Chapter 11 - Regulation of water, salts and gases Flashcards
Osmoregulation
The active regulation of an organism’s water content. It maintains the fluid balance (water gain and loss) and the concentration of electrolytes (salts in solution) to keep internal fluids from becoming too diluted or concentration
Turgid
Describes a cell into which water had diffused, so that the walls are stretched and the cell is fairly rigid
what are the three functions of the kidney
- Removal of nitrogenous wastes
- Regulation of water concentration in the blood
- Maintaining ion levels in the blood
Nephrons
The basic structural and functional unit of the kidney that filters the blood in order to regulate chemical concentrations, produce urine and eliminate nitrogenous waste
bowmans capsules
A cup shaped structure found at one end of each nephron, in the cortex of the kidney. It surrounds a group of capillaries called a glomerulus
glomerulus
A group of capillaries surrounded by a bowmans capsule
filtration
A process that starts in the glomerulus, where fluid and solutes are filtered out of the blood to form a glomerular filtrate
reabsorption
Process of substances in the filtrate being absorbed back into the blood
what animals secrete which nitrogenous waste of urea, ammonia and uric acid
- Aquatic animals (Fish and amphibians) can’t afford to lose water. Ammonia (most toxic)
- Mammals, most adult amphibians, sharks need to conserve water. Urea (less toxic)
- Birds, insects, many reptiles, snails need to conserve water. Uric acid (least toxic)
ADH
Antidiuretic hormone. A hormone that regulates the level of water reabsorption in the collecting duct of the kidneys nephron
How does ADH reduce the urine output
By acting on the collecting duct of the kidney. The main functions of the collecting ducts are reabsorption of water and carrying a urine to the ureter. ATH increases reabsorption of water and the collecting ducts
Negative feedback loop for low water volume
- Stimulus: Decrease in the blood water content below optimal range
- Receptor: Osmoreceptors cells in the hypothalamus detect the change in the blood water content and send a message to the coordinating centre
- Modulator: The hypothalamus receives a message from the receptor, coordinator response and sent a message to the effector. (The thirst centre is also activated.)
- Effector: The pituitary gland releases ADH, which travels through the blood to the kidney nephron, increasing the permeability of the collecting duct wall, which increases water reabsorption
- Response: An increase in the blood water content, a lower volume of urine and a higher urine concentration
- Negative feedback: The blood water content returns to the normal value. The response count acts the stimulus
Osmoregulators
An organism that has specialised mechanisms for regulating internal water and solute concentration, despite concentration changes in the external environment.
osmoconformers
An organism in which the internal solute concentration changes with the concentration of solutes in the external environment. Eg, Most marine invertebrates, cartilaginous fish such as sharks and rays and some fish
Structural features to maintain water balance in Osmoregulators
Waterproof or impermeable outer layer, reducing water loss. (The scale of reptiles, the hair of mammals, the feathers of birds). The waterproof surface acts as a barrier preventing loss via osmosis or evaporation.
