DIgestion & Reproductive System Flashcards
what is the function of the digestive system
to break down food into nutrients, absorb nutrients into the blood for use by cells of the body, and eliminate waste
what is chemical digestion?
breakdown of food by enzymes into nutrients
what is mechanical digestion?
physical breakdown of food into smaller pieces
what is involved in ingestion?
mastication into bolus (mastication means chewing, so this is putting something into your mouth and chewing, bolus - ball like mixture of saliva and food)
what does digestion start with?
ingestion
what is the next step in digestion?
propulsion
what are the two things that happen in propulsion?
deglutition and peristalsis
deglutition
swallowing & is a voluntary action
peristalsis
the smooth muscles in the walls of the digestive organs take turns contracting and relaxing to squeeze the bolus through the lumen, (the cavity of the digestive tract) from the esophagus to the stomach
what is the next thing to happen in digestion?
mixing in the stomach
what is mixing? and what is its process?
-mixing is the formation of chyme.
- when the food enters the stomach, the stomach glands produce gastric juices (acid) that mix with the bolus and form a semi-thick semi-solid partially digested ball of food called chyme that moves from the stomach to the first part of the small intestine
what are the parts of the small intestine in order?
duodenum, jejunum and ileum
what is the next step in the digestive process?
secretion of enzymes
what is the next step of the digestive process?
absorption
where does absorption happen? what happens?
*from the lumen of the intestines through the intestinal epithelium to the bloodstream
* The small intestine absorbs all the water, vitamins, and minerals of the digested food which are then absorbed into the bloodstream where it is carried to other parts of the body to be used or stored
Egestion
eliminating the undigested food from the body through the anus (pooping)
what are all the steps of the digestive system?
- ingestion
- propulsion
- mixing in the stomach
- secretion of enzymes
- absorption
- egestion
what are the organs involved in digestion?
- mouth
- esophagus
- the stomach
- the small intestine
- the large intestine
- liver
- pancreas
what happens in the mouth?
- the teeth do mechanical digestion of food into bolus
- the salivary glands (parotid, submandibular, and sublingual) secrete:
- salivary amylase
-mucins
what do the salivary gands secrete
salivary amylase and mucins
salivary amylase
enzyme that breaks down carbohydrates (specifically large starch macromolecules into small simple)
* this enzyme is important because it is the start of chemical digestion
mucins
acts as lubricants and buffers
* mucins are glycoproteins that form a protective layer in the oral cavity (mouth) and act as lubricant for the food and protect the mouth from strong acids and invading organisms
stomach
- smooth muscle contractions for mixing (this is apart of mechanical digestion)
- secretion of enzymes ( this is apart of chemical digestion)
what happens during the smooth muscle contraction of the stomach
- the food remains in the stomach for 3-4 hours
- No nutrients are absorbed in the stomach
what can be absorbed in the stomach?
some medicines and alcohol
what glands are involved during secretion of enzymes ( to form chyme)?
1.Gastric glands- located in the gastric pits of the stomach walls
2. Pyloric glands
what does it mean that oral medications are enterically coated?
the medication is coated in a polymer barrier that resists the gastric acids of the stomach and slows the dissolvent and absorption of the medicine
what type of cells are in the gastric glands?
- parietal cells and chief cells
parietal cells
cells in the gastric glands that produce HCl (hydrochloric acid ) and intrinsic factor ( for the absorption of vitamin b 12)
what does HCL reduce pH to ?
1.5 - 2
what does intrinsic factor do?
for the absorption of vitamin b 12
what types of glands are gastric glands and what do they do?
gastric glands are exocrine glands that secrete gastric juice into the stomach
chief cells
produce pepsinogen
what is pepsinogen converted into and by what?
pepsinogen is converted into pepsin by hydrochloric acid
what does pepsin do?
pepsin denatures (breaks down) proteins
pyloric glands
contain G cells and D cells
G cells
produce gastrin
* gastrin:
- stimulates the chief and parietal cells (which then stimulates the production of HCL, intrinsic factor, and pepsinogen which then become pepsin)
-stimulates the muscle contractions (also known as mixing)
D cells
- produce somatostatin
- somatostatin inhibits gastrin when food is not present in the stomach
what are the phases of stomach activity
- cephalic stage
- gastric phase
- intestinal phase
what happens during the cephalic stage?
