2.4 - adaptations for nutrition Flashcards
(86 cards)
1
Q
What is nutrition?
A
the process by which organisms obtain energy to maintain life functions and matter to create and maintain structure
obtained from nutrients
2
Q
Autotrophic organisms?
A
such as green plants use the simple materials carbon dioxide and water to synthesise their organic requrirements
3
Q
Autotrophs?
A
living organisms that can make their own food
they provide food for all other life forms and so they are known as producers
4
Q
2 types of autotrophic nutrition?
A
photosynthesis
chemosynthesis
5
Q
Photosynthesis?
A
process by which green plants build up complex organic molecules such as sugars, from carbon dioxide and water
source of energy comes from sunlight which is absorbed by chlorophyll and accessory pigments
algae and certain types of bacteria can also photosynthesise using energy from sunlight
6
Q
Chemosynthesis?
A
a process carried out by autotrophic bacteria
they use the energy derived from special methods of respiration to synthesise organic food
7
Q
heterotrophic nutrition?
A
cannot make their own organic food
they have to consume complex organic food material produced by autotrophs
known as consumers - since they consume ready made food
all animals = consumers and are dependent on producers for food
8
Q
Types of heterotrophic nutrition?
A
holozoic feeders
9
Q
holozoic feeders?
A
this includes nearly all animals
they take their food into their bodies and break it down by digestion
most carry out process within a specialised digestive system
digested material is absorbed into the body tissues and used by the body cells
10
Q
Animals that feed on?
A
plant - herbivores
other animals - carnivores
decaying / dead material - detritivores
11
Q
Saphtrophtes?
A
group = saprobionts
include all fungi and some bacteria
they feed on dead or decaying matter and do not have a specialised digestive system
feed by secreting enzymes such as proteases, amylases,lipases and cellulases to food material outside the body and then absorb soluble products across the cell membrane by diffusion
known as extracellular digestion
12
Q
What are called decomposers?
A
microscopic saprophytes
and their activities are important in the decomposition of leaf litter and the recycling of valuable nutrients such as N or C
13
Q
Mutualism?
A
known as symbiosis - involves a close association between members of 2 different species, where both species derive from the relationship
for example cows and sheep feed mainly on grass, made of cellulose cell walls
cows and sheep do not secrete cellulase and so cannot digest cellulose
insead have mutualistic bacteria which live in the ru,em
bacteria produces enzymes for them and in return the bacteria gain other digestive products and suitable conditions for growth
14
Q
Parasotedef?
A
organism that lives in or on another organism, gaining nourishment at the expense of the host
some live in the body endoparasites
some live on surface
ectoparasites
15
Q
Parasitism?
A
host always suffers harm to some degree and often death
they are considered to be very highly specialised organisms and show considerable adaptations to their particular way of life
e.g tapeworm , head lice, potato blight cased by fungus
plasmodium - malarial parasite
16
Q
Commensalism?
A
association between 2 species - 1 benefits
other one - either harmed or benefits
17
Q
Holozoic nutrition?
A
feeding on solid organic matter
involves 5 main processes
Ingestion
Digestion
Mechanical
Chemical
Absorption
Assimilation
Egestion
18
Q
Ingestion?
A
act of eating, taking food into gut where can be processsed
19
Q
Digestion?
A
breakdown of large biological molecules in food into smaller constituent moleucules
20
Q
Mechanical digestion?
A
by chewing action of jaws and teeth
and also the churning action of the stomach wall
21
Q
Chemical digestion?
A
as a series of hydrolytic reactions in different regions of the gut
each regions has its own specific types of enzymes
22
Q
Absorption?
A
any useful digested products and other soluble substances are transported across the gut lining into the bloodstream and lymph
23
Q
Assimilation?
A
absorbed digested food are transported by the bloodstream to the body cells
these molecules = used in respiration to build new cells or cell structures or simply stored for future use
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Q
Egestion?
