Animal Nutrition and Human Digestion Flashcards
What do animals need to live?
food, oxygen, water
How to animals make energy?
using food and oxygen
How to animals build bodies?
using food for raw material (amino acids, sugars, fats, nucleotides) and ATP for energy synthesis.
What are the 4 ways animals get their food?
fliter feeding, living in the food, fluid feeding, and bulk feeding
What are the 3 animal diets?
heribivores, carnivoes, omnivores
What is an herbivore?
an animals that eats mainly plants
What are examples of herbivores?
gorillas, cows, rabbits, snails
Whst is a carnivore?
an animal that eats only other animals
What are examples of carnivores?
sharks, hawks, spiders, snakes
What are omnivores?
animals that eat both animals and plants
What are examples of omnivores?
cockroaches, bears, racoons, humans
What are the 4 main steps in getting and using food?
- Injest
- Digest
- absorb
- Eliminate
What is injesting?
taking in food
What are the two steps within digestion?
mecahnical digestion and chemical digestion
What is mechanical digestion?
breaking up food into smaller pieces?
What is chemical digestion?
breaking down food into molecules small enough to be absorbed into cells. Involves enzymes
What is absorption in digestion?
absorb nutrients accross cell membranes. Involves diffusion and active transport
What is elimination in digestion?
when undigested material passes out by body
What is the function of the mouth?
mechanical digestion using teeth and chemical digestion using saliva
What are the components of saliva?
amylase enzyme, mucus, buffers, and antibacterial chemicals
What is an amylase enzyme?
and enzyme that digests starch
What does the mucus in saliva do?
- protect soft lining for the digestive system and it lubricates food for easier swallowing
What do the buffers in saliva do?
they neutralize acid to prevent tooth decay
What do the anti-baterial chemicals in saliva do?
they kill bacteria that enter the mouth with food
What are the 4 types of teeth?
Canine, Molars, Premolard, and Incisors
What is the purpose of canine teeth?
tearing
What is the purpose of molars?
grinding
What is the purpose of premolars?
tearing and grinding
What is the purpose of incisors?
cutting
What does the uvula do?
It secretes a large amount of saliva and prevents food from coming up once swallowed.
What are the 3 kinds of salivary glands?
- sublingual gland
- parotid gland
- submandibular gland
What is the tongue covered by?
papillae
What are papillae/?
Thy are small projections. Most of them house taste buds
What are taste buds?
receptors that send messages to the brain
What is a food bolus
It is a lump of chewed food that goes on into the next part of the digestive tract
What is a pharynx?
The part of the digestive system and connects the oral cavity to the esophagus. It is a shared passageway with respiratory system.
What is the epiglottis?
a flap of cartilage that closes the trachea when swallowing. It makes food go down the esophagus and prevents food from entering the respiratory system.
What is the trachea?
The windpipe
What is the esophagus made of and what does it do?
It is two layers of muscle circular and longitudinal. It moves food from the pharynx to the stomach.
peristalsis definition
involuntary muscle contractions which forms waves that move the food bolus along the digestive tract. It prevents the backward flow of food
What is the inside of the esophagus lubricated with?
mucous membranes
What do the circular muscles do?
They contract and narrow the passage behind the bolus and push it forward
What do the longitudinal muscles do?
the contract ahead of the bolus, causing the tube to shorten and slide the bolus
What are the two types of muscles in the esophagus?
circular muscles and longitudinal muscles
What is the upper esophageal sphincter (UES)?
skeletal muscles triggered by a swallowing reflex and the top of the tube. prevents against reflux of food and food from entering the respiratory system and air into the digestive tract.
What is the lower esophageal sphincter (LES) also known as?
the cardiac sphinter
Where the LES?
end of the rube leasing to the stomach
What does the lower esophageal sphincter do?
it prevents stomach contents from going back into esophagus and manages acid reflux. It is under autonomic control
What is reflux?
somach contents in reverse flow. Acid from the stomach enters the lower esophagus.
When does reflux often occur?
because the LES doesn’t close properly
GERD stands for…
Gastroesophageal reflux disease
What happens if GERD occurs frequently?
it can damage the esophagus
What are treatments for acid reflux?
- lifestyle and dietary changes
- use antacids to neutralize acid in the stomach and esophagus
- use medications to reduce the amount of acid secreted into the stomach
- surgery to tighten esophageal sphincter (only in serious cases)
What is vomiting?
expulsion of stomach contents through esophagus and mouth. It is a protective mechanism for removing toxin or foreign substances from the body
vomitus
liquid contents being expelled
What is the mecahnism of vomiting?
- relaxation of the LES
- contraction in small intestine and stomach to move contents into the esophagus
- contraction of diaphragm and abdominal walls squeeze stomach
- results in expulsion of contents up the esophagus and out through the mouth
- epiglottis closes entrance to trachea as breathing stops
What does the stomach do?
- disinfects food
- food storage
- digests proteins
How does the stomach disinfect food?
It contains hydrochloric acid with a pH of 2 that kills bacteria
How much food can the stomach fit?
1.5L
What enzyme digests protein?
pepsin enzyme
If the stomach is made out of protein, what stops the stomach from digesting itself?
mucus secreted by stomach cells protects stomach lining
Which muscles control the amount of food that enters and exit the stomach?