- the medulla oblongata is stimulated by the smell, sight, taste, or thought of food
-parasympathetic (rest and digest) is activated ( this helps move food through the intestines) - The parietal, chief, and g cells are stimulated
what happens during the gastric phase?
-stomach distention (stomach stretching/stomach filled with food) stimulates enteric reflexes (mixing:)
- continued secretion of gastric enzymes
what happens during the intestinal phase?
duodenal secretions inhibit the gastric glands
what is the first part of the small intestine?
the dueodenum
what is the first thing to happen in the duodenum?
the chyme leaves the stomach
the chyme leaves through what and enters which part of the small intestine?
leaves through the pyloric sphincter and enters through the duodenum
what happens after this
pancreatic juice and bile enter the small intestine
where do pancreatic juice and bile enter the small intestine from ?
duodenal ampulla (also known as the ampulla of vator) - this is where the pancreatic duct and common bile duct meet
mucins and lubricants in the duodenum protect cells from what?
acidic chyme
what raises the pH in the dueodenum? what does it raise it to?
buffers raise the pH and it raises it to 7-8
plicae
the circular folds in the duodenum
villi
line the small intestine & provide cellular extension of blood capillaries and increase surface area
what does Villi do? how does it do this?
absorb the nutrients in the chyme and the product of digestion. It does this by diffusion and active transport
microvilli
smaller cellular extension
brush border
layer of microvilli that increases the surface area in the small intestine
what are the different cell types in the duodenum?
-goblet cells
-paneth’s cells
-absorptive cells
-enteroendocrine cells (s cells, cells, Brunner’s glands, and I cells)
goblet cells
secrete mucus
paneths cells
lymphatic tissue
absorptive cells
produce brush border enzymes
what are the types of cell in the enteroendocrine cells?
S cells, K cells, Brunners glands, and I cells
S cells
- found in the crypts of Lieberkuhn
- produce secretin
- secretin stimulates the production of bile from the liver and insulin from beta cells in the pancreas
K cells
produces gastric inhibitory glycoprotein
- this inhibits gastrin and stimulates insulin
insulin
- produced by the beta cells in the pancreas
- take excess glucose and convert it into its stored form called glycogen to regulate blood glucose level
brunners gland
-produces mucus & urogastrone (inhibits all gastric glands)
I cells
- produce cholecystokinin ( stimulates pancreatic juice from acini)
what is the middle part of the small intestine?
jejunum
what happens in the jejunum?
most absorption happens in the jejunum
* it has lots of plicae (circular folds in the small intestine) that helps greatly with absorptive area
what is the last part of the small intestine?
ileum
what happens in the ileum? what does the ileum contain?
-in the ileum, there is a smoothening of plicae
- the ileum contains peyers patches:
- clusters of lymphatic tissue that protects against the bacteria of the large intestine
what are the functions of the large intestine?
- water and vitamin absorption
- compaction and storage of feces
what are the first part of the large intestine?
cecum
what is within the cecum? what does it do
veriform appendix; develops immunity and maintains the gut flora in the large
what is the order of digestion in the large intestine?
ascending colon -> transverse colon -> descending colon -> sigmoid colon -> anus/ rectum
what are the structures within the large intestine?
haustra & goblet cells
haustra/ what is the name for inflammation of the haustra?
pouches for expansion / diverticulitis
what do goblet cells do?
secrete mucus
what are the three parts of the mucosa of the digestive system?
- the epithelium
- lamina propira
- muscalaris mucosae
epithelium of the digestive tract
- simple columnar - stomach and the intestines
- stratified squamous - anal canal, mouth, oropharynx, and esophagus
what is the lamina propria? what does it contain?
*underlying connective tissue
* blood vessels, nerves, and lymphatic vessels
mucosal mucosae
longitudinal and circular layers of smooth muscle
what is the submucosa? what does it contain?
thick layer of connective tissue containing nerves, blood vessels, and lymphatic vessels.
- contains a submucosal plexus
what is a submucosal plexus?
a network of sympathetic, parasympathetic, and enteric nerve fibers
muscularis externa and what does it contain?
