1/66
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
Heterotrophy
An organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. (EATING)
all animals use this type of nutrition
Digestion + types (2)
Process of breaking down complex organics
Mechanical
Chemical
Mechanical Digestion Characteristics (3)
breaking down big pieces → small pieces
Increases surface area
allows for enzymes to easily mix w the food
Chemical Digestion Characteristics (2)
Enzymes break down food → hydrolysis (adding water (H₂O) to break the bonds within larger molecule)
Enzymes hydrolyze biological molecules in animals → this results in:
amino acids from proteins
sugars from carbohydrates
fatty acids from fats.
Ingestion
Food enters body
Absorption
Process where the small intestine takes in digested nutrients, like carbohydrates, proteins, fats, vitamins, and minerals, from the food and transports them into the bloodstream,
Cells take up molecules
Elimination
Undigested food passes out of system
Why dont we digest ourselves?
Solution: Compartmentalization
Your digestive system uses physical and chemical separation to prevent self-digestion
Digestion in Single-Celled Organisms Location + (2) important parts
Location: Single cell - Intracellular (inside cell)
- Food taken into a food vacuole.
Lysosomes (w/ enzymes) fuse with the food vacuole and break down the food.
Example: Amoeba, Paramecium
Digestion in Multicellular Organisms
Extracellular digestion - compartments
Extracellular digestion: food is broken down outside cells, in a digestive cavity, then nutrients are absorbed.
Gastrovascular Cavity (2)
A single compartment w/ one opening (acts as both mouth and anus).
Thin/tiny animals have it
Example: Hydra, flatworms
Alimentary canal (3)
Complete digestive tract in big animals
Two openings: mouth (entrance) and anus (exit).
Food moves in one direction.
Example: Humans, mammals, birds
Alimentary Canal - Accessory Glands (not part of the tube but aid digestion) (4)
Salivary glands (3 pairs): Secrete saliva with enzymes like amylase.
Pancreas: Secretes digestive enzymes and bicarbonate (neutralizes acid).
Liver: Produces bile (emulsifies fats).
Gallbladder: Stores and releases bile into the small intestine.
Movement of food Things (2)
Peristalsis
Sphincters
Peristalsis
Waves of smooth muscle contractions push food through the canal.
Sphincters
Ring-like muscle valves that open and close to control movement between sections (like the stomach or small intestine or anus)
8 Steps of Food Processing in Humans
Ingestion – taking in food.
Propulsion – moving food along (swallowing and peristalsis).
Mechanical digestion – physical breakdown (e.g., chewing, churning).
Chemical digestion – enzymatic breakdown of macromolecules.
Secretion – digestive juices added.
Absorption – nutrients enter the bloodstream or lymph.
Compaction – absorbing water and forming feces.
Defecation – elimination of indigestible waste.
Pre-digestion Trigger
Seeing, smelling, or thinking about food causes salivary secretion
Ingestion Location
Oral Cavity
Oral Cavity things (3)
Teeth - mechanical digestion (chew!)
Tongue → forms food into a bolus
Salivary Glands
Salivary glands add: (2 enzymes)
Amylase hydrolyze polysaccharides (ie: starch)
Mucus → mucins (slippery glycoproteins)
Pharynx
Throat Area - connects mouth/larynx/esophagus
Epiglottis
A flap of cartilage that closes over the trachea (windpipe) during swallowing:
*Prevents food from entering the airway
Esophagus
Muscular tube between pharynx and stomach
Moves food via peristalsis (smooth muscles moves food)
Cardiac Sphincter
A muscular ring located at the end of the esophagus and stomach that prevents the backflow of stomach contents.
Stomach Characteristics (4)
Very elastic
Holds 2 liters
Digests protein
Makes food into chyme
Stomach lining structure
Lining of this is Pitted lining that leads to gastric glands
Cells screted by Gastric glands (3)
Mucus cells → mucus, protect tissue from acid
Parietal cells → pump H+ and Cl- ions = HCL (acid) is antimicrobial
Chief Cells → secrete pepsinogen (inactive enzyme - To avoid digesting the stomach itself.)
Mucus cells
secretes mucus, protect tissue from acid
Parietal cells
Pump H+ and Cl- ions into the stomach lumen
= HCL (acid) is antimicrobial
Chief Cells
Secrete pepsinogen (inactive enzyme - To avoid digesting the stomach itself.)
