Digestion Flashcards

Flashcards for reviewing key concepts from a lecture on digestion.

What are the four stages of food processing?

Ingestion, digestion, absorption, and elimination

Why is digestion necessary?

To break down large macromolecules into smaller, absorbable components with the help of enzymes.

What do protein-digesting enzymes break down proteins into?

Amino acids

What do carbohydrate-digesting enzymes break down poly- and disaccharides into?

Monosaccharides

What do nucleic acid-digesting enzymes break down nucleic acids into?

Nucleotides

What do fat-digesting enzymes break down fats into?

Glycerol and fatty acids

Which glands produce saliva to initiate carbohydrate breakdown?

Salivary glands

What is the function of the esophagus?

Transports food from the mouth to the stomach through peristalsis.

What is the role of the stomach in digestion?

Mixes food with gastric juices to break down proteins and kill bacteria.

Which organ stores and concentrates bile?

Gallbladder

What is the function of the liver in digestion?

Produces bile and plays a role in metabolism and detoxification.

Which organ secretes digestive enzymes and hormones to regulate blood sugar?

Pancreas

Where does the primary nutrient absorption take place?

Small intestine

What is stored in the rectum before elimination?

Feces (undigested waste)

What elements do carbohydrates mostly consist of?

Carbon, hydrogen, and oxygen atoms

What is the ratio of carbon, hydrogen, and oxygen in carbohydrates?

1:2:1 (e.g., C6H12O6)

Name two possible orientations for the hydroxy group at carbon 1 in carbohydrates?

Alpha and beta ring structures

What two things occur when a carbohydrate is broken down?

Two hydrogen atoms and an oxygen atom are split off, making water.

What is the most common carbohydrate in the human diet?

Starch

Why is starch a good molecule for energy storage?

It's not soluble in water, making it a light molecule.

What shape do long chains of alpha 1-4 linked glucose units form?

Helix

What are aldoses and ketoses?

Structural isomers of monosaccharides

Why is fructose often used in sweets and diet foods?

It is sweeter than sucrose, so less is needed for the same sweetness.

How do taste buds sense taste?

Through taste-sensitive cells with taste receptors.

Where does starch digestion begin?

In the mouth, due to salivary amylase

What does saliva contain besides amylase?

Proteins that make food more slippery.

What is the function of an enzyme's active center?

To bind a specific substrate.

What does an enzyme do to catalyze a chemical reaction?

Lowers the activation energy.

What is the Fehling test used to detect?

Reducing sugars

What is the Lugol's solution used for?

Stain starch.

What does Lugol's solution do to starch?

Turns the starch dark blue-black color in the presence of iodine.

How can amylase be deactivated?

With acid (HCl) or boiling

What two monosaccharides make up lactose?

Galactose and glucose

What is the function of the enzyme lactase?

Hydrolysis of lactose into glucose and galactose.

What enzyme converts maltose into two glucose molecules?

Glucosidase

What are the symptoms of lactose intolerance?

Abdominal cramps, diarrhea, flatulence, or vomiting

What is the function of lactose tablets?

They digest the lactose when taken by intolerant people.

What is the approximate pH of the stomach?

Approximately 2

How is the stomach protected from HCl?

By a layer of mucus, only making HCl after a meal, and fast renewing of the outer cells

What is a protease?

An enzyme that performs proteolysis by hydrolysis of peptide bonds.

What does thrombin do to fibrinogen?

Converts fibrinogen to fibrin.

What is the role of pepsin in protein digestion?

Hydrolyzes proteins into oligopeptides in the stomach.

Where is pepsin released?

Chief cells in the stomach

What is the inactive form of pepsin called?

Pepsinogen

What are the most common symptoms of stomach ulcers?

Waking up at night with upper abdominal pain, that gets worse when eating.

What are the four classes of essential nutrients?

Amino acids, fatty acids, vitamins, and minerals

What deficiency results in scurvy?

Vitamin C deficiency

What does the pancreas release to neutralize the HCl from the stomach?

Alkaline substances

What are the four types of lipids?

Fats and oils, waxes, phospholipids, and steroids

What is the role of bile in fat digestion?

Emulsifying fats.

What are the four compartments of the ruminant stomach?

Rumen, reticulum, omasum, and abomasum.

What type of epithelium lines the rumen, reticulum, and omasum?

Stratified squamous epithelium.

What is the abomasum and what is its function?

The true (glandular) stomach of ruminants, similar histologically to the stomach of monogastrics; It is where ruminants digest their food.

How do the reticulum and rumen interact?

Ingesta flows freely between the reticulum and rumen; the reticulum can be considered a cranioventral sac of the rumen.

What is the appearance of the reticular epithelium?

The epithelium forms folds that create polygonal cells, resulting in a honey-combed (reticular) appearance with small papillae on the cell floors.

What are the key characteristics of the omasum?

It contains broad longitudinal folds or leaves, resembling pages in a book, which are packed with finely ground ingesta.

How does the forestomach anatomy of camelids differ from that of typical ruminants?

Camelids have a reticulum with gland-like cells and an omasum that is tubular and almost indistinct; they are sometimes referred to as pseudoruminants with "three stomachs".

How are the volatile fatty acids absorbed in the rumen?

Despite the stratified squamous epithelium not being a typical absorptive type, the abundant volatile fatty acids produced by fermentation are readily absorbed across the epithelium into the richly vascularized ruminal papillae.

Where do the nutrients absorbed from the forestomachs go?

Venous blood from the forestomachs, as well as the abomasum, carries absorbed nutrients into the portal vein, directly to the liver.

What is the primary function of the rumen?

It serves as a fermentation vat where microorganisms break down cellulose and other complex carbohydrates into volatile fatty acids.

Describe the structure of the rumen.

The rumen is divided into several sacs by muscular pillars, including dorsal, ventral, caudodorsal, and caudoventral sacs.

How does the omasum contribute to digestion?

The omasum has numerous folds that increase surface area for absorption of water, electrolytes, and volatile fatty acids.

What histological feature is common to the rumen, reticulum, and omasum?

All three compartments are lined with stratified squamous epithelium.

Where are the volatile fatty acids absorbed after fermentation in ruminants?

The volatile fatty acids are absorbed across the epithelium of the rumen and into the richly vascularized ruminal papillae.

Describe the reticulum's location relative to other digestive organs.

The reticulum lies against the diaphragm and is connected to the rumen by a fold of tissue, often considered a 'cranioventral sac' of the rumen.

What unique features are found in the reticulum's epithelium?

The epithelium forms folds that create polygonal cells, giving it a honey-combed appearance, with small papillae on the cell floors.

How does the anatomy of camelid forestomachs differ from those of typical ruminants?

Camelids have a reticulum with gland-like cells and an omasum that is tubular and indistinct, sometimes referred to as pseudoruminants with 'three stomachs'.

What is the role of the abomasum in ruminant digestion?

The abomasum is the true glandular stomach where enzymatic digestion occurs, similar to the stomach in monogastric animals.

Where do absorbed nutrients from the forestomachs and abomasum go?

Absorbed nutrients enter the portal vein and are transported directly to the liver for further processing.

What is the function of an enzyme's active center?

To bind a specific substrate.

What does an enzyme do to catalyze a chemical reaction?

Lowers the activation energy.

What is a protease?

An enzyme that performs proteolysis by hydrolysis of peptide bonds.

What is the function of the enzyme lactase?

Hydrolysis of lactose into glucose and galactose.

What enzyme converts maltose into two glucose molecules?

Glucosidase