“outermost layer of the mucosa”
_-longitudinal and circular smooth muscle layers
- contains the myenteric plexus
the muscularis externa is an addition of what type of muscle to the stomach?
oblique
myentric plexus
parasympathetic, sympathetic, and enteric nerves that control the muscle layers
serosa/ adventitia
outer most layer of the membranous layer
serosa
below the diaphragm & visceral peritoneum
adevntitia
- above the diaphragm & connects the esophagus to the trachea and the aorta
what is the blood flow in the live?
- Nutrient-rich and oxygen-poor blood enters from the hepatic portal vein
- Nutrient-poor and oxygen-rich blood enters from the hepatic artery
- these bloods mix in the hepatic sinusoids and leave the liver via the hepatic veins
what are the different types of liver cells?
- hepatocytes
- kupffer cells
what are the functions of heptaocytes?
- produce bile from bilirubin
- nutrient introconversion
- detoxification
- produce plasma proteins
- deamination/;transamination
what are the parts of nutrient introconversion?
- glycogenesis ( production of glycogen )
- sugar levels are high in the blood, so insulin stimulates the production of glycogen to store it - glycogenolysis (breakdown of glycogen)
- when there is not enough sugar in the blood (in between meals and when we are exercising), glycogen is broken down into glucose to enter the blood stream - ## gluconeogenesis: (body synthesizes new glucose from noncarbohydrate precursors like amino acids, lactate, and glycerol
what inhibits gluconeogenesis?
insulin
deamination
the removal of an amino acid group and hydrogen from an amino acid that thus form ammonia (toxic byproduct) and ketoacid
transamination
the removal of an amino acid group from an amino acid and attaching it -;[o a-+ keto acid
Kupffer cells
store heavy metals like iron and perform phagocytosis
what are the two things included in liver pathology?
cirrhosis and hemachromotosis
what is cirrhosis? what is it caused by? what are the symptoms?
damage to the hepatocytes (chronic liver damage)
- caused virally (hepatitis) or alcohol-related
- symptoms: jaundice, edema, ascites
jaundice
too much bilirubin
ascites
accumulation of fluid between the visceral and parietal peritoneum from hypertension in the hepatic portal vein
edema
peripheral swelling due to decreased production of plasma proteins leading to decreased BCOP… means more filtration to the tissues
hematochromotosis
Kupffer cells hoard iron
- the same symptoms as cirrhosis including high plasma iron and damages other organs
what happens in the pancreas?
the acini is stimulated by the cholecystokinin andthe parasympathetic nervous system to produce pancreatic juices
what do pancreatic juices contain?
- proteases (trypsin, chymotrypsin, and elastase
- pancreatic amylase
- lipase
- deoxyribose and ribose nucleases
what does a protease do?
- are enzymes that catalyze the hydrolysis of peptide binds between amino acids
trypsin
produced and released by the pancreas in its inactive form of trypsinogen
what converts chymotrypsinogen into chymotrypsin?
trypsin
elastase
breaks down elastin (protein that provide elasticity to the tissue)
what is the autoregulation for the digestive system?
stretch, pH, and paracrine factors that stimulate secretion/inhibition of glands and cells (enteroendocrine cells)
what is involved in nervous system regulation of the digestive system?
- parasympathetic regulation: stimulates digestive activities
-sympathetic regulation: inhibits digestive activities
-enteric division: (short reflexes) the sensory receptors in the enteric motor neurons in the submucosal and myenteric plexuses activate peristalsis
break down/absorption of carbohydrates
*salivary amylase and pancreatic amylase break carbohydrates down into disaccharides and trisaccharides
* brush border enzymes break disaccharides and trisaccharides down into monosaccarhdirdes
what are the types of monosaccharides are di and trisaccarides broken down into?
*lactase - breaks lactose into glucose and galactose
*maltase - breaks maltose into tow glucose
*sucrose- breaks sucrose into glucose and fructose
how are monosaccarides absorbed into the intestinal epithelium?
facilitated diffusion, this uses uni porters, then the monosaccharide is cotransporter with sodium into the blood stream
protein breakdown and absorption
proteases break down proteins into dipeptides,tripeptides, and amino acids
how are proteins absorbed into the intestinal epithelium?
