Exam 4 Flashcards
alimentary canal organs
mouth
esophagus
stomach
small intestine
large intestine
rectum
anus
common themes of animal digestion
-chemical digestion involving hydrolytic enzymes and water
-physical digestion involving muscles and specialized structures
-specialized organ/tissue/structure where absorption can occur
catalytic cycle of an enzyme
substrate enters active site specialized for substrate -> binds to enzyme -> substrate converted to products -> products are released -> water molecule is required
hydrolytic enzymes
water molecule is needed in order for it to work
works inside cells, lumen or are membrane associated
hydrolytic enzymes and carb digestion
digestion will be completed on gut villi surface
needs to occur before reaching capillaries because no food can be in blood
hydrolytic enzymes and protein digestion
smaller peptides move into the small intestines where peptidases are on brush-border of enterocyte
amino acids are cut form 4 to 3 so they can move into enterocyte
tripeptidase breaks them down so they can exit basolateral side into blood
digestion in simple animal digestive systems
digestion and absorbtion occurs in gastrovascular cavity
whatever cannot be digested will leave out through mouth
food phagocytized -> food vacuole -> digestive vacuole -> exocytosis
peristalsis
involuntary, wave-like muscle contraction that moves food
in humans, contraction of circular muscles behind bolus, longitudinal muscles ahead of bolus, and circular muscle layer moves food forward
physical digestion in birds
birds do not have teeth so food moves straight into esophagus and stored in crop
moves into proventiculus for some chemical digestion
moves into gizzard for physical digestion where a rough surface with coilin acts as teeth
gastric pits
lie in stomach lining
muscle also lines it to help churn food
contain parietal cells, chief cells, and g cells
also contains a thick mucus lining so that acid doesn’t destroy the lining (HCO3- neutralizes)
parietal cells
secrete HCl and intrinsic factor
the HCl secreted here will combine with pepsinogen to form active pepsin
chief cells
secrete the zymogene pepsinogen
g cells
secrete gastrin
digestion from stomach to the small intestine
partially digested foods combine with stomach liquids to make chyme
sphincter at the end of the stomach opens every once in a while to allow a bit of chyme into the small intestine(duodenum)
duodenum
beginning part of the small intestine
liver, pancreas, and gallbladder have ducts here
pancreas and digestion
produces enzymes to digest proteins
acinar cells secrete zymogens into duct
duct cells secrete HCO3- (neutralizes) and H2O (enables hydrolytic enzyme activity)
enteropeptidase allows this activity
pancreas zymogen cells
trypsinogen -> trypsin
chymotrypsinogen -> chymotrypsin
procarboxypeptidase -> carboxypeptidase
fat digestion
begins with lingual lipase (fats) in the mouth
emulsification
lipid droplets and bile salts combine to form emulsion droplets
emulsifying agent has water-loving molecules and fat-loving molecules to mix
liver delivers bile salts and act as elmulsifier
excess bile salts stored in gallbladder
pancreatic lipase
pancreas makes its own and delivers it to duodenum
micelles
carry fatty acids to SI border and diffuse across
chylomicrons
formed inside enterocytes (fatty acids, glycerol, protein)
move out of cells into lymphatic vesicles inside villi and then move into blood to be used by cells or stored in adipose tissue
carb digestion
most occurs in mouth with salivary amylase
once in small intestine, cells on enterocyte further break down carbs (maltase, sucrase, lactase)
pancreatic amylase also aids
any unabsorbed CHO will move to large intestine
large intestine digestion
primarily reabsorbs water from undigested food and stores waste material until it is eliminated
absorbs electrolytes back into blood
gut bacteria in LI can digest food as a final effort, helps gut health
HCl production stimulation
- acetylcholine from parasympathetic vagus nerve
- gastrin from g cells via bloodstream
- histamine released by released by neighboring mucosal cells
when all three bind, HCl is high
gastrin and gastric emptying
gastrin encourages sphincter muscles to relax and begin emptying
emptying is inhibited by prescence of acidic chyme in SI (duodenal cells secrete CCK and secretin to act on stomach, nerve reflexes slow down stomach contraction and rate of emptying)
glucose absorption
too big to simply diffuse across membrane
has to move against concentration gradient because higher conc in cell vs intestinal lumen
need help to cross membrane
permeability across lipid bilayer
ions with electrical charge are less permeable
hydrophobic molecules (fatty acids, hormones) and small gases are very soluble
water is permeable but crosses very slowly
facilitated diffusion
utilizing membrane proteins (channel or carrier)
still considered passive diffusion because no energy is required
membrane proteins are very selective
channel protein transport
transmembrane proteins permit passage of ions or water
gated channels open/close, leaky channels open all the time
faster than carrier-mediated transport
carrier protein transport
