Adaptations for nutrition

Role of glands

Make and release digestive juices containing enzymes

Role of the stomach and small intestine

Digest food by enzymes breaking down molecules

Role of the small intestine

End products of digestion absorbed into the blood

Role of the large intestine

Absorb water

Role of the rectum and anus

Store and pass faeces out of body

Amylase breaks ? Into ?

Starch into glucose

Protease breaks ? Into ?

Protein into amino acids

Lipase breaks ? Into ?

Lipids into glycerol and fatty acids

What is bile? And it’s functions

Made by the liver, stored in the gall bladder

Emulsifies lipids to increase their surface area for lipase

Neutralised acid in stomach for optimum pH as it is basic

autotrophic nutrition

uses simple inorganic molecules to synthesise complex inorganic molecules using light energy and chemical energy

heterotrophic nutrition

obtaining complex organic molecules from other organisms (consumers) 4 types= holozoic, saphratrophic, parasitic, mutalistic

holozoic

internal digestion, involves enzymes, steps= ingestion, digestion, absorption, assimilation, egestion

saphratrophic

all fungi and some bacteria, external digestion of decaying material, enzymes are secreted, includes digestion and absorption through active transport or diffusion

parasitic

obtains nutrients from living in/on another (host) living organism, causing harm to the host

mutualistic

association of two organisms of different species where both receive a nutritional benefit

4 layers of the gut wall from inner to outer

Mucosa

Submucosa

Muscle layer

Serosa

Role of the mucosa

Lubricated passage of food with mucus produced by goblet cells, mucus also prevents auto-digestion, lined with specialised epithelial that produce digestive enzymes and absorb end products

Role of submucosa

Connective tissue that contains capillary beds for the blood transporting absorbed food products, also contains nerve fibres that coordinate peristalsis

Muscle layer role

Contains two layers of muscle, innermost is circular arranged in rings and then longitudinal which has fibres running lengthways, these control wave of muscle contractions in peristalsis and can form sphinsters in places

Role of serosa

Outermost layer of tough connective tissue which provides protection from friction against other organs

2 types of digestion

physical - breaking up food

chemical - action of enzymes

what happens in the mouth in digestion

teeth chew food to break it down, increasing surface area

tongue mixes food with saliva

salivary glands secrete saliva containing water, mucus, salivary amylase, hydrogen carbonate, carbonate and lysozome

what happens in the oesophagus in digestion

no digestion, only transport of food from mouth to stomach by peristalysis by the muscle layers and mucus, there are no glands, enzymes or villi

what happens in the stomach in digestion

mechanical digestion by folds in the stomach called rugae allow the stomach to expand, there is an additional layer of muscle called oblique which is at an angle and allows further contractions

chemical digestion by hydrochloric acid secreted by gastric glands from oxyntic cells creates a high pH for protein digestion (activates pepsinogen) and kills bacteria, enzymes: pepsin breaks down proteins into smaller amino acids, gastric lipase break down lipids into glycerol and fatty acids

what does gastric juice contain?

mucus from goblet cells - lubricates passage

hydrochloric acid from oxyntic cells - maintains pH killing bacteria

pepsinogen from chief cells - prevents auto-digestion

What sort of enzyme is Pepsin? +role?

Endopeptidase - hydrolyses the peptide bonds in an amino acid to produce peptides

What is the duodenum?

First, short part of the small intestine that has folds (villi) with ‘crypts of lieberkuhn’ in between. It is the main site of chemical digestion

3 secretions to the duodenum

1. Secretions from the liver - bile, contains salts that emulsify lipids, sodium hydrogen carbonate which neutralises acid in chyme to provide optimum pH for enzymes

2. Secretions from pancreas - pancreatic juice, includes pancreatic amylase which breaks starch into maltose and pancreatic lipase which breaks triglycerides into monoglycerides. Also includes trypsinogen which is an inactive precursor and sodium hydrogen carbonate which neutralises acid in chyme

3. Secretions from the duodenum: intestinal juice from Brunners glands in the submucosa, mucus is alkeline. Enterkinase activates tryspinogen which breaks polypetises into peptides

What is intracellular digestion?

Breakdown of disaccharides into monosaccharides on a cell membrane using enzymes present

What does dipeptidase do?

Hydrolises dipeptides into two amino acids that can pass into the cell

adaptations of the ilium for absorption

folds in the mucosa, villi with microvilli on epithelial cells, one layer of epithelium for diffusion, very long (6m) for a large surface area

how are amino acids absorbed?

active transport into epithelial cells and facilitated diffusion into capillaries

how are glucose and other monosaccharides absorbed?

by co-transport with sodium ions into epithelial cells and facilitated diffusion into capillaries

how are amino acids and glucose transported?

by the hepatic portal vein in the liver

what happens to fatty acids and glycerol in absorption?

diffusion into epithelial cells where they are reassembled into triglycerides, then passed into the lacteal and are carried by the lymphatic system to the blood

Dentition in carnivores (front to back)

Incisors, enlarged canines, premolar, carnassials, molars

Adaptations of carnivores dentition

Sharp to tear and shear muscle from bone

Dentition in herbivores (front to back)

Incisors, canine, dental pad, diastema, premolar, molars

Adaptations of herbivores dentition

Small and sharp for cutting vegetation, diastema allows for tounge to wrap around and move vegetation over teeth, teeth get worn down by grinding but are open-rooted to allow for continuous growth

Why do carnivores have a smaller small intestine than herbivores?

Meats main component is protein which is easier to digest than plant material which is mainly carbohydrates

what is a ruminant?

an animal with a stomach consisting of 4 chambers: rumen, reticulum, omasum, abomasum

digestion in ruminants

in rumen, cellulose broken down into beta glucose by fermentation, co2 and methane are waste products, organic acids are absorbed into blood. reticulum regurgitates cud into mouth to be rechewed (mechanical digestion). re-swallowed and enters the omasum where water is absorbed. rest of digestion occurs in abomasum which contains HCl and endopeptidase

adaptations of the rumen and reticulum

villi and honeycomb like surface providing a large surface area for absorption

what is rumination?

partially digested food being regurgitated and re-chewed

Why do rabbits eat their soft faeces?

Soft faeces contains more reducing sugars, their stomach doesn’t produce cellulase to break down cellulose but their caecum does produce bacteria containing cellulase. the caecum comes after the small intestine in rabbits digestion so no absorption of the sugars can occur unless the faeces are re digested

headlice’s adaptations (ectoparasite)

mouthpart can pierce skin to take blood from capillary, claws that grip onto the hair, spiracles that close under water, eggs glue onto hair

tapeworms adaptations (endoparasite)

hooks and suckers that attach to the small intestine to resist peristalsis, thick cuticle that secretes anti-enzymes to resist digestion, large surface area to volume ratio, thin for short diffusion pathway, reduced digestion system as it can absorb nutrients from host, hermaphrodite so can produce lots of eggs

pepsins role and site of secretion

breaks proteins/polypeptides into peptides, secreted from gastric pits in stomach

peptidases’ role and site of secretion

breaks peptides into amino acids, secreted by duodenum

where is lipase secreted from?

pancreas

salivary amylase breaks ? into ?

starch / glycogen into maltose / glucose

define digestion

large insoluble molecules are broken down into small soluble molecules

in which 2 areas are proteins, carbs and lipids digested together?

duodenum and ilium

what do epithelial cells have lots of? and why?

mitochondria for ATP synthesis for active transport