Unit 2.4 - nutrition Flashcards
Nutrition?
process by which organisms obtain energy to maintain life functions and matter to create and maintain structure
What are the 2 types of nutrition?
autotrophic and hetertrophic
Autrophic nutrition?
living ogranisms that can make their own food called autotrophs. They provide food for all other life forms and so they are also known as producers. (they occupy the first trophic level in a food chain
What are the 2 types of autrophic nutrition?
Photosynthesis and chemosynthesis
Photosynthesis?
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 from chlorophyll.
chemosynthesis?
process carried out by autotropic bacteria. they use energy dervived from special methods of respiration to synthesise organic food
Heterotrophic nutrition?
heterotrophs cannot make their own organic food. they have to consume complex organic food material produced by autotrophs.
what do heterotrophs include?
animals, fungi, some types of protoctists and bacteria
Holozoic feeders?
include nearly all animals.
They take their food into their bodies and break it down by digestion. most carry out this process inside the body within a specialised digestive system.
The digestive material is then absorbed into the body issues and used by the body cells
what are animals that feed solely on plant animal called?
herbivores
what are animals that feed on other animals called?
carnivores
what are animals that feed on dead and decaying material ?
detritivores
saprophytes?
group is also known as saprobionts and include all fungi and some bacteria. They feed on dead or decaying matter and don’t have a specialised digestive system.
feed by secreting enzymes such as proteases, amylases, lipases and cellulases onto the food material outside the body and then absorb the soluble products across the cell membrane by diffusion.
known as extracellular digestion
what are microscopic saprophtes?
decomposers and their activities are important in the decomposition of leaf litter and the recycling of valuable nutrients such as nitrogen and carbon
mutualism?
also known as symbiosis and involves a close association between members of 2 species, where both species dervive benefit from the relationship, e.g the digestion of cellulose by microorganisms in the gut of a herbivore.
cows and sheeps feed mainly on grass , a high proportion of which is made up of cellulose cell walls.
cows and sheep don’t secrete the enzyme cellulase and so can’t digest cellulose.
instead they have mutualistic bacteria which live in a specific part of the specialised stomach.
these bacteria produce the enzymes for them and in return the bacteria gain other digestive products and suitable conditions for growth
parastitism?
parasite = an organism that lives in or another organism, referred to as a host, gaining nourishment at the expense of the host.
some parasites live in the body - endoparasites and other live on the surface - exoparasites - others live on the surface
host always suffers harm to some degree and often death
parasties - considered to be very highly specalised organisms and show considerable adaptations to their particular way of life
examples of parasites?
tapeworm, headlice, potato blight and plasmodium
holozoic nutrition?
involves 5 main processes
ingestion?
act of eating, taking food into the gut where it can be processed
digestion?
the breakdown of large biological molecules in food into smaller constituent molecules
mechanical digestion?
chewing action of the jaws and teeth and also churning action of the stomach wall
chemical digestion?
as a series of hydrolytic reactions in different regions of the gut. each region has its own specific types of enzymes
absorption?
any useful digested products and other soluble substances are transported across the gut lining into the bloodstream
Assmiliation?
Absorbed digested food molecules are transported by the bloodstream to the body cells. These molecules can be used in respiration, to build new cells or cell structures, or simply stored for future use.
Egestion?
the removal of undigestible material , in the form of faeces, from the gut through the anus
Human alimentary canal?
is a tubular passage divided into different regions where different digestive processes take place.
what are the main parts of the alimentary canal?
the mouth, tongue,pharnyx,oesphagus,stomach,small intestine,large intestine,rectum and anus.
what are the 4 main layers of the alimentary canal?
mucosa
submucosa
muscularis externa
serosa
what is the mucosa?
nearest layer to the lumen
on its inner surface = thin epithelium
the epithelium contain goblet cells which secrete mucus to lubricate and protect the cells from abrasion by food and from hydrolysis to digestive enzymes.
what is the submucosa?
made up of connective tissue, within which lie blood vessels and nerves. Connective tissue contains a high proportion of collagen and elastin.
muscularis externa?
made up of smooth muscle.
muscle is arranged in 2 bands, in one of ehich is the fibres lie length wise along the wall of the canal (longitudinal muscle) and in one in which lie around the wall (circular muscle)
serosa?
thin layer of connective tissue that makes up the outer layer of the wall
villi?