undergo reversible shape changes, binding on either side
transport large, water soluble substances
movement of uncharged particles
governed only by conc gradients
movement of charged ions is also based on electrical diff
typical animal cell electricity
ICF is more negatively charged than ECF in general
electrical differences actually enables cells to do work
movement guided by overall electrical gradient and differences
conduction
movement of ions due to electrical difference
active transport
movement of molecules across cell membranes against their conc or electrochemical gradient
requires ATP
principles of active transport
-uphill transport requires ATP
-specialized membrane protein is either active (creates own ATP) or secondary (using ATP from other sources)
properties of active transport carriers/channels
-bind noncovalently and reversibly
-binding is influenced by conformational changes in carrier
-carriers switch between open/close
-use up to 40% of an animals energy
-can move multiple specific molecules
-can be electrogenic (pumps generate electrical diff across membrane)
sodium potassium ATPase pumps
always active
typically more Na outside cell and more K inside
Na wants to move in because of conc and charge, K wants to move out because of conc
every cell has Na and K leak channels so ATPase pump fixes the problem with leaky channels
steps of ATPase
3 Na bind to protein channel -> ATP provides energy to change shape -> one phosphate stays bonded -> Na released in cell -> 2 K bind -> changes shape -> phosphate unbinds -> K leaves
glucose absorption in the gut
enabled by SGLT1, secondary active transport protein/carrier
glucose is low in gut and blood but high in cell
Na is low in cell and high in gut/blood
SGLT1 can move glucose into cell against conc gradient if it moves out an Na
substrate and enzyme activity at different temps
with inc temps, faster movement means more random movement and connections
when temps get too high, enzymes will denature
endothermy
ability of an organism to maintain a constant body temp through metabolic processes rather than relying on env temps
poikilotherm
organism with a variable body temp that tends to fluctuate with and is similar to/slightly higher than env temp
can thermoregulate through behavioral choices
temperature
random movement of matter
conduction vs radiation
- physical transfer between two surfaces
- transfer via air (sun reflecting off cloud)
convection vs evaporation
- wind taking away heat trying to be radiated
- sweat evaporates and takes heat with it
stenothermal vs eurythermal animals
- survive only in narrow body temp range, lots of behavioral thermoregulation
- tolerate wider range of body temps
acute temp changes impact on metabolic rate
with an incremental rise in temp, metabolic rate will increase, O2 consumption will inc, energy consumption will inc, and utilization of nutrients will inc
acclimation
something physiologically happens to lessen impact of metabolism brought on by long-term exposure to non-ideal temps
metabolic/aerobic scope
when metabolism at rest matches max rate of oxygen consumption, scope = 1
means no exercise can be done
occurs at critically high temps
pejus range
just above preferred temp range and turning worse
homeoflexibility adaptation
cold- flexible enzyme binding sites
warm- rigid enzyme binding sites
lipid difference with animals
cold- unsaturated (double bonds)
warm- saturated (rigid)
too much fluidity will denature the fatty acid
pros of being an endotherm
roam and survive in diverse env
less dependence on external heat sources
inc biochemical processes
day activities can move into the night
higher digestive rates
sustained locomotion
cons of being an endotherm
metabolic costs
have to generate internal heat
consume more energy (20x)
remove excess heat
thermoneutral zone
animal’s metabolic rate is ideal and unaffected by ambient temperature
basal metabolic rate
metabolic rate of a homeotherm within the thermoneutral range
vasomotor control
keeps blood warmed by core away from shell
reflex innervation of human skin circulation occurs via sympathetic noradrenic vasoconstrictor nerves
countercurrent exchange
arteries and veins organized side by side
allows for blood coming from the core to warm up blood going back
pilomotor response
goosebumps
arrector pili muscle stimulated by sympathetic ns
traps a thick layer of air closer to animal surface
neuromuscular activity
increases heat production
locomotion, breathing, and circulatory flow
larger animals stay warmer because core area is greater that shell area
thermogenesis
shivering- individual muscle fibers contracting at random
involuntary when muscle tone is inc when temps dec
not mechanical work so everything is heat
thyroid hormones and heat
thermogenic and help produce heat
increases basal metabolic activity, makes cell membranes more leaky, and increases size/# of mitochondria
brown fat
non shivering thermogenesis
contains triglycerides and specialized mitochondria
mitochondria contains UCP1 (thermogenin)
uncouples proton gradient in electron transport chain which means no ATP produced and all energy converted to heat
high quantities of brown fat in newborns, small animals, and hibernators
