Adaptations For Nutrition Flashcards
(94 cards)
1
Q
What are autotrophic organisms?
A
Organisms that synthesise their own food their own food (complex molecules) from simple inorganic raw materials (light or chemical energy)
2
Q
Define photoautotrophic
A
- Organisms that use light as the source and perform photosynthesis
- They are green plants, some protoctista and some bacteria
- This type of nutrition is described as holophytic
3
Q
Define chemoautotrophic organisms
A
- Use the energy from chemical reactions
- These organisms are all prokaryotes and they perform chemosynthesis
- This is less efficient than photosynthesis and the organisms that do this are no longer dominant life forms
4
Q
Define heterotrophic
What do heterotrophic organisms eat?
A
- organisms that cannot make their own food and consume complex organic molecules produced by autotrophs, so are consumers
- they eat autotrophs or organisms that have, themselves, eaten autotrophs
- dependent on producers for food
5
Q
Define saphrotrophic (saprobiont)
- how do they absorb soluble products?
A
- An organism that derives energy and raw materials for growth from the extracellular digestion of dead or decaying material
- they absorb the soluble products of digestion across their cell membranes by diffusion and active transport
6
Q
Define parasitic
A
- obtaining nutrition from another living organism, the host
- endoparasites= live in the body of the host
- ectoparasites= live on its surface
E.g. Tapeworm
7
Q
Define holozoic
A
- nutrition used by most animals
- They ingest food, digest it and egrets the indigestible remains
- digested material is absorbed into the body tissues in a specialised digestive system
- animals that eat plants are herbivores
- animals that eat other animals are carnivores
8
Q
Explain nutrition in unicellular organisms
A
- animal-like protoctista, such as Amoeba use holozoic nutrition
- single celled organisms with large surface area to volume ratio
- They obtain all the nutrients they need by diffusion, facilitated diffusion or active transport across the cell membrane
- they take in larger molecules and microbes by endocytosis, into food vacuoles, which fuse with lysosomes, and their contents are digested by lysosomal enzymes
- the products of digestion are absorbed into the cytoplasm and indigestible remains are whetted by exocytosis
9
Q
Nutrition in multicellular organisms
A
- hydra live in fresh water, attached to leaves or twigs by a basal disc
- When hungry it extends its tentacles and when small organisms brush against them, their stinging cells discharge and paralyse the prey
- the tentacles move the prey through the mouth into the hollow body cavity
- Endodermal cells secrete protease and lipase, through not amylase, and they prey is digested extracellularly
- The products of digestion are absorbed into the cells and indigestible remains are egested through the mouth
10
Q
What is a tube gut?
A
- Many animals have a distinct anterior and posterior end and a digestive system that is a tube with two openings
- Food is ingested at the mouth and indigestible wastes are egested at the anus
- More complex animals have a more complex gut, including different sections with different roles
11
Q
Why must food be digested?
A
Because the molecules are:
- Insoluble and too big to cross membranes and be absorbed into the blood
- Polymers,and must be converted to their monomers, so they can be rebuilt into molecules needed by body cells
12
Q
Where does digestion and absorption occur?
Why?
A
- In a long, hollow, muscular tube
- It allows the movement of its contents in one direction only
- Each section is specialised and performs particular steps in the processes of mechanical and chemical digestion and absorption
13
Q
How is the food propelled along the gut?
A
By peristalsis
14
Q
What are the 4 main functions of the human gut?
