GI Tract and Kidneys

Question 1

Process in which food is broken down and ultimately absorbed by the intestinal tract.

Answer 1

Digestion

Question 2

Starch is a characteristic of _____ cells and glycogen is a characteristic of ______ cells. Both are hydrolyzed by which enzymes within the digestive tract?

Answer 2

1) Plant
2) Animal
3) Amylase (hydrolyzes carbohydrates in the mouth, causes these polymers to release monosaccharides of glucose)

Question 3

Where is cellulose found? What is it? Why can’t humans digest cellulose?

Answer 3

1) Found within cell walls of plants
2) consist of glucose residues linked together
3) Cellulose residues are linked together in a different configuration than glucose residues in starch and glycogen. Humans do not have the enzyme, cellulase, which is necessary for hydrlyzing the glucose linkages in Cellulose.

Question 4

Which vertebrates are able to digest cellulose and how?

Answer 4

1) Ruminants (i.e. Goats and cows)
2) Symbiotic relationship between the ruminants and the microorganism that secret cellulase in their rumen

Question 5

Hydrolyzes proteins to their constituent AA residues.

Answer 5

Proteases

Question 6

Hydrolyzes fats into fatty acids and glycerol molecules.

Answer 6

Lipae (only active in the stomach at acidic pH)

Question 7

What are essential AA? How many are there?

Answer 7

1) AA that we do synthesize and must ingest/digest
2) 9 out of the necassary 20 AA

Question 8

What are the five general components for a health diet?

Answer 8

1) Fats
2) Protein
3) Carbohydrates (in the form of sugars like glucose)
4) Vitamins - essential to prevent nutritional deficiencies
5) Inorganic Minerals: (i.e. Fe, K+, Ca+, and zink) – essential for proper development (i.e. Fe+ in myoglobin and hemoglobin)

Question 9

Scattered throughout the epithelial layer of the small intestine are ducts from external ___________ glands like the _______ and ________. (as well as salivary glands in the oral cavity)

Question 10

Juxtaposed to many of the epithelial cells are _______ cells. What do they contain? Where are these release?

Answer 10

1) endocrine cells
2) Hormones
3) These hormones are released into the blood stream

Question 11

What is the purpose for the hormones in endocrine cells in the epithelial layer of the small intestine?

Answer 11

Influence other cells in GI system

Question 12

Both of these systems control the GI system. This specific system is most often associated with the GI system.

Answer 12

1) PSN and SNS
2) PSN (rest and digest)

Question 13

Describe what happens during the first part of digestion (up Tunis food reaches the stomach).

Answer 13

1) Teeth grind up food and food is further broken apart by rubbing food up against hard palate
2) Salivary amylase is secreted and begins hydrolyzing and digesting starches and glycogen
3) Food is swallowed and passes into the pharynx (access to nasal cavity closes at this point)

4) Epiglottis (flap) closes the opening to the larynx (protects the airway so food does not go down that path)
5) Food passes down esophagus and into stomach (GI sphincter closes after food enters stomach)

Question 14

What controls the swallowing reflex?

Answer 14

The centers in the medulla

Question 15

What happens when the GI sphincter at the beginning of the stomach does not fully close?

Question 16

Two main purposes of the stomach?

Answer 16

1) Further digestion (break down food into smaller pieces)
2) Detoxify food (with acidic secretions)

Question 17

What do the surface cells in the stomach secrete? What is their purpose?

Answer 17

1) Secret mucous
2) Protect lining of the stomach and lubricate food

Question 18

A hormone secreted by the endocrine cells in the lower portion of the stomach in response to proteins entering the stomach.

Answer 18

Gastric

Question 19

Secretion of gastric initiates the secretion of these? (Secreted by parietal and chielf cells)

Answer 19

1) HCL and Pepsinogen

Question 20

Parietal cells secrete this.

Answer 20

HCL

Question 21

Chief Cells secrete this.

Answer 21

Pepsinogen

Question 22

Pepesinogen is the inactive form of this. What is the purpose of this enzyme?

Answer 22

1) Pepsin - is activated by HCL, once activated, can autocalytically act on Pepsinogen to create more pepsin.
2) Cleaves peptide bonds (hydrolyzing proteins in the stomach further break them down into AA)

Question 23

Purpose of the intrinsic factor and what would happen if there was a defect in the synthesis of this factor?

Answer 23

1) Glycoproteins secreted by parietal cells
2) Complexes with Vitamin B12, which is necassary for this vitamin to be absorbed by the epithelial cells if in the instestine for it to enter the blood stream
3) If there was a defect in the synthesis of this glycoprotein, vitamin B12 would not be able to enter the blood stream (this vitamin is important in red blood cell formation)

Question 24

Happens when too much HCL is secreted in the stomach.

Answer 24

Gastric ulcers - in small intestine and stomach (if they are big enough can bleed)

Question 25

Powerful stimulant that can cause HCL to be release in the lumen of the stomach. What can combat this and inhibit too much HCL from being secereted?

Answer 25

1) Histamine
2) Cimetidine (inhibits binding of histamine to its receptor on parietal cells, if histamine cannot bind to its receptor on parietal cells, parietal cells will not secrete as much HCL)

Question 26

As the dissolved food (referred to as chyme) passes from the lower stomach to the small intestine, more enzymatic activity takes place. What are two major events that take place in the small intestine as a result of enzymatic activity?