A
the removal of indigestible material in the form of faeces from the gut to the anus
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Excretion?
removal of metabolic waste
urea
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Human alimentary canal?
tubular passage divided into different regions where different processes take place
main parts =
mouth
tongue
pharynx
oesophagus
stomach
small intestine
large intestine
rectum
anus
other organs ourside alimentary canal also contribute to the process of digestion by secreting digestive juices into thealimentary canal through the ducts
includes salivary glands, pancreas and liver
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Bile?
digestive secretion of the liver = stored in the
gallbladder before passes to the small intestine
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Structure of alimentary canal?
epithelial tissue lines the lumen of the gut
tissue = glandular secreting the chemicals into the gut lumen to ease the passage of food or to help with the process of digestion
type of secretion with the gut region
in some regions, only mucus is secreted, whereas in other regions mucus and enzymes are secreted
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4 layers of alimentary canal?
Mucosa
Submucosa
Muscularis externa
Serosa
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Mucosa?
nearest layer to the lumen
inner surface = thin epithelium
Epithelium contains goblet cells , which secrete mucus to lubricate and protect the cells from abrasion by food and from hydrolysis by digestive enzymes
However, epithelium still parts of the mucosa, is a layer of connective tissue and beneath that is a thin layer of smooth muscle, = muscularis mucosa
sooth muscle = attached to the skeleton - is not under voluntary control
able to contract slowly and rhythmically for long periods of time without tiring
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Submucosa?
made of connective tissue within which blood vessels and nerves
connective tissues contains high proportion of collagen and elastin
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Muscularis externa?
made up of smooth muscle
muscle = arranged in 2 band
one of which fibres lie lengthwise along wall
( longitudinal muscle )
one of which they lie around the wall
( circular muscle )
contraction and relaxation of these muscles move the food through the alimentary canal by peristalsis and also help to mix the food within the canal and with various secretions
by means of churning movements
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serosa?
thin layer of connective tissue that makes up the outer layer of the wall
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Vili?
highly folded structures
which increase the surface area for digestion and absorption
all parts of the gut contain longitudinal and circular muscles which propel food along alimentary canal by peristalsis
takes approx 12 hours for food to travel entire length of gut, although time can vary depending on persons diet
e.g fatty diet, extends time considerably
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peristalsis def?
wave of rhythmic contraction
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Digestion?
process starts in the mouth
food = bitten and chewed using teeth
while chewing, food = mixed with saliva from salivary glands
saliva consists mainly of water and mucoproteins which lubricate food
also contains buffers to moderate effects of acids in foods, antibacterial agents to kill some bacteria before they enter the stomach
amylase hydrolyses starch to maltose
food = lubricated and moulded into a rounded ball, a bolus by the muscular tongue before being swallowed
food = delivered rapidly to the stomach by contractions of longitudinal and circular muscles in oesophagus
entry of food into stomach = controlled by cardiac sphincter ,a ring of smooth muscle which relaxes when food = swallowed
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Somach?
highly muscular wall and elastic organ which expands easily to hold a large meal
stomach = highly folded and dotted with pits leading to gastric glands which secretes gastric juices
presence of food in mouth stimulates secretion of gastric juices from gastric glands in stomach lining
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What do gastric juices consist mainly of?
Mucus - from goblet cells
HCl - from oxyntic cells
Pepsinogen - from chief cells
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Pepsinogen?
inactive precursor of protease enzymme pepsin
converted to active form by HCl acid in the stomach
Pepsin = endopeptidase, breaks down large polypeptide chains into smaller polypeptide chains by hydrolysing peptide bonds within polypeptide chain
by secreting enzyme in an inactive form, this prevents damage to protein containing cells lining stomach
( self digestion or autolysis)
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Prorennin?
important in young mammals
Precursor of enzyme rennin which catalyses the conversion of the soluble milk protein caseinogen to casein which = insoluble
this causes milk to coagulate and helps to keep the milk in the stomach for longer and allows more complete digestion
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Mechanical breakdown?
also occurs within the stomach by continual churning movements of muscular stomach wall
this also helps to mix food with the gastric juices
combination of mechanical and chemical digestion in the stomach reduces the food into a uniform creamy paste called acid chyme
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How long does food remain in the stomach?