A
- INGESTSION: taking food into the body through the mouth
- DIGESTION: the breakdown of large insoluble molecules into soluble molecules that are small enough to be absorbed into the blood
- ABSORPTION: The passage of molecules and ions through the gut wall into the blood
- EGESTION: the elimination of waste nor made by the body, including food that cannot be digested e.g. Cellulose
15
Q
Functions of parts of the digestive system: Mouth
A
- ingestion
- digestion of starch
16
Q
Functions of parts of the digestive system: oesophagus
A
- carriage of food to stomach
17
Q
Functions of parts of the digestive system: stomach
A
- digestion of protein
18
Q
Functions of parts of the digestive system: duodenum
A
- digestion of carbohydrates, facts and proteins
19
Q
Functions of parts of the digestive system: ileum
A
- digestion of carbohydrates, fats, proteins
- absorption of digested food
20
Q
Functions of parts of the digestive system: colon
A
- absorption of water
21
Q
Functions of parts of the digestive system: rectum
A
- storage of faeces
22
Q
Functions of parts of the digestive system: anus
A
- egestion
23
Q
Define mechanical digestion
Define chemical digestion
A
- mechanical digestion: cutting and crushing by teeth and muscle contractions of the gut wall, increases the surface area over which enzymes can act
- Chemical digestion by the secretion of digestive enzymes. Bile and stomach acid contribute to chemical digestion
24
Q
Structure of the gut wall:
A
- throughout its length, the gut wall consists of four tissue layers surrounding a cavity, the lumen of the gut
- The proportions of the different layers of the gut wall vary, depending on the function of the part of the gut
25
The structure of the gut wall: serosa
- the outermost layer, the serosa, is tough connective tissue protecting the gut wall
- The gut moves while processing food and the serosa reduces friction with other abdominal organs
26
The structure of the gut wall: muscle
- the muscle comprises two layers in different directions, the inner circular muscles and outer longitudinal muscles
- They make coordinated waves of contractions, peristalsis
- behind the ball of food, circular muscles contract and longitudinal muscles relax, pushing the food along
27
The structure of the gut wall: submucosa
- the submucosa is connective tissue containing blood and lymph vessels, which remove absorbed products of digestion, and nerves that co-ordinate peristalsis
28
The structure of the gut wall: mucosa
- The mucosa is the innermost layer and lines the gut wall
- It's epithelium secretes mucus, lubricating and protecting the mucosa
- In some regions of the gut, it secretes digestive juices and in others, absorbs digested food
29
Absorption of nutrients by gut epithelium cells is only possible if ...
- macromolecules i.e. Carbohydrates, fats and proteins, are first digested into smaller molecules
30
Different enzymes digest the different food molecules and usually
More than one type is needed for the complete digestion of a particular food
31
Digestion of carbohydrates
- polysaccharides are digested into disaccharides and then monosaccharides
- Amylase hydrolysed starch to the disaccharide maltose and maltase digests maltose to the monosaccharide, glucose
- Similarly, sucrase digests sucrose and lactase digests lactose
- The general name for carbohydrate-digesting enzyme is carbohydrase
32
How are proteins digested
- Proteins are extremely large molecules
- They are digested into polypeptides, then dipeptides and then amino acids
- the general name for protein digestion enzymes are proteases and peptidase
- endopeptidases hydrolyse peptide bonds within the protein molecule, then exopeptidases hydrolyse peptide bonds at the ends of these shorter polypeptides
33
What enzyme breaks down fats and what does it produce?
Fats are digested to fatty acids and monoglycerides by lipase
34
Regional specialisation of the mammalian gut: buccal cavity
What is the effect of chewing the food?
What does saliva contain?
What is the function of Mucus?
mechanical digestion begins in the mouth or buccal cavity, where food is mixed with saliva by the tongue and chewed with the teeth.
- chewing increases the surface area of the food, giving enzymes more access
- amylase, beginning the digestion of starch into maltose
- HCO3- and CO3- 2- Ions, so the pH in the mouth is slightly alkaline, the optimum for amylase
- Mucus, lubricating the foods passage down the oesophagus
35
Regional specialisation of the mammalian gut: oesophagus
- has no role in digestion, but carries food to the stomach
| - its wall shows the tissue layers in their simplest forms
36
Regional specialisation of the mammalian gut: the stomach
What keeps food in the stomach?
What is the volume of the stomach?
- Food enters the stomach and is kept there by the contraction of two spincters, or rings of muscles
- the stomach has a volume of 2dm³ and food may stay there for several hours
- the stomach walls contract rhythmically and mix the food with gastric juice secreted by glands in the stomach wall
37
Where is gastric juice secreted?