Answer 26

Most of the digestion and absorption. Things are further broken down and absorbed in the small intestine. (About 90% of digestion and absorption takes place here).

Question 27

The small intestine release these two hormones in response to the chyme entering the small intestine. What is the purpose of these hormones and what are they secereted in response to?

Answer 27

1) CCK: triggers gallbladder to release bile salts to help emulsify fats so they can be absorbed in the small intestine (released in response to fat entering small intestine)
2) Secretin: trigger acini in pancreas to release a high bicarbonate content (alkaline) to the small intestine to help neutralize stomach acid (released in response to chyme entering small intestine)

SIDE NOT: Secretin is ALWAYS release. CCK is ONLY released in response to fats entering small intestine.

Question 28

What happens why high bicarbonate content enters small intestine?

Answer 28

Bicarbonate combines with protons in HCL to produce CARBONIC ACID. This is then converted to H20 AND CO2. CO2 enters the bloodstream and is transported to lungs where it is expired.

Question 29

1) This synthesizes bile.
2) This is where bile is stored

Answer 29

1) Liver
2) Gallbladder

Interesting fact: main pigment in bile is bilirubin, which is a breakdown of hemoglobin

Question 30

Opens to release bile into the small intestine.

Answer 30

Sphincter of Oddi

Question 32

What happens during absorption of compounds across the apical to the basolateral region of epithelial cells.

Answer 32

Transport proteins (i.e. Na+ or K+) are necassary for “carrying” the compounds (i.e. Glucose) across the cell. As concentrations of of the compound increases, that compound will then diffuse out the basolateral side and eventually into the blood. As concentration of Na+ increases, Na+ is pumped out and K+ is pumped in via Na+ and K+ pump.

Question 33

What does the diffusion of ions through the membrane of the epithelial cells cause?

Answer 33

Diffusion of water through the membrane (as H20 is trying to equilibrium on both sides of membrane by osmosis)

Question 34

Causes massive loss of fluid by diarrhea

Answer 34

cholera toxin

Question 35

Where or triglycerides resynthesized and what do they form?

Answer 35

1) In intestine epithelial cells
2) aggregates into chylomycrins (which are released at the basolateral membrane, enters extrcllular fluids, enters lymph, and is then transported to veins and eventuallly tissues)

Question 36

In the large intestine, sodium and calcium ions are absorbed. What does this create?

Answer 36

Osmotic gradient that is established for the absorption of H20 (what is no absorbed is excreted as feces).

Question 37

Water lost from the body matches water gained by the body through consumption of fluids and regulation of what bodily organ?

Answer 37

Kidneys

Question 38

Higher osmolarity of a given solution means a _______ concentration of H2O.

Answer 38

Smaller

Question 39

Osmoregulators vs. Osmoconformers

Answer 39

1) Osmoconformer: maintain an internal environment that equals the osmolarity of the external environment (osmolarity of their cells equals the surround environment) - marine animals
2) Osmnoregulators: do not change the osmolarity of their cells (internal environment) to match that of the external environment (most vertebrates)

Question 40

Give a broad description of what takes place in the kidneys.

Answer 40

1) Blood enters renal artery, which branches off into networks that are dissimnated
2) Filtration of blood
3) From that filtrate, we then reabsorb ions and water (important nutrients that we want to go back into our blood and circulate through the rest of our body)
4) These ions and water (that was removed from the filtrate) collects into our renal vein
5) Reabsorbed nutrients go back into the blood (and send it on its way to the rest of the body)

Question 41

Two functions of the kidney.

Answer 41

1) Filtration
2) Collection

Question 42

Single smallest functional unit of a kidney. Responsible for filtration and collection.

Answer 42

Nephron (situated in the adrenal cortex (shell of kidney) and adrenal medulla (middle part of the kidney))

NOTE: The function of a part of the nephron is dependent on where it is located in the kidney

Question 43

Tips that “collect urine” – first place where urine is collected (collection part)

Answer 43

Renal calyx

Question 44

Central area where renal calyces collect together.

Answer 44

Renal pelvis

Question 45

Where urine exits the kidneys.

Answer 45

Ureter (two that sends urine away from kidneys and into the bladder)

Question 46

Place here renal artery, renal vein, and ureter exit

Answer 46

Hilum

Question 47

Kidney’s are important for maintaining this in the body. (Important H-Word (Not Heffa))

Answer 47

Homeostasis (maintaing a stable condition of an organism and its internal environment, i.e. BP, osmolarity, and Blood PH)

Question 48

The region where urine exits the bladder.

Answer 48

Urethra

Question 49

Describe the glomerulus.

Question 50

Function of glomerulus.

Answer 50

Main site for filtration (where we take blood and turn it into filtrate, and let the rest of the blood flow on)

Question 51

1) Connected to glomerulus
2) Collects filtrate that comes out of the glomerulus

Answer 51

Bowman’s Capsule

Question 52

Why are endothelial cells in our kidney’s important?

Answer 52

They are fenestrated and allow filtrate to leak out of glomerulus into bowman’ capsule (right under these endothelial cells is a basement membrane that only allows very small things to pass through and go to the Bowma’s capsule)

Question 53

Cells just under basement membrane in the kidneys

Answer 53

Tubule (type of epithelial cell) cells

(some with podocytes that extend up into and “hug” the arterioles and endothelial cells to keep everything close)