1. Adaptations for Nutrition
BY2 Biology

2. Nutrition The process organisms use to get
energy to maintain life functions and
matter to build and maintain their structure (from nutrients)

3. Types of Nutrition
Autotrophs - use simple inorganic materials to manufacture complex organic compounds (also called producers)
Ex: photosynthesis - plants use carbon dioxide, water and light energy to make sugars
Ex: chemosynthesis - bacteria around deep sea vents-use carbon dioxide and sulphur compounds (as energy) to create organic compounds
Heterotrophs - consume complex organic food material (also called consumers)

4. What do heterotrophs need to live?
They make energy using:
Food (organic compounds such as carbohydrates, protein..)
Oxygen
They build bodies using:
food for raw materials
amino acids, sugars, fats, nucleotides
ATP energy for synthesis O2
food
ATP
This includes animals, fungi, some protoctists and some bacteria

5. Overview of food processing
Ingest
taking in food
Digest
mechanical digestion
breaking up food into smaller pieces
chemical digestion
breaking down food into soluble molecules small enough to be absorbed into cells
uses enzymes (hydrolysis)
Absorb
Digested food moves across cell membrane
diffusion
active transport
Assimilate
use compounds in the body
Egestion
undigested extracellular material passes out of digestive system (ex: cellulose in humans)
intracellular digestion
extracellular digestion

6. Types of Heterotrophic Nutrition
Holozoic feeders:
Take food into their bodies and break is down during digestion
Have specialised organs in a digestive system (gut)
After digestion, the nutrients are absorbed into the body
Saprophytes (saprobionts):
Fungi and some bacteria
Feed on dead or decaying matter
No specialised digestive system
Secrete enzymes onto the food source outside their body for extra- cellular digestion and absorb the soluble products by diffusion
(enzymes include protease, amylase, lipase, cellulase)
Some are decomposers and help to recycle nutrients in the ecosystem

7. Mutualism (symbiosis):
Parasites:
Highly specialised organisms
Feed on other living organisms (a host)
Some live inside the host (endoparasites) other live on the outside (ectoparasites)
The host is always harmed
Ex: tapeworm, potato blight (fungus), plasmodium (causes malaria)
Mutualism (symbiosis):
2 different species live in a helpful relationship
Ex: cows use bacteria in their stomach to help digest cellulose and the bacteria gain nutrients from the broken plant material for growth and energy

8. How do animals get their food?
filter (suspension) feeding
substrate feeding
fluid feeding
bulk feeding

9. Food types/feeding mechanisms
Heterotrophs
Opportunistic
Herbivore: eat autotrophs
Carnivore: eat other animals
Omnivore: both
Feeding Adaptations
Suspension feeders - sift food from water (baleen whale)
Substrate feeders -live in or on their food (leaf miner) (earthworm: deposit-feeder)
Fluid-feeders -suck fluids from a host (mosquito)
Bulk-feeders: eat large pieces of food (most animals)

10. Digestive systems

11. Simple More complex In simple organisms: In more advanced organisms:
feeding on only one type of food
the gut is undifferentiated
In more advanced organisms:
Often have a varied diet,
the gut is divided into various parts along its length and each part is specialised to carry out particular functions
Organisms with a varied diet require more than one type of enzyme to carry out the digestion of the different food substrates

12. Human Digestive System
Overview animation

13. Mouth (buccal cavity)
mechanical digestion by teeth to break up food (mastication/chewing)
moistens food by mixing with saliva to lubricate it for swallowing
chemical digestion - amylase digests starch
saliva
Contains:
water (to soften food)
mucus (to protect the lining of the digestive system)
amylase (breaks starch to maltose)
mineral ions to keep mouth pH alkaline (act as a buffer)
Anti-bacterial chemicals to kill germs

14. Swallowing (& not choking)
Epiglottis
problem: breathe & swallow through same orifice
flap of cartilage
closes trachea (windpipe) when swallowing
food travels down esophagus
Esophagus
move food along to stomach by peristalsis

