Digestive Flashcards
Homeostasis
internal stability of the body
How does the digestive system aid in homeostasis
digestive system provides energy
How does the digestive system rely on other systems
needs blood and O2 to function
Autotrophs
make energy by making their own food using sunshine
Heterotrophs
consume other organisms to obtain energy
4 feeding mechanisms
1) filter feeding
2) substrate feeding
3) fluid feeding
4) bulk feeding
filter feeding
use structure similar to a filter basket to gather food suspended in water
ex: sponges, tube worms, clams, barnacles
Substrate feeding
live in their food source and eat through it
ex: caterpillars, earthworms
Fluid feeding
suck or lick nutrient rich fluid from plants or animals
ex: mosquitoes, ticks, spiders, bees
bulk feeding
ingest large pieces of food
ex: humans and all other mammals
what type of organisms have longer digestive tracts
Herbivores and omnivores have longer tracts than carnivores
main function of the digestive system
break down foods into their molecules so they can be used by the body
why must food be broken down into soluble units
so they can pass through the plasma membranes of each cell
how are broken down substances transported through the body
circulatory system
4 phases for the digestive system to function
Ingestion → Digestion → absorbtion → Egestion
Ingestion
Bringing Nutrients into the body
usually happens in the mouth
Digestion
Breaks down food into smaller pieces
2 types of digestion
mechanical and chemical
mechanical digestion
physically break down food
decreases surface area
chops and grinds food
chemical digestion
Enzymes break down food to a molecular level
chemical bonds in food particles are separated
Absorption
nutrients are absorbed mainly in the small intestine
products are moved to circulatory system to be distributed to the rest of the body
Egestion (elimination)
Food molecules are removed from body
it is usually the food that the body is unable to digest
Alimentary Canal (digestive tract)
long, open tube (usually one-way)
How is the alimentary canal organized
specialized regions, with different organs along the tube processing food in different ways.
what is the alimentary canal lined with
mucus lining to protect canal and move food more easily along
what do parts of the alimentary canal produce
digestive enzymes to help break down food.
mouth
1st point of contact with food
performs chemical and mechanical digestion
what parts is the mouth divided into
roof of the mouth is made up of a hard palate and a soft palate
separates the oral cavity from the nasal cavity
hard palate
anterior (front)
mainly made up of bones
soft palate
posterior (back)
muscular
what produces saliva
salivary glands
What does saliva contain
mucus, digestive enzymes (like salivary amylase), and other chemicals`
what does salivary amylase do
begins the chemical digestion of food by breaking down starches
this is a form of chemical digestion
Teeth
Perform mechanical digestion by physically breaking food
bite, tear and grind food into smaller pieces
Tongue
Mixes chewed up food with saliva
what is the tongue made out of
skeletal muscles which help to push food down into the esophagus
taste buds are located here
when do taste buds activate
once food is present, taste buds will be activated
sight or smell of food can trigger the salivary glands to produce saliva
Tonsils
help body fight infections
located at the back of the mouth on both sides of the tongue
what other system are tonsils a part of
lymphatic system
may need to be removed if they become infected
Bolus
name of food once they’ve been digested in the mouth
Uvula
finger like shape at end of soft palate
pharynx
upper portion of the throat
gets air from nasal cavity & food from mouth
Epiglottis
flap of cartilage
when food is present it seals off airway to prevent from entering (usually covers the esophagus)
Swallowing
occurs in the pharynx
can start by choice when it begins it turns involuntary
what happens to bolus during swallowing
gets moved to the back of the mouth by the tongue
once the bolus reaches the pharynx, it triggers the swallowing response
moves down the esophagus by peristalsis
esophagus
a hollow, muscular tube that connects the pharynx to the stomach
transport food (bolus) from the mouth to the stomach
why does the esophagus produce mucus
keep the passage moist and make it easier for the bolus to move
Peristalsis
series of muscle contractions
starts in the esophagus and continues through the rest of the digestive tract
Sphincters
muscles that are found along the digestive tract
open & close to allow materials to pass through
what happens when sphincters are relaxed
esophagus is open and food will go into the stomach
when they are contracted, the esophagus is closed
normally closed to prevent the acidic contents of stomach from going into the esophagus
stomach
Temporarily stores food while both mechanical & chemical digestion takes place
structure of stomach
has thick walls - Elastic and very muscular
has folds that allow it to grow up to 20 times larger than normal
folded like an accordion - expands when food is inside
can stretch to hold more food
Gastric Juice
Performs chemical digestion; unique to the stomach
Millions of gastric glands produce gastric juice, stimulated by food.