the shape lining of the gut
what does the villi do?
increase the surface area for digestion and absorption
what do parts of the gut contain?
circular and longtidunal muscles which propel food along the alimentary canal by peristalsis
what does saliva do?
lubricate the food - also contains buffers to moderate the effects of acids in foods, antibacterial agents to kill some bacteria before they enter the stomach
peristalsis?
waves of rhythmic contraction - takes 12 hrs for food to travel the entire length of the gut
where does digestion start?
in the mouth
food = bitten and chewed using teeth.
while chewing, food = mixed w saliva from the salivary glands
food is lubricated and moulded into a rounded ball, a bolus by the muscular tongue before being swallowed
food = delivered rapidly to the stomach by peristalic contractions of the longitudinal and circular muscles in the oesophagus.
food entry into stomach = controlled by cardiac sphincter - a ring of smooth muscle which relaxes when food = swallowed
stomach?
highly muscular and elastic organ which can expand easily to hold a large meal.
stomach wall = highly folded and is dotted w pits leading to gastric glands which secrete gastric juices.
what do gastric juices consist mainly of?
water, along w three 3 types of sexretion
mucus - from goblet cells
HCL - from oxyntic cells
pepsinogen - from chief cells
what is pepsinogen?
an inactive precursor of pepsin. it is converted to its active form by HCL in the stomach.
what is pepsin?
an endopeptidse and it breaks down by large polypeptide chains into smaller polypeptide chains by hydrolysing peptide bonds within th e polypeptide cain
what is preorennin?
a precursor of rennin which catalyses the conversion of soluble milk protein caseinogen to caesin which is insoluble. this causes milk to coagulate and helps to keep milk in the stomach for longer and allow a more complete digestion
mechanical breakdown of food?
also occurs within the stomach by continual churning movements of the muscular stomach wall
this also helps to mix the food with the gastric juices. the combination of mechanical and chemical digestion reduces the food into a creamy paste callled chyme
duodenum?
receives acid chyme from the stomach and secretions from the gall bladder and pancreas.
duodenum = site of intense chemical activity, where
carbohydrates
fats
proteins
nucleic acids = digested by specific enzymes w the help of other substances
endopeptidases?
hydrolyse peptide bonds within the polypeptide chain, resulting in the formation of smaller polypeptide fragments
exopeptidases?
hydrolyses peptide bonds at the terminal ends of the polypeptide chain, releasing individual amino acids
why are hydrogencarbonate ions secreted by the pancreas and the brunners glands in the duodenum?
they neutralise the acidic pH of the acid chyme as it enters the duodenum and provides the optimum pH for the activity of the enzymes in the small intestime
what does bile do?
produced by the liver cells - emulsifies large gobules of fat into tiny droplets, increasing the surface are of the fats for the activity of the lipase enzymes
Source and function of bile salts?
source - liver
function - emulsify fats
Source and function of sodium hydrogencarbonate?
Source - liver (bile) pancreas
function - neutralises stomach acid
Source and function of typsinogen
Source - pancreas
function - converted to trypsin in duodenum
Source and function of nuclease?
Source - pancreas
function -nucleic acids — nucleotides
source and function of peptidases?
source - pancreas
function - starch — maltose
source and function of chymotrypsin?
source - pancreas
function - proteins ——– small polypeptides
source and function of lipase?
source - pancreas
function - triglycerides —— fatty acids + glycerol
source and function of enterokinase?
source - small intestine
function - trypsinogen – trypsin; trypsin converts proteins —- peptides
source and function of maltase?
source - small intestine
function - maltose + glucose
source and function of sucrase?
source - small intestine
function - sucrose——glucose + fructose
source and function of lactase?
source - small intestine
function - lactose —– glucose + galactose
source and function of peptidase?
source - small intestine
function - peptides—— amino acids
source and function of nucleotides?
source —– small intestine
function - nucleotides—– base + sugar+ phosphate
source and function of mucus?
source - small intestine
function - protection and lubrication
source and function of water?
source - liver, pancreas and small intestine
function - essential for hydrolytic breakdown of food ; transport mediu
what is the ileum?
the second part of the small intestine and its the most important site of absorption in the gut
The intestinal wall = highly folded, giving it a large surface area. The finger like projections called villi also have a miscropic folds called microvilli.
microvilli and villi form brush border and further add to the surface area available for absorption.
