bio 3 Flashcards
what is the purpose of the digestive system?
To mechanically and chemically digest food into monomers and simple components for absorption and later use as a source of energy, carbon chains and amino acids.
Human are heterotrophs os they cannot___
make their own energy/food
What are the two types of digestion?
Physical digestion: chewing, churning in stomach, breaking of food into smaller pieces and emulsification of fats by bile.
chemical: all breakdown of food that involves the breaking of bonds through the use of digestive enzymes.
If the liver, pancreas and gallbladder are accessories to digestive organs, why are they part of digestive system outline? what do each do that is important to digestion?
The liver manufactures bile. The gall bladder concentrates and stores bile (but does NOT manufacture it). The pancreas secretes bicarbonate into the duodenum to neutralize the acidic chyme coming from the stomach. The pancreas also secretes six pancreatic digestive enzymes.
all essential to digestion
What is saliva?
provides lubrication and amylase –> first digestive enzyme to which food is exposed to.
Digestion begins in the mouth with the physical digestion of all food types and the chemical digestion of _____ only (via the enzyme ____)
carbohydrates; alpha amylase.
Where is epiglottis?
u shaped fly that covers trachea when we eat food or swallow and lets air pass through when breathing.
Where does the first stage of protein digestion happen?
stomach.
Proteins in the stomach undergo _____ , a reaction catalyzed by the enzyme _____ . This enzyme begins as ____ , an example of a
zymogen. Zymogens are inactive enzyme precursors.
hydrolysis
pepsin
pepsinogen
What are the four cell types of stomach lining?
1) mucous neck cells: make and secrete alkaline mucus to provide protection to neck cells from the stomach acidity.
2) chief cells: make and secrete zymogen pepsinogen into gastric pits/ stomach lumen.
3) parietal cells: secrete HCL, responsible for extreme acuity of stomach (pH=2) and turning pepsin into pepsinogen.
4) G- cells: make and secrete gastrin. Gastrin is released into the BLOOD and not gastric pit or stomach lumen like the others. Gastrin circulates back to parietal and chief cells and stimulate release of HCL and pepsinogen POSITIVE FEEDBACK.
Is gastrin a peptide, a steroid, or a tyrosine derivative? Is gastrin likely to bind at a membrane receptor? If so, where would the receptor be?
peptide because it has to be soluble in blood
receptor on outside of membrane.
In addition to pepsin, what other molecule assists in protein metabolism in the stomach?
The acid in the stomach denatures proteins. Recall from the Biology 1 lesson that acid is a protein denaturing agent.
What prevents the tissues lining the stomach from being digested by pepsin?
The lining cells of the stomach are protected by a thick layer of mucus secreted by the mucus cells that line the gastric pits, one of four cell types present.
What is the function of the liver?
metabolic brain of human body. It regulated blood concentrations of many different solutes, plays key roles in the metabolism of proteins, fats, and carbohydrates, detoxify chemicals, recycles metabolites and manufactures several key biomolecules.
Key functions:
- produces bile
-filters blood to remove toxins, drugs, metabolites, bacteria, etc.
-produces blood plasma proteins, including albumin, fibrinogen,
- regulated amin acid levels in the blood
-produces cholesterol and lipoproteins and packages them for transport (LDL, HDL, etc).
What does the pancreas and liver release when there’s low blood glucose levels?
alpha cells in pancreas secrete glycogen, which stimulates glycogenolysis in the liver (breakdown of glycogen stored in the liver to form free glucose for release into the blood.
What does the pancreas and liver release when there’s high blood glucose levels?
beta cells in pancreas release insulin, which stimulates glycogenesis in the liver and synthesize glycogen in liver,
Insulin also stimulates the uptake of glucose from the blood into the cells. Finally, the liver converts lactate, glycerol, amino acids, and some TCA-cycle intermediates into glucose. Q9. This process, by which the liver makes new glucose, is called ___________________.
Gluconeogenesis
What is the function of the pancreas?
- Pancreas is both an endocrine and an exocrine gland.