HCL Function
HCl removes a segment from pepsinogen
Exposes active site of enzyme → pepsin (active enzyme)
lowers stomach pH to about 2
Pepsin Fuction
Active enzyme
Breaks down proteins into smaller polypeptides - not all the way
It does not break proteins all the way into amino acids (that happens later in the small intestine).
Chyme
Food + gastric juice (HCl + mucus + pepsin)
Stomach churns the mixture to aid digestion and create this semi-liquid form.
Pyloric Sphincter
Chyme exists stomach through here into small intestine
Small Intestine Characteristics (5)
6 meters long, but thin
Main site of chemical digestion and nutrient absorption
High surface area due to:
Villi (finger-like projections)
Microvilli ("brush border") on cells lining the villi
Digestive Secretions into the SI
Pancreatic Juice (from the pancreas)
2. Bile (produced in liver, stored in gallbladder):
Pancreatic Juice Contents (2)
Bicarbonate – neutralizes stomach acid
Digestive enzymes – for carbs, proteins, nucleic acids, lipids
Bile
Produced in liver, stored in gallbladder
Released via bile duct into SI
Release Bile salts tgat break large fats
Bile salts
Emulsify fats (break large fat globules into smaller droplets)
Divisions of the SI (3)
Duodenum - first part - most chemical digestion
Jejunum - middle
Ileum - lower portion
Duodenum
Most chemical digestion in SI
Digestion of Nutrients Enzymes - Carbohydrates
Mouth - Salivary amylase
Stomach - none
SI - Pancreatic amylase, enzymes from SI
Digestion of Nutrients Enzymes - Proteins
Mouth - none
Stomach - Pepsin
SI - Pancreatic trypsin & chymotrypsin + 3 peptidases from SI
Digestion of Nutrients Enzymes - Nucleic Acids (DNA & RNA)
Mouth - none
Stomach - none
SI - Pancreatic nucleases + nucleotidases from SI
Digestion of Nutrients Enzymes - Lipids
Mouth - none
Stomach - none
SI - Pancreatic lipase and Bile salts emulsify fats bc they are hydrophobic
Lipids digested as?
Triglycerides(polymer), emulsified by bile salts
Villi and what each contains (2)
fingerlike projections lining the intestinal walls where absorption happens
Each contains:
Capillaries (carry nutrients to bloodstream)
Lacteal (a lymph vessel for fat absorption)
Lacteal
a lymph vessel for fat absorption in villi
Transport Mechanisms - Simple Diffusion
Absorbs: Water
Moves down concentration gradient
Transport Mechanisms - Facilitated Diffusion
Absorbs: Fructose
Requires a transport protein
Transport Mechanism - Active Transport
Absorbs: Ions
Requires energy (ATP), moves against gradient
Monoglycerides & fatty acids (lipids)
Use simple diffusion across intestinal epithelium
After Absorption (inside the cell) (Absorption of Lipids)
Body rebuilds triglycerides and packages into chylomicrons
Chylomicrons (Absorption of Lipids)
(fat + protein globules) - Reassembled into triglycerides packed into this
Chylomicrons after packaging (Absorption of Lipids)
enter the lacteal → into lymphatic system → into blood
Ileocecal valve
Entry Point of the large intestine (digestion is done)
Function of the Large Intestine
Mainly Water absorption
4 division of large intestine
Ascending
Transverse
Descending
Sigmoid Colon (before rectum)
Vitamins produced by bacteria in colon (4) + 1 function
K vitamins
Thiamine
Riboflavin
B12
function: help fight pathogens
Feces compose of (%)
~75% water, ~25% solids
How many sphincters in anus?
2 total: 1 voluntary / 1 involuntary
Functions of liver (4)
Processes absorbed nutrients:
Stores excess glucose as glycogen
Converts nutrients into new molecules/substances
Detoxifies and Modifies (e.g., alcohol, drugs)
Produces bile (for fat emulsification in SI)
Hepatic Portal Vein (liver)
Liver gets 1st access to nutrients absorbed by intestine
Emulsifying Fats
Breaking down large fat globules into smaller, more manageable droplets
SI fat enzymes
Pancreatic Lipase and bile salts
Fat polymer and what it breaks down to in SI
triglycerides →glycerol + fatty acids + monoglycerides