Chapter 44 bio
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Cannot tolerate substantial changes in external osmolarity
Can survive large fluctuations in external osmolarity.
How do marine sharks osmoregulate?
Internal salt concentration less than seawater, so salt tends to diffuse in. However, not hypoosmotic to water. Contains urea in its tissues. Also contains trimethylamine oxide, which protects proteins from damage from urea. This combination of salts, urea, and TMAO results in similar osmolarity to seawater which is why they are considered osmoconformers. However, they are actually slightly hyperosmotic to seawater, which results in water flowing in (not too much). Also sharks get water from food. Sharks remove this water by urine, which also removes some salts.
What is the process in which an aquatic animal that lives in temporary ponds loses almost all of its water?
What is transport epithelia?
Specialized epithelial cells which regulate solute movement in controlled amounts and specific directions.
Kind of nitrogenous waste excreted depends on what?
Availability of water and reproductive mode (animals that lay hard-shelled eggs secrete wastes as uric acid)
Protonephridia vs metanephridia (where are they found)?
Pro- flatworms, rotifers, etc
metanephridia - some annelids (such as earthworm)
How do arthropods osmoregulate and remove waste??
Use malpighian tubules
What occurs in proximal tubule?
Reabsorption of salts, glucose, amino acids, other essential nutrients, and water. Processing in the proximal tubule helps to maintain a constant pH; the transport epithelium secretes H+ into the proximal tubule but also secretes NH3 to buffer the H+. 90% of HCO3 absorbed. Also, some toxic materials are secreted into the filtrate from surrounding tissues (liver).
What occurs in descending limb of loop of henle?
Reabsorption of water continues since Inner medulla is hyperosmotic to filtrate.
What occurs in ascending limb of loop of henle?
NaCl diffuses out in the thin and thick segments of the ascending limb.
What occurs in the distal tube?
The distal tube regulates the amount of NaCl secreted out of the filtrate and the amount of K+ into the filtrate based on concentrations in body fluids. The controlled secretion of H+ and reabsorption of HCO3 contributes to pH regulation
What occurs in the collecting duct?
The collecting duct permeability is dependent on hormones that together regulate osmolarity, blood pressure, and blood volume. If the kidney is absorbing water, aquaporin channels in the collecting duct will open, causing water to diffuse into the interstitial fluid while the membrane is impermeable to salt and urea (in renal cortex). To produce dilute urine, the collecting duct allows salts to pass but not water.
The inner medulla collecting duct becomes permeable to urea, allowing some to pass into interstitial fluid.
What is a mOsm?
1 mOsm = 10^-3 M
Juxtamedullary nephron contributes to ____ conservation in terrestrial animals
Juxtamedullary nephron contributes to water conservation in terrestrial animals
ADH is produced and stored where?
produced in hypothalamus and stored in posterior pituitary gland.
How does ADH work?
ADH is released when blood osmolarity >300. Opens aquaporins in distal tubules and collecting ducts. When blood osmolarity low, ADH secretion decreases which means less aquaporins, which means more dilute urine.
How does RAAS work?
When blood pressure/volume decreases substantially (reduced salt intake, dehydration, blood loss), the JGA releases enzyme renin, cleaves plasma protein angiotensinogen to angiotensin II. Angiotensin II causes arterioles to constrict, which decreases blood flow to kidney. This stimulates the release of aldosterone, which causes distal tubule to absorb more salt and water.
How does ANP work?
ANP is released in response to increased blood pressure/volume. Inhibits release of renin and aldosterone and inhibits NaCl reabsorption.
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