Bio Unit 2.4 - Adaptations for Nutrition Flashcards
3 reasons why all organisms require nutrition?
- Supply energy for all chemical reactions
- Supply raw materials for growth, replacement and repair
- Ensure micronutrients are provided for good health
Autotrophic
automatically make their own foods by synthesis of complex organic chemicals from inorganic substances using an energy source
Two types of autotrophic
Photoautotrophic and Chemoautotrophic
Photoautotrophic
Using light energy to combine inorganic substances into complex organic chemicals
Chemoautotrophic
Uses chemical energy to combine inorganic substances into complex organic chemicals
Heterotrophic
Must digest organic chemicals produced by other organisms and use the products of digestion to synthesise their own organic chemicals
Saprotrophic
Extracellular digestion of dead/decayed organic matter, enzymes are secreted by an organism which then digest organic chemicals of the substrate on which they live. Products absorbed by saprotroph
Characteristics of parasites
Live/on another organism, obtain nourishment at the expense of the host, usually cause harm to the host
Primary Host
where adult forms of the parasite develops
Secondary Host
larval forms of parasite found
Vectors
secondary hosts which directly transfer parasite from primary host to another
Absorption
Passage of molecules/ions through gut wall into the capillaries
Assimilation
The use of digested food molecules (e.g glucose in respiration.)
Digestion
Elimination of undigested waste
A single celled organism that ingests and digests its food?
Amoeba
Holozoic nutrition in amoeba
Amoeba senses food, pseudopodia surrounds food, food enclosed in food vacuole, enzymes from the lysosomes secreted into food vacuole, food digested and soluble materials absorbed/assimilated, digestion
Multi cellular holozoic animals
Digestive systems that carry out extracellular digestion within the organism. Products os digestion are absorbed and undigested food digested.
How does the hydra feed?
Cylindrical with tentacles at the top surround mouth leading to a hollow body cavity. Tentacles discharge stinging cells to paralyse prey . Enzymes secreted into body vanity for digestion then nutrients absorbed
Role of protocstista in tentacles of hydra?
Can photosynthesise, protected by tentacles
Definition of digestion
Large insoluble molecules ingested into mouth must be digested into small soluble molecules. Polymers converted to monomers so they can be absorbed into the blood.
Where are molecules absorbed into blood?
Gut Wall
What is mucus secreted by along the gut during peristalsis?
Glandular Tissue
How do longitudinal and circular muscles move during peristalsis to push bolus of food?
Circular Muscles - contract behind bolus of food to push it along
Longitudinal Muscles - relax
Muscles contract and relax in waves
Structure and function of mesentery
Thin sheet of connective tissue, supports the intestines from the abdominal wall, through it runs blood vessels, nerves and lymph vessels
What happens in the mouth?
Ingestion, digestion of starch
What happens in the stomach?
Digestion of protein
What happens in the duodenum?
Digestion of carbohydrates, fats, proteins
What happens in the ileum?
Digestion of carbohydrates, fats, proteins, absorption of digested food
What happens in the colon?
Absorption of colon
Mesentry Function (Structure of gut wall)
Carries nerves, vessels and lymph vessels/holds intestines together
Serosa Function (Structure of Gut Wall)
Forms a tight layer around the gut
Submucosa Function (Structure of Gut Wall)
Removes absorbed products of digestion and nerves that coordinate peristalsis
Muscularis Mucosa Function (Structure of Gut Wall)
Moves villi amongst the food
Mucosa Function (Structure of Gut Wall)
Epithelium cells secrete mucus lubricating and protecting the mucosa/makes enzymes
Amylase hydrolyses starch to…
Maltose
Maltase digests maltose to…
Glucose
Endopeptidases
Breaks down internal peptide bonds
Exopeptidases
Breaks down external peptide bonds
What does saliva have and what does it do?
Amylase, breaks down starch into maltose
What type of digestion happens in the stomach?
Chemical (enzymes and HCl) and Mechanical - muscles contracting to mix food and gastric juice, break down for larger surface area
What is on the outside of the oesophagus wall?
Longitudinal Muscle
End result of digestion in stomach?
Chyme
Where are gastric pits found?
Mucosa
What do oxyntic cells do?
Produce HCl - very acidic
. optimum PH for enzymes, denatures proteins and softens connective tissue in food; activates pepsin
Once pepsin is active why does it not digest stomach wall?
Mucus lines the wall and prevents damage
What do zymogenic cells do?
