Adaptions for nutrition Flashcards
What is an autotroph?
An organism that makes it’s own complex organic materials via photosynthesis or chemosynthesis
What is a photoautotroph?
An organism that uses light energy to make complex organic materials
What is a chemoautotroph?
An organism that uses chemical energy to make complex organic materials
What is a heterotroph?
An organism that consumes ready-made complex organic material (it’s food) e.g. animals
What does holozoic mean?
A type of heterotrophic nutrition performed by most animals where organisms obtain nourishment by ingesting and internally processing complex organic matter
What are saprophytes?
Organisms that feed on dead, decaying matter by extracellular digestion and absorption of the products of digestion e.g. fungi, bacteria
What is a parasite?
An organism that obtains nutrients from another living organism, it’s host, to which it causes harm
How do unicellular organisms e.g. amoeba gain nutrition?
Holozoic nutrition
Nutrients diffuse across cell membrane
Larger products absorbed by endocytosis into food vacuoles
Products absorbed into cytoplasm
Indigestible remains egested via exocytosis
How do simple multicellular organisms e.g. Hydra gain nutrition?
Extend tentacles and discharge stinging cells to paralyse prey
Prey to hollow body cavity through mouth
Endodermal cells secrete protease and lipase
Prey extracellularly digested
Products absorbed by cells
Indigestible remains egested through mouth
Why do complex organisms e.g. humans need a more complex digestive system than other simple organisms?
Have a more complex and varied diet
How do saprophytes gain nutrition?
Feed on dead decaying matter
Extend hyphae into food material
Digestive enzymes secreted (protease, lipase, amylase and cellulase)
Soluble products absorbed by diffusion and active transport
What is a decomposer?
Microscopic saprotroph involved in decaying leaf litter and recycling nutrients
What is a detritivore?
A type of heterotroph that consumes dead and decaying organic matter e.g. cockroach
What is the function of the digestive system?
Breakdown food
Absorb nutrients
What is the function of the salivary glands?
Produce saliva
What is the function of the oesophagus?
Carry food from the mouth to the stomach
What is the function of the stomach?
Produce hydrochloric acid to breakdown the food
What is the function of the pyloric sphincter muscle?
Controls the amount of food leaving the stomach
What is the function of the duodenum?
Receive juices from the gall bladder and the pancreas
What is the function of the ileum?
Where most the digested food is absorbed
What is the function of the bile duct?
Takes bile from the gall bladder to the duodenum
What is the function of the pancreas?
Produce enzymes which pass into the duodenum
What is the function of the gall bladder?
Store bile
What is the function of the colon/large intestine?
Where most the water is absorbed
What is the function of the rectum?
Store waste faeces for several hours
What is the function of the anus?
Controls the passing of the faeces
Which part of the digestive system produces saliva?
Salivary glands
Which part of the digestive system carries food from the mouth to the stomach?
The oesophagus
Which part of the digestive system produces hydrochloric acid?
The stomach
Which part of the digestive system controls the amount of food leaving the stomach?
The pyloric sphincter muscle
Which part of the digestive system receives juices from the gall bladder and the pancreas?
The duodenum
Which part of the digestive system is where most the digested food is absorbed?
The ilium
Which part of the digestive system takes bile from the gall bladder to the duodenum?
The bile duct
Which part of the digestive system produces enzymes which pass into the duodenum?
The pancreas
Which part of the digestive system stores bile?
The gall bladder
Which part of the digestive system is where most the water is absorbed?
The colon/large intestine
Which part of the digestive system stores waste faeces for several hours?
The rectum
Which part of the digestive system controls the passing of faeces?
The anus
What do peptic/chief cells do?
Secrete pepsinogen (inactive precursor to pepsin)
Endopeptidase
What is the result of peptic/chief cells?
Contact with HCl turns it into pepsin
What do oxyntic cells do?
Secrete HCl into stomach
What is the result of oxyntic cells?
Kill bacteria
Provide optimum pH for enzymes
Convert pepsinogen to pepsin
What do goblet cells do?
Produce mucus
What is the result of goblet cells?
Form protective layer on stomach wall against pepsin and HCl.
Lubrication of bolus
What does muscularis do?
Cause peristalsis
What is the result of muscularis?
Food pushed through stomach by repeated contractions
Circular and longitudinal smooth muscles alternate contraction
Which muscles contract during peristalsis (muscularis)?
Circular smooth muscles and longitudinal smooth muscles alternate contraction
What does the pyloric sphincter do?
Control amount of food leaving the stomach to the duodenum
What does protease/peptidase do?
Break down proteins
How do endopeptidases work?
Catalyse hydrolysis. Break peptide bonds in the middle of polypeptides (interior peptide bonds)
What secretes pepsinogen?
Chief cells in the stomach
What secretes trypsinogen?
The pancreas
How does trypsinogen become trypsin?
