Adaptations For Nutrition🍽 Flashcards
What does autotrophic mean?
Uses light energy/energy from chemical reactions to make their own food.
E.g. green plants, algae and some bacteria
What does photoautotrophic mean? (Autotrophic)
Gets energy for food synthesis from light and uses CO2 as its primary source of carbon.
E.g. autotrophic plants, algae, some bacteria
What does chemoautotrophic mean? (Autotrophic)
Uses energy from chemical reactions to make food.
Allows them to survive in areas with no light.
E.g. nitrogen-fixing bacteria and iron oxidising bacteria
What does heterotrophic mean?
Feed on other organisms.
Animals, fungi, some protoctists and bacteria
What does saprotrophic mean? (Heterotrophic)
Feed on dead or decaying material using extracelluar digestion.
E.g. fungi and bacteria
What is extracellular digestion?
Secrete digestive enzymes into food externally.
Food is digested and soluble products are absorbed.
What does holozoic mean? (Heterotrophic)
Take food into body and digest it - many use a specialised digestive system.
E.g. herbivores, carnivores and detritivors
What does symbiotic mean? (Heterotrophic)
Interaction between two different organisms living in close physical association
What does mutualistic mean? (Symbiotic)
A close association between two species where both partners benefit.
E.g. lichens made up of algae and fungi
What does parasitic mean? (Symbiotic)
Feed on host organisms by digesting their cells and absorbing the products.
E.g. tapeworms, fleas
What does endoparasitic mean? (Parasitic)
Feed inside the host.
E.g. tapeworm
What does ectoparasitic mean? (Parasitic)
Feed on outside of the host.
E.g. fleas
Info on headlouse/pediculus humanus capitis (ectoparasite)
- Eggs are laid in different areas, depending on temperature
- Female secretes glue which hardens into nit sheath
- Travel directly from head to head and feed using mouthparts
Information on pork tapeworm/Taenia solium (endoparasite)
- Flat, ribbon-like body - increases SA:V
- 2-3m long
- No body cavity, no circulation, no digestive system
- Scolex with 4 suckers and chitinous hooks as organs of attachment to intestinal wall of host
- Thick cuticle protects from immune responses and digestion by host
- Hermaphrodite - self-fertilisation
- Each proglottid is a complete reproductive unit
- Body growth starts from neck
- Accidental infection by humans at larval stage causes cysticercosis
- Primary host is humans - cysticercus from pork
- Secondary host is pigs - ingest eggs from human faeces which hatch inside intestine and use digestive enzymes to enter blood and lymphatic vessels. Embryos migrate to tissues to from cysticerci
- Prevent by not eating undercooked pork and ensuring prevention of faecal contamination of pig feeds
How do holozoic feeders such as an amoeba obtain nutrition?
- Intracellular digestion
- Diffusion, facilitated diffusion or active transport across the cell membrane
- Take in larger molecules by endocytosis
Hydra features (extracellular digestion and intracellular digestion)
- Tentacles - stinging cells paralyse prey and move into mouth, into hollow cavity
- Endodermal cells - secrete protease and lipase
- Ectoderm
- Jelly layer
- Hollow body cavity - digestion
- Mouth - egests indigestible remains
What are the functions of the digestive system?