15. stomach
acid (secreted from oxyntic cells in wall) kills germs
stores food for up to 4 hrs (sphincter at each end)
mixes food by moving wall with contractions (churning)
gastric juice secreted from glands (peptic cells) in stomach wall digest proteins
secretes mucus (from goblet cells) to protect stomach lining from acid and enzymes
Gastric juice
Contains:
Acid (pH =2) kills germs and provide optimum pH for pepsin
Peptidase enzymes (ex: pepsin) to hydrolyse protein to polypetides
cardiac sphincter
pyloric sphincter

16. Human Digestion
Peristalsis: rhythmic waves of contraction by smooth muscle
Sphincters: ring-like valves that regulate passage of material
Accessory glands: salivary glands; pancreas; liver; gall bladder (secrete digestive juices)

17. Tissue Layers
The gut wall consists of four tissue layers surrounding a central cavity (lumen)-
Serosa – tough connective tissue to protect the wall and reduce friction with other organs when it moves)
Muscle Layer – longitudinal muscle and circular muscle running in different directions
Cause peristalsis when circular muscles contract and longitudinal relax)

18. Submucosa – connective tissue with blood vessels and lymph vessels to carry away absorbed food
Has nerves to coordinate peristalsis
Mucosa- secretes music to lubricate and protect the mucosa
Secretes digestive juices in some areas
Absorbs digested food in others

19. Glands
There are a number of different glands which produce digestive secretions:
Some are found in the wall of the gut with the secretions passing directly into the gut cavity
Mucus secreting glands (submucosa)
Gastric glands (mucosa)
Glands at base of villi (mucosa)
Others are found outside the gut with the secretions passing along ducts into the gut cavity
Salivary
Pancreas
Liver

20. The human alimentary canal
Consists of:
buccal cavity
Tongue
Salivary glands
Oesophagus
Stomach
Duodenum
Ileum
Colon
Rectum
Anus
associated organs; liver and pancreas

21. Small intestine Function Structure
major organ of digestion & absorption
chemical digestion
digestive enzymes
absorption through lining
over 6 meters!
small intestine has huge surface area = 300m2 (~size of tennis court)
Structure
3 sections
duodenum = most digestion
jejunum = absorption of nutrients & water
ileum = absorption of nutrients & water
About every 20 seconds, the stomach contents are mixed by the churning action of smooth muscles.
As a result of mixing and enzyme action, what begins in the stomach as a recently swallowed meal becomes a nutrient-rich broth known as acid chyme.
At the opening from the stomach to the small intestine is the pyloric sphincter, which helps regulate the passage of chyme into the intestine.
A squirt at a time, it takes about 2 to 6 hours after a meal for the stomach to empty.

22. Duodenum 1st section of small intestine Liver gall bladder pancreas
acid food from stomach mixes with digestive juices from accessory glands:
Glands in wall also
secrete: alkaline juice
(optimum for enzymes)
and mucus (lubrication
and protection)
Liver
gall bladder
pancreas

23. Duodenum Enzymes on the tip of the villi complete digestion: Maltase
Endopepsidase
Exopepsidase

24. Liver produces bile salts Digestive System Functions
stored in gallbladder until needed
Help neutralise stomach acid
breaks up fats by lowering the surface tension of lipids
act like detergents to breakup fats into tiny droplets (emulsifier)
Circulatory System Connection
bile contains colors from old red blood cells collected in liver =
iron in RBC rusts & makes feces brown

25. Pancreas Secretes pancreatic juice via pancreatic duct
Digestive enzymes
Endopeptidases (protein peptides)
Pancreatic amylase (starch  maltose)
Lipase (lipids  fatty acids + glycerol)
Buffers
reduces acidity
alkaline solution rich in bicarbonate (HCO3-)
buffers acidity of material from stomach

26. Absorption by Small Intestines
Adaptations for absorption
Very long
Highly folded for higher surface area
Folds contain finger-like villi
Villi contain microvilli

27. Absorption by Small Intestines
Absorption through villi & microvilli
Glucose and amino acids are absorbed by diffusion and active transport into capillaries and then travel via the hepatic portal vein to the liver.
There are lots of mitochondria present in these cells
Fatty acids and glycerol are passed into the lacteal, then through the then through the lymphatic system to the blood stream opening at the thoracic duct.

