1
Q
What is a herbivore?
A
An animal that only eats plant material.
2
Q
What is a carnivore?
A
An animal that only eats animal material.
3
Q
What is an omnivore?
A
An animal that eats both plant and animal material.
4
Q
What are the four main stages to the process of nutrition in animals?
A
- Ingestion
- Digestion
- Absorption
- Egestion
5
Q
What is ingestion?
A
The process of taking in food (eating).
6
Q
What is digestion?
A
The breaking of food into its constituent molecules, which can then be absorbed into the bloodstream.
7
Q
What are the two types of digestion?
A
- Mechanical
- Chemical
8
Q
What is mechanical digestion?
A
- Involves the action of teeth, the rhythmical contractions of the gut and churning of the stomach to break food down into smaller particles.
- Mechanical digestion enables chemical digestion to occur more efficiently.
9
Q
What is chemical digestion?
A
Involves the action of enzymes present in digestive juices and acid produced by the cells lining the stomach to break down the food into smaller molecules.
10
Q
What is absorption?
A
The passage of single biomolecules from the gut in to the bloodstream, and then in to the cells.
11
Q
What is meant by the term passive?
A
No energy is needed.
12
Q
What is meant by the term active?
A
Requires energy.
13
Q
What is egestion?
A
The removal/getting rid of the undigested food material (faeces).
14
Q
What is the undigested material called and what does it look like?
A
Faeces. It is usually brown in colour, semi-solid in nature and has a characteristic unpleasant odour.
15
Q
Where does the digestive system start and end?
A
It starts at the mouth and ends at the anus.
16
Q
What is the mouth also known as?
A
The oral or buccal cavity.
17
Q
What is the digestive system also known as?
A
The “gut” or alimentary canal.
18
Q
What is the digestive system composed of?
A
It is composed of the oral cavity and associated glands (salivary glands); larynx; oesophagus; stomach; duodenum; and associated organs (liver, gall bladder and pancreas); bile duct; small intestine (ileum); appendix; caecum; large intestine (colon); rectum and anus.
19
Q
What is between each major sector of the alimentary canal and what is the function of them?
A
Sphincters (types of muscle). Sphincters control the movement of food through the various sections of the digestive system.
20
Q
What is the internal surface of the gut made of?
A
Specialised epithelial cells.
21
Q
What parts of the body does mechanical digestion involve?
A
The mouth, teeth, tongue and stomach.
22
Q
(3 points)
Explain the mechanical digestion of food.
A
- The muscles lining the mouth, along with the tongue, mix the food with saliva and move it around the mouth helping to break it up.
- The mouth and tongue also move the food into the positions where the teeth can break down food further.
- Salts are produced in the liver and stored in the gall bladder as bile salts. They emulsify (break up) lipids physically.
23
Q
Where are bile salts produced and stored?
A
Produced in the liver and stored in the gall bladder.
24
Q
What is the function of bile salts?
A
The emulsify (break up) lipids physically.
25
Salts are produced in the liver. What else produces salts and what is the function of these salts?
Salts are also produced by the pancreas (sodium hydrogen carbonate). Sodium hydrogen carbonate neutralises the acid that enters into the duodenum from the stomach.
26
What mixes with food in the mouth and what is the purpose of this?
Saliva. Saliva helps to dissolve the food particles.
27
How is saliva produced?
Produced by the salivary glands.
28
What does saliva consist of?
It consists of water, mucous, salts and the enzymes amylase and lysozymes.
29
Water and salts are some of the components of saliva. What is their function?
Water and salts help to dissolve the food particles and enable the enzymes to work on the substrates.
30
Amylase and lysozyme are some of the components of saliva. What is their function?
Amylase acts on starch converting it to maltose. Lysozyme is an enzyme that breaks open bacterial cell walls, killing the bacteria in the process.
31
What does the tongue do?
It plays a role in ingestion, mechanical digestion, taste and swallow.
32
What is a ball of soft food called?
The bolus.
33
What occurs to ensure the bolus travels down the oesophagus and not the trachea?
The epiglottis closes over the glottis.
34
How many teeth are in a fully formed, healthy adult human mouth?
32 teeth.
35
What are the four different types of teeth and how many of each typically are there?
* 8 incisors
* 4 canines
* 8 premolars
* 12 molars
36
What is the human dental formula?
2 ( I 2/2 ; C 1/1 ; PM 2/2 ; M 3;3 )
37
What are incisors and what are they designed for?
Incisors are chisel shaped teeth with a sharp edge. They are designed for cutting through food.
38
What are canines and what are they designed for?
Canines are pointed teeth. Their pointed shape makes them useful for ripping and tearing through food (grip).
39
What are premolars and molars, and what is their function?
