Digestive system

What is mechancial digestion?

the physical breakdown of food

• Mastication, chewing happens in your mouth, your teeth break down the food to makes bolus

• Churning happens in the stomach muscular walls mash up the food becomes chyme

• Segmentation happens in small intestine, mixes chyme w digestive juices

What is mastication?

chewing happens in your mouth, your teeth break down the food to makes bolus

What is churning?

• happens in the stomach muscular walls mash up the food becomes chyme  

• mixing in stomach

What is segmentation?

• happens in small intestine, mixes chyme w digestive juices

• mixing in small intestine

What is chemical digestion?

• Involves enzymes

• Breaks organic molecules down ultimately to building blocks so they can be absorbed

• Everything that cant be digested passes through the digestive system

  • Somethings like fiber are partially broken down in the large intestine

  • Everything not broken down goes out in feces

Chemical digestion in the mouth mostly breaks down what?

carbs

Chemical digestion involves __________________ that break down molecules.

enzymes

List the four layers of the alimentary canal in order from inside out

• mucosa

• submucosa

• muscularis

• serosa

Identify this:

mucous membranes line body cavities that open to the outside, usually not sterile

function: protection, secretion, absorption

mucosa

What are some examples of mucosa?

• Epithlium differences

• mouth/ pharynx/esophagus- stratified squamous epithelium

• stomach/ small intestine/ large intestine- simple columnar epithelium

• Anus- stratified squamous epitheliym

• Functions: protection, secretion, absorption

Identify this:

Rich in blood vessels, brings in nutrients and helps with absorption of nutrients 

submucosa

Identify this:

• Helps move food and waste

• Pharynx and anus- skeletal muscle

• Esophagus through large intestine- smooth muscle

• Circular layer- constricts

• Longitudinal layer- shortens

• Peristalsis- rhythmic wave-like contractions

• Works best with parasymapthetic branch of the autonomic nervous system “rest and digest”

muscularis

Where is muscularis (part of the alimentary canal) located?

• Pharynx and anus- skeletal muscle

• Esophagus through large intestine- smooth muscle

Identify this:

serous membranes, line body cavities that dont open to the outside

function: protection and secretion (serous fluid)

Simple squamous epithelium overlying a thin layer of connective tissue

serosa

Mucosa functions in?

protection, secretion, absorption

Submucosa functions in?

Blood vessels, nutrient supply

Muscularis functions in?

movement

Function of serosa

outer protective layer

complete digestive system:

• How long? About 25-30 feet long, mostly small intestines

• Where does the food go? 

  • Mouth 

  • Pharynx

  • Esophagus

  • Stomach

  • Small intestine

  • Large intestine

  • Anus 

What are accessory organs?

They help with the digestion of food but the food doesnt pass through them

What are the major acessory glands?

salivary glands

liver

gallbladder

pancreas

What is the function of the salivary gland?

• help with digestion and contains lots of water to moisturize food

• Saliva contains the enzyme amylase which digests start to maltose

  • Starch is a ploysaccharide

  • Maltose is a disachharide

• Saliva contains lots of bicarbonate ions that help neutralize acid

• Saliva has lysozymes to kill bacteria (nonspecific immunity) 

What enzyme does the salviary gland contain and what kind of digestion takes place?

enzmye: amylase (diegsts stach to maltose)

digestion: chemical, digestion of carbs

What is the function of the liver?

releases bile which includes bile salts

What kind of digestion is associated with the liver?

digestion: breaking down fats

What is the function of the gallbladder?

• stores bile

What kind of diestion is the gallbladder assciated with

fat digestion

What does bile contain and what is its function?

Bile salts which emulsify fats and break them down into smaller pieces 

What are Gall stones= choleliths

• Usually crystillaized cholesterol or bile salts/pigments

• Common causes

  • High cholesterol/  high fad diet

  • overweight/ pregnancy

  • Rapid weight loss

Symptoms and treatment of gall stones?

symptoms:

• Bad pain in upper quadrant, too low for heart attack 

• Severe pain in back by shoulder blades

treatment:

• Surgical removal of the gall bladder

• Should limit fats in the diet after that

What is the function of the pancreas?

• Releases hormones insulin and glucagon to regulate blood sugar (islets of langerhans- endocrine)

• Ancinar cells release digestive enzymens through pantcreatic duct, goes into duodenum

  • Prorteinases or proteases digest proteins (to polypeptides and ultimately amino acids)

  • Lipases digest lipids or fats to glycerol and three fatty acids

  • Amylase digest startch to maltose

• Releases bicarbonate ions

  • Neutralize acids

What is the pancreatic duct?

