animal digestion Flashcards
What are the three dietary categories ?
Herbivores, omnivores, carnivores
What is ingestion?
taking in of food into the body
what is digestion ?
Breaking the food down into smaller pieces
what is absorption ?
Food molecules enter body cells
what is elimination?
removal of undigested waste material
What is intracellular
within a cell
eg. food vacuole and lysosomes
what is extracellular
in a specific compartment
eg, gastrovascular cavity
why do animals process food in compartments ?
to avoid self-digestion
What are the functions of a gastrovascular cavity ?
Digests food and distributes nutrients
Describe digestion in animals with simple body parts
Digestion begins in cavity (gastrodermis secretes enzymes) and is completed intracellularly.engulfed by nutritive muscular cells) Excreted out through the mouth
what is a gastrovascular cavity ?
a tube with one opening everything has to go in and out through this opening
complete digestive system
2 openings
incomplete digestive system
1 opening
what forms the bolus in the oral cavity?
salivary amylase+mucin+food=bolus
what does salivary amylase hydrolyse?
starch and gylcogen
how does food move down the esophagus ?
food moves to stomach by involuntary contractions (peristalsis)
What is the role of the epiglottis ?
when you swallow the epiglottis covers the glottis to prevent food from entering the trachea
peristalsis
waves of muscular contraction
Breakdown of carbohydrates
polysaccharides broken down by salivary amylase to form maltose in the oral cavity.
Polysaccharide broken down into maltose and other disaccharides by pancreatic amylase in the lumen of the small intestine.
Disaccharides broken down into monosaccharides by disaccharidases in the epithelium of small intestine.
protein digestion
proteins to small polypeptides by pepsin in stomach.
Polypeptides to smaller polypeptides by pancreatic trypsin and chymotrypsin in lumen of small intestine.
Smaller polypeptides to amino acids by pancreatic carboxypeptidase in lumen of small intestine.
Small peptides to amino acids by dipeptidases, carboxypeptidase and aminopeptidase in epithelium of small intestine.
Nucleic acid digestion
DNA,RNA to nucleotides by pancreatic nucleases in the lumen of the small intestine.
Nucleotides to nucleosides by nucleotidases in small intestine.
Nucleosides to nitrogenous bases, sugars and phosphates by nucleosides and phosphatases in the epithelium of the small intestine.
fat digestion
fat globules to fat droplets by bile salts.
fat droplets to glycerol, fatty acids and glycerides by pancreatic lipase. All in the lumen of the small intestine.
What happens if the stomach doesn’t have a lining ?
Ulcers
Why is mucus important?
to protect from HCL
Describe the gastric gland
It has three different types of cells that secrete different components of gastric juice. : mucus cells, chief cells and parietal cells
Mucus cells
secrete mucus which lubricates and protects the cells lining the stomach
Chief cells
secrete pepsinogen. an inactive form of the digestive enzyme pepsin. HCL converts pepsinogen to pepsin.
parietal cells
secrete hydrochloric acid
Do gastric juices contain HCL.
yes
what is chyme?
Gastric juices and partly digested food
what causes heartburn?
backflow of acid chyme through cardiac orifice
What does the pyloric sphincter do?
Regulates passage of chyme to the small intestine.
what are some glands in the human body?
salivary glands, gallbladder, liver and pancreas
Duodenum
First part of intestine. enzymes are secreted from pancreas.
what activates proteases
trypsin
what is the endocrine function of the pancreas?
secretion of insulin and glucagon into the blood
what is the exocrine function of the pancreas?
Secretion of digestive enzymes into the duodenum
What produces bile?
the liver produces bile which is stored in the gallbladder
what does bile consist of?
Bile salts which act as emulsifiers (fat digestion)
pigments from destruction of red blood cells
Enterogastrone
secreted by the duodenum inhibits peristalsis and acid secretion by the stomach. slowing digestion when acid chyme rich in fats enters the duodenum.
Gastrin
from the stomach recirculates back to the stomach where it stimulates the production of gastric juices.
Secretin
Secreted by the duodenum, stimulates the pancreas to release sodium bicarbonate which neutralises acid chyme.
Cholecystokinin
triggered by amino acids or fatty acids in the duodenum. it stimulates the release of digestive enzymes from the pancreas and bile from the gallbladder.
how long is the colon?
1.5 m
Three functions of the colon?
Reabsorption of water, absorption of vitamins, production of faeces.