- Ingestion
- Peristalsis
- Digestion
- Absorption
- Egestion
What is the inner mucosa? (structure of gut wall)
- Lines gut wall and secretes mucus - lubricate passage of food and protects gut
- Cells are layered for protection
- Some regions secrete digestive enzymes, some absorb food
- Acid/alkaline fluid to provide optimum pH for enzymes
What is the sub mucosa? (Structure of gut wall)
- Contains blood and lymph vessels which take away the absorbed products
- Contains a network of nerve fibres that coordinate the muscular contractions involved in peristalsis
- Contains glands that produce alkaline fluid
What is the muscle layer? (Structure of gut wall)
- Two layers of muscle running in different directions
- Circular muscle (inner) - fibres arranged in rings
- Longitudinal muscle (outer) - fibres rubbing lengthways
- Antagonistic muscle pair - both layers are made up of smooth involuntary muscle and are responsible for peristalsis
What is the serosa? (Structure of gut wall)
Layer of tough connective tissue which protects the gut wall from friction from other organs in the abdomen
What happens behind the food? (peristalsis)
- Circular muscle contracts
* Longitudinal muscle relaxes
What happens in front of food? (Peristalsis)
•Longitudinal muscle contracts
•Circular muscle relaxes
Widens and shortens the gut
Different body parts and different roles
- Mouth - ingestion
- Stomach - digestion
- Duodenum - digestion
- Ileum - absorption
- Colon - absorption of water
- Rectum - egestion
What is mastication?
- The chewing of ingested food
- Makes food easier to swallow
- Increases surface area for enzyme action
Incisor function
Chisel-shaped for biting and cutting
Canine function
Pointed for piercing and tearing in carnivores
Premolar function
Uneven cusps for grinding and chewing
Molar function
Used for chewing
Digestion of lipids
- Bile salts - emulsifies lipids (mechanical)
* Lipase - fatty acids + glycerol (chemical)
Digestion of starch
- Amylase (pH 8) - disaccharide
* Disaccharidase - monosaccharides (inside cells of gut mucosa)
Protein digestion
- Endopeptidase - polypeptides
- Exopeptidase - dipeptides
- Dipeptidase - amino acids (inside cells of gut mucosa)
Mouth conditions (digestion)
- Salivary glands produce saliva
- 6.5-7.5 pH
- Enzymes - amylase
- Substrates - starch
- Products - maltose
Stomach conditions (digestion)
Aided by mechanical digestion •Gastric glands produce gastric juice •2 pH •Enzymes - pepsin and rennin •Substrates - protein and milk protein •Products - polypeptides
Duodenum conditions (digestion)
•Pancreas produces pancreatic juice
-alkaline fluid & enzymes
•Intestinal glands
-alkaline fluid & enzymes
•7 pH
•Enzymes - amylase, trypsin, chymotrypsin, carboxypeptidase, lipase
•Substrate - starch, protein, polypeptides, fats
•Products - maltose, polypeptides, amino acids, fatty acids and glycerol
Ileum conditions (digestion)
- Ileum mucosa produces intestinal juice
- 8.5 pH
- Enzymes - maltase, sucrase, lactase, peptidase, lipase
- Substrates - maltose, sucrose, lactose, polypeptides, fats
- Products - glucose, glucose and fructose, glucose and galactose, amino acids, fatty acids and glycerol
What does saliva contain? (Mouth digestion)
- Salivary amylase - hydrolyses starch to maltose
- Mineral salts - maintains pH and activated amylase
- Mucus - binds particles of food together and lubricates passage
What are the cardiac sphincter and pyloric sphincter? (Stomach digestion)
- Two rings of smooth muscle
* Contractions keep food in stomach
What does gastric juice contain? (Stomach digestion)
- HYDROCHLORIC ACID secreted by oxyntic cells - activates enzymes, provides optimum pH, kills most bacteria and inactivates salivary amylase
- PEPSIN secreted by zymogen cells - activated by stomach acid and hydrolyses protein to polypeptides
- RENNIN secreted by zymogen cells - converts soluble caseinogen to insoluble casein
- MUCUS secreted by goblet cells - protects stomach wall
What is chyme? (Small intestine digestion)
