AP Bio 12 Digestive system

Functions of the digestive system

ingestion, propulsion (movement of food), Digestion and Absorption, Egestion (elimination of food)

Layers of the alimentary canal

serosa, musculares, submucosa, mucosa

(visceral peritoneum) membrane that secretes a slippery, watery fluid, reduces friction as digestive organs contract and more

serosa

layer of muscle extending in two directions, circular and longitudinal layer

muscularis

contains glands, nerve fibres and blood vessels, secretes hormones and carries things away

Submucosa

secreting mucus, digestive enzyme and hormones, absorption of nutrients, protection from pathogens (lymphatic tissue)

mucosa

how do teeth aid in digestion (4 parts of teeth)

incisors, canines, premolars and molars

anatomy of a tooth

2 portions of the digestive system

alimentary canal and accessory organs

child’s teeth vs adults

20 vs 32 teeth

Digestive structures found in the mouth

Salvary glands (99% water), mucus, amylase, lysozymes, antibodies. lingual lipase

lingua lipase

breaks down lipids

Uvula

prevents swallowed food from entering the nasal cavity

deglutition

(swallowing)

2 major phases of deglutition

Buccal phase and pharyngeal

buccal phase

chewing (mastication) being mixed with saliva and food club is called bolus. forced into the pharynx by the tongue

Pharyngeal

thin flat Calle the epiglottis blocks the larynx and the uvula blocks the nasal cavity . causes food to travel down the esophagus rather than the respiratory system

How is the bolus moved towards the esophagus

using waves of muscle contractions —> process called peristalsis.
- involuntary and caused by the parasympathetic nervous system

stomach

muscular sac with thick walls

sphincters and function in digestive system

thick rings fo muscle that allows food to enter and leave appropriately

2 sphincters located in the stomach

cardiac sphincter, pyloric sphincter

anatomy of a stomach

slippery outer layer of the stomach

serosa

3 muscles after the serosa in the stomach

longitudinal muscularis

circular muscularis

oblique muscularis

what do the 3 muscles after the serosa do

help churn food and propel towards small intestine

maceration

process of churning

Rugae

“wrinkles” that stretch when the stomach is full

how does chemical digestion occur in the stomach

specialized gastric gland cells in the mucosa layer of the stomach:

mucuous cells

chief cells

parietal cells

mucuous cells

secrete mucus to protect stomach lining

chief cells

secrete pepsinogen (inactive enzyme)

parietal cells

secrete HCL to kill microbes in food and convert pepsinogen into the digestive enzyme pepsin —> breaks down food protein

soupy mixture formed from the squeezing fo the stomach and the addition of gastric juices

chyme

Small intestine function

digestion and absorption

length of the small intestine

10 ft long

3 sections of the small intestine

Duodenum

jejunum

ileum

where does the ileum join the large intestine

at the ileoceral sphincter

what lines the small intestine to help the absorption of nutrients

villi and microvilli

villi

tiny fingers like projections in the lining of the intestine filled with blood vessels

what process occur in the small intestine glands

secrete digestive hormones

mucus

alkaline mucus from mucuous glands and duodenal glands protects them from pathogens

secretin

inhibits the release of gastric juices when chyme is very acidic

cholecystokinin (CCK)

causes gallbladder to release bile

maltase, sucrase, lactase

breaks down sugar

peptidase, enterokinase

breaks down protein

how does chyme work

slowed down to help small intestine absorb nutrients

circular muscles in the intestinal wall cause segmentation of the chyme

3 major sections of the large intestine

cecum

colon

rectum

2 major functions of the large intestine

absorption of water

removal of waste t

what vitamins do bacteria located in the large intestine help produce

Vitamin B and K → eat cellulose since we can’t break it down

what occurs in the rectum and anus

collects and stores undigested waste and bacteria

Liver

largets internal organ

2 major lobes of the liver

left and right

what do the lobes contain

hepatic sinusoids which are full of blood

function of liver cells

Reeves bacteria and old red blood cells

detoxifies blood from drugs and poison

stores glycogen and produced fat

manufacturing proteins and storing iron and copper

Bile

secreted from the liver to help break down fats

gallbladder

small green sac that stores bile before sending to the small intestine to digest fat

pancreas

long thin gland just behind the stomach

2 functions of the pancreas

secreting digestive enzymes

secreting hormones

life sustaining chemical reaction in the body

metabolism

Catabolism

breaking down of complex molecules while releasing energy

Anabolism

formation of complex molecules while using energy

reaction cascade

energy used for catabolic releases energy used to power anabolism reaction then the products causes another catabolic reaction… etc

4 types of macronutrients required by the body

carbs, protein, lipids, water

2 micronutrients required for the Boyd

vitamins and minerals

how are carbohydrates digested

Carbohydrates → broken by salivary amylase (mouth) and pancreatic amylase (small intestine), then by epithelial/brush border enzymes into glucose by breaking glycosidic bonds → absorbed → used in cellular respiration (citric acid cycle + electron transport chain) to make energy.

how are lipids digested

Lipids → emulsified by bile salts (small intestine) → broken down by pancreatic lipase into fatty acids and glycerol → absorbed → metabolized into ATP through cellular respiration.

how are proteins digested

Proteins → denatured by HCl and broken into polypeptide chains by pepsin (stomach) → further digested by pancreatic enzymes and brush border enzymes into amino acids → absorbed and used to make proteins or energy (ATP).

water use in the body

chemical reacrtions

painting blood pH levels

regulating body temp through sweat

dissolving food and digestion

fat soluble and water soluble vitamins

fat soluble → A and D water soluble → B and C

what micronutrients are needed in the body

vitamins and minerals

vitamins → organic molecules in small quantities

minerals → inorganic molecules

Nucleases

breaks down DNA in the food we eat