Chapter 44: Osmoregulation And Excrestion Flashcards
What is Osmoregulation?
the maintenance of constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations.
Gets rid of nitrogenous metabolites and other waste products
Excretion
The solute concentration of a solution, determines the movement of water across a selectively permeable membrane
Osmolarity
Isoosmotic with their surroundings and do not regulate their osmolarity
consisting only of some marine animals
Osmocomformers
expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment
- most organisms cannot withstand significant changes
Osmoregulators
Most animals cannot tolerate substantial changes in external osmolarity these animals are called…
Stenohalines
Animals that can survive large fluctuations in external osmolarity
Euryhaline animals
Euryhaline osmocomformers and Euryhaline osmoregulators
Most marine animals are ___________________
Most marine vertebrates and some invertebrates are _____________
Osmocomformers
Osmoregulators
Marine bony fish are ___________ to seawater.
Hypoosmotic
Lose water by osmosis and gain salt by diffusion and from food
How do you they balance water loss? Excretion of salt ions from gills?
How do you freshwater animals maintain water balance?
Constantly take in water by osmosis from their hypoosmotic environment (lose salts by diffusion)
Salt loss by diffusion are replaced in foods and by uptake across the gills
Adaptation in some aquatic invertebrates in temporary ponds lose almost all their body water and survive in a dormant state
Anhydrobiosis (means life without water)
Land animals maintain water balance by eating moist food and producing water metabolically through ____________
Cellular respiration
Kangaroo rats get most of their water from metabolism
Some animals convert ____________to less toxic compounds prior to excretion
Ammonia (very toxic)
Animals excrete nitrogenous wastes in different forms:
- ammonia
-urea
-Uric acid
These differ in toxicity and the energy costs of producing them
Where is ammonia released?
Across the whole body surface or through gills
The liver of mammals and most adult amphibians coverts ammonia to the less toxic ____
Urea
What is the advantage of excretion of wasted as urea?
Low toxicity but higher energy cost
- relatively non-toxic and does not dissolve readily in water
- it can be secreted as a paste with little water loss
- more energetically expensive to produce than urea
- insects, land snails, and many reptiles, including birds
Uric acid
What influences nitrogenous wastes of animals?
- depends on the animals availability to water
- the immediate environment of the animals egg
- the amount of nitrogenous waste is coupled to the animals energy budget
Key functions of most excretory systems
- filtration
- reabsorption
- secretion
- excretion
Two functions of the kidneys?
Excretion and osmoregulation
What is the difference between cortical nephrons and juxtamedullary nephrons?
Cortical is short- extends from renal cortex and a little bit into the renal medulla
Juxtamedullary nephrons- extend deeper into the renal medulla (seen more in dessert animals) allows for more water absorption
Breakdown of nucleotides (crystals of this can result in gout)
Uric acid
Amino acid metabolism. Ammonia combines with carbon dioxide.
Urea
What are the functions of the urinary system?
- excretion of metabolic wastes
- maintenance of water-salt balance (regulate blood pressure)
- maintenances is acid-base balance (blood pH 7.4)
- secretion of hormones(renin —> aldosterone adrenal cortex) —>reabsorption of sodium by Kinsey’s), erythropoietin
Kindest are located in the __________ region
Covered by a tough capsule of_________
Lumbar
Fibrous connective tissue
The ureters have a ________-layered wall consisting of….
Conveys urine by…
Mucosa, smooth muscle, outer connective tissue
peristalsis
_____ Sphincter muscles in the bladder control the release of urine into the urethra
Two
Urination is also known as …
Micturition
Stretch receptors in the wall of the badder send impulses when bladder fills to _____ml
-motor impulses from spinal cord, bladder contractions, Micturition occurs
250
Where does filtration take place?
What is the functional units of the kidneys?
Nephron
Each kidney has over one million nephrons
Each nephron has its own blood supply
From the renal artery, ________ leads into the glomareous
Blood leaves the glomareous via an ____________ . This takes blood to peritubular capillaries (these surround the rest of the nephron) blood then goes to renal vein
Afferent arterioles
Efferent arteriole
-cubodial epithelial cells with microvilli
Increased surface area for absorption
Proximal convoluted tubule
Part of the nephron that has simple squamous epithelium
It’s surrounded by peritubular capillaries
Loop of Henle
- cuboidal epithelial cells- lack microvilli
- designed for tubular excretion rather than reabsorption
Distal convoluted tubule
Distal convoluted tubule of several nephrons enter one _____________. Many of these carry urine to the renal pelvis
Collecting ducts
The contents of Bowmens capsule is called …
Filtrate
Glomerular filtration….