- from glands in depressions in the mucosa, called gastric pits
38
What does gastric juice contain?
| peptidases
peptidases, secreted zymogen, or chief cells at the base of the gastric pit. Pepsinogen, an inactive enzyme, is secreted and activated by H+ ions to pepsin, an endopeptidases which hydrolyses protein into polypeptides
39
Gastric juice contains: (HCL)
What cells is it secreted by?
What is its function?
- hydrochloric acid, secreted by oxytoc cells
- It lowers the pH of the stomach contents to about pH2, the optimum pH for the enzymes,
- kills most bacteria in the food
40
Gastric juice contains: mucus
What cells secrete Mucus?
What is the function of Mucus?
- goblet cells secrete Mucus at the top of the gastric pit
| - Mucus forms a lining which protects the stomach wall from the enzymes and lubricates the food
41
What are the two religions of the small intestine?
- the duodenum
| - the ileum
42
What allow partially digested food into the duodenum?
Relaxation of the pyloric sphincter muscle at the base of the stomach
43
Where is the duodenum?
| What does it receive?
The duodenum is the first 25 cm
| and it receives secretions from the liver and the pancreas
44
What is bile?
Bile is made in the liver, stored in the gall bladder and then passes through the bile duct into the duodenum
45
Bile contains:
- No enzymes
- bile salts, which are amphipathic, i.e. their molecules have hydrophilic and hydrophobic parts
- they emulsify lipids in the food, by lowering their surface tension and breaking up large globules into smaller globules, which increases the surface area
- this makes lipid digestion more efficient
46
Is bile acidic or alkaline?
| Why is this useful?
- Bile is alkaline and neutralises the acid in food coming from the stomach
- it provides a suitable pH for the enzymes in the small intestine
47
What is pancreatic juice?
| How does it enter the duodenum?
- It is secreted by islet cells, which are exocrine glands in the pancreas
- It enters the duodenum through the pancreatic duct
48
What enzymes does pancreatic juice contain and what is their function?
ENDOPEPSIDASES- hydrolyse protein to peptides
TRYPSINOGEN- inactive enzyme converted into the protease trypsin by the duodenal enzyme, enterokinase
AMYLASE- digests any remaining starch to maltose
LIPASE- hydrolyses lipids into fatty acids and monoglycerides
49
What other substance (besides enzymes) does pancreatic juice contain?
Sodium hydrogen carbonate
- raises the pH to make pancreatic juice slightly alkaline and contributes to:
* neutralising acid from the stomach
* providing the appropriate pH for the pancreatic enzymes to work efficiently
50
What is the food coming from the stomach lubricated by and what is it neutralised by?
The food coming form the stomach is lubricated by mucus and neutralised by alkaline secretion from cells at the base of the crypts of Lieberkühn, called Brunners glands
51
What are villi?
Finger-like projections
52
What are endopeptidases and exopeptidases?
- they are secreted by cells at the villus tips into the gut lumen and continue the digestion of polypeptides
- Dipeptides are digested to amino acids by enzymes on the cell membranes of the epithelial cells
53
How are disaccharides digested?
- disaccharides are absorbed into the epithelial cells of the villi
- Carbohydrates in their cell membrane digest them into monosaccharides so the final stage of carbohydrate digestion is intracellular:
* Maltese hydrolyses maltose into two glucose molecules
* Sucrase hydrolyses sucrose into glucose and fructose
* Lactase hydrolyses lactose into glucose and galactose
54
Explain absorption:
- The region of the small intestine called the ileum is well adapted for absorption
- In humans it is very long, about 6 metres and its lining is folded
- On the surface of the folds are villi and their epithelial cells have microscopic projections called microvilli and microvilli produce a very large surface for absorption
55
Where and how does absorption occur?
