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Biology Component 3 > Nutrition > Flashcards

Nutrition Flashcards

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1
Q

What is a parasite?

A

An organism that obtains nutrients at the expense of another species, the host causing some degree of harm or often death.

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2
Q

What does a parasite living in a human gut have to withstand?

A

A lack of oxygen. Extreme acidic or alkaline conditions. Food mix with digestive juices including digestive enzymes. Food being churned by the digestive system and moved along by peristaltic waves. Being washed away by food and juices. The hosts immune system. Killing the host, as it would results in the parasites death. Competition, to avoid becoming prey.

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3
Q

What are endoparasites?

A

They live in the hosts body

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4
Q

What are ectoparasites?

A

Live on the hosts surface

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5
Q

What is the primary host of a pork tapeworm?

A

The human

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6
Q

What is the secondary house of a pork tapeworm?

A

The pig

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7
Q

Where does the adult tapeworm live within the human?

A

In the intestine

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8
Q

Describe the cycle of a tapeworm?

A

The adult take one leaves in human testing which produces eggs which are then carried in a human faeces. A pig becomes infected when the vegetation (food) is contaminated with human faeces. The pigs ingest the eggs which hatch into larvae which spread through the blood and infect the animals muscle tissues. Larvae forms cysts in the muscle. If a person must eat undercooked pork, then the cysts would be introduced into the body, moving through the digestive system, where they would attach at the intestine and mature into an adult tapeworm. This cycle continues.

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9
Q

What must a tape worm do in order to survive the hostile environment?

A

Penetrate the host
Attach to the host
Protect itself from the hosts immune system
Develop essential organs for survival
Produce a large number of eggs, increasing the chance of transmission to the secondary host
Have an intermediate host
Have resistant stages to overcome the period away from the host

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10
Q

How long is the tapeworm?

A

10m long

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11
Q

Describe the structure of the tapeworm?

A

It has a ribbon like structure allowing plenty of space for the hosts food to move past. Its anterior end, the scolex is made of muscle containing suckers and hookers which attach strongly to the duodenum wall. Its body has a series of segments called proglottids.

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12
Q

What is the role of the suckers and double row of curved hookers?

A

To attach to the duodenum/gut wall. Prevents movement of the tapeworm during the peristlltaltic movements of the gut.

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13
Q

How does the tapeworm prevent the host from digesting it?

A

It produces enzyme inhibitors which prevent the hosts digestive enzymes from digesting it.

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14
Q

Describe the tapeworms simple structure?

A

It is geared for reproduction only. Simple excretory in nervous system is present. As they live in a fairly stable environment unnecessary organs are degenerated so the main focus is reproduction.

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15
Q

What does it mean when they say a tapeworm is a hermaphrodite?

A

Each proglottid contains both female and male reproductive organs. An uninfected gut can only accommodate one tapeworm, a large number of eggs are produced to increase transmission to the secondary host.

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16
Q

How many eggs does a mature segment contain?

A

40,000 eggs which are passed through into the faeces

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17
Q

Why does it have a thick body covering?

A

The cuticle is found on the segment surfaces which protects the tapeworm, and prevents digestion by the host’s enzymes and any host immune responses

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18
Q

What are the harmful effects of a tapeworm?

A

Another tapeworm can cause discomfort but can cause long-term infection which can produce taeniasis, giving abdominal pains and weakness. It is treated with drugs. If a person becomes infected by eating the eggs directly, dormant embryos can form cysts in various organ ie eyes and brain which can cause damage to surrounding tissue and is harder to treat.

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19
Q

How has the effect of a tapeworm being reduced?

A

Reducing the incidence of tapeworm infection is caused by education on the cause and public health measures i.e. improved sanitation and frequent inspection of the meat

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20
Q

What is a pediculus - ectoparasite?

A

It is lice, which are wingless insects which can’t fly and their legs are poorly adapted to jumping, so are transferred vis direct contact. If removed from the host, the parasite dies. Head lice suck on the blood found at the hosts scalp, with their claws latching onto the hair and eggs gluing to the base of the hairs.

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21
Q

What are the three stages of a louse life cycle?

