CHAPTER 44: HOMEOSTASISJsrcc BIO 102

KEY TERM

•osmoregulation

•process by which animals control solute concentrations and balance water gain an loss

•osmolarity

•solute concentration expressed as molarity

•hyperosmotic

•higher solute concentration, lower free H2O concentration

•Hyposmotic

•Lower solute concentration, higher free H2) concentration

•osmoconformers

•isosmotic with their surroundings

• osmoregulator• regulate their internal osmolarity of their surroundings

• anhydrobiosis • animals that can lose almost all their body water and survive in a dormant state

• transport epithelia• specialized cells that regulate solute movement

• urea• Less toxic than ammonia, carried to kidneys, concentrated and excreted with a minimal loss of water

• ammonia• animals that excrete nitrogenous wastes as ammonia need access to lots of water, release it across whole body surface or through

gills

• uric acid • insects ,snails, and many reptiles excrete this, largely insoluble in water and can be secreted as a paste with little water loss

• Gilomerulus Filtration• separation of filtrate from cellular components

• Vasopressin• AKA ADH

• produced by the pituitary gland, it increases the body’s ability to retain water at collecting duct

• Aldosterone• Produced by the adrenal glands, it promotes sodium re-absorption from the filrate at the loop of Henle’ its action depends on blood salt concentration

• Dessication• Water loss

• Ammonia • Formed during protein or nucleic acid breakdown

• Contractile Vacuoles• Found in the cytoplasm of various protests. The vacuoles accumulate water. merge with the plasma membrane, and release water to the environment

• Paramecia• Have contractile vacuoles

• Amoebas• Have contractile vacuoles

• Flame Cells• distributed along a branched tube system that permeated the flatworm. Body fluids are filtered across the flame cells. who’s internal cilia move the

fluids though the tube system. Wastes are excreted from the tube system through pores that exit the body

• Malpighian tubles• tubes attach to the midsection of the digestive tract of insects collect body fluids from the hemolymph that bathe the cells. The fluids, which include

both nitrogen wastes ad materials to be retained are deposited into the mid gut. As the fluids pass through the hindgut of the insect materials to be

retained pass back out through the walls of the digestive tract. Wastes counties in the tract and are excreted through the anus

• Planaria• have flame cells

• Filtration• Pressure-filtering of body fluids producing a filtrate

• Reabsorption• reclaiming valuable solutes from the filtrate

• Secretion• addition of toxins and other solutes from the body fluids to the filtrate

• Renal artery• supplies the kidney with blood

• Renal vein• drains the kidney of blood

• renal cortex• outer kidney

• Renal medulla • inner kidney

• Glomerulus• ball of capillaries

• juxtamedullary nephrons• this nephron extends deeply into renal medulla

• countercurrent multiplier system• Maintains a high salt concentration in the interior of the Kidney, enables the kidney to form concentrated urine

•Juxaglomerular apparatus

•Specialized tissue that release the enzyme renin when blood pressure or blood volume drops in the afferent arteriole that supplies

blood to the glomerulus

•Aldosterone

•adrenal hormone that stimulates the reabsorption of sodium and passive flow of water that functions in homeostasis

•Secretion

•addition of toxins and other solutes from body fluids to filrate

•Metanephridia

•excretory system that collect fluid directly from the coelom. Each segment of the worm as a pair of metanephridia. Two systems on

either side of the body

• Tubules• Proximal tubules; loop of Henle; distal tublule; where processing takes place

• glomerulus• ball of capillaries in a nephron

• peritubluar capillaries• capillaries that surround the tublus of the nephron

• vasa recta• capillaries that serve the loop of Henle

• angiotesnsin II• hormone that raises blood pressure by constricting arterioles and decreasing blood flow to the capillaries

• renin-angiotensin-aldosterone system (RAAS)• complex feedback circuit that functions in homeostasis. A drop in blood pressure triggers renin release from JGA. This makes angiotensin II and aldosterone which, when they

build up, reducer lease of renin

• atrial natriuretic factor (ANF)• hormone that opposes the RAAS when blood pressure gets two high. Inhibits release of renin from JGA

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PURPOSE OF THE URINARY SYSTEM

• To remove waste from the body and to regulated blood and pH

• Collection of organs in the vertebrate that counter shift in compositions and volume of extracellular fluid • Kidneys filter blood• Form urine• Maintain water-salt balance• Helps regulated pH levels and blood pressure

STRUCTURE OF THE KIDNEY

• Two main tissues• Cortex ( the outer tissues)• Medulla ( inner tissue)

• Blood flow through the renal artery and vein

• Urine collects in renal pelvis

NEPHRON

• Functional unit of the kidney• Filters water and solutes from the blood• Adjusts how much is reabsorbed • Several steps

STEPS OF NEPHRON

• Bowman’s Capsule• Where glomerular capillaries are at

• Glomerular filtration• Water and solute smove

• Tubular reabsorption

Proximal tubule pumps sodium and water into the interstitial fluid

• Tubular secretion• Transporters in tubular capillaries move ions into interstitial fluid

• Concentrating urine• Occurs in the loop of Henle• Descending arm of the loop of Henle is permeable of water but no salts• Ascending arm of the loop of Henle become perambulator salts aandnutrients but not

wate

• Further Resorption • Further reabsorption of water in the distal tubule and collecting duct

ACID-BASE BALANCE

• Internal pH 7.35-7.45

• Controlled by the kidneys

• Maintained through a buffering system

• Excess carbon dioxide released through respiration• Excess acid binds to buffer and expelled by kidney

• Reponses of the kidney to acid base imbalance of the kidney to acid base imbalance is governed by the relative magnitudes of proton secretion and HCO3 filtration because these two factors affect the rate of acid and alkali execration

• If PCO2 rise proton secretion become dominant and the kidney excretes acid raising blood pH

• If HCO3 rise, HCO3 filtration increase and kidney excretes alkali, reducing blood pH

• Helps regulates your pH, carbonates and carbonic