- It secretes a bicarbonate rich solution, which neutralizes the stomach acid, decreasing acidity of intestine pH=6.
- Secretes trypsin, chymotrypsin, pancreatic amylase, lipase, ribonuclease and deoxyribonuclease.
what is function of trypsin, chymotrypsin, pancreatic amylase, lipase, ribonuclease and deoxyribonuclease
- Trypsin and chymotrypsin are both proteases that cleave peptide bonds at specific amino acid sequences.
- Pancreatic amylase catalyzes the hydrolysis of carbohydrates.
- Lipase catalyzes the hydrolysis of fats.
- Ribonuclease and deoxyribonuclease catalyze the hydrolysis of RNA and DNA respectively. Some students find this odd, thinking “Who eats DNA and RNA?” While it’s true we don’t think of either as a food group, anything made of living cells—plant, fungi, animal, etc.– will contain both of these polynucleotides.
what is function of gallbladder?
stores and concentrates bile, but does not produce bile.
where is bile produced?
liver
Is bile’s action an example of physical or chemical digestion?
Bile emulsifies fats, but it does not break any bonds—therefore it is an example of physical rather than chemical digestion.
What happens in the small intestine?
where majority of all digestion and absorption occurs; digestion in duodenum, absorption primarily in jejunum and ileum.
Provide definition for:
villi, microvilli, lacteal and brush border.
how do they intertwine?
The villi are finger-like projections of the wall of the small intestine. They are hollow and contain both blood vessels and a single lymphatic vessel called a lacteal. Fats are absorbed into the lymph system via the lacteals and carbohydrates and proteins are absorbed into the blood. The villi dramatically increase the surface area available for absorption. Further, each epithelial cell lining a villus contains fingerlike projections of the cell membrane called microvilli.
The brush border is a name given to the microvilli and the collection of mucus and digestive enzymes intermingled within them.
What happens in large intestine?
“water absorption” , “vitamin absorption”.
As a review from the Biology 1 Lesson, the relationship between humans and the E. coli in the colon is an example of what type of inter-species relationship?
mutualism
A disease or illness that inhibits the normal function of the large intestine will most likely result in ____ .
diarrhea, constipation, vitamin deficiency
Describes digestion:
Include the following terms: mouth, pharynx, epiglottis, esophagus, peristalsis, stomach, pepsin, gastric pits, small intestine (i.e., duodenum, jejunum, and ileum), bile, pancreatic enzymes, villi, microvilli, large intestine, colon (i.e., ascending, transverse, descending, and sigmoid), and rectum.
The most important roles of the mouth in digestion are to break up food into small pieces by chewing and to mix it with saliva, which contains the enzyme alpha-amylase and some specific classes of antibodies. The saliva lubricates the food, which aids its passage down the esophagus. Amylase initiates carbohydrate digestion. The pharynx ensures the bolus is delivered to the esophagus without entering the nasal cavities or the larynx, but no digestion of any kind occurs here and nothing is added to the bolus. The epiglottis is an upward-oriented cartilaginous flap that folds down over the opening to the larynx during swallowing to prevent food from entering the larynx. The esophagus utilizes peristalsis to push the bolus down and into the stomach. Peristalsis is the rhythmic contraction of smooth muscle in the wall of the gastrointestinal track that moves food forward. Once again, no digestion occurs in the esophagus and nothing is added. Food enters the stomach by passing through the cardiac sphincter, which is located at the junction of the esophagus and the stomach. The churning of the stomach continues physical digestion. The stomach is lined with gastric pits. Chief cells are one of four cell types lining these pits, which are, in turn, lined with four cell types. Chief cells, one of these cell types, release pepsinogen, a zymogen that will be converted to its active form, pepsin, by the low pH of the stomach lumen. Pepsin will hydrolyze proteins. Another of these cell types lining the gastric pits, the parietal cells, secrete the HCl that lowers the pH of the stomach to about 2. The partially digested food mix, now referred to as chyme, passes through the pyloric sphincter and into the upper portion of the small intestine, called the duodenum. The common bile duct and the pancreatic duct both release products into the duodenum. As a result, the duodenum receives bile from the liver and gallbladder, and, from the pancreas, a bicarbonate-rich solution and six digestive enzymes: trypsin and chymotrypsin digest protein, pancreatic amylase digests carbohydrates, lipase digests fats, and ribo- and deoxynuclease digest RNA and DNA. The bicarbonate ions are important because they raise the pH of the chyme to around 6—a necessary step because the enzymes just listed could not function at the much lower pH of the mixture arriving from the stomach. The chyme progresses through the small intestine to its middle section, the jejunum, and then to the final section, the ileum. There are no distinct
