Chapter 9 Excretion in Humans Flashcards
Define the term Excretion and state it’s importance in the functioning of the body [3] (2011/A4)
Excretion is the removal [1] of metabolic waste [1] from the body. It is important as metabolic waste accumulated in the body in excess is toxic and harmful, interfering with metabolic processes. [1]
Name the nitrogen-containing substances found in the liquid in the ureter [1] (2011/A4)
Urea
State why groups of 10 people rather than individuals are used in an investigation [1] (2012/A2)
A group of 10 people rather than individuals were used in this investigation helps to exclude anomalous results and improve the reliability of the data/results obtained.
(R: average or accuracy)
explain the absence of protein and glucose in urine. [4]
Protein molecules are too large [1] to pass through the partially permeable basement membrane at the glomerulus and are not filtered from the blood to form part of the glomerular filtrate [1]
Glucose molecules are small enough to be filtered by ultrafiltration into the Bowman’s capsule. [1] Selective reabsorption took place and all glucose molecules are selectively reabsorbed into the blood capillaries at the proximal convoluted tubule. [1]
Explain how ADH affects the composition of liquid passing through the collecting duct in the kidney. [3] (2013/A3)
ADH produced by the pituitary gland increases the permeability of the kidney tubules to water and works on the distal convoluted tubules and the
collecting duct [1], causing an increase in the amount of water absorbed. [1]
As more water is reabsorbed, there will be less water in the liquid passing through region R, resulting in an increase in the concentration of
solutes present. [1]
Define the term excretion and explain its importance [2] (2014/A1)
Excretion is the removal of metabolic waste products [1]
from the body which when left accumulated in excess will be
toxic to the body. [1]
State one other excretory product other than urea, sodium, chloride and ammonia. [1] (2014/A1)
Excess water/ carbon dioxide/ uric acid/ creatinine
Describe and explain how reduced production of ADH will affect the composition of urine [3] (2014/A1)
Reduced secretion of anti-diuretic hormone (ADH) decreases
the permeability of cells in walls of collecting duct to water. [1] Hence less water is reabsorbed from the collecting duct into the blood capillaries [1] and a higher volume of water is found in the urine, making the urine less concentrated/ more diluted [1]
Suggest how vigorous exercise may affect the concentration of ADH in the blood. [2] (2017/A7)
During vigorous exercise, more sweat is produced due to more heat released. Increased sweating increases water loss and decreases the water potential in the blood plasma. [1]
The hypothalamus in the brain detects the change and stimulates the pituitary gland to produce more ADH, releasing more ADH into the bloodstream, and increasing its concentration. [1]
Describe the role of the glomerulus and the venule [3] (2018/A5)
The glomerulus is the site of ultrafiltration where high hydrostatic blood pressure forces small molecules such as urea out of the glomerulus across the partially permeable basement membrane into the Bowman’s capsule; [1]
Structure B is the venule which transports blood containing glucose,
amino acids, water and mineral salts which are reabsorbed by selective reabsorption at the kidney tubules through diffusion and active transport back to the heart via the renal vein; [1]
To ensure that useful substances are not excreted in the urine; [1]
Suggest how the water loss from a person would change if the person was in an environment where the air temperature drops. [3] (2017/B9)
When the air temperature was 5oC, water lost through sweat decreases
because the lesser latent heat of vapourisation is lost to conserve heat.[1]
Lower sweat production increases the water potential in the blood
plasma. Thus, a higher volume of water loss through urine.[1]
Water loss in breathing decreases to conserve heat. [1]. Water loss in
faeces remains unchanged.[1]
The ______ is the outer dark red region of the kidney. It is covered by the fibrous capsule.
Cortex
The _______ is the inner pale red region. The renal pyramids are located in this region.
Medulla
The kidney tubes are called ________, urine is formed in them
Nephrons
At the proximal convoluted tubile, most of the _______ _____ and all of the _______ and _____ ______ are reabsorbed throught the walls of the surrounding blood capillaries.
Most of the _____ in the filtrate is reabsorbed by osmosis here.
Mineral salts, glucose and amino acids
Water