- Absorption occurs mainly in the small intestine, by diffusion, facilitated diffusion and active transport
- Active transport needs ATP so epithelial cells have many mitochondria
56
Explain absorption of amino acids:
- Amino acids, are absorbed into the epithelial cells by active transport and, as individual amino acids
- They pass into the capillaries by facilitated diffusion
- They are water soluble and dissolve in the plasma
57
Explain the absorption of glucose
What is done to prevent glucose leaving the body in faeces
- Glucose passes into the epithelial cells with sodium ions by co-transport
- They move into the capillaries, sodium by active transport and glucose by facilitated diffusion, and dissolve in the plasma
- Diffusion and facilitated diffusion are slow and not all the glucose is absorbed by activated transported
58
How are fatty acids absorbed into the body?
- Fatty acids and monoglycerides diffuse into the epithelial cells and into the lacteals, blindly ending lymph capillaries in the vill
- The lacteals are part of the lymphatic system, which transports fat-soluble molecules to the left subclavian vein near the heart
59
How are minerals absorbed into the body?
- Minerals are taken into the body by diffusion, facilitated diffusion and active transport and in the plasma
60
How are vitamins absorbed into the body?
- Vitamins B and C are water-soluble and are absorbed into the blood
- Vitamins A, D and E are fat-soluble and are absorbed into lacteals
61
How is water absorbed into the body?
- Water is absorbed into epithelial cells in the ileum and into capillaries by osmosis
62
What are lipids used for?
lipids are used in membranes and to make some hormones but the excess is stored
63
Where are other molecules taken into?
Other molecules are taken into the hepatic portal vein to the liver, after which fates vary
64
Where does glucose go?
Glucose is taken to body cells and respired for energy or stored as glycogen, in liver and muscle cells. Excess is stored as fat
65
Why are amino acids taken into the body and where do they go?
- Amino acids are taken to the body cells for protein synthesis
- Excess cannot be stored so the liver deaminates the amino acids and converts -NH2 groups to urea, which is carried in the blood and excreted at the kidney
- The remains of the amino acid molecules are converted into carbohydrate for storage or conversion to fat
66
The large intestine:
What does the large intestine comprise?
What happens to undigested food?
- The large intestine is about 1.5 m and comprises the caecum, the appendix, the colon and the rectum
- Undigested food, mucus, bacteria and dead cells pass into the colon
- The colon wall has fewer villi than the ileum and they have a major role in water absorption
67
briefly explain defection
- Vitamin K and folic acid are secreted by mutualistic micro-organisms living there and minerals are absorbed from the colon
- As material passes along the colon, water is absorbed, and by the time it reaches the rectum, the material is semi-solid
- It passes along the rectum and is egested as faeces, in a process called defecation
68
Adaptations to different diets:
When reptiles and amphibians ingest their food, they swallow it whole
- Mammals retain their food in the mouth, while it is cut and chewed
- Mammals are the only vertebrates to have a palate separating the nasal and mouth cavities, so they hold food in the mouth and chew while breathing
69
What is a carnivore?
What are their large intestine like?
* A carnivore eats only animals and so its diet is mostly protein. Its small intestine is short in relation to its body length, reflecting the ease with which protein is digested
- The carnivores large intestine is straight with a smooth lining
70
What is a herbivore?
What are their large intestines like?
* A herbivore eats only plant material. Its small intestine is long in relation to its body length, because plant material is not readily digested and a long gut allows enough time for digestion and absorption of nutrients
- The large intestine of a herbivore is pouched
- It can stretch to accommodate the larger volume of faeces produced in digesting plants, much of which are cellulose
- The large intestine are also long, with villi, where water is absorbed
71
Dentition:
- Since food must be cut, crushed, ground or shred, according to diet mammals have evolved different types of teeth, specialised for different functions, to suit the diet
72
What are the 4 types of teeth that humans have?