A

The nits are empty eggs which are visible on hair or clothing etc. After 1-2 weeks an egg hatches into a nymph ( like an adult but smaller). The nymph then becomes an adult about 10 days later.

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22
Q

What type of energy does living organisms use?

A

They use chemical energy which derives from complex organisms ie food as living organisms can’t use direct light energy from the sun.

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23
Q

What is meant by the term autotroph?

A

An organism which synthesises its own complex organic molecules from simpler molecules using either light or chemical energy.

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24
Q

What is meant by the term heterotroph?

A

An organism which obtains complex organic molecules from other organisms

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25
Q

What is meant by the term saprotroph?

A

An organism which derives energy and raw materials for growth from extracellular digestion of dead and decaying material.

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26
Q

What does autotrophic organisms do?

A

They synthesise complex molecules from simple organic raw materials, CO2 and water

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27
Q

What are the two types of autotrophic organisms?

A

Photoautotrophic and chemoautotrophic.

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28
Q

What are photoautotrophic organisms?

A

They use light energy from photosynthesis. They are green plants some protoctista and bacteria. This is described as holophytic.

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29
Q

What are chemoautotrophic organisms?

A

They use energy from chemical reactions. These are all prokaryotes and carry chemosynthesis. This is less efficient in photosynthesis and the organisms that do this are no longer dominant lifeforms.

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30
Q

What are heterotropic organisms?

A

They can’t produce their own food so consume complex organic molecules which are produced by autotrophs (they are consumers). They either eat autotrophs or organisms which in cells have eaten autotroph’s. These are dependent on the produces for food. Heterotrophs include animals, fungi, some protoctista and some bacteria.

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31
Q

What is saprotrophic nutrition?

A

It is used by fungi and some bacteria which feed on dead or decaying matter. They have no specialised digestive system but feed by secreting enzymes onto food outside the body for extracellular digestion. These enzymes include protease, amylase and lipase and cellulase. They absorb the soluble products of digestion across the membrane by diffusion and active transport.

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32
Q

What are decomposers?

A

These are microscopic saprotrophs which are important in decaying leaf litter and recycling nutrients
ie nitrogen

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33
Q

What is parasitic nutrition?

A

Eight obtains nutrition from another living organism the host. The host always suffers harm or death. Parasites a highly specialised for their way of life.

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34
Q

What is holozoic nutrition?

A

It is used by most animals. Ingest –> digest –> Egest
(undigestible remains). The food is processed in the body, in the digestive system. Digested material is absorbed into the body tissues and is used by cells.

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35
Q

What do herbivores eat?

A

Plant material only

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36
Q

What do carnivores eat?

A

Other animals only

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37
Q

What do omnivores eat?

A

Both plant material and animals

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38
Q

What do detritivores eat?

A

Feed on dead and decaying material

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39
Q

What is fungal feeding?

A

Fungi secrete enzymes from the growing tip called the hyphae. Digestion occurs extracellularly, the growing tip penetrates food, secreting enzymes which diffuse out of the cell wall onto the food’s surface. The soluble products are absorbed into the hyphae through the cell wall by FD or AT. These products are transported around the fungi and excess is stored. E.g sugars, amino acids, glycerol, fatty acids are absorbed through the cell wall.

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40
Q

What type of nutrition does amoeba use?

A

Holozoic nutrition

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41
Q

Describe the nutrition of unicellular organisms?

A

As they have a large SA:V ratio, nutrients is absorbed and obtained by diffusion, FD or AT across the membrane. Large molecules are taken in by endocytosis into food vacuoles which fuse with lysosomes with their contents being digested by lysosomal enzymes. The products are then absorbed in the cytoplasm, with the undigestible remains digested by exocytosis.

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42
Q

Describe the nutrition of the hydra?

A

It has a single body opening, with a sac like structure. They are more complex and contain diploblastic ie contains two layers of cells the ectoderm and the endoderm which is separated by a jelly layer containing a network of nerve fibres. It is cylindrical shape, with tentacles at the top, where the mouth is. The hydra can extend their tentacles, so when organisms brush their stinging cells which discharge and paralyse the prey. The tentacles move the food through the mouth to the hollow body cavity. Endothermal cells secrete protease, lipase NOT amylase, with the prey being digested extracellularly. The digestion products are absorbed into the cells and the indigestible remains are egested out the mouth.