for about 4 hours, after which the pyloric sphincter relaxes and regulates the flow of acid chyme into the duodenum of the small intestine
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Duodenum?
receives acid chyme from the stomach and secretions from the
gallbladder and the pancreas
duodenum = a site of intense chemical activity where all 4 types of macromolecules
( carbohydrates, fats, proteins + nucleic acids = digested by specific hydrolytic enzymes with the help of the other substances)
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What does the protease enzymes in the duodenum include?
endopeptidases and exopeptidases
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endopeptidases?
hydrolyse peptide bonds within the polypeptide chain
resulting in the formation of smaller polypeptide fragments
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exopeptidases?
hydrolyses peptide bonds at the terminal ends of the polypeptide chain, releasing individual amino acids
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Hydrogen carbonate ions?
are secreted by the pancreas and by the Brunner's Glands in the duodenum
they neutralise the acidic pH of the acid chyme as it enters the duodenum and provides the optimum pH for he activity of the enzymes in the small intestine
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Bile?
produced by the liver cells, emulsifies large globules of fat into tiny droplets
increasing the surface area of the fats for the activity of lipase enzymes
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Ileum?
second part of the small intestine and is the most important site of absorption in the gut
has a structure that is highly suited to its function
intestinal wall = highly folded, giving it a large surface are
finger like projections called villi
villi + microvilli form the brush border and further add to the surface area available for absorption
epithelial cells - large number of mitochondria which provides energy required for active transport of nutrients that need to be absorbed against a conc gradient
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Each villi?
has good blood supply to carry sugars, amino acids, minerals and other water soluble substances to the liver
laceals (branches of the lymphatic system )
transport fat soluble substances
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triglycerides?
hydrolysed to fatty acids and glycerol and pass into lacteal where they recombine to form neutral fat
lymphatic system returns the products of fat digestion to the main circulation ( along with any excess tissue fluid_
at the thoracic duct, where it drains into the subclavian vein
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How are glucose and amino acids absorbed across the epithelium of the villi?
by a combination of diffusion and active transport and pass into the capillary network that supplies each villus
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What are excess glucose and other monosaccharides converted to?
fat and stored as adipose tissue
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excess amino acids?
deaminated in the liver as body is unable to store excess nitrogen
remaining keto acid can either be converted to respiratory intermediate and respired ot converted to fat and stored
excess lipids are also converted to fat and stored
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Large intestine?
after most nutrients have been absorbed in small intestine
intestinal contents ( faeces)
pass slowly along large intestine
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Function of large intestine?
reabsorb water into bloodstream, making faeces less bulky
failure to do so would result in individual becoming badly dehydrated with potentially fatal consequences
large intestine is also where vitamins such as vitamin k and folic acid = secreted by microorganisms are also reabsorbed
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Dentition?
teeth are important in the mechanical digestion of food,
Chewing food is important as it makes it easier to swallow and increases the surface area for enzyme action
Humans = omnivores, as they eat both plant and animal material
teeth = not specialized but having 4 different types of teeth to carry out different function reflects a mixed diet
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What are the teeth for Humans?
32 teeth
8 chisel-shaped incisors at the front of the mouth for biting and cutting
4 pointed canines that function as incisors
10 large flat teeth on each side used for chewing
these are premolars and molars
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Dentition in herbivores?
plant food is a tough material and the teeth of herbivores are modified to ensure that it is thoroughly ground up before it is swallowed
Grazing herbivores e.g cows or sheep have incisors on the lower jaw only and cut against a horny pad on the upper jaw
canine teeth = indistinguishable from the incisors
gap called diastema separates front teeth from side teeth or premolars
tongue operates in this gap moving the freshly cut grass to the large grinding surfaces of the cheek teeth
jaw move in circular grinding action in a horizontal plane
cheek teeth interlock like the letter W fitting into the letter N
with time, grinding surfaces become women down, exposing the sharp-edge enamel ridges which further increases the efficiency of the grinding process
teeth have open, unrestricted roots so they can continue to grow throughout the life of the animal
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Dentition in carnivores?