- Creamy substance - food after a few hours in the stomach
* Periodic relaxation of the pyloric sphincter releases the chyme into the duodenum
Contents of bile (digestion in the small intestine)
- Sodium hydrogen carbonate (alkaline fluid) - neutralises the acid chyme and provides a neutral pH
- Bile salts - emulsify fats and give a large S.A. for lipase to act
What is the journey of bile? (Digestion in the small intestine)
- Made in the liver
- Stored in the gall bladder
- Enters duodenum among the bile duct
Contents of pancreatic juice (digestion in the small intestine)
- Trypsin - hydrolyses proteins to polypeptides
- Chymotrypsin - hydrolyses proteins to peptides
- Carboxypeptidase - hydrolyses polypeptides to peptides and amino acids
- Pancreatic amylase - completes hydrolysis of starch to maltose
- Lipase - hydrolyses fats
What is the journey of pancreatic juice? (Digestion in the small intestine)
- Made in pancreas by secretory cells
* Released into pancreatic duct and neutralises stomach acid
What enzymes are on the villi in the ileum? (Digestion in the small intestine)
- Aminopeptidase - exopeptidase that hydrolyses peptides to smaller peptides and amino acids
- Dipeptidase - hydrolyses dipeptides to amino acids
- Maltase - hydrolyses maltose to glucose
- Lactase - hydrolyses lactose to glucose and galactose
- Sucrase - hydrolyses sucrose to glucose and fructose
What diffusion occurs in the small intestine? (Absorption in the small intestine)
- Fatty acids, glycerol and most vitamins diffuse easily into epithelial cells
- Fatty acids and glycerol recombine in cells to form triglycerides
- They leave the epithelial cells and enter a lacteal to be circulated by the lymph system
What facilitated diffusion occurs in the small intestine? (Absorption in the small intestine)
- Some molecules cross the cell surface membrane of the epithelial cell via carrier proteins
- Does NOT involve energy from ATP
What active transport occurs in the small intestine? (Absorption in the small intestine)
- Epithelial cells of small intestine use energy from ATP for active uptake of glucose, galactose, amino acids, dipeptides and some salts
- Dipeptides are digested intracellularly into simple amino acids
How does the ileum create a large S.A? (Structure of the ileum) (Absorption in the small intestine)
- Very long
- Internal lining is folded
- Villi along folds
- Microvilli on villi
How does the ileum create a short diffusion pathway? (Structure of the ileum) (Absorption in the small intestine)
- Thin epithelial layer
- Blood vessels close to surface
- Lacteals close to surface
How does the ileum maintain a concentration gradient? (Structure of the ileum) (Absorption in the small intestine)
- Circulation of blood - removes glucose and amino acids
* Circulation of lymph - removes fatty acids and glycerol
What happens to the products of digestion once they have been absorbed from the ileum? (Absorption in the small intestine)
- Simple sugars, amino acids, salts and vitamins pass out of epithelial cells into a capillary inside villus
- Blood travels along hepatic portal vein to liver - levels of absorbed food are monitored and regulated before being delivered to cells
- Excess glucose is converted to glycogen
- Excess amino acids are hydrolysed by deamination - makes urea
- Triglycerides are transported by lymph system
How is glucose absorbed?
Facilitated diffusion/active transport - co-transport with Na-
Into capillaries
How are amino acids absorbed?
Facilitated diffusion/active transport - co-transport with Na-
Into capillaries
How are glycerol and fatty acids absorbed?
- Simple diffusion into epithelial cells - non-polar
- Reassemble info triglycerides which are coated with protein to form soluble structures
- Absorbed into lacteals
How is water absorbed?
Osmosis
How are fat soluble vitamins absorbed?
Simple diffusion
Into lacteals
How are water soluble vitamins and mineral ions absorbed?
Facilitated diffusion/active transport
Into capillaries
How does co-transport work in absorption?