epthilieum cells have a large number of mitochondria which provide the energy required for active transport of nutrients that need to be absorbed against a conc gradient. each villus has a good blood supply to carry sugars, amino acids, minerals and other water - soluble substances to the liver.
what does a lacteal do?
transport fat soluble substances
what is absorbed across the epithelium of the villi by a combination of diffusion and active transport and pass into the capillary network that supplies each villi?
glucose and amino acids
what is converted to fat and stored as adipose tissue?
excess glucose
what is deaminated in the liver?
excess amino acids
what is the remaining keto acid converted to?
intermediate and respired or converted to fat and stored. excess lipids = also converted to fat and stored
what happens in the large intestine?
after most of the nutrients have been absorbed in the small intestine, the intestinal contents pass slowly along the large intestine.
The main function of the large intestine is to reabsorb water into the bloodstream, making the faeces less bulky
This is a vital function as failure to do so would result in the individual becoming severly dehydrated with potentially fatally consequences!
the large intestine also the site where vitamins secreted by microorganisms are also reabsorbed
What are the adaptations to different diets?
Reptiles and amphibians swallow food whole immediately after it is caught, but in mammals food is retained in the mouth whilst its cut up and chewed
mammals have a palate that seperates the air path from the mouth
this allows food to be retained in the mouth rather than being swallowed between breaths
the gut of carinvore = long bc digestion of plant material = difficult, since food = retained for cutting, crushing, grinding or shearing according to diet, mammals have evolved for different types of teeth w each type being specialised for a different function. Herbivores and carnivores have teeth specialised to suit their diets
what does chewing food do?
makes it easier to swallow and also increases the surface area for enzyme acion
How are humans teeth adapted
humans = omnivorous, eat both plant and animal material. teeth = not particularly specalised but having 4 different types of teeth to carryout different function reflects a mixed diet. in total humans have 32 teeth and these are made up of:
8 chisel shaped incisors at 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 = premolars and molars
detention in herbivores?
plant = tough material and the teeth of herbivores = modified to ensure that it is thoroughly ground up before its swallowed
grazing herbivore such as a cow or sheep has incisors on the lower jaw only and cuts against a horny pad on the upper teeth.
a gap called the diastema seperates the front teeth from the side teeth or premolars.
the tongue operates in this gap to move the freshly cut grass to the cheek teeth.
The jaw moves in a circular grinding action in a horizontal plane. the cheek teeth interlock,like the letter W fitting into the letter M.
with time, the grinding surfaces become worn down, exposing the sharp - edged enamel ridges which further increase the efficiency of the grinding process.
teeth have open, unrestricted roots so they can continue to grow throughout the life of the animal.
detention in carnivores
carnivorous mammals such as tiger have teeth adapted for catching and killing prey, cutting, or crushing bones and for tearing meat.
sharp incisors grip and tear flesh from the bone
canine teeth = large, curve and pointed for seizing prey, for killing and also tearing flesh
premolars + molars = cutting and crushing
carnivores have a pair of specAlised cheek teeth, called carnaissals which slide past each other like the blades of gardening shears.
Jaw muscles = well developed and powerful and enable the carnivore to grip the prey firmly and help in crushing bone
No side to side movement of the jaw, this would lead to the jaw being dislocated when dealing with prey.
The vertical jaw movement = greater than in herbivores, allowing the jaw to open widely for capturing and killing prey
what common problem do all herbivores share?
the nutrient content of their food is low and a high proportion of it = difficult to digest. this is because of the large amount of cellulose in their diet
what does it mean that mammals cant produce cellulase themselves?
cellulose is digested in their guts. it’s also digested in other herbivores such as horses and rabbits
what are ruminants?
they have a specalised stomach or rumen in which mutualistic bacteria live
mutualism?
close association between members of 2 different species and where both organisms dervive some benefit from the relationship. Herbivorous mammals such as cows and sheep lack the ability to produce cellulase enymes and so cannot digest cellulose.