Secrete pepsinogen
. Digestion of protein into polypeptides, digestion of milk protein
What three cells do gastric pits contain?
Zymogen, Goblet, Oxynitic
What does HCl secreted by oxyntic cells do?
Kills bacteria and activates precursor enzymes pepsinogen and prorennin, initiates hydrolysis of sucrose
What is pepsinogen the precursor of?
Pepsin
What happens to the remainder of pepsinogen?
Converted to pepsin by autocatalysis
What is small intestine composed of?
Duodenum and ileum
What do goblet cells do?
Secrete mucus
. Protects stomach wall and glands from HCl
. Lubricates passage of food
What does HCl remove?
Masking sequence which activates enzyme to produce working pepsin (protease)
Why are precursors produced?
Inactive so they will not digest your stomach
What happens if stomach doesn’t produce enough mucus?
Stomach ulcers
Three processes of digestion
- Neutralise acid from stomach to prevent denaturing of enzymes
- Adds bile for emulsification
- Adds enzymes
Inside each villi is:
network of capillaries to supply O2, glucose, central lacteal, smooth muscle fibres
Two functions of small intestine?
Digestion and absorption
Glands in small intestine?
Brunners Gland, Crypts of Lieberkuhn, Goblet Cells
Outside each villi is:
lining of columnar epithelial cells, brush border of microvilli to increase surface area, desmosomes, goblet cells found between epithelial cells
Where are Brunner’s Gland found?
Submucosa of small intestine
What do Brunners Gland do?
Secretes alkaline mucus, neutralises acidity of chyme and protects duodenum lining from auto digestion
Where are Crypts of Lieberkuhn found?
mucos
What do Crypts of Lieberkuhn do?
At the base are paneth cells (epithelial cells which contain enzymes maltase, sucrase, endopeptidases and exopeptidase)
What do paneth cells do?
Constantly dividing, replace worn out cells. Paneth cells then die and enzymes mix with the food
What does the duodenum receive?
Bile from liver and pancreatic juice from pancreas
What does bile contain?
From red blood cells:
Bile pigments
Cholesterol
Bile salts
Mineral salts (neutralises chyme)
What do pancreatic juices contain?
Mineral salts, enzymes - pancreatic amylase and pancreatic lipase
Why can’t pancreatic protease be secreted in active form?
Digest the pancreatic duct so it is secreted as a precursor
Enzymes in pancreatic secretion?
Trypsinogen, Endopeptidase, Amylase, Lipase
How does trypsinogen work?
Protein digestion after conversion to trypsin
What does sodium hydrogen carbonate do in pancreatic secretion?
Buffer to neutralise chyme
What does trypsin do?
Converts precursor enzyme chymotrypsinogen to chymotrypsin
What does trypsin and chymotrypsin convert protein to?
Peptides
Role of epithelial cells in small intestine?
Release enzymes after they lyse (paneth cells are epithelial cells)
What are found at the base of Crypts of Lieberkuhn?
Paneth cells - secrete maltase, sucrase, endopeptidases, exopeptidase
What do goblet cells do in small intestine?
Secrete mucus - lubricates food as it passes along gut, prevents auto digestion of gut wall
What is in the duodenum?
Bile from liver, pancreatic juices from pancreas
Why are mineral salts in liver alkaline?
Neutralises chyme which causes pepsin to denature - won’t eat away at small intestine
What does pancreatic amylase do?
Breaks down starch to maltose
What does pancreatic lipase do?
Breaks down fats to monoglycerides
Precursor to pepsin and activated by?
Pepsinogen, HCl
Precursor to trypsin and activated by?
Trypsinogen, Enterokinase
Why is long length of ileum good for absorption?
Allows plenty of time for diffusion to occur
Why is folded tube in ileum good for absorption?
Maximises surface area
What does mucosa in ileum do to maximise surface area?
Highly folded forming many villi
What is in epithelium of ileum that increases surface area?
Microvilli
How does rich capillary network help absorption in ileum?
Rapidly remove nutrients and maintain concentration gradient
How does lacteal in ileum help absorption?
Rich network, rapidly removes nutrients and maintains concentration gradient
How does absorption occur (3 things)?
Diffusion, Facilitated Diffusion, Active Transport
Why is most food absorbed by active transport?
Diffusion is too slow
If epithelium cells were permeable to small molecules glucose could move out of blood into intestine
What happens to glucose after in the blood?