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43
Q

Where does the food enter and exit in a human?

A

Food enters the gut at the buccal cavity and leaves via the anus (known as the alimentary canal)

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44
Q

What happens to more complex animals in terms of their gut?

A

More advanced organisms with a varied diet, have an evolved tube gut that is divided into various parts along its length and each part is specialised to carry out a particular function.

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45
Q

What is the gut like within simple organisms?

A

It is undifferentiated as they feed off one type of organism

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46
Q

Why does food need to be digested?

A

Because the food molecules are too large and insoluble to pass through the membrane to get absorbed into the blood. It needs to be broken down into its monomer units in order to be rebuilt into molecules needed by the body cells.

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47
Q

What direction does materials flow in?

A

In one direction only

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48
Q

What are the 4 main functions of a human gut?

A

Ingestion, digestion, absorption and egestion

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49
Q

What the 2 types of digestion?

A

Mechanical and Chemical digestion

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50
Q

What is mechanical digestion?

A

It is the breakdown of food by the crushing and cutting action of the teeth and tongue (mastication). As well as moistened by saliva. Muscle contractions increases the surface area at which the enzymes act on.

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51
Q

What is chemical digestion?

A

It is when digestive enzymes are secreted, with bile and stomach acid contributing to chemical digestion.

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52
Q

What happens during ingestion?

A

It is when food is taken into the body via the mouth

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53
Q

What happens during digestion?

A

It id the breakdown of large, insoluble molecules into smaller and soluble molecules, which can then be absorbed into the blood.

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54
Q

What happens during absorption?

A

The small, soluble molecules and ions travels through the gut into the small intestine and then into the blood stream.

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55
Q

What happens during egestion?

A

The elimination of waste, not made by the body as well as undigested food, this exits as faeces via the colon, rectum and anus.

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56
Q

What is the outermost part of the gut?

A

The serosa

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57
Q

What is the serosa and its role?

A

It is made by rough connective tissue, which protects the gut wall. As the gut moves as food is processed, it reduces friction against any abdominal organs.

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58
Q

What are the two layers found within the muscularis externa ?

A

The inner circular muscles and the outer longitudinal muscles.

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59
Q

What does the circular and longitudinal muscles do?

A

They make rhythmic contractions called peristalsis, where the circular muscles contract and the longitudinal muscles relax pushing the bolus along.

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60
Q

What is the submucosa made from and its role?

A

It is made of connective tissue containing lymph vessels and blood, where products of digestion are absorbed and nerves coordinate peristalsis.

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61
Q

What is the innermost part of the gut?

A

The mucosa

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62
Q

What is the mucosa made from and its role?

A

It lines the gut wall. The epithelium secretes mucus which lubricates and protects the mucosa. In some regions it secretes digestive enzymes and in other regions it absorbs digested food.

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63
Q

What does starch break down into and what enzyme is required?

A

Maltose, amylase

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64
Q

What does lactose break down into and what enzyme is required?

A

Glucose + Galactose, lactase

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65
Q

What does sucrose break down into and what enzyme is required?

A

Glucose + Fructose, sucrase

66
Q

What does maltose break down into and what enzyme is required?

A

Glucose + Glucose, maltase

67
Q

What does lipids break down into and what enzyme is required?

A

Triglycerides –> monoglycerides (glycerol) + 3 fatty acids by the enzyme lipase

68
Q

What are the stages of the breakdown of proteins?

A

Polypeptides —> Dipeptides —> Amino acids

69
Q

What are the enzymes which breakdown proteins?

A

Protease and peptidase

70
Q

What are the two types of protease?

A

Endopeptidase and exopeptidase

71
Q

What does endopeptidase do?

A

It hydrolyses peptide bonds, in the middle of the polypeptide chain, forming smaller polypeptide chains/ peptides

72
Q

What does exopeptidase do?

A

It hydrolyses the terminal ends of the peptide bonds forming dipeptides or amino acids.

73
Q

What the areas which the food travels through during digestion?

A

Buccal Cavity –> Oesophagus –> Stomach –> Duodenum –> Ileum –> Large intestine/ colon (rectum as well) –> anus

74
Q

What happens at the buccal cavity?

