Homeostasis

Question 1

What is excretion?

The process by which ________ _____ ________ , are removed.

Answer 1

The process by which UNWANTED WASTE PRODUCTS, resulting from metabolic reactions in cells, are removed.

Question 2

Waste products transported by the blood are:

Answer 2

• Carbon dioxide and heat energy made in all cells by respiration.
• Ammonia made in the liver by deamination of amino acids, immediatley converted to urea.
• Bilirubin (bile pigments) from the breakdown of RBC’s in the liver and excreted in the feaces
• Toxic substances from metabolic reactions (especially those of the liver)

RBC = red blood cell

Question 3

Mammals have four special excretory organs, which are:

Answer 3

• Skin: heat, salts and water and some urea as sweat from sweat glands
• Lungs: CO2 from respiration and water vapour.
• Kidneys: Amino acids are de-aminated in the liver, to produce ammonia, which is converted into urea. This is carried around the blood and excreated out of the body with urine. The kidneys also remove excess salts.
• Liver: Bile pigments from the breakdown of RBC’s are excreted from the liver into the large intestines to be egested with the feaces.

RBC = red blood cell

Used hormones are also changed by the liver into inactive compounds and passed to the kidneys for excretion.

Question 4

Mention 2 functions carried out in the kidneys.

Answer 4

• Excretion
• Osmoregulation

Question 5

Each kidney recieves ________ blood through the ____ artery and returns ____ blood through the ____ vein.

Answer 5

Each kidney recieves oxygenated blood through the renal artery and returns deoxygenated blood through the renal vein.

Question 6

Each kidney empties its contents into a narrow tube, called

Answer 6

ureter

Question 7

The ureter is connected to the

Answer 7

bladder

Question 8

Urine is excreted from the body body through the

Answer 8

urethra

Question 9

What muscle controls control urination?

Answer 9

Sphincter muscle

Question 10

Internally, the kidney has a light red, outer ____ and a dark red, inner ______

Answer 10

Internally, the kidney has a light red, outer cortex and a dark red, inner medulla

Question 11

The ____ are very long and are responsible for filtering the blood from the waste products carried in it.

Answer 11

The nephrons are very long and are responsible for filtering the blood from the waste products carried in it.

Question 12

Each nephron is made up of four parts:

Answer 12

• Bowman’s capsule
• First coiled tubule (also known as Proximal Convoluted Tubule)
• Loop of Henle (U-shaped loop)
• Second coiled tubule (also known as Distal convoluted Tubule)

Question 13

Every ____ nephrons, join up to form a ________ duct.

Answer 13

Every **12 ** nephrons, join up to form a collecting duct.

Question 14

To clean the blood the kidney performs 2 important process, which are

Answer 14

• Ultrafiltration (filtration under pressure)
• Selective reabsorbtion

Question 15

Blood entering the kidneys from the ____ ____, branches into smaller afferent arterioles that keep on branching until they form a bunch of many small capillaries called ________.

Answer 15

Blood entering the kidneys from the renal arteries, branches into smaller afferent arterioles that keep on branching until they form a bunch of many small capillaries called glomerulus.

Question 16

Blood pressure in the glomerulus is ______ ______.

Answer 16

Blood pressure in the glomerulus is very high.

Question 17

Why is the pressure in the glomerulus high?

Answer 17

• It has been pumped from the left side of the heart
• The blood capillaries of the glomerulus are very thin and narrow
• Large molecules in the blood cannot pass through the walls of the glomerular capillaries

Such large molecules are red blood cells, white blood cells, platelets a

Question 18

The high pressure causes the liquid part of the blood to move out of the glomerulus. This ____ contains substances such as:

Answer 18

The high pressure causes the liquid part of the blood to move out of the glomerulus. This plasma contains substances such as:
*urea
* glucose
* salts
* amino acids
* vitamins
* minerals
* water

Question 19

The liquid collects in the first part of the nephron, called the ______ ______. The liquid (which was once plasma) is now called ________ _______.

Answer 19

The liquid collects in the first part of the nephron, called the Bowman’s capsule. The liquid (which was once plasma) is now called glomerular filtrate.

Question 20

As the glomerular filtrate passes through the first coiled tubule, molecules of useful substances such as _______, _______ and ____, move back into the blood flowing in the capilleries that are closely wrapped around the tubules.

Answer 20

As the glomerular filtrate passes through the first coiled tubule, molecules of useful substances such as ,glucose,salts, amino acids and water, move back into the blood flowing in the capilleries that are closely wrapped around the tubules.

Question 21

In the ____ ___ __ and the ______ ______ ____ more water and useful salts are reabsorbed into the blood.

Answer 21

In the loop of Henle and the second coiled tubule more water and useful salts are reabsorbed into the blood.

Question 22

The substances that aren’t reabsorbed from the ________ ________ into the blood, are ______, ______ ____ and ____. Together these substances make up ____, which is poured from the nephron into the ___________ ____.

Answer 22

The substances that aren’t reabsorbed from the** glomerular filtrate** into the blood, are urea, some salts and water. Together these substances make up urine, which is poured from the nephron into the collecting duct.

Question 23

The amount of water secreted in urine is controlled by the ________________________

Answer 23

The amount of water secreted in urine is controlled by the Anti-Diuretic Hormone (ADH)

Question 24

Water-regulating-mechanism is called ___________________________.

Answer 24

Water-regulating-mechanism is called osmoregulation

Question 25

In some cases of a kidney failure it can be treated using a ____________ _______________ ______________.

Answer 25

In some cases of a kidney failure it can be treated using a kidney dialysis machine.

Question 26

What is osmoregulation?

Answer 26

The process by which the concentration of water and mineral salts in the blood are kept constant.