Part of a system of ducts in the pancreas.

Pancreatic juices containing enzymes are released into these ducts and flow into the small intestine.

What enzymes/ digestion is associated with the pancrease?

enzymes:

• lipase

  • digest lipids or fats to glycerol and three fatty acids

• amylase

  • digests starch to maltose

• proteinases/proteases

  • digest proteins to polypeptides and ultimately amino acids

diestion of : fats, proteins, and starches

What is the hepatopancreatic ampulla (ampulla of Vater)

• where your common bile duct and pancreatic duct merge empty into your duodenum (first part of your small intestine) Here, bile (from your liver) and enzymes (from your pancreas) merge before entering your duodenum. These substances help to break down the food in your intestine for digestion.

• The ampulla is a reservoir that holds bile and pancreatic enzymes and releases them into your intestine to help digest food. Rarely, it can be the site of a biliary obstruction or cancer.

• important landmark in your biliary system.

What is the Sphincter of Oddi (hepatopancreatic sphincter)

a muscle that opens and closes to allow bile and pancreatic juice to flow into your small intestine

What is the duodenum?

• “mixing bowl”; acid neutralization

• the first part of your small intestine. Its main job is to transform the partially digested food it receives from your stomach into nutrients your body can use.

• Makes food traveling from your stomach less acidic

• Transforms chyme into nutrients.

• Moves food molecules along.

What is peristalsis?

rhythmic wave-like contractions

What innervates perastalsis?

The parasympathetic nervous system

What is the lingual frenulum?

This thin band of tissue connects your tongue to the floor of your mouth. If you open your mouth and lift your tongue, you can see your lingual frenulum.

What is the hard palate?

the bony anterior part of the palate forming the roof of the mouth

What is the soft palate?

the muscular back portion of the roof of the mouth

What is the uvula?

• fleshy hanging ball in the back of your throat.

• As part of your soft palate, it helps prevent food and liquid from going up your nose when you swallow.

• It also secretes saliva to keep your mouth hydrated

What keeps food from going into the nasopharynx?

uvula

What kind of teeth are these?

• These are the teeth that fall out (baby teeth/primary teeth)

• eventually fall out and are replaced by permanent (adult) teeth.

• Babies dont have premolars

• 20 teeth of these kinds of teeth

deciduous teeth

What kind of teeth are these?

• Incisors(4): good for biting through something 

• Premorlars(2) and molars(3): grind food up

• Canines(1): pronouced teeth, sharper, good for grasping 

• these replace the baby teeth

• 32 teeth of these teeth

Wisdom tooth: 3^rd molar not always present

permanent teeth

What are incisors?

• have a single narrow edge, which helps cut into food/ good for biting through something

• the most visible teeth in your mouth

• Most people have four incisors on the upper jaw and four on the lower. These include your front two teeth and the teeth on either side of them.

What are canines

•  pronouced teeth, sharper, good for grasping 

• help you tear into foods like meat and crunchy vegetables

• They’re pointier than other types of teeth. Most people have four canine teeth — one in each quadrant (upper right, upper left, lower right, lower left).

What are premolars?

• have features of both canines and molars. They help you tear, crush and grind food into smaller pieces.

• premolars sit between your canines and your molars (the teeth in the back of your mouth).

What are molars?

• Because molars are your main chewing teeth, they’re good for crushing and grinding up your food.

• in the very back of your mouth. Most of your chewing — about 90% — takes place here. Most adults have 12 of these teeth — three in each quadrant.

• include wisdom teeth (third molars)

What is a third molar?

• another name for wisdom teeth

• at the back of the mouth, the last adult teeth to come in

• not always present

What is enamel?

• the protective outer layer of each tooth.

• helps shield your teeth from cavity-causing bacteria

• the hardest substance in the human body.

• cavities usually start here

What is dentin?

• just underneath your enamel, there’s a layer of it: yellowish, and bone-like

• protects the nerves

• it isn’t as strong as enamel

• When missing enamel exposes dentin, your risk for cavities increases

What is gingiva?

Gums: the tissues that surround the base of your teeth and help keep them in place

What is pulp cavity?

the pulp is the innermost layer of your tooth. It contains nerves, blood vessels, specialized cells and connective tissues, which provide nutrients for your tooth

• The pulp itself fits within the hollowed-out spaces inside your tooth (pulp cavity)

has three parts:

• Pulp chamber

• Pulp horns

• Radicular canals

What is a root canal?