have teeth adapted for catching and killing prey,cutting or crushing bones and for tearing meat
sharp incisors grip and tear flesh from bone
Canine teeth - large,curved and pointed for seizing prey, for killing and also tearing fresh
premolars and molars are for cutting and crushing
carnivores have a pair of specialized cheek teeth called carnassials which slide past each other like the blades of gardening shears
Jaw muscles = well developed and powerful and enable the carnivore to group the prey firmly and help in crushing bone
there is no side to side movement of the jaw
as this would lead to the jaw being dislocated when dealing with prey
Vertical jaw movement = greater than inherbivores, allowing jaw to open widely for capturing and killing prey
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Cellulose digestion?
Herbivores all share the commonproblem that the nutrient content of their food is low and a high proportion of it is difficult to digest
this is due to the large amount of cellulose in their diet
If maximum value = to be derived from plant food, cellulose must be digested
requires the enzyme cellulase, a powerful carbohydrate which breaks beta glycosidic links and so splits cellulose into its consituent monosaccharides
Variety of microorganisms are able to secrete cellulase so can fungi which use it to dissolve cell walls so a to penetrate the cells
but apart from this cellulase is really rare so is practically unheard of in the animal kingdom
Mammals cannot produce cellulase themselves and yet so many of the meat and milk producers, such as cattle, sheep, goats and camels have herbivores and cellulose is certainly digested in their guts
cellulose is also digested in other herbivores such as horses and rabbits
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Ruminants?
they have a specialised stomach or rumen in which mutualistic bacteria live
mutualism involves a close association between members of 2 different species and where both organisms derive some benefit from the relationship
Herbivorous mammals such as cows and sheep lack the ability to produce cellulase enzymes and so cannot digest cellulose
In this association, the mammal acquires the products of cellulose digestion and the bacteria receive a constant supply of food and can grow in a suitable sheltered environment
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What does the cow provide?
a region of the gut for the bacteria to inhibit and in return the bacteria digest the cellulose for the cow
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Why does he region of the gut must be kept separate from the main digestive system?
food can be kept there long enough for the bacteria to carry out the digestion of the cellulose
the bacteria are isolated from the mammal's own digestive juices so they are in optimum pH for their activities and they are not killed by extremes of pH
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How many chambers does Ruminants have?
4
rumen reticulum and omasum - derived from lower partof esophagus and 1 chamber - the abomasum = true stomach
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Process of celllulose digestion?
grass = chopped by the teeth, mixed with copious amounts of saliva and the crud formed = swallowed
In the rumen, the cud is mixed with cellulose digesting bacteria to produce glucose, this is fermented to form organic acids that are absorbed into the blood and provides energy for the cow. the waste products = carbon dioxide + methane that are passed out from both ends of the digestive tract
The cud passes to the next region before being regurgitated into the mouth and chewed again
the cud passes directly into the third chamber where water is reabsorbed. the fourth and final chamber functions like a normal stomach and protein is digested
digested food passes to the next region, the small intestine, where the products of digestion are absorbed
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how are the ruminants more efficient?
in terms of nutrients extracted from cellulose than other herbivores
the rumen contains a greater variety of mutualistic organisms than the caecum and they are able to achieve a more complete breakdown of cellulose
Another advantage in ruminants is that the rumen is the first chamber located before the main region of enzyme production so that when the bacteria die they pass through this region with the food and form an important source of protein to the organism
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Non Ruminants?
Horses + Rabbits
non ruminant herbiverous mamals also posess fermentation chambers where microorganisms digest cellulose
In horses and rabbits, they are caecum and appendix - a blind ending diverticulum of the gut situated at the junction of the small and large intestines
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What is the disdvantages of having a fermentation chamber near the end of the gut?
food cannot be regurgitated and the producs of digestion cannot be efficiently shunted forwards into the small intestine for absorption to take place
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How do rabbits and hares make up for this deficiency?
The first are soft and are eaten directly from the anus, a phemenin known as coprophagy.