A

Mechanical digestion occurs as food is broken down into small pieces by the chewing of the teeth (mastication). As well as being moistened by the saliva. The surface area of the food has been increased, giving more access for enzymes to act on the surface.

75
Q

Saliva is a watery secretion what does it contain?

A

It contains salivary amylase which breaks down starch into maltose. Saliva has a ph of 7.5 which is the optimum for the function of the salivary amylase. It contains the ions HCO3 and CO3 ions which cause slightly alkaline conditions. Mucus helps lubricate the food passage down the oesophagus as its swallowed.

76
Q

What does saliva consist of?

A

95% Water
Mineral salts to maintain the alkaline conditions
Mucus which acts as the lubricant
Lysozyme which is an enzyme which kills bacteria

77
Q

What happens at the oesophagus?

A

It carries the bolus from the mouth to the stomach by a series of rhythmic contractions called peristalsis. Peristalsis propels the food along the gut, the circular muscles contract and the longitudinal muscles relax helping move the food along.

78
Q

How much can a stomach store?

A

5 litres

79
Q

What are the ridges called on the stomach?

A

Rugae which help with the breakdown of food.

80
Q

What are the muscles which are found at the upper and lower parts of the stomach?

A

The cardiac sphincter which relaxes at the top to let food in and the pyloric sphincter relaxes when food exits in order to go to the duodenum.

81
Q

How long does food remain in the stomach?

A

2-4 Hours

82
Q

Why is mucus secreted?

A

It is secreted to protect the stomach wall from pepsin and HCl acid

83
Q

What are secreted from the glands (gastric pits)?

A

Gastric Juices

84
Q

What does the gastric juice contain?

A

HCl acid, Peptidase, Mucus

85
Q

How is HCl produced in the stomach?

A

It is secreted from oxyntic cells, which kills most bacteria in the food, and provides an optimum ph for enzymes (1-2). It activates peptidases e.g pepsin

86
Q

How is peptidase secreted and its role?

A

It is secreted by chief cells which are found at the base of the gastric glands in the inactive form of pepsinogen. It is then activated by HCl acid into pepsin. Secreting the enzymes into inactive form prevents self digestion and digestion of the stomach lining. (Peptidase hydrolyses proteins into smaller polypeptides)

87
Q

How is mucus secreted and its role?

A

Its secreted by goblet cells found at the top of the gastric pit. Mucus forms a lining which protects the stomach wall from enzymes and lubricates food.

88
Q

What does the stomach absorb?

A

It contains 3 layers of muscle to contract and relax and grind food. It absorbs: alcohol, water, aspirin, salts

89
Q

What secretions does the duodenum receive?

A

Pancreatic and liver secretions

90
Q

What does the liver produce which is important ?

A

Bile is produced which is stored in the gall bladder (a large gland) where it then enters the duodenum via the bile duct.

91
Q

What does bile contain?

A

It contains NO enzymes, but does contain hydrogen carbonate ions which help neutralise the acid chyme.
It contains bile salts (amphiphatic - contain hydrophobic and hydrophilic parts), which emulsifies lipid gobbles.
Bile emulsifies lipids into small droplets (which lowers the surface tension and increase the surface area, increasing the rate of digestion).
Bile is alkaline, so neutralises acid which enters the duodenum with food from the stomach. It provides a suitable ph for enzymes.

92
Q

What is the role of the pancreas for the duodenum?

A

The exocrine glands ( islet cells )produce pancreatic juice, which enters the duodenum via the pancreatic duct.

93
Q

What does the pancreatic juice contain?

A

Endopeptidase - hydrolyses proteins into polypeptides
Exopeptidase - hydrolyse terminal ends into dipeptides
Pancreatic amylase - hydrolyses any remaining starch into maltose
Lipase - hydrolyses triglycerides into monoglycerides and 3 fatty acid chains

94
Q

What is the endopeptidase is secreted by the pancreas?

A

Trypsin which is secreted in the inactive form trypsinogen which is activated by enterokinase.

95
Q

What does the sodium hydrogen carbonate do in the juice located in the duodenum?

A

They raise the pH making the juice slightly alkaline, neutralising stomach acid. It provides an appropriate ph for pancreatic enzymes to work efficiently.