Physiological processes to maintain water balance in Osmoregulators
Many reptiles and birds reabsorb water from their cloaca, Excreting nitrogen as wastes as uric acid is affective in saving water, slowing down the production of urine by reducing the rate of glomerular filtration, concentrate it’s a urine (water is conserved when it’s reabsorbed in the descending portion of the loop of henle). Some animals can use water stored in fats or carbs
Behaviour maintain water balance in Osmoregulators
Borrowing in the sand for several months at a time after filling its bladder, aestivation, burrowing (Lower temperatures and higher humidity so water loss is reduced also traps exhaled water vapour)
why is transpiration important
- Supplies photosynthesis with the water it needs
- cooling affect
- Distributing mineral salts throughout the plant
how is water transported up a plant
Roots have fine root has attached to them (high SA:V) So they can achieve high rates of osmosis and diffusion, as well as active transport of dissolved substances (salts) To be transported to the stem of a vascular plants (via xylem and phloem). Water is pulled from the roots through the xylem to the leaves due to the set of forces known as the transformation pull. Including cohesion and adhesion. As water evaporates from the leaves, columns of water are drawn up through the xylem vessels
Adhesion
The attractive force between water molecules and the inner walls of a vessel (e.g. the xylem vessels)
cohesion
The attractive force between water molecules
Capillary action
The movement of water within the spaces of a porous material or a narrow tube due to the forces of adhesion and cohesion
root pressure
A force pushing on the water in the xylem, resulting from the active transport of salt ions into the root hairs, which causes osmosis to occur and water to move in from the soil into the room hairs. Is one of the forces involved in the transpiration stream
Transpiration pull
The set of forces that pull water from the roots to the leaves, including cohesion and adhesion. As water evaporates from the leaves, columns of water are drawn up through the xylem vessels
Transpiration stream
The continuous flow of water from the roots to the leaves via xylem vessels due to the forces of cohesion, adhesion and root-pressure
Xylem
A form of vascular tissue that contains tubes within which water is transported from roots to leaves in a vascular plant
Phloem
A type of vascular tissue (tubes) within which sugars and other dissolved organic substances are transported in a vascular plant
Xerophytes
A plant that is adapted to live in arid environments. It has developed specialised features that minimise water loss, while maintaining gas exchange
Halophytes
A plant adapted to live in environments with high soil salinity (i.e. a high salt concentration), such as salt marshes and the mudflats of estuaries
5 structural and physiological adaptations of Xerophytes
- Sunken stomata, which prevent water loss by increasing the relative humidity near each stoma, decreasing the concentration gradient and reducing evaporation and diffusion. This creates a microclimate
- Deep roots to reach water sources underground such as the water table which increase water uptake preventing dehydration of the plant
- Rolled leaves, With the stomata inside and the inner surface covered in hairs. The rolled leaf and hairs serve to trap moist and thus reducing the concentration gradient of water vapour, the diffusion rate of water vapour out of the leave, the evaporation rate and the transpiration rate, creating a humid micro climate and reducing water loss
- Thick, waxy leaf cuticle that is impermeable to water, preventing evaporation and water loss. The cuticle is also shiny and can reflect light, reducing the amount of light absorbed that could transform into heat and increase transpiration rate
- Shallow spreading roots to collect the occasional rainfall and increase water uptake and reduce the risk of dehydration of the plant
5 structural and physiological adaptations of Halophytes
- Filtration at the roots to regulate the amount of salt entering the plant. Root cells that are in permeable to prevent salt from entering the plant
- Secretion of salt by special salt glands on leaves, stems and roots. This reduces the amount of salt in the plant
- Succulence, the development of water storage structures in the leaves and other parts of the plant, dilutes the salt content of the cells
- Accumulation of salt in older leaves, salt bladders or bark which can later to be discarded. This reduces the amount of salt in the plant (Physiological)
- Vacuoles in root cells to store salt which increases the salt concentration of the roots so it is a greater than that of the soil. This allows water movement into the roots. Storing salt in vacuoles rather than in the cytoplasm stops it from interfering with cell functioning (Physiological)
Transpiration
The evaporative loss of water from plants usually through small pores called stomata found on the surface of a plant, mostly on the underside of leaves. The evaporation and diffusion out of the stomata occurs because of the concentration gradient in the water vapour between the inside and outside of the leaf. Water vapour moves down the concentration gradient from an area of high water content to an area of low water concentration. The transport of water through the plant results in water loss
nitrogenous waste pathway
Ammonia (highly toxic) –> urea (moderately toxic) –> uric acid (least toxic, little water, energy cost)
hypotonic
(water enters cell) At a lower concentration than another solution. When a cell is surrounded by a hypotonic solution, water moves into the cell via osmosis to dilute the cell, so the cell swells. (animal cells which have no cell wall sometimes burst)
hypertonic
(water leaves cell) At a higher concentration than another solution. When a cell is surrounded by a hypertonic solution, water moves out of the cell via osmosis to dilute the surroundings, so the cell shrinks