28. A longitudinal section through a villus - you can see the 'brush border' created by the microvilli, the arrow points to mucus in a goblet cell

29. mouth
break up food
moisten food
digest starch
kill germs
stomach
kills germs
break up food
digest proteins
store food
liver
produces bile
- stored in gall bladder
break up fats
small intestines
breakdown all foods
- proteins
- starch
- fats
- nucleic acids
absorb nutrients
pancreas
produces enzymes to
digest proteins & starch

30. Large intestine 4 parts: Caecum Appendix Colon Rectum Function
re-absorb water and mineral salts in colon
use ~9 liters of water every day in digestive juices
> 90% of water reabsorbed
not enough water absorbed back to body
diarrhea
too much water absorbed back to body
constipation

31. Flora of the large intestine
Living in the large intestine is a rich flora of harmless, helpful bacteria
Escherichia coli (E. coli)
bacteria produce vitamins
vitamin K, folic acid & other B vitamins
generate gases
by-product of bacterial metabolism
methane, hydrogen sulfide
Folic acid: coenzyme needed for DNA & RNA synthesis and proper neural tube growth, may have role in cancer prevention
Biotin: coenzyme needed for Krebs cycle, fatty acid synthesis & gluconeogenesis

32. Rectum Salts cells that have sloughed off masses of bacteria
Last section of large intestine
eliminate faeces
undigested materials
mainly cellulose from plants (roughage or fiber)
Salts
extracellular waste
cells that have sloughed off
masses of bacteria
Cellulose fibre is required to provide bulk and stimulate peristalsis.
The study of the rabbit is fascinating, and from periods of quiet observation we learn some of the peculiarities of its life and habits. One of the most interesting of these is coprophagy. The word comes from the Greek kopros (dung) and phago (eating). This dung eating is not quite so revolting as it sounds at first, for the rabbit makes a special form of pellet which it takes directly from its anus. Coprophagy plays an important part in the digestive/nutritional process.
This practice involves ingestion of special soft fecal pellets which are excreted in the early morning hours. This is a significant practice in that the bacterial synthesis of certain B vitamins in the cecum are excreted at this time and if rabbits are prevented from this practice they will die from vitamin B deficiency within a rather short period of time.
The special soft pellets are produced at night or during periods of rest and are often called "nocturnal pellets" to distinguish them from the fecal pellets excreted at other times. The process has a distinct analogy with the chewing of the cud by ruminants.
Like the cow, rabbits are herbivorous and their diet contains a high proportion of crude fiber. The cellulose of the fiber has to be broken down before complete digestion and absorption can take place. The rabbit has a comparatively large caecum and colon to facilitate this. In order to obtain the maximum nutriment from its food the rabbit has developed the habit of coprophagy, passing certain of its intestinal contents through the system twice.
In addition to the improved nutrition, it is possible that the soft pellets fulfill a need to give greater bulk to the stomach contents. The rabbit's stomach and intestines are geared to bulk supplies and under some conditions the diet may lack bulk. The stomach has a comparatively poor muscular action and relies to a great extent on the pressure of successive meals to push the mass of food along the digestive tract.
The composition of the two types of pellets is interesting, the soft pellets having much more protein and less crude fiber. The process is controlled by adrenal glands.

33. mouth
break up food
moisten food
digest starch
kill germs
stomach
kills germs
break up food
digest proteins
store food
liver
produces bile
- stored in gall bladder
break up fats
small intestines
breakdown food
- proteins
- starch
- fats
absorb nutrients
pancreas
produces enzymes to
digest proteins & carbs
large intestines
absorb water

34. Summary of enzymes
Called hydrolases as they catalyse the hydrolysis of molecules
Enzyme group
Enzyme
Location
Substrate
Products
Other
Carbohydrases
Amylase
Mouth
Duodenum
Pancreas
Starch
Maltose
Maltose is further broken down
Maltase
Glucose
Glucose used as an energy source in respiration
Excess glucose is converted to fat
Proteases
Peptidase
(ex: pepsin)
Stomach
Polypeptides then amino acids
Amino acids
Endopeptidases hydrolyse peptide bonds within the protein
Exopeptidases hydrolyse peptide bonds near the end of proteins
Amino acids are absorbed for protein synthesis
Excess amino acids cannot be stored so
is deaminated, whereby the removed amino groups are converted to urea and
the deaminated remainder is converted to carbohydrate and stored
lipase
Lipase
Fats
Fatty acids & glycerol
Lipids are used for membranes and hormones, and the excess is stored as
fat.