• a dental procedure to remove inflamed or infected pulp on the inside of the tooth which is then carefully cleaned and disinfected, then filled and sealed.

Importance of flossing teeth and brushing teeth:

• What diseases linked with not flossing? gigivitis, peridontitis

• Gum disease/ tooth loss (just floss the teeth u want to keep)

• Heart disease

• Chronic inflammation

What diseases are linked with not flossing daily?

• gingivitis

• peridontitis

• heart disease

• chronic inflammation

• gum disease/tooth loss

Diestion in the mouth

• mechanical

• chemical

  • Chemical digestion- mainly carbohydrates (starch)

    • Three macronutrients for: cabs, proteins, and lipids (fats)

    • Salivary glands help with digestion and contains lots of water to moisturize food

    • We release about 1 to 1.5 L of saliva per day

function of the salivary glands:

• contain enzmyes contains the enzyme amylase which digests start to maltose

  • Starch is a ploysaccharide

  • Maltose is a disachharide

• Saliva contains lots of bicarbonate ions that help neutralize acid

• Saliva has lysozymes to kill bacteria (nonspecific immunity) 

What salivary gland is this?

• largest salivary gland

• located just beneath and in front of each ear, you have two of these glands

• these glands produce about 10% of the total saliva in your mouth — even more when you eat.

parotid gland

What salivary gland is this?

• a mixed salivary gland, secreting both mucus and serous secretions, located in the posterior floor of the mouth

• the second largest salivary gland

• produces approximately 70% of the saliva in the unstimulated state

submandibular gland

What salivary gland is this?

• smallest salivary gland

• produces a thick mucinous fluid and lubricates the oral cavity which allows for swallowing, initiating digestion, buffering pH, dental hygine

• below either side of your tongue, under the floor of your mouth.

sublingual gland

What keeps food from going into the larynx and respiratory system?

epiglottis

What covers the glottis during swallowing

the epiglottis

What is the glottis?

The middle part of the larynx; the area where the vocal cords are located.

What structure is this?

• the long tube that connects your larynx (voice box) to your bronchi

• “Windpipe”- from larynx into mediastinum

  • Mucosa- pseudostartified ciliated columnar epithelium with goblet cells

  • Outermost layer made of connective tissue; encases C-shaped rings of hyaline cartilage

trachea

What structure is this?

• Muscular tube

• Connects nasal cavity and mouth to larynx and esophagus

  • Composed of skeletal muscle 

• Skeletal muscle 

• Routes air coming in your nose and mouth down to your larynx (voice box), which, in turn, moves air to your trachea and lungs.

• Delivers food and liquid to your esophagus, which sends them on to your stomach. More than that, it helps to make sure particles of food and liquid don’t tumble into your trachea and your lungs.

pharynx

What structure is this?

• Attaches to hyoid bone; opens into larygopharnyx; continuous with trachea

• Provides patent airway (keeps it open)

• Routes air and food into proper channels

• Voice production

  • houses vocal cords

larynx

What structure is this?

hollow, muscular tube that carries food and liquid from your throat to your stomach.

Muscles in your esophagus propel food down to your stomach

esophagus

What is esopgagheal hiatus?

the opening in the diaphragm through which the esophagus passes and then enters the stomach.

What is a hiatal hernia?

• Tear in the esophageal hiatus in the diaphragm

• May contribute to heartburn

• May slide

• Can be hard to repair 

The stomach:

• Protein is the main nutrient digested in the stomach\

• The pH of the stomach is 2. This is very acidic environment denatures proteins

• The stomach releases pepsin, a proteinase that digests into polypeptides

  • Pepsinogen is releases, and its activated by HCl to become pepsin

• Alchohol is mainly absorbed in the stomach

• Intrinsic factor and hydrochloric acid are released from tthe stomach. Hcl makesw the pH very acidic. Intrinsic factor helps with the absorption of Vitamin B₁₂  in the small intestine

• Gastric juice would include pepsi, HCl, and intrinsic factor. Alkaline protects the stomach 

What are the major componenets of gastric juice?

• pepsin, proteinase that digests proteins into polypeptides

• HCl, makes the pH very acididic

• intrinsic factor, helps w the absorption of Vitamin B₁₂ in the small intestine

• alkaline, protects the stomach

function of pepsin in gastric juice

proteinase that digests proteins into polypeptides

function of HCl in gastric juice

makes the pH very acididic

function of intrinsic factor in gastric juice

helps w the absorption of Vitamin B₁₂ in the small intestine

function of alkaline in gastric juice

protects the stomach

What are the four parts of the stomach?

