excretory system,

Question 1

what is excretion

Answer 1

All chemical processes in the body produce by-products some that can be used by the body or as wastes.
If wastes are accumulated in body, then harmful to health, so removal is important

Question 2

lugns

Answer 2

excretion of co2

Question 3

liver

Answer 3

processes many substances for secretion

Question 4

sweat glands

Answer 4

secretes sweat, water for cooling

sweat consists of urea, lactic acid and salts

Question 5

kidneys

Answer 5

maintaining the constant concentration. of materials in body fluids
toxic wastes are removed nitrogenous wastes like urea , uric acid and creatinine.

Question 6

liver

Answer 6

The liver is an organ that is part of the excretory system.
Located in the upper abdominal cavity of the body
Has many functions such as preparing materials for excretion
If the body has sufficient supply of carbohydrates, fats or stored fats, then little protein is used in energy releasing reactions
excess protein cannot be stored in the cells, so required to be removed by liver
Some protein broken down all the time, although most of the breakdown is incomplete.
Worn out cells such as red blood cells, are a source of protein, they are broken down into constituent amino acids
Some of the amino acids are then used to make protein
A very small amount of amino acids and protein are lost via urine, hair, fingernails, skin
If other energy sources have been used up, then the body is able to metabolise large amounts of protein
The amino group NH2 must be removed from the amino acids.
Process called deamination, aided by enzymes.
Once the amino acid is removed, then it is converted by the liver cells into ammonia NH3 and then finally to urea.
Urea is eliminated from the body through urine
The remaining part of the amino acid is hydrogen and carbon, this is converted into a carbohydrate
This carbohydrate is readily broken down by cells to release energy, CO2 and H20.
Ammonia is very soluble in water and highly toxic to cells (one thousandth of a milligram of ammonia in a litre of blood can kill person)
The cells of the liver rapidly convert ammonia to less toxic urea molecule
Urea is excreted by the kidneys and eliminated from the urine in the body
Small amounts of urea are lost in sweat from sweat glands
The liver detoxifies alcohol and many other drugs like antibiotics
The liver deactivates many hormones and converts them to a form that can be excreted by the kidneys.
Haemoglobin from dead red blood cells is broken down in the liver to produce bile pigments, that are then passed out of the body through faeces.

Question 7

deamination eautions

Answer 7

amino acids plus oxygen -> (through enzymes) carbohydrates and ammonia
\then
ammonia + energy +co2 -> urea+water

Question 8

skin

Answer 8

The main functions of the skin are to provide a protective covering over the surface of the body and to regulate the body’s temperature. Skin has important role in excretion
On the skin, the sweat glands secrete 500mL of water per day. Dissolved in the water are sodium chloride, lactic acid and urea.
Sweat glands are located in the lower layers of the skin.
A duct carries the sweat to a hair follicle or to the skin surface where it opens at a pore
Cells surrounding the glands are able to squeeze and contract the sweat to the skin surface

Question 9

kidneys

Answer 9

A pair of reddish brown organs located in the abdomen and is approx 11cm long
The kidneys, the bladder and associated ducts are referred to as the urinary system
They are composed of nephrons and collecting ducts
There are 1.2 m nephrons and are surrounded by complex network of blood capillaries.
Nephron is the functional unit of the kidney
Each nephron has a renal corpuscle and a renal tubule.
The nephron begins with an expanded end called the glomerular capsule (bowman’s capsule).

Question 10

renal tubule

Answer 10

Renal tubule is the kidney tube; it leads away from the glomerular capsule and empties into na collecting tube.

Question 11

glomerular capsule`

Answer 11

Glomerular capsule is double walled cup structure at the end of each kidney tubule. It collects filtered water and other substances from the blood; bowman’s capsule.

Question 12

glomerulus

Answer 12

Glomerulus is the tightly coiled mass of capillaries that is surrounded by the expanded part of each kidney tube.

Question 13

proximal convoluted tubule

Answer 13

The proximal convoluted tubule is the first set of convolutions of the kidney tubule, located between the glomerular capsule and the loop of Henle.

