Final: Excretion Flashcards
What is the primary function of excretion?
Remove excess materials from the body while preserving those needed.
What are the minerals reabsorbed?
water and ions (Na, K, Ca)
What are the minerals secreted?
nitrogen waste and blood break down products
What are the excretory structures?
- contractile vacuoles
- nephridium
- atennae glands
- malpighian tubules
- kidneys
What organisms have contractive vacuoles?
protozoa and freshwater sponges
What makes contractile vacuoles not a true excretory organ?
Nitrogen waste readily diffuses across cell membranes into surrounding water.
What is the primary function of contractile vacuoles?
To excrete excess water
What kind of organisms is contractile vacuoles more common in and why?
freshwater organisms, they’re isoosmotic
Describe the process contractile vassicles use
- conversion of carbon dioxide and water to form carbonic acid
- carbonic anhydrase as catalyst
- proton and bicarbonate pumped into vacuole (both solutes osmotically active)
- water follows
- fluid within vacuole is released to outside of cell
What is the most common excretory organ in invertebrate?
Nephridium
Protonephridium characteristics
- closed system
- flame cells system
- simplest of nephridium
Where are flame cells found?
at the end of nephridia
What do flame cells get their name from?
They are flagella grouped into a flame-like cluster
Describe the process that flame cells use.
- beat and drive fluid down ducts to outside through nephridiopores
- active absorption and excretion occures through cells on walls of collecting ducts
What is considered a true nephridium?
Metanephridia
What organisms have attennae glands?
Crustaceans
What organisms have metanephriadia?
Annelida
Decribe metanephridia funciton
- long tube open at both ends
- fluid enters by filtration
- reabsorption of salts and amino acids occurs in tubular system
- tubules surrounded by extensive capillaries (carry reabsorbed materials away)
Where are attennae glands located?
In the ventral part of the head
Describe the function of attennae glands?
- filtrate of blood formed at end sac
- selective reabsorption and active secretion occurs in tubular portion
What is the ideal form of exretion for terrestrial environments and what organisms have this?
malpighian tubules, arthopods
Describe the process of malpighian tubules
- work in conjunction with cells lining rectum
- closed tubules that lack direct arterial blood supply
- tubules float in hemolymph and actively pull material out of hemolymph and secrete into tubules
- work by utilizing a proton pump
- hydrogen ions are moved back in exchange for other ions (Na, K)
- water flows by osmosis
- fluid from tubules enter gut and move to rectum
- rectal cells reabsorb water
- excess water, salts, and waste such as uric acid are excreted with fecal matter
What are the 6 fuctions of the vertebrate kidney?
- Filtering the blood
- Regulation of blood volume
- Regulation of extracellular osmolarity
- Regulation of extracellular fluid pH
- Regulation of red blood cell synthesis
- Vitamin D activation
Describe how the kidney filters the blood (simple)
- metabolic waste removal (ammonia, urea, uric acid)
- excess water removed
- excess ions removed
- excess nutrients removed
How does the kidney regulate blood volume?
Controlling the amount of extracellular fluid
How does the kidney control extracellular osmolarity?
Control ion concentration (Na+, Cl-, K+, Ca++, HPO4 -2)
How does the kidney regulate pH?
Along with the buffer system, it aids in maintaining a constant internal pH
How does the kidney regulate RBC synthesis?
Uses erythropoietin, produced by the peritubular cells of the kidney, to stimulate the production of RBC in red marrow
How does the kidney do Vitamin D activation?
- cholecalciferol hydroxilation in kidney into active vitamin D (1,25-dihydroxycholecalciferol)
- necissary for dietary Ca++ absorption
What is the funcitonal unit of the kidney?
Nephron
Describe nephrons
- smallest structural component capable of producing urine
- large number increases chances of survival (1.25 million per kidney)
You can lose ___% of functional nephrons before renal insufficiency
75%
What are the 3 components of urine production?
- filtration
- reabsorption
- secretion
Describe filtration for urine production.
- the movement of fluid across filtration membrane
- filtrate is fluid entering nephron
Describe reabsorption for urine production
The movement of substances back into the blood
Describe secretion for urine production
The active transport of solute into the nephron
What is the formula for urine?
urine = filtration - reabsorption + secretion
What is the formula for filtration pressure?
Filtration pressure = GCP - COP - CP
What is GCP?
glomerular capillary pressure
What is COP?
colloid osmotic pressure
What is CP?
capsule pressure