Trypsinogen enters the duodenum via the pancreatic duct
Activated by enteropeptidase (produced by duodenum) into trypsin
Why would some enzymes be secreted as inactive enzymes?
If active they would break down the pancreas cells
How do exopeptidases work?
Catalyse hydrolysis. Break peptide bonds at the ends of polypeptide chain
What do dipeptidases do?
Break down dipeptides into amino acids
Where are dipeptidases found?
In the membrane of the epithelium cells in the duodenum and ileum
What are the dimers?
Maltose, sucrose, lactose and dipeptides
What breaks down carbohydrates?
Carbohydrases
What is amylase produced by?
Salivary glands
What are the five features of the ileum which makes it a good exchange surface?
Lots of villi and microvilli, meaning a large SA for diffusion
Large blood supply - steeper diffusion gradient
1 cell thick - shorter diffusion gradient
Lots of mitochondria - ATP for active transport
Moist - goblet cells produce mucus which aids diffusion
How are carbs and proteins absorbed from the ileum?
Na+ actively transported out of epithelial cells into blood
Creates low conc of Na+ inside cell
Na+ cotransports glucose down the diffusion gradient into the cell from the lumen of the ileum
Glucose move by facilitated diffusion into the capillaries down a diffusion gradient
How are lipids absorbed from the ileum?
Enzymes in the cell membrane of the small intestine epithelium hydrolyse the dimers (maltose, sucrose, lactose and dipeptides)
The monomers formed enter the epithelium by cotransport and then pass into the blood by facilitated diffusion
How are carbohydrates digested in the gut?
Via aerobic respiration. Reabsorbed in the PCT. Excess converted to glycogen or fat for storage. Moves via cotransport with Na+ and glucose, and secondary active transport
How are proteins absorbed in the gut?
Absorbed by cells for protein synthesis. Excess cannot be stored so is deaminated - the NH2 group is removed, converted to urea and excreted by the kidney
How are lipids reabsorbed in the gut?
Transported by the lymphatic system. Synthesised by SER - used as an energy source and to produce phospholipids. Excess stored as fats.
What is the function and shape of incisors in carnivores?
Small, sharp, shaped like chisels. Used to snip or gnaw meat off bones and cut lump of meat up
What teeth do carnivores have?
Incisors
Canines
Molars and premolars
Carnassials
What is the shape and function of canines?
Very long and sharp. Impale, grip and tear meat
What is the shape and function of molars and premolars in carnivores?
Strong pointed cusps for cutting and tearing meat
What is the shape and function of carnassials?
Fit together when mouth is closed. Odd shape and large
What teeth do herbivores have?
Incisors and horny pad
Diastema
Premolars and molars
What is the shape and function of the incisors and horny pad in herbivores?
Incisors - sharp and bite against horny pad
Horny pad - used by incisors to snip vegetation
What is the shape and function of the diastema?
Characteristic of herbivorous mammals. Fill extra grass. Allow free movement and circular grinding.
Empty gap between the horny pad and incisors and the premolars
What is the shape and function of the premolars and molars in herbivores?
Have sharp enamel ridges (ridges of cement) to grind food as molars slide over each other. Break open cellulose walls in vegetation. Grow throughout life
How does a dogs articulation of the lower jaw differ from a sheep?
Dog - Gnaw, snip, up and down movement
Sheep - Grind, side to side movement
Why would the length of the gut in a carnivore be shorter than in a herbivore?
Plant material takes longer to digest and absorb
What is a ruminant animal?
An animal that regurgitates it’s food for further chewing (also has a rumen)
What is the function of a rumen?
Largest component
Contains micro-organisms
Ferments cellulose
Absorbs organic acids
Contracts continually
Produces CO2 and CH4
pH close to neutral
What is the function of the reticulum?
Smallest compartment
Catches dense heavy feed for later rumination
Contracts for regurgitation
What is the order of food as it goes through a ruminants digestive system?
Through oesophagus - rumen - reticulum - oesophagus - omasum - abomasum
What is the function of the omasum?
Third compartment
Globe-shaped
Many ply lining
Reduces feed particle size
Absorb water and dries out ingesta
Absorb volatile fatty acids
What is the function of the abomasum?
‘True’ stomach
Secrete HCl and enzymes for chemical digestion
Reduce pH to 2.5 which dissolves minerals, kills rumen bacteria and breaks down proteins
Passes ingesta to small intestine
What is the first compartment in a ruminants digestive system?
Rumen
What is the second compartment in a ruminants digestive system?
Reticulum
What is the third compartment in a ruminants digestive system?
Omasum
What is the tfourth compartment in a ruminants digestive system?
Abomasum
What is the function of fibre in the body?
Provide bulk and stimulate peristalsis
How are the cells lining the villi adapted for efficient absorption of molecules?
Many intrinsic proteins which allow co-transport to take place