- lower esophageal sphincter (enter)
- pyloric sphincter (exit)
What is the shape of the stomach?
J shape
What kind of muscles are in the stomach?
smooth muscles
What are the 3 types of smooth muscles in the stomach?
oblique, circular, longitudinal
What folds in the stomach lining to provide elasticity allowing the stomach to expand when the bolus enters it?
rugae
Hw many tissue layers are in the stomach?
4
What are the 4 tissue layers in the stoach IN ORDER?
mucos, submucosa, muscularis, serosa
What is the mucosa layer in the stomach?
it is the innermost layer that is extensively folded. It secretes gastric juice.
What is the submucosa layer in the stomach?
layer of connective tissue contains nerves and blood vessels
What is the muscularis layer in the stomach
smooth muscle
What does the serosa layer in the stomach do?
it holds the stomach in place
What is the mechanical digestion in the stomach?
Nerve endings detect stretching of the stomach lining that occurs when food enters which causes a release of signals to cause an increase in muscular contractions which mixes food with gastric juice
What are the 3 gastric juice components?
Hydrochloric acid, inactive enzyme pepsinogen, and mucus
What does the hydrochloric acid (HCl) do?
- destroys microbes
- deactivates amylase
- chemically breaks down food
- it has a pH of approximately 2
What happens to the inactive enzyme popsinogen?
It gets activated by the low pH and turned into pepsin. It breaks down protein into amino acids
What does the mucus in gastric juice do?
It protects the stomach from the low pH
What is released into the blood stream to be transported to gastric cells in the stomach?
gastrin
What does gastrin do?
it stimulates the release of gastric juice by gastric glands.
What does gastric juice do?
it contributes to chemical digestion of food
What is chyme?
When the food bolus forms a half liquid - half solid of partially digested food and gastric juice
What is an ulcer?
an open sore on the stomach with damage to all layers of the stomach that causes bleeding and pain. It happens when acid burns through the stomach lining in an area that doesn’t have enough mucus
What are ulcers caused by?
bacterial infection of stomach like H. pylori
How are ulcers cured?
antibiotics
What does the pyloric sphincter do?
it controls the amount of chyme released into the small intestine. It releases 1 chyme at a time
How does the pyloric sphincter release chyme and why?
It releases the chyme slow and steady in small proteins of time. It prevents overloading the small intestine and allows time for digestion
What are the functions of the small intestine?
- digestion (in the 1st section)
- absorption (in the 2nd and 3rd section)
What kind of digestiong occurs in the small intestine?
The digestion of carbohydrates, proteins and lipids.
What enzyme digests the carbohydrates?
amylase from the pancreas
what enzyme digests the proteins?
trypsin & chrymotrypsin from pancreas
what component of the stomach digests the lipids
bile from liver and lipase enzyme from pancreas
What is the absorption that occurs in the small intestine?
nutrients move into body cells by diffusion and active transport
What are the dimensions of the small intestine?
7m long
2.5 cm in diameter
What is the small intestine lined with?
longitudinal and circular muscles
What moves food along the small intestine?
peristalsis
What is peristalsis?
the involuntary contraction and relaxation of longitudinal and circular muscles throughout the digestive tract
What are villi and microvilli? What is their purpose?
They absorb things in the small intestine. They are finger-like projections that increase surface area for absorption
By how much does a villus increase surface area?
10x
What are villus lined with?
epithelial cells
What is the structure of the epithelial cells on villi?
They are assymetrical, with one side having a projection called a microvilli.
What are microvilli and what do they do?
they are a very thin membrance that increase surface area 500x
How do the villi absorb nutrients?
Each villus contains a small blood vessel (capillaries). All nutrients EXCEPT FATS are absorbed directly into the bloodstream.
How are fats absorbed?
they are transported by lactela into the lymphatic system, then the bloodstream
What is passive transport?
the transport of nutrients not requiring energy
How does passive transport work?
It follows the concentration gradient -> goes from high to low concentration, using diffusion, facilated diffusion, and osmosis(water)
What is active tranport?
the transport of nutrients that requires energy
How does Active transport work?
It requires a transport protein that goes against the concentration gradient being, from low to high
How many parts does the small intestine have?
- duodenum
- jejunum
- ileum
What happens in the duodenum?
digestion
What happens in the jejunum?
digestion and absorption
What happens in the Ileum?
absorption
What is the duodenum?
The first and shortest section of small intestine.
What is the function duodenum?
digestion and acid control
how does the duodenum perform acid control
the HCI in the chyme coverts inactive prosecretin in epithelial cell to active secretin. The secretin stimulates the pancreas to secrete bicarbonate (basic pH) into duodenum raising pH from 2.5 to 9. By doing this is neutralizes the acidic chyme to protect the walls of the small intestine.
What is secretin?
a hormone that stimulates the pancreas to secrete bicarbonate
How long is the jejunum?
roughly 2.5 m long
What is the length and width of the ileum?
1.5 m in length and 7.6 cm in diameter
What happens inside the ileum?
It is where the majority of absorption occurs, it then empties into the large intestine
What does the pancreas look like and where is it situated?
It is a long flat gland situated across the upper abdomen behind the stomach and spleen