96
Q

What do the Brunner glands do?

A

They are found in the submucosa and secrete mucus for lubrication and protection. They secrete alkaline secretions to maintain optimum ph for enzymes (sodium hydrogen carbonate)

97
Q

What digestion finishes by membrane fixed enzymes in the mucosa?

A

Carbohydrates and protein

98
Q

How is proteins digested in the SI?

A

Endopeptidase and exopeptidase is secreted at the villi tips into the gut lumen which continues the digestion of the polypeptides. Dipeptidase breaks down dipeptides into amino acids via enzymes of the cell membrane of the epithelial cells.

99
Q

How is carbohydrates continued digestion occur at the SI?

A

Dissacharides are absorbed into the epithelial cells of the villi. Carbohydrates found in the cell membrane digest them into monosaccharides. Maltose, sucrose, lactose.

100
Q

What type of digestion can occur at the villi of the SI?

A

Intracellular digestion can occur as some enzymes are membrane bound, so can be reused, increasing efficiency and reducing waste.

101
Q

How long is the iluem ?

A

5m long

102
Q

How is the ileum adapted for absorption?

A

Its lining is folded increasing the SA. On the folds are many projections called villi. On the surface of the villi are made up of specialised epithelial cells with projections called microvilli (brush border)

103
Q

What are the processes of absorption?

A

Diffusion, FD, AT (many epithelial cells have mitochondria)

104
Q

How is glucose and other monosaccharides absorbed?

A

Absorbed into the epithelial cells by co transport, with sodium ions and then into the capillaries by facilitated diffusion. Sodium ions are pumped actively out of the epithelial cells into the capillaries.

Na is actively transported out into the capillaries by Co transport, this lowers the concentration of Na inside the cell so there is more Na in the lumen than inside, so more will move back in via FD, with it only passing through if the carrier protein has a glucose attached. Glucose moves in with Na, with glucose then moving into the capillary by FD into a lower concentration down a concentration gradient. The glucose is then carried away, to maintain the gradient. Na is actively transported out lowering the concentration inside the cell which will cause Na+ to move into the lumen again

105
Q

How is amino acids absorbed?

A

They are absorbed into the epithelium cell by active transport and facilitated diffusion into the capillaries.

Na is pumped out the epithelial cells creating a low conc inside the cell, so Na will move in through the lumen by a carrier protein with a amino acid attached by Co transport. Amino acids will move into the capillaries via FD down a concentration gradient into the blood.

106
Q

How are glucose and amino acids transported?

A

They are transported via the hepatic portal vein to the liver.

107
Q

How is fatty acids and glycerol absorbed?

A

They diffuse across the epithelial cells into SER, which are resembled into triglycerides. They are packaged into vesicles along with cholesterol and phospholipids. The lipids are then transferred from cells into lacteals (blind ended lymph capillaries) by exocytosis. The lacteal is found at the centre of each villus. It is then transported in the lymphatic system to the subclavian vein where it enters the bloodstream at the thoracic duct.

108
Q

How are minerals absorbed?

A

Taken into the epithelial cells via diffusion, FD ( transport proteins) and AT which dissolve into the plasma.

109
Q

How are vitamins B and C absorbed?

A

As they are water soluble they are absorbed into the blood.

110
Q

How are vitamins A, D, E absorbed?

A

As they are fat soluble they are absorbed into lacteals (diffuse across the lacteal membrane)

111
Q

How is water absorbed?

A

Down a water potential gradient by osmosis. Water is absorbed into the epithelial cells in the ileum and capillaries

112
Q

What are lipids used for?

A

They make phospholipid cell membranes, hormones and excess is stored as fat

113
Q

What is glucose used for?

A

Its absorbed into the blood as is used in respiration. Excess is stored as fat or converted into glycogen.

114
Q

What are amino acids used for?

A

Absorbed by the cells for protein synthesis. Excess amino acids can’t be stored as they are very toxic, so are deaminated in the liver where the NH2 group is removed, and converted into urea for excretion (travels to the kidneys). The remaining C,H,O is then converted into carbohydrates which are respired or absorbed.

115
Q

What are the 4 sections of the large intestine?