• cardia

• fundus

• pyloric canal

• pyloric antrum

• body

What part of the stomach is this:

• top part of your stomach.

• It contains the cardiac sphincter, which prevents food from traveling back up your esophagus.

the cardia

What part of the stomach is this?

• is a rounded section next to the cardia.

• It's below your diaphragm (the dome-shaped muscle that helps you breathe).

the fundus

What part of the stomach is this?

• is the largest section of your stomach.

• In the body, your stomach contracts and begins to mix food.

body (corpus)

What part of the stomach is this?

• lies below the body.

• It holds food until your stomach is ready to send it to your small intestine.

the pyloric antrum

What part of the stomach is this?

• the bottom part of your stomach. It includes the pyloric sphincter.

• This ring of tissue controls when and how your stomach contents move to your small intestine.

pylororic canal

What are rugae?

ridges that increase the surface area of the stomach and stretch out to increase stomach volume when the stomach is ful

Separations of segments by sphincter muscles:

• Why? Separates stomach (w/ pH of 2) from esophagus and small intestine, separates small and large intestine (large intestine is like a septic tank teaming w/ bacteria), separates large intestine from outside

• Cardiac sphincter= lower esophageal sphincter

  • Between esopahgus and stomach

• Pyloric sphincter

  • Between stomach and small intestine( duodenum- first part of small intestine)

• Illeoccecal valve

  • Between ileum (last part of small intestine) and cecum (first part of large intestin)

• Anus

  • Between large intestine and outside, controls defecation

what is the purpose of sphincter muscles?

Separates stomach (w/ pH of 2) from esophagus and small intestine, separates small and large intestine (large intestine is like a septic tank teaming w/ bacteria), separates large intestine from outside

What is the cardiac sphincter?

• lower esophageal sphincter

  • Between esopahgus and stomach

What is the pyloric sphincter?

Between stomach and small intestine( duodenum- first part of small intestine)

What is the illeocal valve?

Between ileum (last part of small intestine) and cecum (first part of large intestin)

What is the anus?

Between large intestine and outside, controls defecation

What is the pH of the stomach?

2

What is the greater omentum?

a large apron-like fold of paratonium that hangs from the stomach, covering the intestines, with roles in fat and immunity.

What is mesentery?

fold of the peritoneum/abdomen which attaches the stomach, small intestine, pancreas, spleen, and other organs to the posterior wall of the abdomen.

It carries blood vessels, lymph vessels and nerves that serve these organs.

What causes stomach ulcers?

• Helicobacter pylori (H. pylori) *** treatable w/ antibiotics

• Overuse of aspirin/ motrin 

• Alcohol abuse

What can happen is stomach ulcers are not treated?

• bleeding/ anemia 

  • basically with the ulcer, the mucosa and submucosa are damaged and ulcerated, so when you get to the submucosa, you start having bleeding 

    • If continues goes through all the layers including serosa, which gives a perforated ulcer- can cause peritonitis

      • Peritonitis can be really serious if somebody has a massive infection, and then setting off with inflammation, so they have swelling, and usually with this, somebody can go into septic shock 

• Stomach cancer—> H. pylori 

What is a bolus?

• Formed in the mouth and esophagus

• Processed  by saliva

What is chyme?

• Created in the stomach

• Mixed with gastric juices before moving into small intestine

• In the stomach, food is mixed into a substance this

What is the enterogastric reflex?

• triggered when more and more chyme leaves the stomach, distending stretch receptors in the duodenum

• inhibits excessrive amounts of chyme entering the duodenum

• reduces intestinal cell erosion by limiting inflow of gastric acid

• increases the duration of the digestion of chyme before it is moved to the small intestine

• the motor impulses in this reflex are sympathetic

What is vomiting?

• Reverse peristalsis 

  • So we can think of everything going the opposite direction

  • Somethings things are gonna go through the mouth usually, sometimes it goes through the nose

What might cause vomiting?

• Microbes/ toxins 

  • Food poisioning, viruses 

• Smells or anything that triggers the nausea center, theres a vomiting center (located in the medulla) and when its triggered usually it sets off nauseousness, and then whatever it is keeps up then normally we vomit

• A visual of something, for ex: something graphic 

• Motion sickness