2.69 Urinary system

describe the structure of the urinary system, including the kidneys, ureters, bladder and the urethra.
-2 kidneys- right and left kidney- each with its own blood supply carry out the process of excretion and filtration and osmoregulation.
-from each kidney there is a tube that leads to the bladder- called the ureter- carries the urine from the kidney to the bladder.
-there is a common bladder for both ureters- urine is conducted from the outside of the body through the urethra down through the vagina or through the penis.

2.68b Osmoregulation

understand how the kidney carries out its role of excretion and of osmoregulation.
-osmo: osmosis
-regulation: control

-the fluid which surrounds the cell- must be isotonic with the cytoplasm of the cells- the water going in and out of is equal and the cells will remain the same size and the same shape and maintain their function.

-the danger to the tissue is that blood circulating into the tissue would be concentrated causing a hypertonic tissue fluid (remove to much water) or it may be very dilute causing a hypotonic tissue fluid (add too much water).

-so we want to keep the tissue fluid isotonic to the cells cytoplasm- achieved by controlling the composition of blood.

-blood forms the tissue fluid- role of kidney to control the composition of blood.

-blood with circulates through our kidney excess water, salts can be removed and excreted down the ureter.

-by controlling the content of water and salts in the blood the kidney can keep the blood and therefore the tissue fluid isotonic with the cells cytoplasm maintaining the function of the cell.

2.68a Excretion

understand how the kidney carries out its role of excretion and of osmoregulation
-excretion of the molecule urea (carries nitrogen and it is toxic to the body and cannot be stored)
-the original form of nitrogen circulating in our blood stream and is potential toxic are the amino acids.
-amino acids are normally used for growth but extra amino acids must be removed- they are toxic, rule of both liver and kidney.
-first stage- blood circulates to the liver and the amino acids are broken down and converted into the molecule urea.
-the urea re-enters the bloodstream and circulates to both kidneys.
-the kidneys will filter the urea from the blood and the urea will be added to the water to form urine.
-urine drains down the ureter to collect in the bladder.
-the urea is now in the bladder in the form of urine- been removed from the body.
-the filtered blood returns to the circulation in the veins with the toxic amino acids and urea removed- example of excretion.

2.67b Human organs of Excretion

recall that the lungs, kidneys and skin are the organs of excretion.
-1) lungs- lungs excrete carbon dioxide- waste from respiration that need to be eliminated from the body.
-2) kidney- kidneys excrete excess water, the molecule urea (the nitrogen waste from amino acids- we cannot store them so we excrete them) and salts.
-3) skin- known to excrete water (sweat), salts (sweat), and a little bit of urea. (mainly water and salt)

2.67a Excretion in plants

recall the origin of carbon dioxide and oxygen as waste products of metabolism and their loss from the stomata of a leaf
-photosynthesis: absorbing light energy and in the process of doing so it combines (CO2) carbon dioxide and water (H2O) to form glucose (C6H12O6) and gives of the gas (O2) oxygen- waste molecule example of excretion which is the release of metabolic waste.
-process of respiration: glucose (C6H12O6) + O2 (oxygen) --enzyme reaction-----> ATP (produced in the process) + CO2 (waste molecules also excretion) + H2O.

-plants excrete O2 (oxygen) or CO2 (carbon dioxide) depending on whether they are doing photosynthesis or respiration.

3.31 Evolution

describe the process of evolution by means of natural selection.
-evolution: change in the form of organisms. (new form of organisms arising)
                : change in frequency (how many) of alleles.
-natural selection: the mechanism of evolution (first proposed by Charles Darwin)
-SA (Staphlococcus aureus) causes skin infection and also lung infection

evolving SA

first graph

-normal form is susceptible to methicillin (antibiotic) (antibiotic can kill SA)

-MSSA (methicillin susceptible SA)

second graph

-random mutation in SA allow breaking down of methicillin. 

-because it can break down it can no longer killed by the antibiotic (resistant form)

-MSRA (red on graph)

-2 forms of bacteria (called evolution) [MSSA, MSRA]

-when antibiotic are applied to the population MSSA is decreased and MRSA is becoming increasing common

-evolution: increase in frequency of allele (or resistance) 

2 features

-random mutation produces MRSA form

-the non random selection (due to antibiotics) selects MRSA to survive and MSSA to be selected and killed.

-natural selection is a process not a list.

3.34 Causes of mutation

understand that the incidence of mutations can be increased by exposure to ionizing radiation (for example gamma rays, X-rays and ultraviolet rays) and some chemical mutagents (for example tobacco)
-radiation (ionizing radiation) eg. x-rays and UVB (ultraviolet) rays (sunshine) can cause skin cancer.
-due to chemicals (tars in tobacco) cause mutation to base sequence producing new alleles and causes cancer.
-chemicals that cause mutations are called mutagens.
-mutagens which also causes cancer are called carcinogens.