They all have cusps. These allow grinding and crushing of food. This breaks the food into very fine particles.
40
# (3 points)
Why do foods high in sugar cause food decay?
* Foods high in sugar allow large numbers of bacteria to grow.
* When bacteria acts on the sugars in the mouth, lactic acid is produced. It is this acid that corrodes the enamel of the teeth creating cavities.
* If the teeth are not cleaned properly, bacteria can lodge themselves in the cavities and make the decay even worse.
41
What is the function of the pharynx?
The pharynx functions in swallowing and ensuring food travels down the oesophagus.
42
What is the oesophagus?
A muscular tube approx. 30cm long, through which food passes on its way to the stomach.
43
What kind of muscle is found throughout the entire digestive system?
Smooth muscle.
44
What is peristalsis?
The rhythmical waves of contractions pushing the food along the alimentary canal in one direction only
45
What can occur if peristalsis is slow or ineffective?
Food can build up causing parts of the digestive system to distend (widen) and fill with food. This is called constipation
46
What reduces the risk of constipation?
Fibre.
47
What is the stomach?
A muscular bag sitting on the upper left-hand side of the abdomen.
48
How much can the stomach approx. hold?
It holds approx. 1L when full, but can distend up to 2L if enough food and drink are consumed.
49
The stomach has a large surface area. How?
It has a highly folded internal wall.
50
Through which sphincter does the food enter the stomach?
The cardiac sphincter.
51
The cardiac sphincter controls the entry of food from the oesophagus. What does it also prevent?
Reflux (heartburn).
52
How long does the food remain in the stomach for and what happens to it during this time?
Food remains in the stomach for approx. 1 to 2 hours. During this time, it is mixed with gastric juice.
53
What is gastric juice produced by?
Thousands of gastric glands located in the wall (mucosa) of the stomach.
54
What are the four main components of gastric juice and what are their functions?
* Water: This fucntions as the solvent in which food dissolves and enzymes act.
* Hydrochloric acid: This fucntions in killing pathogens and denaturing proteins, making them easier to digest.
* Mucous: This coats the internal wall of the stomach and protects it fron the very acidic condiitons of the stomach. The mucous is slightly alkaline which helps in protection.
* Pepsin: This protein-digesting enzyme digests proteins into smaller peptide. However, pepsin is first released as an inactive enzyme, called pepsinogen. Once in the lumen of the stomach, pepsinogen is converted to pepsin by the acidic conditions. The reason for this is so that it does not start digesting the cell contents before release.
55
How low can the pH of the stomach be?
Can be as low as 1.
56
What is the optimum pH for the action of pepsin.
1-2
57
The food is partially digested through the action of the acid and proteases. What is this partially digested food called?
Chyme.
58
How is chyme passed on the duodenum from the stomach?
Through the pyloric sphincter.
59
How is the stomach involved in mechanical digestion?
It contracts every few seconds. This churns the food mixing it with acid.
60
How can stomach ulcers be formed?
They form in a number of ways ranging from too much acid production or too much alcohol consumption to infection with pathogenic bacterium.
61
What is the largest organ in the body?
The liver
62
How much does the liver weigh?
1.5kg
63
# (8 points)
What are the functions of the liver?
* It produces large amounts of heat.
* It stores glycogen, iron and fat-soluble vitamins (A, D, E and K).
* It breaks down red blood cells.
* It breaks down excess amino acids in the body (deamination) forming urea.
* It produces bile.
* It produces cholesterol.
* It synthesises plasma proteins.
* It detoxifies alcohol.
64
How does the liver receive blood?
The liver receives blood via the hepatic artery (a branch of the aorta) and from the small intestine via the hepatic portal vein.
65
How does blood leave the liver?
Blood leaves the liver via the hepatic vein and is returned to the heart.
66
What colour is bile?
Dark green
67
Where is bile stored?
In the gall bladder.
68
What is the gall bladder?
A small bag-like organ that sits just underneath the liver.
69
When is bile released?
Bile is released slowly when food passes through the duodenum.
70
What does bile contain?
Water, mucous, salts, cholesterol and pigments called bilirubin and biliverdin.
71
What are the pigments bilirubin and biliverdin breakdown products of?
Haemoglobin from red blood cells. They give faeces its characteristic brown colour.
72
What is the purpose of water in bile?
The water in bile provides the medium in which the active substances in bile travel and act.
73
What is the function of bile salts in bile?
The bile salts neutralise the acid from the stomach and function in emulsifying lipids.
74
What is the emulsification of lipids?
The breaking up of lipids (large fat droplets) into small fat droplets.
75
Why does the emulsification of lipids speed up the chemical digestive process?
Gives a larger surface area upon which the enzymes can act.