- Sodium-potassium pump transports Na+ out of the epithelial cell via active transport - generates concentration gradient
- Glucose enters the cell with sodium via facilitated diffusion (carrier protein) from the intestinal lumen
- Conc. of glucose inside increases
- Glucose leaves the cell via facilitated diffusion and enters the blood
- Sodium leaves the cell via a sodium potassium pump
What is the caecum? (Large intestine)
Indigestible food enters here
Not needed by humans
What is the appendix? (Large intestine)
A small tube at the base of the caecum
Not needed by humans
What is the colon? (Large intestine)
Involved in reabsorption of water and vitamins to produce solidified faeces
What is the rectum? (Large intestine)
Faeces stored here
Features of a herbivore
- Long gut
- Incisors and canines to cut through plants
- Diastema to separate front teeth from premolars - horny pad
- Molars interlock and grind and continue to flat with enamel ridges
- WM interlocking molars
Features of a carnivore
- Short small intestine
- Sharp incisors to grip and tear muscle
- Curved and pointed canines backward facing
- Premolars and molars have cusps for cutting and crushing
- Carnassials in cheeks tear muscle
What are ruminants?
- Fungi, bacteria or protoctista living in rumen
* Animals can’t digest cell wall so rely on mutualistic microbes
What are the stomachs four chambers?
- Rumen - food mixes with microbes which break cellulose into glucose
- Reticulum - where fermented grass reforms into cud
- Omasum - water and organic acids are absorbed into blood
- Abomasum - protein is digested by pepsin
Rabbits digestion (hind gut digesters)
- Enlarged caecum for cellulose digestion
- Digestion of cellulose by bacteria occurs AFTER the small intestine so a lot of nutrients aren’t absorbed
- Eat faeces which contain nutrients
- Nutrients absorbed by ileum
Why are peptidase enzymes secreted in inactive forms?
To prevent the enzymes digesting the proteins in the stomach and duodenum walls
What is the role of lacteals?
Absorbs fats
How do amoebas carry out digestion? (Movement of large, insoluble molecules across membranes)
Intracellular digestion
•Phagocytosis - engulfs bacteria which is then enclosed within a vacuole
•Lysosomes fuse with vacuole membrane, releasing hydrolytic enzymes into it
•Large, insoluble molecules broken down into small, soluble molecules
•Products passed out into cytoplasm via diffusion and active transport
•Undigested material carried by vacuole to cell membrane and removed via exocytosis
How do hydra carry out digestion?
- Tentacles trap prey and carry them through the mouth, into gut cavity
- Endodermis secretes hydrolytic enzymes into gut, which initiates extracellular digestion - partially digests food
- Partially digested food is transported into endodermal cells via phagocytosis
- Digested intracellularly
- Undigested material is egested from gut via single opening
Where does peristalsis occur?
The oesophagus
How does endopeptidase work?
- Hydrolyse peptide bonds within the polypeptide chain
- Produce shorter polypeptide chains
- Found in gastric juice and pancreatic juice
How does exopeptidase work?
- Hydrolyse terminal peptide bonds at the ends of the polypeptide
- Produce dipeptides and amino acids
- Produced by pancreas
Digestion of carbohydrates
- Starch is hydrolysed into maltose by amylase (pH 8)
- Amylase is found in saliva and pancreatic juice
- Maltose is hydrolysed to glucose by maltase
- Sucrose is hydrolysed to glucose and fructose by sucrase
- Lactose is hydrolysed to glucose and galactose by lactase
- Maltase, sucrase and lactase are located on the cell surface membrane of the epithelial cells of the small intestine
Osmosis in the small intestine (Absorption in the small intestine)
- Absorption of solutes causes the water potential of the blood to fall
- Generates a water potential gradient
- Causes a large volume of water to be absorbed into the blood by osmosis
Epithelial cell adaptations (Absorption)
- Microvili - large surface area for absorption
* Many mitochondria - ATP for active transport
Why are some molecules absorbed by active transport rather than facilitated diffusion? (co transport)
- Facilitated diffusion is slow
* Active transport ensures all glucose/amino acids are absorbed from the lumen of the gut
Why do ruminants saliva contain urea?
Source of nitrogen for
Why do ruminants chew cud?
Increases surface area and mixes it with urea
