerves (for sensitivity)
5 & 4. Secures and anchors the teeth to the jaw bone allowing for some movement
10. Define the term mechanical digestion and state its importance.
i.
It is the physical breakup of larger food particles into smaller pieces of itself. There is no chemical
change as the atomic bonds of the substances are not broken.
And this is important as it increases the surface area (more surface of the food exposed as in
smaller pieces) for enzymes to more easily chemically digest food.
11. Define the term chemical digestion.
i.
This is the process of breaking the chemical bonds that hold the atoms of the food particles
together thus resulting in smaller new substances. This is often aided by the action of enzymes.
12. Describe the structure and function of the stomach.
i.
It is a muscular sac, that contains
i. Thick muscular layer that churns/ liquefies sold food and mix it with gastric juices into
CHYME.
ii. Gastric glands that are made up of cooperating cells that secrete mixture called gastric
juices.
13. State the function of the following cells of the gastic gland as shown in the diagram
14.
15.
16.
17.
18.
.
i.
Mucous cells secrete mucus protective lining.
ii.
Parietal cells secrete hydrochloric acid that kills germs and acts as an enzyme activator.
iii.
Chief cell secrete inactive pepsin called pepsinogen that chemically digests protein to
polypepetides.
Explain what is gastric juice?
i.
This is a mixture of mucus + HCl acid + enzyme pepsinogen used to lubricate food, line and protect
the stomach + kill germs and activate the enzymes + break down proteins to polypeptides.
Describe the structure and function of the small intestines
i.
It is the longest part of the intestines divided into the duodenum, jejunum and ileum.
ii.
All sections are covered with villi and microvilli that increase surface area.
iii.
All sections help digest food while the ileum also performs absorption of digested food products.
Explain the function of the duodenum.
i.
Receives bile salts from the gall bladder via the pancreatic duct, that neutralize chyme and
mechanically digests fats
ii.
Receives pancreatic juice that contains enzymes to chemically digest starch, polypeptides,
complex sugars and fats.
iii.
Enzymes of the villi converting carbohydrate/ disaccharides and peptides to simple sugars and
amino acids.
Explain the effects of bile and enzymes operating at the duodenum and the rest of the small intestines.
i.
Bile salt sodium hydrogen carbonates (from liver) - neutralizes acidic chyme and emulsifies fat.
ii.
All starch to maltose by pancreatic amylase.
iii.
Proteins to polypeptides by trypsin.
iv.
Emulsified fats to fatty acids and glycerol by lipase.
v.
Polypeptides to amino acids by peptidase.
vi.
Maltose to glucose by maltase.
vii.
Sucrose sugar to glucose and fructose by sucrase.
viii.
Lactose to glucose and galactose by lactase.
Explain the function of the ileum
i.
This is the final and Largest part of the small intestines that leads to the large intestines via the
caecum and blind ending appendix (contains bacteria native to your gut)
ii.
Is the site of digestion completion and covered with many villi and microvilli for the process of
absorption of all products of digestion.
iii.
Here sugar and amino acids are absorbed into the blood capillaries of the villi
iv.
Here fatty acids and glycerol are absorbed into lacteal system.
19. Discuss the function of the large intestines
i.
The colon is the site of water absorption, faeces formation with the aid of roughage/fibre and
extraction of some vitamins with the aid or symbiotic bacteria.
ii.
The rectum acts as a temporary store of faeces.
iii.
Anus the site where undigested waste is egested from the alimentary canal.