35. Review
digestive system in humans
Overview animation

36. Evolutionary adaptations to different diets
Adaptations of herbivore vs. carnivore
specialization in teeth
length of digestive system
number & size of stomachs

37. Evolutionary adaptations to different diets
Animals have different diets and methods of feeding.
Ex: Retiles and amphibians-swallow food whole immediately so no need for teeth for chewing
Mammals cut and chew food before swallowing and so have adapted different types of teeth

38. Dentition
Mechanical digestion (cutting and chewing food) increases surface area for enzyme action and make swallowing easier
Mammals have evolved different types of teeth with each type being specialised for a different function

39. Teeth
There are differences between the teeth of carnivores and herbivores reflecting their differing diets

40. Carnivore teeth Adapted for:
Catching/piercing skin & killing – large, curved pointed canines
Crushing bones – premolars and molars
Tearing meat – canines
Scrape meat off the bone - incisors
Carnassials – specialized molars (cheek teeth) that slide past each other like scissors to cut and crush
Jaw
Powerful with strong muscles
Does not move side to side (to prevent dislocation)
Greater vertical movement to open wide to capture prey

41. Herbivore Teeth Adapted for: Jaw: Must grind plant material
(due to cellulose) before swallowing
Adapted for:
Cutting plants - Incisors on the lower jaw only and a horny pad on the upper jaw to cut against or help to pull grass (no canines).
Grinding - wide molars and premolars (cheek teeth) that interlock/fit into each other. These teeth get worn down but can regrow throughout life
Jaw:
Diastema – gap between front teeth and premolars at side where the tongue can push the cut grass to the grinding surface at the back and push food to the back over again and again
Moves in a circular grinding action on the horizontal plane

42. Omnivore Teeth Example: 32 Human teeth (adult) both kinds of teeth
8 incisors (chisel shape) for biting and cutting
4 canines (pointed) for tearing
8 premolars
12 molars (flat) for grinding

43. Length of digestive system
Carnivores
No need to digest cellulose or starch so less chemical digestion in mouth
More acid in stomach (so can often eat rancid food)
short digestive system
protein easier to digest than cellulose
Herbivores & omnivores
long digestive system
more time to digest cellulose
symbiotic bacteria in gut

44. Symbiotic organisms How can cows digest cellulose efficiently?
symbiotic bacteria in stomachs help digest cellulose-rich meals
rabbit vs. cow adaptation: eat feces vs. chew cud
caprophagy
ruminant
Ruminants
additional mechanical digestion by chewing food multiple times after mixing it with enzymes

45. Ruminants (ex: cows and sheep)
Eat mainly grass, a large proportion of which consists of cellulose cell walls
Have a 4 chambered stomach
Process:
Food chewed and mixed with saliva
Then passed to the rumen (first stomach) in which mutualistic bacteria live and break down cellulose to glucose (since ruminants do not have the enzyme cellulase)
Glucose is fermented to an organic acid and absorbed into the blood for energy. Waste gases include carbon dioxide and methane

46. Ruminants
plant material is passed up from the rumen and reticulum back into the mouth periodically until it is completely chewed up (known as chewing the cud).
Material is then passed from the rumen and reticulum (no real function) into the omasum (next chamber) where water is absorbed
Then it is passes to the abomason (last chamber) where hydrochloric acid and protease digest protein
Then the material continues into the small intestine for absorption of products

47. The Bacteria
Mutualistic - both benefit – mammals gets food broken down further and bacteria gets food supply brought to it and shelter
bacteria must be kept in an isolated area with optimum pH (not killed by pH in other parts of gut)
More bacteria than in caecum, so more efficient at breaking down cellulose
When bacteria die they get passed along the digestive system as a source or protein

48. Rabbits Coprophagy is consumption of faeces by animals.
Rabbits do not have a complex ruminant digestive system.
They must extract excess amount of nutrition from grass by giving their food a second pass through the gut.
Soft fecal pellets or partially digested food are excreted and consumed immediately
Consuming this matter is important for adequate nutritional intake of vitamin B 12.