A

Caecum, appendix, colon and rectum

116
Q

What is the role of the colon?

A

The colon absorbed any remaining water or mineral salts. Absorption of vitamin K and folic acid secreted by micro-organisms living in the colon to produce solidified faeces.

117
Q

What is the role of the rectum?

A

Food is in a semi solidified state which consists of residues of undigested cellulose, bacteria, sloughed (dead) cells. Which pass through the colon, is then digested as solidified faeces - known as defaecation. Cellulose fibre is required to provide bulk and stimulate peristalsis.

118
Q

Why are mammals the only ones who can hold food in their mouth whilst breathing?

A

As we have a palate which separates the nasal cavity and mouth cavity.

119
Q

Does a carnivore have a short or long gut?

A

It has a short gut relative to its body length, as it has a high protein diet, it reflects the ease at which protein is digested.

120
Q

Do herbivores have long or short guts?

A

They have a long gut in relation to their body length. As their diet consists of plant material which is not readily digested, a long gut allows time for digestion and absorption of nutrients. It has more space to accommodate the bulkier plant material.

121
Q

What size gut does omnivores have?

A

An intermediate one

122
Q

What has diets caused in dentition?

A

It has caused mammals to evolve different types of teeth specialised for different functions to suit the diet.

123
Q

What teeth do humans have?

A

Incisors, canines, premolars and molar’s

124
Q

Describe the dentition of a herbivore?

A

As they have a high cellulose diet, with plant walls being tough to eat as they contain cellulose, lignin and some silica. Dentition is designed for cutting grass when grazing and for grinding grass efficiently to smash cellulose walls which release the digestible contents.

125
Q

What can you say about the incisors of sheep?

A

They have lower incisors only which cut against the horny pad.

126
Q

What can you say about the canines of sheep?

A

They are indistinguishable from the incisors.

127
Q

What does the tongue, incisors and horny pad do?

A

The animals tongue wraps around the grass, where the horny pad on the upper jaw, incisors and canines slice through the grass enabling the vegetation to be snipped off the plants during feeding.

128
Q

What is the space between the horny pad and the upper premolars?

A

Diastema

129
Q

What is the diastema role?

A

The tongue and cheeks operate in this gap moving freshly cut grass to the large grinding surfaces of the cheek teeth, which operate in a circular grinding motion. It can also allow extra feed within its mouth, and will stop until all grass is chewed, this allows the animals to look out for any predators.

130
Q

What is the motion of the jaw?

A

As the lower jaw and skull joint is fairly free moving, the circular grinding effect is achieved, where the lower jaw moves horizontally whilst chewing, so the grass is ground up in a circular motion opening cell walls.

131
Q

What can you say about the premolars and molars on sheep?

A

They are strengthened by ridges of cement, which prevent the teeth from being chipped away by the abrasive movements. The upper surfaces make a very effective grinding surface consisting of ridges and grooves.

132
Q

What are the molar and premolar root cavities open throughout life?

A

As the grinding effects wear down their teeth, the remain open, as a good supply is maintained in the teeth.

133
Q

What is a herbivores skull like?

A

Smooth reflecting the absence of strong muscles attached.

134
Q

Describe dentition of a carnivore?

A

They have teeth adapted for catching, killing prey, cracking or crushing bones and tearing meat. They have a high lipid and protein diet with a short gut.

135
Q

What can you say about a carnivores incisors?

A

They are small but sharp which are chisel shaped which are used to grip and tear flesh from the bones and cut lumps of meat up.

136
Q

What can you say about a carnivores canines?

A

They are long, sharp, which are pointed/curved, which pierce, seize and kill prey and tear flesh. Which can impale and grip prey

137
Q

What can you say about a carnivores premolars and molars?

A

They have strong pointed cusps for cutting and tearing meat.

138
Q

What are the specialised cheek teeth called?

A

Carnassial

139
Q

What can you say about a carnivores carnassial’s ?

A

They are found on each side, on the last upper premolar and first lower molar. They fit together when the mouth is closed, which slide past each other like scissor blades, which snip meat off, and crush bone. These are identifiable.

140
Q

What can you say about a carnivores jaw?

