week 11 (digestive system -digestion, eliminative, absorptive & distributive processes; utilization processes: liver & cell metabolism) Flashcards
digestion
l: digestive system
f: complex process of turning the food you eat into nutrient
absorption
l: happens mostly in small inestine
f: absorp nutrients and vitmins in food
metabolism
l: mostly liver
f: keeps the body at homeostatis
mechincal digestion
purely physical process that does not change the chemical nature of the food. Instead, it makes the food smaller to increase both surface area and mobility.
chemical digestion
Chemical digestion involves the secretions of enzymes throughout your digestive tract. These enzymes break the chemical bonds that hold food particles together.
mastication
definition: chewing
area(s): mouth
how it process facilitates digestion: mechinal digestion
muscle tissue: in the jaw and mouth region
branch of motor nervous system: voluntary
degulitition
definition: swallowing
area(s): throat/buccal cavity
how it process facilitates digestion: allows food to go to eposgus
muscle tissue: touge
branch of motor nervous system: voluntary
propulsion
definition: pushing/forcing food towards an area
area(s): buccal cavity, stomach, small intestine, large, rectum
how it process facilitates digestion: allows food to continue to move throughout the tract
muscle tissue: tonuge, smooth muscle tissue
branch of motor nervous system: voluntary/involuntary
perisalisis
definition: wave like contractions
area(s): eposgus and stomach
how it process facilitates digestion: moves food and further digests it
muscle tissue: smooth muscle tissue
branch of motor nervous system:involuntary
segmantation
definition: separates chyme and then pushes it back together
area(s): intestines
how it process facilitates digestion: always chyme to be chemical digested and absported
muscle tissue: smooth muscle
branch of motor nervous system: involuntary
defactation
definition: pooping
area(s): rectum/anus
how it process facilitates digestion: release of feces
muscle tissue: smooth mucle
branch of motor nervous system: involuntary/ vountary
vomiting
Vomiting is the body’s way of protecting you from threats. When it detects a harmful substance or something irritating, your body actually thinks you’re being poisoned. The body’s natural reaction is to rid the body of that threat, causing it to expel the contents of the stomach.
diaharring
the contents in your digestive system move so quickly through the digestive system that the intestines don’t have enough time to absorb the fluids, or when the digestive system produces extra fluid. The result is stools that contain excess fluids, making them loose and watery.
consitputation
waste or stool moves too slowly through the digestive tract or cannot be eliminated effectively from the rectum, which may cause the stool to become hard and dry.
digestive enzymes
Amylase
- made in the pancreas and salivary glands
- startch to maltose
Maltase
- maltose to glucose
- made in small intestine
Lactase
- lactose to glucose/galactose
- made in small intestine
Lipase
- lipids (fats/oils) to fatty acids/glycerol
- made in pancreas
Proteases
- protien to amino acids
- made in pancreas/stomach
what must ____ be reduced to to be digested
a. carbohydrates (polysaccharides) - glucose
b. fats (lipids) - fatty acids
c. proteins (polypeptides) - amino acids
chyme
the pulpy acidic fluid which passes from the stomach to the small intestine, consisting of gastric juices and partly digested food.
hydrolysis
Hydrolysis is any chemical reaction in which a molecule of water breaks one or more chemical bonds
chemical digestion of the stomach
a. Hydrochloric acid
Hydrochloric acid helps your body to break down, digest, and absorb nutrients such as protein. actives pepsinogen
b. Pepsinogen (inactive pepsin)
a substance which is secreted by the stomach wall and converted into the enzyme pepsin by gastric acid.
c. Mucus
Gastric mucus is a gel-mucous barrier secreted by epithelial cells and glandular cells in the stomach wall. It acts as part of a barrier that protects the stomach wall from the acid and digestive enzymes within the stomach lumen.
d. Gastric lipase
an acidic lipase secreted by the gastric chief cells in the fundic mucosa in the stomach
pancreatic juices
a. Trypsin (inactive to not digest pancreas)
-digest proteins into peptides
b. Chymotrypsin
-digest proteins into peptides
c. Carboxypeptidase (inactive to not digest pancreas)
-digest proteins into peptides
d. Pancreatic lipase
-the principal triglyceride–digesting enzyme in adults
e. Pancreatic amylase
-starch-digesting enzyme
enterokinase
a protease of the intestinal brush border that specifically cleaves the acidic propeptide from trypsinogen to yield active trypsin
how do bicarbonates in pancratic juices help with digestion
in neutralising the low pH of the chyme coming from the stomach
role of bile in lipid molecules
lipid carriers and are able to solubilize many lipids by forming micelles - aggregates of lipids such as fatty acids, cholesterol and monoglycerides
small intestine enzymes
protease
- protien to amino acids
- made in pancreas/stomach
maltase
- maltose to glucose
- made in small intestine
lactase
- lactose to glucose/galactose
- made in small intestine
sucrase
-sucrose to fructose/glucose
-made in small intestine
mechincal digestion in large intestine
a. haustral churning
haustra remains relaxed and become distended while they fill up. - when distension reaches maximum fill, walls contract and squeeze contents into next haustra.
b. peristalsis
wave like contractions to move food
c. mass peristalsis
strong peristaltic wave that begins in transverse colon and drives contents of the colon into the rectum
body flora in large intestine
plays important roles in angiogenesis and maintenance of mucosal barrier integrity
endocrine hormones which aid in digestion
a. Gastrin
- stimulation of acid secretion from gastric parietal cells
- stimulation of mucosal growth in the acid-secreting part of the stomach
- produced by ‘G’ cells in the lining of the stomach and upper small intestine
b. Cholecystokinin (CCK)
- stimulates the gallbladder to contract and release stored bile into the intestine
- made on duodenum
c. Secretin
- hormone released into the bloodstream by the duodenum (especially in response to acidity) to stimulate secretion by the liver and pancreas.