Question 14

loop of henle

Answer 14

U shaped section of the kidney tubule, it plays a major role in the reabsorption water salts from the filtrate. Like hairpin bend with straight section leading into the bend and another straight section leading away from the bend.

Question 15

distal convoluted tubule.

Answer 15

The tubule then becomes convoluted and highly coiled.
It joins into a collecting duct that opens into a chamber in the kidney called the renal pelvis.
second set of convolutions of the kidney tubule; it receives the forming urine after it has passed through the loop of henle.

Question 16

collecting duct

Answer 16

the tube in the kidney that collects filtrate from a number of nephrons.

Question 17

renal pelvis

Answer 17

shaped like a funnel and it channels fluids from the collecting ducts into the ureter.

Question 18

ureter

Answer 18

is the tube that leaves each kidney and drains into the urinary bladder.

Question 19

nephrons

Answer 19

` responsible fro removing wastes form the blood and regulating blood composition. Therefore, they are supplied with blood vessels.

Question 20

how does the kidney work

Answer 20

Blood enters the kidney throat the renal arteries. These arteries are large, together the two kidneys receive ¼ of blood from the left side of the heart. Around 1.2L of blood pass through the 2 kidneys every minute.
Shortly after after entering the kidney, the renal artery divides into small arteries and arterioles. Each renal corpuscle is supplied by an arteriole, the afferent arteriole which then forms a knot of capillaries called the glomerulus.

Question 21

afferent arteriole

Answer 21

the blood vessels that enters an organ. located in the gomerular capsule

Question 22

efferent arteriole

Answer 22

The capillaries unite to form another arteriole, the efferent arteriole, which passes out of the renal corpuscle.
Efferent arteriole is the blood vessel that leaves a glomerulus in the kidney.

Question 23

peritubular capillaries``

Answer 23

After leaving the real corpuscle, the efferent arteriole breaks up into a second capillary network.

Question 24

how is urine formed

Answer 24

glomerular filtration
the filtration of blood in the kidney. This process takes place in the renal corpuscle, when fluid is forced out of the blood and entered into the glomerular capsule
Fluid is normally forced out of the capillaries in all parts of the body, but in the glomerular, process is enhanced by high pressure of blood.
The afferent arteriole has a wider diameter than the efferent arteriole leaving it.
This narrowing of the efferent arteriole increases resistance to the flow of blood and produces high pressure in the glomerular.

Question 25

how is urine formed

glomerular filtration

Answer 25

glomerular filtration
the filtration of blood in the kidney. This process takes place in the renal corpuscle, when fluid is forced out of the blood and entered into the glomerular capsule
Fluid is normally forced out of the capillaries in all parts of the body, but in the glomerular, process is enhanced by high pressure of blood.
The afferent arteriole has a wider diameter than the efferent arteriole leaving it.
This narrowing of the efferent arteriole increases resistance to the flow of blood and produces high pressure in the glomerular.

Question 26

filtrate

Answer 26

composed of all materials in blood except red and white blood cells and plasma proteins. too big to go through cell membrane so filtrate made of water salts, amino acids, fatty acids, glucose, urea, uric acid, creatinine, hormones, toxins and ions/

Question 27

tubular secretion

Answer 27

Many of the components of the plasma that are filtered are of use to the body and excretion undesirable.
Selective reabsorption of filtrate occurs.
Selective reabsorption occurs in the renal tubules and it is reabsorption of some substances and not others.
Materials that are reabsorbed include water, amino acids glucose. Ions such as sodium, potassium, bicarbonate, chloride and calcium are reabsorbed. Urea can be partially reabsorbed
Facultative Reabsorption is the active reabsorption of water from the filtrate in the renal tubule of the kidney. Controlled by hormones. A large surface area is required, like the body’s other exchange surfaces. The large surface area is achieved by the long length of the kidney tubule - 2 sets of convolutions and the long loop of Henle - and by the big number of nephrons in each kidney.
Depending on the body’s water requirements, the permeability of the plasma membranes of the cells making up parts of the tubules can be changed. So, more or less water can be reabsorbed depending on body’s requirements. Active process and under hormonal control