(2) Homeostasis Flashcards
Diffusion
molecules move passively from high to low concentration
Osmosis
diffusion of water
Freshwater
hypotonic = less solute/ more water outside cell, so water will diffuse INTO cell
Saltwater
hypertonic = more solute/ less ater outside of cell, so water will diffuse OUT of cell
Isotonic
balance/equilibrium
Marine Environment (invertebrates)
Ex. cnidarians, crustaceans, echinoderms
-MOST invertebrates are in osmotic equilibrium with saltwater
Freshwater Environment
water is flowing in and ions are flowing out = hypotonic
-crabs and fish need to maintain a higher ion concentration
-hypersomatic regulators
Marine Environment (fish)
- water is flowing out and ions are flowing in = hypertonic
-Hyposomatic regulators
-must drink saltwater
-excrete salt via salt glands
Terrestrial Environment
lose water in respiration, evaporation, excretion
- ions ingested
-H2O ingested and produced by metabolism
-Protein -> ammonia to be excreted
Invertebrates (Excretion)
Nephridium (kidney in greek) filters blood -> body waste
a). Protonephridium: flame cekk, flatworm
b). Metanephridium: more advanced design; molluscs, annelids
c). Antennal Gland: crustaceans
d). Malphigian Tubules: insects, spiders
Vertebrates (Excretion)
kidney
Mammalian Kidney Structure
(outer) Cortex -> hypotonic
(inner) Medulla -> hypertonic
- blood via renal artery and vein
- urine via ureter -> bladder->urethra
Nephron
functional unit
Functioning of Kidney
- Glomerular filtration
- Tubular reabsorption
- Water excretion
- Tubular secretion
Glomerular Filtration
- Blood pressure filters out the glomerulus, collected in Bowmans’s capsule
- Filtrate included H2O, inorganic ions, glucose, amino acids, vitamins, urea, etc = small
- Leaves behind rbc, plasma proteins = large
Tubular Reabsorption
- Diffusion and active transport of solutes back into interstitial fluid and blood capillaries from the primary filtrate
- Water by osmosis follows these solutes out of primary filtrate to be retained by body
- H2O, urea, and Na+ are left behind as the primary filtrate
Aquaporins
water needs these protein channels in the cell membrane of PCT wall to pass through plasma amembrane
Microvilli
epithelial cells of wall of PCT have increased surface area to aid movement of these solutes out of primary filtarte
Water Excretion
- Preliminary structural features
- movement of H2O leaves primary filtrate by osmosis in descending LoH via aquaporins
- Movement of NaCl
Tubular Excretion
- Inorganic ions are secreted actively or passively into urine
- drugs, and other foreign materials also secreted
3 Homeostatic regulation of blood pressure/osmotic concentration
Vasopressin
hypothalamus of brain signals anterior pituitary to release antidiuretic (ADH)
Vasoconstriction=
Renin activates angiotensis
ADH=
more aquaporins = more water from urine
Aldosterone=
more Na+ and H2O from urine - also thirst
Natural Diuretics
caffeine, alcohol, celery, tomatoes, watermelon
Urinary Bladder Structure
- Bladder wall=smooth muscle
- Internal urethral sphincter at bottom= smooth muscle
- external urethral sphincter at very bottom= skeletal muscle
Urinary Bladder Functioning
200-400ml produces pressure; stretch receptors initiate reflex arc
- bladder wall contracts
- internal and external urethral sphincter relaxs
- urination =micturate
Incontinence
prior to two years of age, urination is involuntary. the sphincter is not fully developed, it must be learned.
Ectotherms (Cold blooded)
heat is produced by metabolism, but it is lost as fast as it is produced, body temperature is determined by the environmental temperature
Ectotherms Behavioral Adjustments
bask, seek shade
Ectotherms Physiological Adjustments
vasodilatation and vasoconstriction to shunt blood closer to or farther from surface to aid warming and cooling
Ectotherms Metabolic Adjustments
“temperature compensation”=enzyme variants designed to function better under warmer or cooler temperatures
Endotherms (warm-blooded)
heat production is by metabolism and muscle contraction; van be regulated to some degree
Radiation (endotherms)
by electromagnetic waves
Conduction (endotherms)
by direct contact
Convection (endotherms)
by moving air
Evaporation (endotherms)
cooling as water evaporated from a surface
Small Mammals Hot Environment Response
nocturnal, fossorial
Large Mammals Hot Environment Response
- Light fur reflects heat
- Heat lost from the underside
- Body heat stored during day and lost passively at night
- Concentrated urine, dry feces
- fat concentrated is one spot on back to avoid trapping heat
Cold weather response- Increase Heat Production
hormones -> mitochondria produce heat vs more ATP
Cold weather response - Decrease Heat Loss
- Behavioral, ectotherms
- Increase insulation (fur, feathers)
- Countercurrent
- Torpor: short-term (night) controlled lowering of body temp. decrease fuel needs