what is in gastric juice
Gastric juice contains hydrochloric acid, salts, enzymes, water, and mucus; highly acidic (more acidic than battery acid)
how is the stomach protected from gastric juice
Stomach lining secretes mucus to protect it from strong acid
how does gastric juice help digest food
Three layers of muscle fibers churn food, breaking it mechanically and mixing it with gastric juice
Nerves around the stomach regulate activities and start contractions to release partially digested food
Chyme
name for food once it leaves stomach
peristaltic wave become strong when chyme is ready to leave stomach -forces chyme out
where is chyme stored
when the small intestine is full and still digesting food, the stomach temporarily stores chyme
Pyloric Sphincter
muscular valve at the lower end of the stomach
closed - food stays in the stomach
opened - food goes into the small intestine
where does the pyloric sphincter move chyme
out of the small intestine into the large intestine then chyme is pushed into duodenum
where are carbohydrates digested
starts in the mouth with saliva
digestion is completed in the stomach
where are proteins digested
starts and finished in the stomach
where are fats digested
start being digested in small intestine
digestion gets completed in the small intestine
small intestine
Primary role is absorption of nutrients
Performs mechanical digestion (peristalsis) and chemical digestion (enzymes)
All digestion is completed here
how are nutrients passed to the circulatory system in the small intestine
walls have folds covered with villi to greatly increase surface area for absorption.
structure of villi
Small, finger-like projections in the small intestine.
Each villus has a capillary beside it
function of the villi
Increase surface area for more efficient absorption
Nutrients diffuse into capillaries
Nutrients travel through the bloodstream to the rest of the body
main parts of small intestine
Duodenum → Jejunum → Ilium
duodenum
digestion occurs
located directly after the stomach V-shaped
receives secretions from the pancreas and gallbladder
Jejunum
absorption occurs
contains more folds than the duodenum
breaks down the remaining proteins and carbohydrates
Ilium
absorption occurs
contains fewer and smaller villi than either the duodenum and jejunum
pushes the remaining undigested materials into the large intestine
main functions of the large intestine
- absorbs water from alimentary canal (recovers it)
- formation & storage of feeces
Feces
Waste product of digestion, composed of 75% water and 25% solid
toxic to the body
What do anaerobic bacteria in the colon do
break down undigested matter and produce essential vitamins
Where are vitamins produced by bacteria absorbed
absorbed into the bloodstream through the large intestine
what is billiruben
A by-product of hemoglobin breakdown, secreted into bile by the liver
makes poop brown
Colon
collective term for most of lange intestine
3 sections of the colon
Ascending Colon → Transverse Colon → Descending Colon
ascending colon
physically runs upwards towards the stomach
transverse colon
runs horizontally across the body
Descending Colon
last part of the colon
runs down towards the anus
Appendix
helps fight infections
attached to the large intestine, but food materials do not physically enter here
may need to be removed if it becomes infected
Rectum
stores feeces until they are eliminated
last 20 cm of the large intestine
opens at the anus, which is where feces leave the body
Defecation (pooping or bowel movement)
removal of feces from body
feces forces into rectum by parastasis
the walls of the rectum stretch
this starts nerve impulses
when feeces leave, rectal muscles contract and the anal sphincters relax
accessory digestive organs
pancreas, gallbladder and liver
pancreas
Lies deep in the abdominal cavity, on the posterior abdominal wall; elongated and flattened
Part of both the digestive and endocrine systems
what does the pancreas secrete
Secretes hormones (insulin and glucagon) to regulate blood sugar
Produces pancreatic juice with sodium bicarbonate to neutralize chyme acidity
Releases enzymes to break down carbohydrates, proteins, and fats
what does the pancreas do to chyme
chyme leaves the stomach with a pH of 1
Pancreatic juice raises the pH to 8, protecting the small intestine
liver
largest internal organ in the body
about the size of a football
located right below the diaphragm
3 Main Structures Between the Lobules
Bile Duct → Branch of Hepatic Artery → Branch of Hepatic Vein
Bile Duct
takes bile away from the liver
Branch of Hepatic Artery
brings oxygen rich blood to the liver
Branch of Hepatic Vein
transports nutrients from intestine
what does the liver filter
filters the blood, removing poisonous substances, detoxifying them, and regulating nutrients and cholesterol levels
also makes plasma proteins from amino acids
how does the liver regulate glucose
store extra glucose as glycogen