boundaries marking these three sections. Most digestion occurs in the duodenum and most absorption (of food molecules, not water) occurs in the jejunum and ileum. The lining of the small intestine features finger-like projections called villi that increase the surface area for absorption. Individual epithelial cells along each villus have microvilli—long fingerlike projections of the cell membrane on their apical surface. Each villus’ center is filled with blood vessels and a single lymph vessel called a lacteal. Fats are absorbed into the lacteal, NOT the blood vessels. Carbohydrates and proteins are absorbed into the blood vessels. The ileum empties into the large intestine on the right side of the abdomen (anatomical right) slightly above a blind (dead-end) pouch called the cecum. The appendix is attached to the cecum. The colon rises upward along the right wall of the abdomen (ascending colon), traverses across the abdomen (transverse colon) and then descends along the left wall (descending colon). The final segment of the colon is somewhat twisted and is therefore appropriately named the sigmoid colon. The primary function of the colon is the absorption of water and vitamins. The colon contains resident commensal bacteria that secrete vitamin K, thiamin, riboflavin, and vitamin B12. The rectum is the final segment of the large intestine. It connects to the anus and stores feces.
What are different places carbohydrates digested and into what?
carbohydrates digestion begins in the mouth with salivary amylase. –> through small intestine to be broken down into monomers BEFORE absorption. they enter bloodstream and travel to the LIVER via hepatic portal vein.
What are different places proteins are digested and into what?
Proteins are first digested in the stomach and is completed by the time they get to the small intestine, where they are small peptides and amino acids before absorption. They enter the blood stream and travel to the liver
What are different places lipids are digested and into what?
Digestion begins in small intestine (duodenum) and is complete by the end of the small intestine. Can only be broken down by bile and lipase which are in small intestine.
Triglycerides ar broken down to small peptides and amino acids before absorption. They enter the LACTELAS in to to travel in blood or lymph, all lipids must be either:
1) bind to protein carrier like albumin
2) from into a chylomicron or micelle.
The lining of the human stomach contains G-cells, cells that are primarily responsible for the secretion of the peptide hormone, gastrin. Some mammals have stomach linings that lack G-cells completely. It is likely that these mammals:
A) have developed immunity to the effects of gastrin.
B) consume a diet high in carbohydrates.
C) consume a diet high in proteins.
D) evolved in an environment where the presence of gastrin was a competitive advantage.
B- Gastrin stimulates the parietal cells to secrete HCl. That HCl serves two purposes: 1) It denatures proteins in the stomach, and 2) it activates pepsinogen to pepsin. Both functions are closely related to the digestion of proteins, so answer B is very plausible.
What is the function of the immune system?
Protect the body from infection and disease; destroy pathogens invading the body.
What are monocytes and what do they mature into?
Monocytes, a type of white blood cell, mature into macrophages, which phagocytize pathogens and cellular debris. Phagocytosis by macrophages is non-specific and a type of innate immunity, but macrophages also present antigens from pathogens they consume for recognition by B and T cells, an aspect of acquired immunity.
What are the three types of granulocytes?
what do they all have in common?
neutrophils, basophils, eosinophils. all granulocytes are short-lived, do not reside permanently in the tissues, circulate in the blood, and are recruited to areas of infection of inflammation.
what are neutrophils?
stain a neutral pink.
