Final Flashcards
Fundamental problem of Osmoregulation and Ion Regulation
Protein function:
- is affected by ion concentration
- is optimal within a narrow range of inorganic ion concentration
What does changes in ion and water content affect?
Protein and cell function
What is the function of macromolecules affected by?
Their aqueous environment
When solutes interact with proteins what does that affect?
Stability and function
What is less inhibitory?
Potassium
Where does water move from?
Low solute concentration to high solute concentration. Across an osmotic gradient
Can water be actively pumped?
No
What does changes in osmolarity cause?
A transmembrane osmotic gradient and therefore water moves across the membrane affecting cell volume
Osmolarity
The measure of solute concentration (number of osmoles per litre)
What is a critical problem faced by all cells?
Maintenance of a constant volume in the face of extracellular and intracellular osmotic perturbations
What does volume perturbations activate?
Volume regulatory mechanisms
3 types of organic osmolytes:
- Carbohydrates
- Amino acids and their derivatives
- Methylamines
Perturbing
Disrubt metabolism when they are in high concentration or when large shifts in their concentrations occur
Compatible (non-perturbing)
Do not affect protein function
Two strategies animals use to deal with osmotic stress
- Osmoconformers
2. Osmoregulators
Osmoconformers
Body fluids and cells are equal in osmotic pressure to the environment. Mainly found in the oceans
Osmoregulators
Osmotic pressure of body fluids is homeostatically regulated and usually different from the external environment
Role of Osmoregulators:
-Maintain extracellular osmolarity and ion composition constant
Role of Osmoconformers:
-Do not actively control the osmotic conditions but may control extracellular osmolytes
What are two types of Osmoconformers?
- Stenohaline
- Euryhaline
Stenohaline Conformer
- Restricted to a narrow range of salinity
- Cannot regulate their osmolytes to compensate
Euryhaline Conformer
- Tolerant of changes in salinity
- Successful in intertidal zones
- Regulate organic osmolytes in their cells
Where are compatible osmolytes conserved?
In Osmoconformers
What do compatible osmolytes have?
Strong selective pressures
What are most vertebrates?
Osmoregulators
What are sharks? Why?
Osmoconformers because they maintain high concentration of a perturbing osmolytes, urea
Osmoregulatory Organs
- Depends on transporting epithelia
- External surfaces (gills, skin)
- Salt glands
- Gut
- Kidneys
What are marine osmoregulators?
Hypo-osmotic
What are freshwater osmoregulators?
Hyperosmotic
Hypo-osmotic osmoregulators
- Have low concentrations of organic osmolytes
- Marine animals must drink seawater and absorb NaCl to absorb water by creating excess salt in the blood
Hyperosmotic osmoregulators
-Cope with the low osmolarity of fresh water
Kidney
-Internal organ concerned with osmoregulation
Two different mechanisms that lead to primary urine:
- Ultrafiltration
- Active Secretion
3 Regions of the Kidney:
- Renal Cortex–Outer
- Renal Medulla–Inner
- Renal Pelvis–drainage are in center
What is the smallest functional unit of the kidney and what does it consist of?
Nephron- Tubule and vascular component
What is nephron responsible for?
Formation of urine
What are 3 basic nephron processes?
- Glomerular Filtration
- Tubular Reabsorption
- Tubular Secretion
Glomerular Filtration
- Separation of plasma fraction of the blood
- Dived by blood hydrostatic pressure
Loop of Henle
- Establishes osmotic gradient in the medulla
- Reduces the osmotic pressure of the filtrate
Distal Convoluted Tubule
- May dilute the filtrate
- Regulates sodium and potassium in the blood
The Collecting Duct
-Permeable to water
Nephridia
- Primitive Kidney
- Filtration-reabsorption systems
What might modify ion concentration?
Some tubule cells
Metanephridia
- Most annelids, mollusks and arthropods
- Osmoregulation and nitrogenous wastes
- Filtrate coelomic fluid
What are involved in nitrogen waste excretion?
Osmoregulatory organs
What is the problem with nitrogen waste?
- Metabolism of proteins and nucleic acids
- Produces ammonia
Ammonia
- Very soluble in water and toxic at low concentrations
- Easily permeates membranes
- Excretes urea
Urea
- Uses energy to create
- Sacrifice less water
- Less toxic that ammonia
Why is there a need for a respiratory system?
- Gas Exchange
- Diffusion of Oxygen
Diffusion
A random walk from a region of high concentration to a region of lower partial pressure
Total Lung Capacity (TLC)
Maximum amount of air that the lungs can hold
Tidal Volume (TV)
Volume of air entering or leaving the lungs during a single breath at rest
Functional Residual Capacity (FRC)
Volume of air in the lungs at the end of a normal passive expirations
Residual Volume (RV)
Maximum volume of air remaining in the lungs after a maximal expiration
Vital Capacity (VC)
Maximum volume of air that can be moved out during a single breath followed by maximal inspiration
How is oxygen transported in animals?
Diffusion