Unit 6: Tissues, Digestion

Question 1

What are the four major types of tissues? What are the basic functions of each tissue?

Answer 1

Epithelial tissue: Covers body surfaces and lines body cavities
Connective tissue: Binds and supports body parts
Muscular tissue: Moves the body and its parts
Nervous tissue: Receives stimuli and conducts nerve impulses

Question 2

Differentiate between the biological levels of organization (Cells, Tissues, Organ & Organ system)

Answer 2

1. Cells, composed of different molecules
2. Tissues, composed of similarly specialized cells to perform a specific function
3. Organs, composed of several types of tissues
4. Organ system, composed of several organs

Question 3

Mechanical digestion vs Chemical digestion

Answer 3

Mechanical digestion: Changes large particles to smaller particles without any chemical energy. This readies the food for chemical digestion. (i.e., chewing, churning & mixing of food in the stomach, etc)

Chemical digestion: Chemically breaks down larger molecules to small organic molecules that may be absorbed by the body. This is done by many different enzymes

Question 4

Function of mouth (oral cavity)

Answer 4

Start of the digestive system.

Storage place for food while it is being chewed. Where saliva is mixed with food.

Question 5

Function of lips

Answer 5

Hold food in mouth and help direct food onto teeth.

Question 6

Function of teeth

Answer 6

Physical digestion; breaks food into smaller pieces so it is convenient to swallow and so that enzymes can work on it.

Question 7

Function of salivary glands

Answer 7

Chemical digestion; produces saliva for moistening and chemical digesting food. Saliva has enzyme called the salivary amylase that begins the chemical digestion of starch.

starch is storage form of glucose found in plants

Question 8

Function of tongue

Answer 8

Has taste buds, sensory receptors that enables us to feel texture/taste of food.
Mixes the chewed food with saliva, forming a mixture now called bolus and pushes it to the pharynx.

Question 9

Function of pharynx

Answer 9

The passageway from the mouth to the esophagus.

Where swallowing occurs

Question 10

Describe swallowing

Answer 10

A reflex action, performed automatically most of the time. The soft palate and the epiglottis closes off the air passage during swallowing so that the bolus is forced to move down the esophagus.

This is why we do not breathe during swallowing

Question 11

Function of epiglottis

Answer 11

A flap of tissue that closes off the trachea (windpipe), which is right in front of the esophagus. Keeps the food from entering the air passage, forcing them down the esophagus.

Question 12

Function of esophagus

Answer 12

The passageway from the pharynx to the stomach. No digestion occurs; esophagus’s only purpose is to move the food bolus from the mouth to the stomach.

Question 13

What is peristalsis

Answer 13

Rhythmic contractions that pushes the food along the digestive system. First begins at the esophagus and continues in all the organs of the digestive system.

Question 14

Function of cardiac and pyloric sphincters (location as well)

Answer 14

Sphincters are band of muscles that act as valves on certain passageways. The contraction and relaxation of sphincters can close and open the passageway.

Cardiac (lower esophageal): Located at the junction of the esophagus and stomach. Prevents stomach contents from moving back up into the esophagus
Pyloric: Located at the junction of the stomach and the duodenum. Prevents acid chyme from entering the stomach and regulates so that only small amounts of acid chyme enters the small intestine.

Question 15

Function of stomach (basic functions)

Answer 15

Stores and churns food.
Churning physically digests food, creating surface area for enzymes to work in. Chemical digestion of proteins also begin here.
The food becomes a mushy liquid called the acid chyme when leaving the stomach.

Question 16

Function of gastrin & gastric glands in the stomach

Answer 16

Responsible for the chemical digestion of protein in the stomach

Gastrin: Hormone produced by the lower part of the stomach in the presence of undigested protein. Travels to the upper part of the stomach to activate the gastric glands.
Gastric glands: Produces gastric juice, containing HCL, pepsinogen and mucus. HCL and pepsinogen react with each other to form pepsin, the enzyme that hydrolyzes proteins to peptides. Mucus protects the stomach wall from the highly acidic HCL. Ulcer is the burning of a portion of the stomach if the mucus is penetrated.

Question 17

Function of pancreas

Answer 17

Produces pancreatic juice containing enzymes and sodium bicarbonate.

Sodium bicarbonate neutralizes the acid chyme (pH 2) to a pH of about 8.5 so the enzymes in small intestine do not denature.

Question 18

Function of Liver & Gall bladder (for small intestine)

Answer 18

Liver produces bile which is then stored in the gall bladder until it needs to be secreted into the duodenum.

Question 19

Function of small intestine: the duodenum

Answer 19

The first 10 inches of the small intestine.
Digestion portion of the small intestine; enzyme from pancreas digest all 3 food groups here. Bile from liver emulsify fats as well.