- co transport with Na, or with H in combination with counter transport of K
- or just counter transport with H
(these are all multiporters)
lipid breakdown and abosorption
lipases break down lipids into fatty acids and monoglycerides
how are lipids absorbed through the intestinal epithelium?
the monoglyceride and fatty acid bind with bile salts to produce micelles
- the micelles use simple diffusion to be absorbed by the intestinal epithelium
what happens when the micelle enters the cell?
the micelle is reconverted into a triglyceride and coated with proteins now called a chylomicron (a type of lipoprotein)
what then happens to the chylomicrons?
the chylomicrons are then exocytosed into lacteals, and then returned to the blood
how is water absorbed?
moves osmotically
how are ions absorped?
move according to concentration gradient
how is calcium absorbed?
calcitriol, PTH, an calcitonin
what are the fat soluable vitamins? and how are the absorbed?
vitamin A, D, E, and K
these are absorbed with micelles
what are the water-soluble vitamins and how are they absorbed?
vitamins B and C
* these are asborbed through simple diffusion
what is the water-soluble vitamin that is not absorbed through simple diffusion and how is it absorbed?
vitamin b 12 and binding to intrinsic factors
how is acteyl co A made for the krbes cycle
- deamination made by products of keto acid and ammonia
- the keto acid then reacts with coenzyme A then forms acetyl co A which then enters the Krebs cycle - other amino acids (glucogen amino acids) can break down directly into pyruvate acid and can react with coenzyme A and create acetyl co A
why is it better to not use proteins for energy?
- they are required for structural purposes
- deamination makes a toxic by-product called ammonia
- deamination can result in ketoacidosis
what are the difference between lipids and glucose?
- lipids supply energy at a slower rate (lipids are more effective)
- lipids are used more by muscles during rest and during endurance activities (lipid uptake increased from the blood )
- glucose is used more by muscles during intense activities (glucose uptake from blood is increased)
when is glycolysis/pyruvate used?
when we are in need for quick and easy glucose/ quick energy
when id deamination done?
when we have nothing else
where does spermatogenesis occur?
in the seminifirous tubules in the testes
where are the testes located and why?
the testes are located outside the body because the sperm needs a lower temperature
how what does spermatogenesis start with and what happens during this stage?
it starts with spermatogonia
* in this stage, stem cells are located in the outer pars of the tubule and during mitosis one is split into primary spermatocytes
describe and explain what happens with the primary spermatocytes
- the primary spermatocytes are close to the lumen, has 46 chromosomes, and divide by meiosis one to produce secondary spermatocytes
describe and explain what happens with the secondary spermatocytes?
- these are closer to the lumen, have only 23 chromosomes and divide by meiosis 2 into spermatids
describe and explain what happens with spermatids?
at the lumen, haploid, and they develop into spermoctyes
what is the complete process of spermatogenesis?
it starts with spermatagonia, which is divided by mitosis, then its the primary spermatocytes which is divided by meiosis 1, then the secondary spermatocytes are divided by meiosis 2 into spermatids which then develop into spermatocytes
how do the testes develop and what do they descend down and when?
retroperitoneally, they desecend down into the inguinal canals before birth
cryptorchidism
failure of the testes to descend
sustentacular cells
located in the seminiferous cells in the testes
- these aid in spermatogenesis
functions of sustentacular cells
- blood testes barrier: maintains the required environment for sperm development
- produce inhibins when stimulated by FSH; they inhibit FSH production
*secrete androgen-binding protein: increase testosterone levels
what are the male accessory organs?
the prostate gland, the bulburetoheral glands, and the seminal vesicles
prostate gland
produces seminal plasmin (antibiotic)
seminal vesicles
produce fructose, fibrinogen, and prostaglandins
bulboursthreal (cowlers ) gland
produces lubricants and buffers
male gnRH
- from the hypothalamus
*stimulates the release of FSH and LH
FSH
*stimulates sustentacular cells to promote spermatogenesis
LH
- stimulates interstitial cells to produce testosterone
testosterone
- primary male androgen
- stimulates:
- sustentacular cells
-sex drive
-secondary sex characteristics
-cartilage, muscle, and protein synthesis
