Chapter 18- excretion Flashcards
Excretion
Removal of metabolic wastes produced in the body
Elimination
The removal of indigestible material
Aerobic respiration leads to the production of:
Carbon dioxide and water
Demination of amino acids in the liver leads to the production of
Nitrogenous wastes such as urea and ammonia
All metabolic processes lead to the production of:
mineral salts, which must be excreted by the kidneys
Excretion of protozoans and cnidarians
All cells are in contact with the external, aqueous environment- water soluble wastes such as ammonia and carbon dioxide can exit the cells through diffusion
Paramecium contain what kind of a vacuole?
Contractive vacuole– an organelle specialized for water excretion by active transport
Excretion in annelids
Carbon dioxide excretion occurs directly though moist skin
2 pairs of nephridia in each body segment excrete water, mineral salts, and nitrogenous wastes in the form of urea.
Excretion in arthropods
Carbon dioxide is released from the tissues into adjacent tubelike tracheae, which are continuous with the external air through opening called spiracles
Uric acid
In athropods, nitrogenous wastes are excreted in the form of solid uric acid crystals- helps conserve water
Malpighian tubules
mineral salls and uric acid accumulate here and are then transported to the intestine to be expelled with the solid wastes of digestion
Principal organs of excretion in humans
lungs, liver, skin and kidneys
Lungs and excretion
Carbon dioxide and water vapor diffuse from the blood and are continually exhaled.
Sweat glands and skin excretion
Excrete water and dissolved salts
Perspiration serves to:
Regulate body temperature, since the evaporation of sweat produces cooling
Liver and excretion
Processes nitrogenous wastes, hemoglobin, and other chemicals for excretion
How is urea produced and excreted?
Produced by the deamination of amino acids in the liver and diffuses into the blood for ultimate excretion in the kidneys
Bile salts are excreted as:
Bile and pass out with the feces
What does the kidney function to maintain?
Maintains osmolarity of the blood; excrete numerous waste products and toxic chemicals; and conserve glucose, salt and water.
How do kidneys regulate the concentration of salt and water in the blood?
Through the formation of urine.
Nephrons
Units of kidney- a kidney is composed of about a million nephrons.
Three regions of a kidney
Outer cortex, inner medulla, and the renal pelvis.
Bowman’s capsule
A bulb- nephron consists of a Bowman’s capsule
Bowman’s capsule embraces:
A special capillary called a glomerulus
What does the Bowman’s capsule lead to?
A long, coiled tubule that is divided into functionally distinct unit: proximal convuluted tubule, loop of henle, and distal convulutaed tubule and the collecting duct.
Organization of nephron
Loop of Henle runs through the medulla while the convoluted tubules and Bowman’s capsure are in the cortex
Ureter
Where concentrated urine end up from the collecting tubules flows into the pelvis of the kidney.
The ureters fro the kidneys empty into the:
Urinary bladder
Most of the nephron is surrounded by:
A complex peritubular capillary network to facilitate reabsorption of amino acids, glucose, salts, and water.
Three processes that lead to urine formation
Filtration, secretion, and reabsorption
What kind of a process is filtration?
Passive process driven by the hydrostatic pressure in the blood
FIltrate
Blood pressure forces 20% of the blood plasma entering the glomerulus through the capillary walls and into the Bowman’s capsule. This fluid and small solutes entering the nephron is called the filtrate.
Filtrate is _____ in relation to the blood
isotonic
What happens to particles too large to filter through the glomerulus?
Remain in the circulatory system.
Example: blood cells and albumins
Secretion
Nephron secretes substances such as acids, bases, and ions like potassium and phosphate from the interstitial fluid into the filtrate by both passive and active transport.
Materials are secreted from the peritubular capillaries into the:
Nephron tubule
Body fluid pH
Remains at 7.4
How is body fluid consistency attained?
by the removal of carbon dioxide through lungs or hydrogen ions through the kidneys.
How is assessment of pH measured?
Arterial pressure
Partial pressure of carbon dioxide (PCO2)
Plasma bicarbonate (HCO3)
What are the two types of acid-base disorders?
Respiratory
Metabolic
Respiratory disorder
Affect the blood acidity by causing changes in PCO2
Metabolic disorder
Affect the blood acidity by causing changes in the HCO3-
Acidosis
Increased pCO2- respiratory
Decreased HCO3- decreased
Reabsorption
Essential substances such as glucose, salts, and amino acids and water are reabsorbed from the filtrate and returned to the blood
Where does reabsorption occur primarily?
In the proximal convoluted tubule
What kind of activity is reabsorption?
ACTIVE process
movement of molecules in rebsorption is accompanied by?
Passive movement of water: results in the formation of concentrated urine
Urine is ____ to blood
Hypertonic
What does the nephron do?
Primary function is to clean the blood plasma of unwanted substances as it passes through the kidney.
Through what does the nephron maintain the bloodstream’s solute concentration?
Through selective permeability of its walls and the maintenance of an osmolarity gradient.
Why must the nephron be selective?
Because the blood contains both wanted and unwanted substances.
Primary sites of regulating water, sodium, and potassium loss in the nephron.
Ascending loop of Henle, collected duct, and descending loop of Henle.
What is the distal convoluted tubule the primary site for?
Secretion of substances into the filtrate.
Aldosterone
A hormone increases exchange transport of sodium and potassium ions along the distal convoluted tubule, the collecting duct.
Results in: decreased excretion of sodium ions in the urine and an increased potassium ion excretion in the urine.
Does aldosterone affect renal blood flow?
No
How is an osmolarity gradient established in the interstitial fluid surrounding the tubules?
Because of selective permeability of the tubules
Tissue osmolarity increases from:
The cortex to inner medulla
The solutes that contribute to the maintenance of the gradient are
Urea and salt (Na+ and Cl-)
Counter-current-multiplier system
The anatomic arrangement of the loop of Henle within the kidney permits the establishment of the concentration of gradient that permits the reabsorption of 99% of the filtrate in the collecting tubules.
How the osmolarity of urine is established in the collecting tubule
ADH
increases the permeability of the collecting duct to water, allowing more water to be absorbed and more concentrated urine to be formed.
Also called vasopressin
True false: There is no specific excretory system is plants
True
Unlike animals, plants can ______ their waste poducts
Use
Carbon dioxide can be used in _____ and nitrogen wastes can be reused in the _____ ______ _____
photosynthesis
systhesis of proteins
Transpiration
Exit of water vapor through leaf stomates
Excess carbon dioxide, as well as waste oxygen and water vapor leaves the plant by :
diffusion through the stomata and lenticels (pores in stems).