What does the cows gut do
provides a region of the gut for the bacteria to inhabit and in return bacteria digest the cellulose for the cow. However, region of the gut must be kept seperate from the main digestive system
food can be kept there long enough for the bacteria to carry out the digestion of the cellulose
bacteria = isolated from the mammals’ own digestive juices so that they are in optimum pH for their activities and they are not killed by extremes of pH
What are the 4 chambers of a stomach ?
rumen
reticulum
omasum
all derived from the lower part of the oesophagus and one chamber (abomasum) = true stomach
Steps of cellulose digestion?
grass = chopped by the teeth, mixed w copious amounts of saliva and the cud formed = swallow
in the rumen, cud = mixed w cellulose digesting bacteria to produce glucose. fermented to form organic acids that = absorbed into the blood and provides energy for the cow. Waste products = carbon dioxide and methane = passed out from both ends of the digestive tract
cud passes to the next region before being regurgtitated into the mouth and chewed again
cud passes directly into the third chamber where water = reabsorbed. 4th and final chamber functions like a normal stomach and protein = digested
digested food passes to the next region -small intestine, where products of digestion = absorbed
Advantages of ruminant?
The ruminants = more efficient in terms of nutrients extracted from cellulose than other herbivores. Rumen = greater variety of mutualistic organisms than the caecum + they are able to achieve a more complete breakdown of cellulose.
Another advantage = rumen = first chamber located before the main region of enzyme production, so when bacteria die , they pass through this region w the food and form an important source of protein to the organism
non ruminants?
possess fermentation chambers where microorganisms digest cellulose.
disadvantages?
food cannot be regurgitated and products of digestion cannot be efficiently shunted forwards into the small intestine for absorption to take place
why do rabbits have 2 types of faeces
first = soft and are eaten directly from the anus
soft contains significant amount of digested good which is absorbed as it passes through the gut a second time
if rabbits are prevented from eating their soft faeces, shows signs of nutritional deficiency
second type = familiar form of hard pellets which = dropped and contain little relatively little food material
what are parasites?
organisms that live on (ectoparasite) or in (endoparasite) another organism called the host and obtain nourishment at the expense of the host.
Some cause little harm but most are serious and may lead to death
multicellular parasites?
made up of more than single cell and = relatively complex organisms
how does having more than one host species increase the chances of their survival?
transferring to another host = chance process and many parasites cannot survive outside the body of its host, needing to produce a vast number of eggs.
what is the head louse?
an ectoparasite that feeds on blood but can live for short periods of time away from the body. only affects human and and cannot be passed to, or caught from animals. 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.
The eggs = nits and laid glued to the base of hairs by having claws on the end of their legs. able to walk from one another and = transferred by close hair to hair contact.
what is symptoms of head louse?
itching of the scalp
treating = insecticides for treating head lice = lotions, liquid, cream rinses and very effective
what is the pork tapeworm?
The tapeworm is ribbon like and can be up to 10 metres long. Has a head made up of muscle on which there are suckers and hooks. Its body consists of a liner series of thin segments. The pork tapeworm has 2 hosts: Primary host = human pig = secondary host
pig becomes infected if it feeds in drainage channels contaminated by human faeces
humans = infected by eating undercooked infected pork
although tapeworm lives in an immediate source of food, it needs to survive the hostile environment found in the gut
what is the problems that the gut parasite has to overcome in order to survive ?
lives surrounded by digestive juices and mucus
food, mixed w digestive juices, is in constant motions as it is churned about as well as being propelled along the length of the gut by peristaltic contractions of the muscular wall. It lives in extreme conditions of pH along the length of the gut
immune system of the host
host dies then so does the parasite
What does the adaptations for survival?
In order to survive the tapeworm must
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 = essential for survival
produce many eggs
have an intermediate host
have resistant stages to overcome the period away from the host
what are the adaptations for parasitic way of life?
suckers and a double row of curved hooks for attachment to the wall of the gut
a body covering which protects it from the hosts immune response
a thick cuticle and the production of inhibitory substances on the surfaces of the segments to prevent digestion by the hosts enzymes
bc it lives in a stable environment it doesn’t need to move around and does not require a sensory system. Has led to the degeneration of unnecessary organs .
does have a simple excretory and nervous system but most of the body is concerned with reproduction. Tapeworm = very thin + has a large surface are : volume ratio
has a very simplified digestive system as pre - digested food can be absorbed over the entire body surface
bc gut cannot accommodate 2 tapeworms, each segment contains both male and female reproductive organs. vast numbers of eggs = produced with each mature segments containing 40,000 eggs. mature segments pass out of the host’s body with the faeces. Eggs have resistant coats + 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 pig + remain dormant until the meat of the pig = eaten by a human
