Osmoregulatory and Excretory system Flashcards
What Two processes help maintain fluid and electrolyte (salt) homeostasis in animals?
Osmoregulation and excretion
What challenge do marine animals have in regard to water?
Osmotic water loss
What challenge do freshwater animals have in regard to water?
Osmotic water gain
What challenge do terrestrial animals have in regard to water?
Desiccation (drying out)
What do electrolytes form in solution?
Ions
What are osmoconformers?
No regulation of osmolarity; their internal environment is osmotic in relation to the external environment.
What are osmoregulators?
They tightly regulate their body osmolarity, maintaining constant internal conditions.
What are the pros and cons of being an osmoconformer?
Restricted to certain environments, but expend less energy on osmoregulation.
What is the con of being an osmoregulator?
Energy
Define osmolarity
A measure of the number of osmoles of solute per liter of solution
What are the principal metabolic waste products?
Water, carbon dioxide, and nitrogenous wastes (ammonia, uric acid, urea)
What does extracellular fluid include?
Interstitial fluid, lymph, and blood plasma (or hemolymph)
Define osmotic pressure
The pressure that must be exerted on the hypertonic side of the membrane to prevent net movement of water from the hypotonic side
What do excretory systems do?
Help maintain fluid and electrolyte homeostasis by selectively adjusting the concentrations of salts and other substances in blood and body fluids
Marine invertebrates are ____
osmoconformers
Costal marine animals are ____
osmoregulators
What do nephridial organs do?
Function in osmoregulation and excretion in many invertebrates
What makes up nephridial organs?
Each nephridial organ consists of simple or branching tubes that open to the outside of the body through nephridiopores
What are the two types of nephridial organs?
Protonephridia and metanephridia
The main osmoregulatory and excretory organ in most vertebrates is the _____
kidney
Gills excrete what?
Ammonia
Sweat glands can excrete what percent of metabolic wastes?
5% to 10% of all metabolic wastes
Birds and mammals have a high rate of ____ and produce a large volume of ____ _____.
Birds and mammals have a high rate of metabolism and produce a large volume of nitrogenous wastes
Birds excrete ____ ___, mammals excrete ____
Birds excrete uric acid, mammals excrete urea
What does skin do in regards to the excretory system?
Reptiles, birds, and mammals have skin that minimizes water loss, and many excrete urea or uric acid
What does the urinary system consist of?
Kidneys, urinary bladder, and associated ducts
What is micturition?
When urine is released from the bladder and flows out of the body through the urethra
Describe where urine is created and where it goes from there
Urine is produced in kidneys and flows through a ureter to the urinary bladder, then out the urethra
What covers each kidney?
A connective tissue capsule
What is the outer portion of the kidney called?
Renal cortex
What is the inner portion of the kidney called?
Renal medulla
What does the renal medulla contain?
8 - 10 cone-shaped renal pyramids
What is the type of each pyramid in the renal medulla called?
A renal papilla
What does each renal papilla have?
Several pores, the openings of collecting ducts
How does urine flow through the kidney?
Urine flows from collecting ducts through a renal papilla and into the renal pelvis
What is a nephron?
A functional unit of the kidney
What do the kidneys produce?
Renin and erythropoietin
What does erythropoietin do?
Stimulates RBC production
What does the nephron consist of?
A cuplike Bowman’s capsule connected to a long, coiled renal tubule
What is within the Bowman’s capsule?
A cluster of capillaries called a glomerulus
What are the three main regions of the renal tubule?
Proximal convoluted tubule, the loop of Henle, and distal convoluted tubule
How is blood delivered to the kidneys?
Through the renal artery
Afferent arterioles conduct blood into what?
Capillaries of a glomerulus
As blood flows through glomerulus what happens?
Some plasma is forced into Bowman’s capsule
Where does blood flowing from the glomerular capillaries go?
Into an efferent arteriole
Where does blood go after the efferent arteriole?
Efferent arterioles deliver blood to peritubular capillaries which return materials to the blood, which flows in small veins to the renal vein
What is the juxtaglomerular
apparatus?
A small group of cells located in the walls of the tubule and arterioles near the Bowman’s capsule
What are the two types of nephrons in the kidney?
Juxtamedullary and cortical
What are cortical nephrons?
They’re more numerous, more superficial, have relatively small glomeruli, and are located almost entirely within the cortex or outer medulla
What are juxtamedullary nephrons?
They’re more internal, have large glomeruli, and long loops of Henle that extend deep into the medulla
What does the loop of Henle consist of?
A descending limb and an ascending limb
What does the descending limb of the loop of Henle do?
It receives filtrate from the proximal tubule
What does the ascending limb of the loop of Henle do?
It’s where filtrate passes to the distal tubule
Urine is produced by what three processes?
Filtration, reabsorption, tubular secretion
Blood flows through glomerular capillaries under high pressure, forcing more than ____% of the plasma out of capillaries and into Bowman’s capsule
10%
What forms the filtration membrane?
The porous walls of the glomerular capillaries and the filtration slits between podocytes
What does the filtration membrane do?
It’s highly permeable to water, small molecules, and ions but restricts the passage of blood cells and large molecules.
What permits precise regulation of blood chemistry by the kidneys?
Reabsorption by renal tubules
What is returned to the blood by the kidneys?
Needed substances such as water, salt, glucose and amino acids are returned to the blood
What things remain in the filtrate and are excreted as urine?
Wastes, excess salts, and other materials
~___% of the filtrate is actively reabsorbed as it passes through the proximal tubule
~65%
What things are completely reabsorbed by the proximal tubule?
Glucose, amino acids, vitamins, and other substances of nutritional value
What things are partially reabsorbed by the proximal tubule?
Many ions, including sodium, chloride, bicarbonate, and potassium
Where does reabsorption continue after the proximal tubule?
Through the loop of Henle, the distal tubule, and the collecting duct
What is the tubular transport maximum?
Maximum rate at which a substance can be reabsorbed
What are the general regions of glomerular filtration, tubular reabsorption, and tubular secretion?
The glomerulus filters blood. As the glomerular filtrate moves through the renal tubule, its composition is adjusted by selective reabsorption and tubular secretion. The adjusted filtrate is urine.
Define tubular secretion
The selective transfer of substances from blood in the peritubular capillaries into the renal tubule
What happens when blood becomes too acidic?
Collecting ducts secrete more H+ into the urine
What are 4 examples of hormones involved in the regulation of kidney function?
Antidiuretic hormone, aldosterone, angiotensin II, and atrial natriuretic peptide
Explain how the release of antidiuretic hormone occurs
Receptors in hypothalamus sense osmotic changes in blood due to dehydration, signaling the posterior pituitary lobe to release antidiuretic hormone
What produces Atrial Natriuretic Peptide (ANP)?
The heart
What does ANP do?
Increases Na+ excretion; decreases blood pressure