Soft faeces contain significant amounts of digested food which is absorbed as it passes through the gut a second time
If rabbits are prevented from eating their soft feaces as they show signs of nutritional deficiency
the second type of faeces is the familiar form of hard pellets which are dropped and contain relatively little food material
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What are parasites?
organisms that live on ectoparasite or in endoparasite another organism called the host and obtain the nourishment at the expense of the host
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What are plants paratised by?
bacteria, fungi,viruses, nematodes,insects+ mites
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What are bacteria parasitized by?
bacteriophages
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Multicellular parasites?
made up of more than a single cell and are relatively complex organisms
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Examples of endoparasites?
tapeworms, flukes and roundworms cause disease directly and are highly specalised to live inside their hosts
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Examples of ectoparasites?
insects and arachnids
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Morehighly developed parasites?
have more than one host speciies as this greatly increases its chance of survival
If host dies, then so does the parasite
However, transferring to another host is a chance process and many parasites cannot survive outside the body of its host
therefore there is a need to produce a vast number of eggs
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Head louse
known as pediculus
it is an ectoparasite feeding on blood but can live for short periods away from the body
Affects only humans and cannot be passed on to or caught from animals
They are tiny wingless insects which feed by sucking blood from the scalp
Has a short life cycle and reproduces rapidly with numbers increasing alarmingly if not treated
eggs = nits and are laid glued to the base of hairs
Insects have adapted to grasping and attaching to the fine hairs of the head by having clawws on the end of their legs
they are able to walk from 1 hair to another and are transferred by close hair to hair contact
Symptoms = itching of the scalp
Intesticidies for treating head lice are available as lotions, liquids or cream rinses and are very effective
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Pork tapeworm?
human gut parasite also known as taenia solium
all animals have a struggle to survive to avoid competition with others and to avoid being preyed upon by other animals
Tapeworm is ribbon like and can be up to 10 m long
head made up of muscle on which there are suckers and hookers
Body consists of a linear series of thin segments
Pork tapeworm has 2 hosts
primary host = human and pig = the secondary host
pig becomes infected if it feeds in drainage channels contaminated by human faeces
Humans are infected by eating undercooked infected pork
Althoough tapeworm lives in an immediate source of food if it needs to survive the hostile environmental conditions found in the gut
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Whar are the problems that the gut parasite has to overcome in order to survive?
It lives surrounded by digestive juices and mucus
Food, mixed with digestive juices, is in constant motion as it is churned about us being propelled along the length of the gut by peristalic contractions of the muscular wall
Lives in extreme conditions of pH along the length of the gut
Immune system of the host
If the host dies then so does the parasite
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Adaptations for survival?
have a means of penetrating the host
have a means of attachment to the host
protect itself against the immune response of the host
Develop only those organs that are essential for survival
produce many eggs
have an intermediate host
have resistant stages to overcome the period away from the host
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Adaptations of parasitic way of life?
Sucker sand a double row of curved hooks for attachment to the wall of the gut
A body covering which protects it from the host's immune response
A thick cuticle and production of inhibitory substances on the surfaces of the segments to prevent digestion by the host's enzymes
because it lives in a stable environment it does not need to move around and does not require a sensory system
this has led to the degeneration unnecessary organs
it does have a simple excretory and nervous system but most of the body is concerned with reproduction
tapeworm = thin and has large surface area to volume ratio
has a very simple digestive system as pre digested food can be absorbed over the entire body surface
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The gut cannot accommodate 2 tapeworms?
each segment conrain borh male and female reproductive organs
vast numbers of eggs are produced with each mature segment containing up to 40,000 eggs
mature segment containing up to 40,000 eggs
mature segments pass out of the hosts body with the faeces
eggs have resistant costs and coats and can survive until eaten by the secondary host
further development can then take place and the embryos which hatch from the eggs move into the muscles of the pigs and remain dormant until the meat of the pig = eaten by a human
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Harmful effects of the tapeworm?
The adult worm causes little discomfort but if the eggs are eaten by humans, dormant embryos form cysts in various organs and damage the surrounding tissues
Adults can be treated with appropriate drugs
Public health measures and frequent inspection of meat are essential measures
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