Absorbed by cells for energy release in respiration
Glycogen conversion in liver
Excess stored in fat cells
Why is amino acids absorbed?
Protein synthesis
Explain how amino acids are absorbed
Absorbed into epithelial cell by active transport as individual amino acids
Pass into capillaries by facilitated diffusion
Water soluble and dissolve into plasma
Explanation of absorption of fats
Fatty acids and glycerol diffuse into epithelial cells
Recombine in Golgi body
Pass into vesicles and lacteal by secretion
Explanation of water, minerals and vitamins
Minerals absorbed by diffusion into blood
Water soluble vitamins absorbed into blood
Fat soluble vitamins pass into lacteals
Water moves into blood via osmosis
What are lipids used to produce?
Cell membranes, hormones, excess stored as fat
Where does all arterial blood flow and what does to do?
Mesentric artery: supplied oxygen for respiration to produce ATP
Where does the venous blood from each villus flow into?
Hepatic Portal Vein
What hormone does pancreas release when blood sugar is low?
Glucagon - turns glucagon into glucose
Where is glycogen stored and why?
Liver/muscles for energy for respiration
What hormone does pancreas release when blood sugar is too high?
Insulin - turns glucose into glycogen
Why must amine group be removed from amino acid and how is it done?
Poisonous - NH2-NH3-Urea which is then excreted by kidneys
What does the remaining portion of amino group do after amine group is removed?
Carbohydrate portion used to make ATP during respiration or stored as glycogen
What are fats used for?
Respiration, metabolised into other hormones
Where are fats stored?
Under skin for insulation or around heart for protection
Why can mammals hold food in their mouths and chew it?
Hard palate between mouth and nose - allows breathing and chewing at the same time
Why do herbivores have a longer intestine?
Plant material difficult to digest, more time needed
Why do herbivores have a pouched large intestine?
To accommodate large volume of faeces by digested plants, increases time food spends in large intestine
Four types of omnivore teeth?
Incisors, canines, molar, premolar
Why do sheep’s teeth keep growing help it to feed?
Grinding surfaces on teeth wear away as cellulose is difficult to chew. Teeth grow to replace this.
How does diastema help feeding in sheep?
Separates front and back teeth, allows for food to be cleared and tongue to grasp grass
How do canines help a dog feed?
Long, curved, pointed, seize prey and tear muscle
What do carnassial teeth do?
Slide past one another, sheer muscles off bone
Four compartments of ruminant stomachs
Rumen, reticulum, Omasum, Abomasum
What happens to grass before it reaches the rumen?
Cut by teeth, mixed with saliva to form cud, swallowed via oesophagus
What happens in the rumen?
Grass mixed with microbes to secrete cellulase so cellulose digested by glucose
Fermented into organic acids and absorbed into blood
What waste products are produced in rumen?
CO2 and methane
What happens to fermented grass in reticulum?
Reformed into cud, regurgitated for chewing, breaking up of cell walls and digestion of cellulose
What happens after the cud passes reticulum?
Passes into omasum, water and organic acids from fermented grass absorbed into blood
What happens in abomasum?
Protein digestion into amino acids by pepsin at PH2
What happens after protein digestion in abomasum?
Absorption of small soluble food in ileum and duodenum
What are parasites?
Organisms that live in/on another organism, obtain nourishment at expense of host, usually cause harm to host
Why does tapeworm not have any competition?
Protected inside human gut
How does tapeworm survive attack by digestive enzymes?
Scolex has muscle suckers and hooks to attach to duodenum wall and resist peristalsis dislodgment
Primary and second host of tapeworm?
Primary - humans infected by undercooked infected pork - reaches adult form
Secondary - pigs infected by food contaminated with human faeces - larvae
Adaptations of tapeworm?
Flat - increase surface area for absorption of nutrients
Each proglottid covered in thick cuticle resistant to digestive enzymes and secrete mucus
Why do tapeworms not need a digestive system?
Nutrients are pre digested, no need for alimentary canal and soluble nutrients dissolved through body surface
Why does tapeworm not need to reproduce sexually?
Hermaphrodite - has male and female gonads
What type of parasite is a head lice?
Ectoparasite - lives in outside
Attachment devices of head louse
Large claws to grasp individual hairs
Tail adapted to lag eggs that will stick to hair
How do head louse travel?
Direct contact, clinging to people hair
Lice walk along hair to next host
Secondary infections caused by lice?
Conjunctivitis, rhinitis