76
What can occur if gallstones form in the gall bladder?
* They can block the bile duct.
* They can also prevent the release of bile into the duodenum. The bile pigments then enter the bloodstream and start to be deposited in the tissue of the body, such as the skin. The skin and white of the eyes then turn a characteristic yellow colour.
77
What does the pancreas produce?
Produces pancreatic juice that is released into the pancreatic duct along with bile.
78
# (3 points)
What does pancreatic juice contain, and what are the functions of these components?
* Sodium hydrogen carbonate, which neutralsises chyme from the stomach.
* Lipase, an enzyme that digests lipids into fatty acids and glycerol. It acts in the duodenum, where the pH is approx. 7. This is due to the sodium hydrogen carboante neutralising the acid.
* Amylase, which digests starch into maltose. It also acts in the duodenum and the mouth.
79
How is food moved along in the small intestine?
Peristalsis.
80
Approximately how long is the small intestine?
7m.
81
What is the duodenum?
The first section of the small intestine and it is involved in chemical digestion. Pancreatic juice and bile are released into the duodenum to take part in chemical digestion.
82
Approximately how long is the duodenum?
30cm.
83
Approximately how long is the ileum?
6m.
84
What is the ileum responsible for?
Responsible for the absorption of nutrients.
85
How is the internal wall (mucosa) of the ileum specialised to carry out its function?
The wall is highly folded, with each fold having many smaller folds or projections called villi (singular: villus).
86
What is a villus?
A small out-folding of the wall of the small intestine.
87
# (5 points)
What adaptions do villi have that enable them to carry out their function very efficiently?
* They are very numerous.
* They have thin walls that are one cell thick (ease of diffusion).
* They have a good blood supply.
* They each have a lymph supply (lacteal).
* The cells have small cytoplasmic projections called microvilli to further increase the surface area.
88
What is the surface of the villi composed of?
Epithelial cells.
89
What is the surface where microvilli are present called?
The brush border. This is the location of absorption.
90
A lymph vessel enters each villus. What are these called?
Lacteals.
91
What is the function of lacteals?
Lacteals absorb products of fat digestion (fatty acids and glycerol) and transport them back to the bloodstream.
92
How does the lymph system carry lymph back to the bloodstream?
Via the subclavian veins.
93
What is the large intestine composed of?
The caecum, appendix and colon.
94
Approximately how long is the large intestine?
1.5m.
95
What is the function of the caecum thought to be?
It is thought to be involved in the partial digestion of cellulose by bacteria.
96
What is the appendix?
A very small, blind-ended tube attached to the caecum.
97
What is the function of the appendix thought to be?
It is thought to be involved in protection against pathogens, but its exact functions are unknown.
98
What are the four parts of the colon?
* Ascending section
* Transverse section
* Descending section
* Sigmoid section
99
What is the main function of the colon?
To absorb water from the remaining food. This creates a semi-solid material called faeces.
100
What is another function of the large intestine, apart from water absorption?
To produce vitamins.
101
# (3 points)
How are vitamins produced in the large intestine?
* By "good" bacteria living in the colon. These are called the gut flora.
* They are symbiotic bacteria. They receive a place to live and nutrients present in the gut. In return, they produce vitamins that are absorbed by the lining of the large intestine.
* They also produce vitamins K, B1, B2 and B12 (B group).
102
How does bacteria help to maintain the health of the gut?
By preventing the growth of pathogenic bacteria.
LC Biology
flashcards
Decks in class (39)
# Cards
-
The Scientific Method27
-
Characteristics of Life16
-
Nutrition42
-
Ecology27
-
Energy Carriers13
-
Cell Structure20
-
Diversity of Cells12
-
Movement through Cell Membranes11
-
Enzymes22
-
Photosynthesis8
-
Respiration9
-
Blood38
-
The Human Circulatory System82
-
The Cell Cycle60
-
Homeostasis50
-
DNA and RNA66
-
Protein Synthesis30
-
Inheritance and Genetic Crosses38
-
Variation and Evolution34
-
Genetic Engineering31
-
Diversity of Living Organisms18
-
Kingdom Monera92
-
Viruses29
-
Kingdom Protista21
-
Kingdom Plantae78
-
Kingdom Fungi24
-
Nutrition in the Flowering Plant41
-
Sexual Reproduction in the Flowering Plant95
-
Response in the Flowering Plant39
-
Vegetative Propagation13
-
The Human Reproductive System (1)58
-
The Human Reproductive System (2)78
-
The Human Digestive System102
-
The Human Lymphatic System28
-
The Human Breathing System65
-
The Human Endocrine System73
-
The Human Integumentary System21
-
The Human Urinary System87
-
The Human Musculoskeletal System101