converting glycerol from fats and amino acids into glucose
Where is bile produced and stored
produced in the liver and stored in the gallbladder
What do bile pigments and bile salts do in digestion
do not aid digestion but help eliminate waste,
bile salts emulsify fats and increase the surface area for enzyme action
What is bile made of, and what is its role
Bile is made of bile pigments and bile salts. Bile salts emulsify fats, breaking them into smaller molecules for easier digestion
7 Ways the Liver Helps to Maintain Homeostasis
- Detoxifying blood
- Storing iron
- Making plasma proteins
- Stores glucose as glycogen (also breaks down glycogen to glucose)
- Produces urea after breaking down amino acids
- Removes bilirubin from the blood and excretes it into the bile
- Helps to regulate the blood cholesterol levels
structure of the gallbladder
The gallbladder is a pear-shaped, muscular sac attached to the liver
What happens to water in the gallbladder
reabsorbs water, making bile thicker and more concentrated
What does the gallbladder store
stores bile produced by the liver between meals
Bile is released through the bile duct into the duodenum when fats are present in the small intestine
What role does bile play in fat digestion
Bile breaks down large fat droplets into smaller ones, aiding in mechanical digestion
What causes gallstones and how are they treated
high cholesterol and may block the bile duct,
sometimes requiring gallbladder removal
How do food molecules enter the bloodstream
Small food molecules are absorbed directly by the cells of the villi
Food molecules diffuse into the blood vessels of the villi, entering the bloodstream.
What does the large intestine absorb
mainly absorbs water from waste before elimination
types of enzymes
Carbohydrases digest carbohydrates.
Lipase digests fats.
Proteases digest larger polypeptides.
Nucleases digest nucleic acids
digestive enzymes
proteins that speed up chemical reactions, aiding in chemical digestion.
break down food into nutrient molecules, such as glucose, amino acids, fatty acids, and glycerol
what factors effect enzyme activity
Enzyme activity is affected by temperature and pH, which help maintain the enzyme’s shape and optimal function
Temperature Effect: Higher temperatures increase enzyme activity by adding more energy
Hydrolytic
they break down molecules when water is introduced
salivary amalyase
Found in saliva
Has a neutral pH.
first enzyme to act on carbohydrates (starch)
starch breakdown by salivary amalyse
Starch is digested into maltose, a sugar
Maltose cannot be directly absorbed by the intestine; additional digestive enzymes are needed
Pepsin
enzyme that is found in the stomach
creates gastric juice when it is mixed with hydrochloric acid
protein breakdown by pepsin
chemical digestion of proteins into peptides
peptides are usually too large to be absorbed by the intestines
get broken down into amino acids in the small intestine
Pancreatic Amylase
found in pancreatic juice
created in pancreas but enters the duodenum of the small intestine
digests starch
also works to help neutralize the chyme
Lipase
another pancreatic enzyme
digests fat molecules after they have been emulsified by bile salts
after the lipase digests the fat, it is in the form of glycerol and fatty
these are small enough to be absorbed in the villi
Peptidase
produced in the small intestine
completes the digestion of protein into amino acids
Maltase
Produced in the small intestine, completes starch digestion by breaking down maltose.
Absence of enzymes can cause illness, lactose intolerance (lactase deficiency) leads to trouble digesting dairy.
heartburn
occurs when stomach food enters the throat
burning pain that is felt in the throat
Vomiting
Stomach contents exit through the mouth, causing dehydration.
Diaphragm and abdominal muscles contract, forcing contents through the esophagus.
Can be triggered by illness, stress, or diseases. While often harmless, it can signal a more serious illness.
Flatulence (farting)
A normal process that occurs in every human body
Small amounts of air enter the digestive tract while eating and need to be released through flatulence or burping
people do not often notice when it happens
Diarrhea
Feces exit the body before absorption is complete, resulting in loose stools with high water content
Often caused by bacteria, but can also be triggered by food, stress, or illness
Constipation
Occurs when bowel movements are infrequent, and feces are hard, dry, and difficult to pass
Often linked to diet and lifestyle, with inadequate water intake or poor bowel nerve and muscle function.
Can cause headaches and may be toxic or life-threatening if severe.
Peptic Ulcer
Occurs when the stomach’s protective mucus weakens, allowing stomach acid to damage the walls
abdominal pain, bloating, nausea, and loss of appetite.
Caused by unprotected tissues contacting acidic gastric juices.
Can be life-threatening if left untreated.