- blood enters the afferent arteriole and glomerulus
- the filtrate produced in bowmens capsule contains salts, glucose, amino acids, vitamins, nitrogenous wastes, and other small molecules
- Place of reabsorption of ions, water, and nutrients
- Molecules are transported actively and passively from the filtrate into interstitial fluid and then capillaries
- some toxic materials are actively secreted into the filtrate
- materials to be excreted become more concentrated
Proximal tubule
What is being actively transported in the proximal tubule?
Passively?
Sodium , potassium, glucose…
chloride, and water follows passively
Reabsorption of water continues through channels formed by ____________ proteins in the descending loop of henle. What is left behind?
Aquaporin
Salt, not permeable to salt
Movement of water in the descending loop of Henle is driven by the high ___________ of the interstitial fluid, witch is ____________ to the filtrate
Filtrate becomes increasingly concentrated
Osmolarity
Hyperosmotic
In the ascending limb of the loop of Henle, _______ but not ________ is able to diffuse from the tubule into the interstitial fluid
The filtrate becomes increasing …..
Salt, water
Dilute
What area lacks water channels? And is impermeable to water?
Ascending limb of the loop of Henle
In the ascending loop of Henle, in the bottom portion that is deeper and ___________, salt will leave passively or actively?
What about the top, thicker portion?
Thinner. Passively, Salt concentration is high!
Actively
The main function of the distal tubule is ____________ which will regulate what In the body?
Secretion, pH Regulation (controlled movement of ions)
Leaves the filtrate to go back to the blood
If there is excess it is put into the filtrate to be secreted fine tuning
The distal tubule regulates the _______ and _______ concentrations of body fluids.
K+ and NaCl
- processes filtrate into urine
- carries filtrate through the Medulla to the renal pelvis
- One of the most important task is reabsorption of solutes and water
- urine is hyperosmotic to body fluids
Collecting duct
Hyperosmotic urine can be produced because considerable ___________ is expended to transport solutes against concentration gradients
Energy
The two primary solutes affecting osmolarity are
NaCl and urea
- System is surrounded by vessels
- Opposite of the flow of filtrate
- high energy process!
Countercurrent multiplier system
Where is osmolarity the lowest and where is it the highest?
Cortex —> outer medulla——> inner medulla
The ____________ nephron is key to water conservation in terrestrial animals
Mammals that inhabit dry environments have _______ loops of Henle while those in freshwater have _______ loops of Henle
Juxtamedullary
Long, short
The osmolarity of the urine is regulated by nervous and hormonal control
Permeability of collecting ducts is under ______________ control
Hormonal
An increase in osmolarity triggers the release of _______, which helps to conserve water
ADH
______________ is produced by the posterior pituitary gland. also called?
Antidiuretic hormone
Vasopressin
What happen in the presence and absence of ADH?
- The collecting duct becomes more permeable to water and concentrated urine is produced.
- A dilute urine is produced (diuresis)
Osmoreceptors in the ____________ monitors blood osmolarity, can trigger release of ADH from the ____________.
Hypothalamus
Pituitary gland
This simulates sodium reabsorption to get to set point
The Renin-Angiotensin-Aldosterone System
Hormonal regulation at the distal convoluted tubule occurs when….
Blood volume,therefore , blood pressure of the glomareous is low (not sufficient for glomareous filtration)
In the Renin-Angiotensin-Aldosterone System…
The juxtaglomerular apparatus secretes _________
This is an enzyme that changes ______________ into ____________.
Renin
Angiotensinogen into angiotensinogen 1
Angiotensin 1 gets converted into angiotensin 2.
Angiotensin 2 stimulates the adrenaline cortex to release ________
Aldosterone
Aldosterone promotes the excretion of _______ and the reabsorption of ______. Reabsorption of this is followed by the reabsorption of water
Blood volume and blood pressure then increases
K+, Na+
______________ raises blood pressure and decreases blood flow to the kidneys
Stimulates the release of the hormone ____________, which increases blood volume and pressure
Angiotensin 2
Aldosterone
ADH and RAAS both increase water reabsorption, but only ______ will respond to a decrease in blood volume
RAAS
Another hormone ______________, opposes the RAAS.
When there is an increase in blood volume
Atrial natriuretic peptide (ANP)
- secreted by right atrium in response to stretching
- indicates increased blood volume
- inhibits renin secretion by juxtaglomerular apparatus
- inhibits aldosterone release from adrenal glands
- promotes sodium excretion -(NaCl reabsorption inhibited in collecting duct)
Atrial natriuretic peptide (ANP)