Question 20

Function of small intestine: Secretin and CCK

Answer 20

Hormones produced by the duodenal walls in response to the presence of acid chyme (activates Secretin) and undigested protein/fat (activates CCK).
Secretin stimulates release of pancreatic juice
CCK stimulates release of bile

Question 21

Function of small intestine: Villi, Microvilli, blood capillary, and lacteal

Answer 21

Absorption portion of the small intestine
Small intestine walls are folded and has finger-like projections called villi to increase surface area for absorption. Villi themselves have microvilli, again for surface area.
Within each villus (sing. for villi) are blood capillary that absorbs nutrients other than fat, and a small lymph vessel called a lacteal that absorbs fats.
The absorbed nutrients will be distributed among all cells through the blood stream.

Question 22

Function of appendix

Answer 22

Found at junction of small and large intestine.

Function is actually unknown, may play a role in immunity

Question 23

Function of large intestine (what other name does it have)

Answer 23

Other name is colon
Absorption of water from undigested food
Contains E. Coli and other bacteria that live off undigested substances. Some vitamins, minerals, and other growth factors are produced by these bacteria, but their work give off odorous molecules that causes POO smell.

Question 24

Function of rectum and anal sphincter

Answer 24

Rectum is an enlarged portion of the colon, where undigested food is concentrated and stored temporarily.
Anal sphincter, aka anus, are bands of muscle that allow undigested waste to exit the body.

Question 25

Salivary amylase (source, substrate, product, pH)

Answer 25

Carbohydrate digestion
Produced by salivary glands and secreted into mouth
Substrate: starch
Product: maltose
Begins the process of hydrolyzing starch, doesn’t complete it
pH: 7

Question 26

Pancreatic amylase (source, substrate, product, pH)

Answer 26

Carbohydrate digestion
Produced by pancreas and secreted into duodenum
Substrate: starch
Product: maltose
Completes the hydrolysis of starch to maltose
pH: 7.5

Question 27

Maltase (source, substrate, product, pH)

Answer 27

Carbohydrate digestion
Produced by small intestine, found on the surface of villi
Substrate: maltose
Product: glucose
Glucose is then absorbed into blood capillaries
pH: 7.5

Question 28

Pepsin (source, substrate, product, pH)

Answer 28

Protein digestion
Produced by gastric glands, works in the stomach
substrate: protein
product: peptides
A type of protease, as it hydrolyzes proteins
pH: 3.5

Question 29

Trypsin (source, substrate, product, pH)

Answer 29

Protein digestion
Produced by pancreas, secreted into small intestine
substrate: protein
product: peptides
A type of protease, as it hydrolyzes proteins
pH: 7.5

Question 30

Peptidase (source, substrate, product, pH)

Answer 30

Protein digestion
Produced by small intestine, found on the surface of villi
Substrate: peptides
product: amino acids
Amino acids are then absorbed into blood capillaries
pH: 7.5

Question 31

Function of bile

Answer 31

Emulsifies fat in duodenum into fat droplets; increases surface area for enzymes to work on it.
Bile is not an enzyme; emulsification is a physical digestion, as the larger fat molecules are changed to smaller particles without chemical change

Question 32

Lipase (source, substrate, product, pH)

Answer 32

Fat digestion
Produced by the pancreas, secreted into small intestine
Substrate: fat droplets
Products: 3 fatty acids + glycerol
The products are then absorbed into lacteals
pH: 7.5

Question 33

Nuclease (source, substrate, product, pH)

Answer 33

Nucleic acid digestion 
Produced by the pancreas, secreted into small intestine
Substrate: nucleic acids (DNA/RNA)
Product: nucleotides 
pH: 7.5

Question 34

Nucleosidase (source, substrate, product, pH)

Answer 34

Nucleic acid digestion
Produced in the small intestine 
Substrate: nucleotides
Product: phosphate, pentose sugar, nitrogenous base
pH: 7.5

Question 35

Role of water in the digestive system

Answer 35

All digestive reactions require water

Question 36

Insulin (source and function)

Answer 36

Protein hormone
Produced and secreted by the pancreas
High blood sugar (glucose) levels alerts the pancreas to secrete insulin. Insulin causes the liver and tissue cells to take up and store glucose as glycogen, lowering the blood sugar levels.

Question 37

7 major functions of the liver

Answer 37

• Removes bilirubin
• Produces bile
• Stores glucose as glycogen and breaks down glycogen to glucose, depending on the glucose concentration in blood
• Produces urea
• Makes plasma proteins
• Detoxifies the body
• Stores iron and fat soluble vitamins