Inflammatory Bowel Disease - IBS
A group of diseases causing inflammation in the intestines
Long-lasting or recurring, with no cure—only treatable with medication and a specialized diet
ex Crohn’s Disease and ulcerative colitis.
Hepatitis
An inflammation of the liver
3 types A B & C
Hepatitis A
usually contracted from drinking contaminated water
Hepatitis B
spread by sexual contact
there is a vaccine to protect against it
Hepatitis C
usually contracted by contact with infected blood
Cirrosis
Chronic liver disease where scar tissue replaces healthy tissue, impairing liver function
Often caused by alcoholism and hepatitis C.
Blood tests can detect fatty liver, an early sign of cirrhosis.
Polyps
Small growth in epithelial lining of colon
can be benign or cancerous
often are able to be removed surgically
Dietary fat can increase chance of colon cancer
Diabetes
A condition where blood cells can’t use glucose for energy
After eating, the pancreas releases insulin to control blood glucose levels
Develops when there is insufficient insulin or the body can’t use it properly, preventing glucose from entering cells
Endoscope
helps diagnose medical problems, visually inspects the alimentary canal, and allows for safer, painless procedures with faster recovery, less risk, and no need for cutting
Micronutrients
vital to life in varying amounts
needed by a healthy, functional human body
6 Vital Nutrients
- Carbohydrates
- Proteins
- Lipids
- Water
- Vitamins
- Minerals
digestion of micro and macro nutrients
macronutrients: must be digested
micronutrients: do not need to be digested get absorbed directly into bloodstream
carbohydrates
Composed of carbon, hydrogen, and oxygen
Converted to glucose for energy
Main energy source for the body and brain
Provide short-term and long-term energy storage
2 Functions of Carbohydrates
- release quick energy to be used be calls
- Provide material to build cells
Complex Carbohydrates (polysaccharides)
made up of many sugar molecules
need to be digested and broken down into simple sugars
ex: starches, cellulose, glycogen
Starches
come from plants
can be broken down as a source of energy by plant or animal cells
Cellulose (fiber)
Does not get digested into body
technically not a nutrient because it is not digested
makes up the cell wall that is the tough, outer covering of plant cells
helps to keep our bowel movements regular
Glycogen
energy that is made and stored in animals
Simple Carbohydrates (monosaccharides)
made up of one sugar molecule
able to be absorbed in the small intestine
ex: Glucose
Glucose
main source of energy for the body
can be used immediately or stored in the body as glycogen
Extra glucose is converted to fat
fat gets stored in adipose tissues
protine
large, complex molecules
every body structure needs protein to survive
ex: meat, poultry, fish, eggs, dairy, seeds, nuts
Amino Acids
Building blocks of protein, containing carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur
20 types, linked in specific sequences to form polypeptides; sequence determines protein function
differ in amino acid number, order, and arrangement, creating millions of protein variations
6 Functions of Proteins:
- build, strengthen and repair
- create antibodies for immune system
- make barmanes
- create enzymes - Speed up chemical RN in cells
- allow for muscle contractions
- carries and stores items in the body
complete Protein Sources
food that provides all 20 amino acids
Essential Amino Acids
Body is unable to produce these
need to get these from the food that we eat
8 in total
lipids
Non-polar molecules like fats, oils, and cholesterol, composed of carbon, oxygen, and hydrogen, and insoluble in water
Essential for the body, storing energy and providing half of the fuel needed for bodily functions
Excess calories are stored as fat
Phospholipid
an example of a lipid
found in the membrane of every cell in our bodies
4 Functions of Lipids:
- insulation & protection - layer of fat under skin and around organs
- digestion & absorption bile is created from fat
- helps build cell wall structures
- Creates hormones
what do lipids consist of
molecules called glycerol which are bonded to molecules called fatty acids
Fatty Acids
chains of carbon atoms bonded to hydrogen atoms
2 types: saturated fatty acids and unsaturated fatty acids
Saturated Fats
usually come from animal sources
tend to be solid at room temperature
Unsaturated Fats
usually liquid at room temperature
often considered to be “healthier” dietary fats
come from plant sources
Cholesterol
not a fat
waxy, fat-like substance
HDL Cholesterol
“good cholesterol”
high density lipoprotein
picks up extra cholesterol in the body - takes it to the liver to be broken down
LDL Cholesterol
“bad cholesterol”
low density lipoprotein
carries cholesterol through the body once it is used up, the extra LDL will remain in the blood
can cause blood clots
Hydrolysis
Chemical breakdown of macronutrients
enzymes increase the rate and efficiency of this