- Incisors
- Canines
- Premolars
- molars
73
Dentition of herbivores
- Plant cell walls are tough to eat as they contain cellulose and lignin, and, in some plants, silica
- The teeth of herbivores are modified so that, despite this, the cells are thoroughly group up before entering the stomach
74
Dentition in a grazing herbivore: incisors
- A grazing herbivore, such as a cow or sheep, has incisors on the lower jaw only
- They are sharp for tearing plants
75
Dentition in a grazing herbivore: canine
- The canine teeth are indistinguishable from the incisors in shape and size
76
Dentition in a grazing herbivore: Diastema
- A gap called the diastema, separates the front teeth from the side teeth (premolars)
- The tongue and cheeks operate in this gap moving the freshly cut grass to the large grinding surfaces of the cheek teeth, or molars
77
Dentition in a grazing herbivore: premolars
Premolars are mostly used for grinding plants
78
Dentition in a grazing herbivore: Molars
- The molars interlock, like a W fitting into M
- The lower jaw moves from side to side and produces a circular grinding action in a horizontal plane
- With time the grinding surfaces of the teeth become worn, exposing sharp-edged enamel ridges, which further increase the efficiency of grinding
- The teeth have open, unrestricted roots, so they continue to grow throughout the animals life, replacing material worn by chewing
79
Dentition in a grazing herbivore: jaws
- A herbivore does not need strong muscles attached to its jaws, because its food is not likely to escape
80
Dentition in a grazing herbivore: Skull
-Its skull is relatively smooth, reflecting the absence of sites for strong muscles to attach
81
Dentition of carnivores: Incisors
-The sharp incisors grip and tear muscle from bone
82
Dentition in a grazing herbivore: Canines
- The canine teeth are large, curved and pointed for piercing and seizing prey, for tearing muscle and killing
83
Dentition in a grazing herbivore: Premolars
- The premolars and molars have cusps, which are sharp points that cut and crush
84
Dentition in a grazing herbivore: carnassials
- Carnivores have a pair of specialised cheek teeth, called carnassials, on each side, which slide past each other like scissor blades
- These shear the muscle off the bone. They are large an easily identifiable
85
Dentition in a grazing herbivore: jaws
- The lower jaw moves vertically, not side to side, which could lead to dislocation when dealing with prey
- Carnivores can open their jaws more widely than herbivores
- The jaw muscles are well developed and powerful, enabling the carnivore to grip the prey firmly and crush bone
86
Dentition in a grazing herbivore: Skull
- There are protrusions on the skull, where these muscles insert into the bone
87
What are ruminants?
Nearly 20% of all protein eaten by humans comes from a group of herbivores called ruminants
-This includes cows and sheep and much of their food is cell wall material, mainly cellulose
88
What is the problem with digesting cellulose?
| What do ruminants rely on instead?
- Animals do not make cellulase and cannot digest the beta-glycosidic bonds in cellulose
- Ruminants rely on mutualistic microbes living in their gut to secrete the enzymes, instead
- These includes bacteria, fungi and protoctista which live in a chamber, the rumen
89
explain the process of digestion in ruminants:
1) The grass is cut by the teeth and mixed with saliva to form cud, which is swallowed down the oesophagus to the rumen
2) The rumen is the chamber which digests cellulose to glucose. This is fermented to organic acids that are absorbed into the blood, and are energy source for the cow. The waste products carbon dioxide and methane are released
3) The fermented grass passes to the reticulum and is re-formed into cud. It is regurgitated into the mouth for further chewing
4) Cud may be swallowed and regurgitated to the mouth several times
5) The cud passes next into the osmasum where water and organic acids made from fermented glucose are absorbed into the blood
6) The fourth chamber, the absomasum is the 'true' stomach, where protein is digested by pepsin at pH2
7) Digested food passes to the small intestine, from where the products of digestion are absorbed into the blood
8) The functions of the large intestine with that of a human
90
Ruminants: oesophagus
The grass is cut by the teeth and mixed with saliva to from cud, which is swallowed down the oesophagus to the rumen
91
Ruminants: rumen
The chamber in which the food mixes with microbes
92
Ruminants: retitculum
The fermented grass passes to the reticulum and is re-formed into cud
93
Ruminants: omasum
The cud passes next into the osmasum where water and organic acids made from fermented glucose are absorbed into the blood
94
Ruminants: absomasum
The fourth chamber, the absomasum is the 'true' stomach, where protein is digested by pepsin at pH2
