lesson 2- Digestive chemicals

Physical Digestion

Breakdown of food via

physical movement

● No change in chemical

nature of food

● Breaks down food small

enough(so you don't choke and increase surface area of food) to aid in chemical

digestion

Chemical Digestion

Breakdown of food via

enzymes & chemicals

● Breaks chemical bonds

● Breaks down food small

enough to allow for in

absorption

enzymes

Proteins that help speed up chemical reactions

○ have names that end in "ASE"

Absorption

When digested food from the gut is

passed into the bloodstream or lymph to be

transported throughout the body

Endocrine glands :

responsible for hormones

being secreted into blood

Exocrine glands:

responsible for producing

chemicals and secreting

them on a surface

Salivary Gland:

secretes saliva

Salivary Glands:

-Parotid

● Sublingual

● Submandibular

Mouth conditinons

pH = 7

● temp = 37oC

Saliva:

lubricates food for swallowing

and contains salivary amylase

Salivary Amylase:

digests starch to maltose

Gastrin:

hormone that causes

the secretion of gastric juice

gastric juice

Pepsinogen + HCl + mucus

Pepsinogen:

inactive form of pepsin

HCL

activates pepsinogen to pepsin

Mucus

protects stomach lining from

HCl (ulcers) + lining regenerates every

3 days

stomach conditions

pH = 2

● Temp

= 37oC

Bile

a yellow/green fluid produced in liver that breaks down fat

where is bile stored

Stored in gallbladder and secreted when needed

what is bile made of

Composed of bile salts, water, cholesterol, bilirubin

what does bile do

Bile salts emulsify (break into smaller pieces) fat in the small

intestine

Endocrine functions

the pancreas also secretes the following

hormones directly into the blood via the

Islets of Langerhan:

Insulin:

allows the uptake of blood glucose

by cells

● Triggered by an increase in [blood glucose]

○ Stimulates liver to convert glucose →

glycogen

○ Diabetes I: lack of cells producing insulin

○ Diabetes II: lack of insulin receptors on

cells

Glucagon:

allows the release of glucose into blood

● Triggered by a decrease in [blood glucose]

○ Stimulates liver to convert glycogen → glucose

Endocrine functions p2

the pancrease secretes

the following to continue the breakdown of

molecules

● Pancreatic Juice: a mixture of water + NaHCO3

(sodium

bicarbonate) + enzymes

● NaHCO3 neutralizes the acidic chyme coming from the stomach

Dueodenum

pH = 8

● Temp = 37oC

Endocrine functions jujunum

the jejumum secretes, through its surface

cells, the following digestive enzymes:

Enzyme

Name: Maltase Peptidase Nucleosidase

Digests: Maltose to glucose Peptides to amino acids Nucleotides to

base, sugar, phosphate

Pancreatic enzymes

Pancreatic

Amylase

Trypsin Lipase Nuclease

Digests: Starch to maltose Protein to peptides Lipids to

fatty acids + glycerol

DNA and RNA to

nucleotides

Endocrine Function:

The small intestine also secretes

hormones that stimulate the production of secretin enterogastrones and cholcystokinin

Secretin:

causes the pancreas to secrete NaHCO3

into

duodenum

○ Released when acidic chyme arrives from stomach

Cholecystokinin (CCK):

causes pancreas to secrete

enzymes + the liver to secrete bile into duodenum

○ Released when chyme rich in fatty acids, cholesterol,

amino acids arrive in duodenum

Enterogastrones:

opposes gastrin + inhibits stomach

churning and gastric juice secretion

bacteria in the large intestine

Are anaerobic (dies when there's

oxygen)

2) Break down indigestible

material

3) Produces vitamins (K), amino

acids & growth factors

4) Produce nutrients that are

absorbed by the colon and used by

the body

what does bile form

○ Forms micelles around triglycerides

○ Breaks down large lipid globules into smaller droplets

○ This ↑ the surface area of the fat to be acted upon

● Small fat droplets = lipids