Excretion And Homeostasis Flashcards
Why does the body remove urea
Because it is toxic and if to much builds up in the blood you could get ill
Helps keep quantities of these substances in the blood at the correct level
What organ gets rid of urea
The kidneys constantly remove urea from the blood by excreting it in urine.
What are the 2 main parts of the kidney
The cortex and the medulla
Cortex- the tissue making up the outer layer in a kidney
Medulla- the tissue making up the inner layers in a kidney
What are kidneys made up of
Thousands of tiny tubules called nephrons
Each nephron begins in the cortex then goes to the medulla, back to the cortex and then down again to the medulla
The nephrons join up with the ureter
What does the ureter do
Carries urine that the kidney has made to the bladder
Nephron
One of the thousands of microscopic tubes inside a kidney where urine is made
Glomeruli
A little network of blood capillaries where the blood is filtered in a kidney
Renal artery splits up to make them
Sing. Glomerulus
Urine formation
Blood flows into the kidneys from the renal artery then splits up into gomeruli. As it flows through the glomerulus it is filtered .
The filtrate includes water ions urea and glucose
These move to the nephrons
Some of the ions water and all of the glucose is absorbed back into the blood as it flows through the nephrons (reabsorption!)
What is left is urea and salts in water.
This is urine and it flows out of the kidney along the ureter into the bladder
It is stored in the bladder for a while and then released through the urethra
Reabsorption
In the kidney nephron, taking back required substances into the blood
Internal environment
The conditions inside the body
Homeostasis
The maintenance of a constant internal environment
how does homeostasis help your cells
to work as efficiently as possible
keeping constant temp. helps enzymes work at optimun rate
keeping a constant amount of water means that your cells are not damaged by absorbing or losing too much water
keeping a constant conc. of glucose means that there is always enough fuel for respiration
by what is glucose concentration controlled by
hormones secreted by the pancreas,
insulin reduces the concentration of glucose in the blood.
glucagon increases the concentration of glucose in the blood
insulin
a hormone secreted by the pancreas, which decreases blood glucose concentration
islets
groups of cells scattered through the pancreas
make two hormones called insulin and glucagon
if the glucose blood concentration is too low…
the pancreas secretes glucagon, this causes the liver cells to break down glycogen to glucose and release it into the blood.
if the glucose blood concentration is too high…
the islets in the pancreas detect this and secrete insulin into the blood. when insulin reaches the liver, it cause the liver to absorb glucose from the blood. some is used for respiration
set point
our blood glucose concentration is not absolutely constant.
the range of normal values for a particular parameter is called a set point
negative feedback
a mechanism that detects a move away from the set point and brings about actions that take the value back towards the set point.
type 1 diabetes
a condition in which insufficient insulin is secreted by the pancreas, so that blood glucose concentration is not controlled.
treating type 1 diabetes
it can damage many different organs
patients check their blood glucose conc. regularly using a simply sensor or check their urine for glucose using a simple dipstick.
is urine contain glucose it is bad.(high)
eating little and often helps
injection with insulin (rapid or long acting)
what is one of the most important organs involved in temp. regulation
the human skin
covered in a layer of dead skin cells which form a tough, impermeable barrier that prevents water evaporating from living cells below.
sweat gland
a structure found in the skin of mammals, which secretes a watery fluid onto the skin to reduce body temperature.
hypothalamus
part of the brain that is involved in the control of body temperature.
coordinates the activities of the parts of the body that can help keep temp
sweat formation
sweat glands extract water and ions from the blood and produce sweat. this travels up the sweat duct to the skin surface and is released through the a pore.
arteriols
blood vessels that bring oxygenated to the skin
these divide to from small capillaries that bring it to just below the surface of the skin.
then join together again to form venules
hair erector muscle
small muscle attached to the hair
if the hair erector muscle contracts the hair goes up
what is the last layer of the skin
a layer of fat
contains cells that produce large drops of oil
helps insulate the body against heat loss and acts a energy reserves
how does the hypothalamus work
contains temperature receptors that sense the temp of blood running through it.
if above or below 37 then it send electrical impulses aloong the neurons to parts of the body which have function of regulating body temp.
when temperature falls (below normal body temperature)
(muscles)
muscles contract- muscles in the body contract and relax very quickly (shivering)
they get the energy from respiration and some energy is released as heat.
the heat generated warms the blood as it flows through them. the body distributes the heat.
when temperature falls (below normal body temperature)
(metabolism)
metabolism increases- the speed of chemical reactions may increase, not only in the muscles.
this also releases heat.
when temperature falls (below normal body temperature)
(arteriols)
vasoconstriction- the arterioles become narrower. onyl a little blood can pass through, forcing most to lie underneath the fat layer. making sure that blood does not loose so much heat.
when temperature falls (below normal body temperature)
(hairs)
hair stands up- the erector muscles contract, pulling the hairs up. does not help in humans
in animals, it traps a thick layer of warm air next to the skin.
when temperature falls (below normal body temperature)
(sweat)
sweat glands reduce secretion
when temperature rises (above the normal body temperature)
(arterioles)
vasodilation- the arterioles become wider and allow more blood to flow through.
allows heat to easily leave the blood into the air.
when temperature rises (above the normal body temperature)
(hair)
hairs lay flat- the erector muscles relax
allows heat to leave the skin through radiation into the air
when temperature rises (above the normal body temperature)
(sweat)
sweat production increases- sweat glands secrete more sweat. sweat lies on the surface of the skin and when it evaporates it takes heat from the skin with it
vasodilation
widening of the arterioles, caused by relaxation of the muscle in their walls.
vasoconstriction
narrowing of arterioles, caused by the contraction of the muscle in their walls.