Neutrophils are phagocytes that are recruited to areas of infection and inflammation by chemotaxis. They live for only about 5 days, but are the most abundant of all white blood cells. The pus created at a wound is mostly dead neutrophils.
what are basophils
stain dark blue- least common white blood cell. Their granules contain mostly histamine, which they release along with other chemicals when activated. These chemicals promote inflammation and are integral in the allergic response, so many associate basophils with allergies.
what are eosinophils?
recruited to areas of parasitic invasion, particularly multicellular parasites, where they release their granules containing peroxidases and other enzymes that digest tissue. This would destroy the pathogen but could also destroy host tissue
What are mast cells?
mast cells are permanent resident cells within many tissues. They are activated by allergens and other antigens to release histamine and other chemical mediators. They are usually associated with severe allergic reactions, including anaphylactic shock.
what are dendritic cells?
Dendritic cells are professional antigen-presenting cells. They efficiently phagocytize pathogens and present those antigens on their surface to stimulate other immune cells. Dendritic cells are white blood cells (leukocytes), but are not lymphocytes. They can form from monocytes (which also differentiate into macrophages) or independently in their own cell line from a blood cell precursor.
what are the three types of lymphocytes?
T cells, B cells, and natural killer cells.
what are natural killer cells?
Natural killer cells recognize infected or cancerous cells and release cytotoxic granules that destroy the cell.
What are T cells?
T cells are lymphocytes that mature in the thymus and participate in cell-mediated immunity.
- require receptor
- do NOT produce antibodies
What are B cells?
B-cells are lymphocytes that mature in the bone marrow and lymph tissues and participate in humoral immunity. B-cells produce antibodies,
What are plasma cells?
Plasma cells are formed when a B-cell binds its matching antigen and is activated (with the help of helper T-cells) to undergo mitosis. The division of the B-cells produces mostly plasma cells—clones of the original B-cell that act as “antibody factories,” making and secreting soluble copies of that antibody
What are memory B cells?
A few B cells will differentiate into memory B cells that remain in the body, allowing the immune system to mount a more efficient secondary immune response if there is a later infection by the same pathogen.
- humoral immunity
What are helper T cells?
“help” other immune system cells, such as B-cells and cytotoxic T-cells, to perform their function. The way they “help” other cells is usually to secrete chemicals, such as cytokines, that activate (i.e., “turn-on”) functions or activities in the cell that is being “helped”
What are suppressor T cells?
Suppressor T-cells (a.k.a., regulatory T-cells) suppress the body’s own immune system—which helps prevent severe allergic reactions or autoimmune disease and aids in turning off an immune response once an infection has been eliminated.
What are Killer T- cells?
Killer (or cytotoxic) T-cells target infected and cancerous versions of the body’s own cells and destroy them.
what is part of humoral immunity?
antibody- mediated immunity, includes cytokines, and memory cells. Humoral immunity components are found in both innate and adaptive immune system.
what is innate immunity?
The body’s non-specific attack of pathogens. All forms of innate immunity are
present at birth, NOT acquired in any way.
o Includes all immune responses that are NOT specific to one particular virus, bacteria, pathogen, etc. Examples include: skin, stomach acid, enzymes in the mucus and saliva, digestive enzymes, blood chemicals, fevers, inflammation, and non-specific phagocytosis.
what is adaptive/ acquired immunity?
A specific response to one particular virus, bacteria or other pathogen based upon prior exposure. There are two types of acquired immunity: humoral and cell-mediated.
what happens during an inflammatory response?
first, macrophages, mast cells, dendritic cells which are in all tissues will be activated when there’s damage and release chemicals like histamines, leukotrienes, prostaglandins, which increase blood flow to the injury site and create redness/ heat + increase permeability of veins and lymph vessels, which uses plasm and interstitial fluid to flood the infection site and result in swelling (aka. Edema).
what are the different part of an antibody?
-disulfide bonds between heavy/ light chains.
- hypervariable region on end of chain.
- constan region