- made in small intestine
enteric nervous system
The enteric nervous system consists of the neurons and neuroglia cells found within the wall of the digestive tract. More specifically, it consists of two interconnecting ganglionated plexuses: one located between the circular and longitudinal smooth muscle layers; and one located within the submucosa.
The neural ‘circuitry’ of this system includes sensory, motor and interneurons. This means it can make complex reflex responses even when all connections to external neural ‘circuitry’ are severed.
Normally, the enteric nervous system governs the basic activity of the digestive system including peristaltic contractions of the outer muscle layers, movement of the muscularis mucosa, and secretions of the mucosa and submucosa glands.
Although visceral smooth muscle contracts spontaneously, the coordination required for peristalsis, segmentation, mixing, etc. depends on the enteric nervous system
relationship between enteric and automatic nervous system
The autonomic nervous system alters the activity of the enteric nervous system, as well as having direct contact with other digestive wall tissues.
The parasympathetic axons terminate at the enteric plexuses and at smooth muscle and glandular epithelial tissue directly. Impulses on the parasympathetic neurons cause an increase in smooth muscle motility and an increase in glandular secretions.
The axons of the sympathetic motor axons terminate at the enteric plexuses and on the smooth muscle tissue (both in the wall of the digestive tract and the wall of the blood vessels).
The release of norepinephrine from the axon terminals slows muscle motility in the gut wall and reduces glandular secretions.
neurtal reflexes
Many neurons of the ENS are components of GI (gastrointestinal) reflex pathways that regulate GI secretion and motility in response to stimuli present in the lumen of the GI tract.
The initial components of a typical GI reflex pathway are sensory receptors (such as chemoreceptors and stretch receptors) that are associated with the sensory neurons of the ENS. The axons of these sensory neurons can synapse with other neurons located in the ENS, CNS, or ANS, informing these regions about the nature of the contents and the degree of distension (stretching) of the GI tract.
The neurons of the ENS, CNS, or ANS subsequently activate or inhibit GI glands and smooth muscle, altering GI secretion and motility
digestive gland secretions
a. Saliva
i. average in 24 hrs
ii.
b. Gastric juices
i. average in 24 hrs
ii.
c. Pancreatic juices
i. average in 24 hrs
ii.
d. Bile
i. average in 24 hrs
ii.
e. Intestinal juices
i. average in 24 hrs
ii.
metabolism
is the chemical reactions in the body’s cells that change food into energy
catabolism
the sequences of enzyme-catalyzed reactions by which relatively large molecules in living cells are broken down, or degraded
anabolism
Anabolism requires energy to grow and build
he synthesis of complex molecules in living organisms from simpler ones together with the storage of energy
nutrient
six principle classes
- proteins - building blocks
- carbs - fuel your body
- fats- supports vitamin and mineral absorption, blood clotting, building cells, and muscle movement
- vitamins- warding off disease
- minerals- help support the body
- water - hydrate
protein anabolism
a. nutrient type used in the process
Amino acids
b. key events of protein synthesis
amino acid synthesis
transcription
translation
post translational modifications
protein folding
c. four hormones that stimulate protein synthesis
Insulin, GH and IGF-I
d. four examples of jobs proteins do within all cells
helps repair and build your body’s tissues, allows metabolic reactions to take place and coordinates bodily functions. In addition to providing your body with a structural framework, proteins also maintain proper pH and fluid balance.
e. examples of protein(s) produced by the following cell types in order to do their job:
red blood cell Hemoglobin
skeletal muscle cell actin and myosin
fibroblast fibrin, fibronectin, and collagen
liver cells Major plasma proteins
protein catabolism
a. role of proteases
digesting long protein chains into shorter fragments by splitting the peptide bonds that link amino acid residues
b. product(s) produced
amino acids
c. conditions (e.g. hormone) that could trigger protein catabolism
glucagon, glucocorticoids and adrenaline
cellular respiration in relation to catabolism
C6H12O6 + 6O2 → 6CO2 + 6H2O
catabolism is breaking bonds which is seen here
cellular respiration and throixyn
has a profound effect on cellular respiration. Abnormally high levels of this hormone accelerate respiration in conjunction with a general increase in metabolism while pathologically low amounts cause low levels of respiration with a general slowing of metabolic activity
lipid anabolism
a. description of lipogenesis
Lipogenesis is defined as the synthesis of fatty acids from nonlipid precursors
b. example of hormones which stimulate lipogenesis
high carbohydrate diet
lipid catabolism
a. description of lipolysis
metabolic process through which triacylglycerols (TAGs) break down via hydrolysis into their constituent molecules: glycerol and free fatty acids
b. example of hormones which stimulate lipolysis
noradrenaline (epinephrine), noradrenaline (norepinephrine), glucagon, growth hormone and cortisol
