Excretory Unit Lesson 2: Kidney Function

Question 1

explain the major function of the kidneys that makes them the main organ of the excretory system

Answer 1

it absorbs and removes molecules from the blood

Question 2

how do the kidneys absorb and remove molecules from the blood

Answer 2

it does this by making use of the same biological physics such as concentration gradients and pressure

Question 3

explain concentration gradients

Answer 3

it is when greater differences in concentration promote the movement of molecules from high concentrations to low concentrations

Question 4

break the kidney down into three regions

Answer 4

renal cortex, renal medulla, renal pelvis

Question 5

what is the renal cortex

Answer 5

the outermost region of the kidney

Question 6

what is the renal medulla

Answer 6

the innermost region of the kidney

Question 7

what is the renal pelvis

Answer 7

the cavity of the kidney that marks the beginning of the ureter

Question 8

what are nephrons

Answer 8

tiny regions in the kidney that connect to the renal capillaries and filter the blood

Question 9

describe a singular nephron

Answer 9

it is a small network of capillaries that are interwoven with tubules that act to filter and remove waste molecules

Question 10

break down the nephron into parts

Answer 10

it can be broken down into the glomerulus, the proximal convoluted tubule, the loop of henle, the distal convoluted tube, and the collecting duct

Question 11

what is the glomerulus

Answer 11

a knotted capillary region surrounded by a cuplike structure called the glomerular capsule(aka Bowman’s Capsule). it features a region of the arteriole going towards it(afferent) and away from it(efferent)

Question 12

what is the proximal convoluted tubule(PCT)

Answer 12

a segment of the renal tubule(in the nephron) responsible for the reabsorption and secretion of various solutes and water

Question 13

what is the proximal convoluted tubule composed of

Answer 13

epithelial cells in tightly packed microvilli

Question 14

what is the Loop of Henle

Answer 14

a narrow U-shaped loop that conducts urine within each nephron

Question 15

note:

Answer 15

you should be able to point out the parts of the nephron in a picture

Question 16

how can the Loop of Henle be separated

Answer 16

it can be separated into descending and ascending limbs

Question 17

what is the distal convoluted tubule and what is it composed of

Answer 17

a tubule that is composed of mitochondria-dense epithelial cells

Question 18

what is the function of the distal convoluted tubule

Answer 18

it is specialized to move molecules from the blood into the tubule to send to the collecting duct

Question 19

what is the collecting duct

Answer 19

a region of tubule that is shared between multiple neighbouring nephrons.

Question 20

what is the function of the collecting duct

Answer 20

it is used to collect the produced urine and transport it towards the renal pelvis

Question 21

what are the three processes of the formation of urine

Answer 21

pressure filtration, selective reabsorption, and tubular excretion

Question 22

what is pressure filtration and where does it occur

Answer 22

it is when the glomerulus moves molecules from the blood into the tubule.

Question 23

what is selective reabsorption and where does it occur

Answer 23

it is when the convoluted tubules move molecules from the tubules into the blood

Question 24

what is tubular excretion and where does it occur

Answer 24

it is when the convoluted tubules move molecules from the blood into the tubule

Question 25

explain the process of pressure filtration(with details)

Answer 25

when blood enters the glomerulus, it is subjected to high pressures due to the folding of the capillaries. this high pressure causes water and small molecules(nutrients, nitrogenous wastes, ions) to move from the glomerulus into the surrounding glomerular capsule. large molecules and formed elements will not be able to pass through the capillary walls and will remain

Question 26

explain the process of selective reabsorption

Answer 26

molecules are reabsorbed into the blood capillaries from the nephron. sodium ions are actively reabsorbed into the capillaries which causes chlorine ions to follow passively because of their attraction(their charges), and this causes the concentration of salt (NaCl) in the blood to increase which causes water to move from the tubule back into the blood passively. through selective reabsorption, most nutrients are absorbed

Question 27

explain the process of tubular excretion

Answer 27

molecules are moved from the blood capillaries into the tubules to be excreted through the collecting duct. the secreted molecules are often actively transported into the convoluted tubules as they weren't previously done so at the glomerulus because of their size

Question 28

what thing holds significant importance in regulating the reabsorption and excretion in the urinary process

Answer 28

hormones

Question 29

when and where is renin(a hormone) secreted

Answer 29

when the juxtaglomerular apparatus experiences insufficient blood pressure, it secretes renin into the bloodstream

Question 30

when and where is aldosterone secreted

Answer 30

it is secreted when renin is secreted to promote the reabsorption of salt into the kidneys(it leads to water being absorbed into the kidneys and back into the bloodstream which increases blood pressure)

Question 31

when and where is atrial natriuretic hormone(ANH) released

Answer 31

it is released if blood pressure becomes too high. the atria will release this in response to an excessive stretching of their cells

Question 32

how does ANH(atrial natriuretic hormone) work

Answer 32

it inhibits the secretion of renin which stops aldosterone from producing/secreting

Question 33

when and where is antidiuretic hormone(ADH) released

Answer 33

The posterior pituitary in the brain releases ADH in response to neurons detecting low water-salt levels in the body

Question 34

what is a diuretic

Answer 34

a substance that causes the body to excrete more water and increase urine output

Question 35

where is ADH sent to

Answer 35

the kidneys

Question 36

how is blood filtered at the glomerulus

Answer 36

the glomerulus creates and uses a liquid referred to as glomerular filtrate