A

A dog can’t chew meat, so has to swallow lumps of meat as the lower jaw only moves vertically. The opening and closing of the jaw moves in a vertical motion, so there’s a risk of dislocation. It doesn’t dislocate due to the struggling movements of the prey. Carnivores can open their mouths wider than herbivores. The muscles are well adapted and very powerful, so can grip prey firmly and crush bone. The promisions on the skull where these muscles insert into the bone.

141
Q

What animals have a mono gastric digestive system?

A

Humans, swine, rabbits, chicken and horses

142
Q

What animals have ruminant digestive systems?

A

Goats, cows and sheep

143
Q

What is a ruminant?

A

It is a chewing cud herbivore which possesses a 4 chambered stomach, the largest being the rumen which contains mutualistic bacteria.

144
Q

What is mutualism?

A

It is a close association of organisms from more than one species providing benefit to both.

145
Q

Why do ruminants have to rely on mutualistic bacteria?

A

As mammals don’t secrete cellulases it is unable to digest the glycoside bonds in cellulose, so they rely on microbes living in the gut to secrete the enzymes. This includes, bacteria, fungi and protocista which lives in the rumen (150dm cubed chamber)

146
Q

What are the 4 chambers?

A

Rumen, reticulum, omasum and abomasum

147
Q

Describe the process of the food in the rumen?

A

The grass is cut by the teeth and is mixed with saliva to form cud, which is swallowed down the oesophagus into the rumen. Mutualistic bacteria is found here, the microbes secrete enzymes which digest the cellulose into glucose.

148
Q

What are the products of fermentation?

A

Beta glucose, short fatty acid chains (which provides the major source of energy). With the waste products being CO2 and CH4.

149
Q

What happens at the reticulum?

A

The food travels to the reticulum from the rumen, where it is regurgitated back into the buccal cavity for the chewing of the cud. The cud can be swallowed and regurgitated several times.

150
Q

What happens at the omasum?

A

The chewed cut now enters the omasum where water and organic acids made from the fermented glucose are absorbed into the blood. The food is churned additional allowing further bacterial fermentation which then proceeds to the abomasum.

151
Q

What is the abomasum known as?

A

The true stomach

152
Q

What happens at the abomasum?

A

This is where the typical acids and secretions from mammalian stomachs are produced. It is the site of protein digestion by pepsin at pH 2. Any bacteria which enters is killed by the acid secretions and is digested. The bacteria can build up bacterial protein from non protein nitrogen present in the food or stomach e.g urea and amides.

153
Q

Where does the food go after the abomasum?

A

The digested food then travels to the SI, where the products of digestion are absorbed into the blood. The large intestine function is comparable with a humans.

154
Q

List everything you know about the rumen?

A 
Largest compartment
Contains mutualistic microbes 
Ferments cellulose
Absorbs organic acids
Continuously contracting
Produces CO2 and CH4
pH close to neutral (6-7)
155
Q

List everything you know about the reticulum?

A

Smallest compartment
Catches dense heavy feed for later rumination
Contracts for regurgitation

156
Q

List everything you know about the omasum?

A 
Third compartment
Globe shaped
Lining called manyplies
Reduces feed partial size
Absorbs water and dries out ingesta
Absorbs volatile fatty acids
157
Q

List everything you know about the abomasum?

A 
True stomach (glandular)
Secretes HCl and enzymes for chemical digestion
Reduces pH to 2
Dissolves minerals
Kills bacteria
Breaks down proteins
Passes ingesta to small intestine
158
Q

Show the stages of the ruminant chambers?

A

Rumen –> Reticulum –> Omasum –> Abomasum –> Small intestine

159
Q

What is found in cows saliva?

A

Urea is found, which is a source of nitrogen for bacteria to make proteins, which are digested and absorbed in the true stomach, where the bacteria is then killed by the acid

160
Q

Why do rabbits eat their own faeces?

A

As they aren’t ruminants, they only contain mutualistic microbes in the caecum which is found after the small intestine, so the nutrients can’t be reabsorbed, so it is passed out in the form of faeces which is then reingested in order to absorb the nutrients in the small intestine.

161
Q

Does cows have mutualistic bacteria in the caecum too?

A

It does contain microbes even though they are mainly found in the rumen.

Biology Component 3 (9 decks)

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