Excretion and Homeostasis Flashcards
What is homeostasis?
The maintenance of a constant internal environment.
What is the temperature inside you body?
37 degree Celsius.
Why do brain cells need glucose? and what will happen is there are deprived of it?
for respiration, they die quickly if they are deprived of it.
What happens to the water in cells when glucose concentration is too high?
the water moves out of the cells by osmosis, and move into the blood.
what is blood concentration controlled by?
Hormones, excreted by the pancreas.
Which hormone is excreted when the blood glucose is too high?
Insulin
what are islets?
a group of cells scattered through the pancreas that excrete insulin and glucagon.
what is the role of glucagon?
increases the blood glucose concentration.
how does the insulin decrease the blood glucose concentration? (steps)
The islets detect the increase the glucose concentration and release insulin into the blood, when the insulin reaches the liver it causes the liver to absorb the glucose, using it for respiration and some is converted to glycogen.
Where is the glycogen stored?
in the liver.
what is a set point?
A range of values or normal value for a particular parameter.
how does the blood concentration of glucose rise(steps)?
the islets detect a decrease and secrete glucagon into the blood, the liver breaks down the glycogen store and releases it into the blood.
What is negative feedback?
A mechanism that detects a move away from the set point and takes action to bring it back to it’s normal value.
What is type 1 diabetes?
when the cells that secrete insulin die.
what are the symptoms of type 1 diabetes?
dry mouth, blurred vision, increased heart rate.
how to treat type 1 diabetes?
checking blood concentration regularly, avoiding large amounts of carbohydrates, and injecting insulin.
what covers the skin?
dead cells
what tissues can be found underneath the protective layer on the right hand side?
sweat gland and pore, blood capillary
what is the role of sweat in the human body?
temperature regulation.
what do the arterioles bring? and where do they form again?
arterioles bring oxygenated blood, which divide to capillaries and join again in the venules.
what tissues can be found on the left hand side of the protective layer?
Hair, erector muscles, receptors
what are erector muscles?
muscles attached to the hair, when they contract, the hair are pulled straight.
what are the receptors present?
temperature and pressure receptors.
what is the layer of fat made of? and what is it’s role?
made of drops of oil, insulates your body and acts as a heat reserve.
which part of the brain keeps the internal temperature constant?
Hypothalamus
which 2 parts of the body are temperature receptors present?
skin and brain
where does the motor neuron send electrical impulses when the temperature drops?
Skin, muscles and liver
what happens to the skin when the body is too cold?(5 points)
Erector muscles contract, the upright hairs trap a layer of warm, arterioles constrict(narrow), not much blood flows through them, capillaries remain narrow. production of sweat decreases and muscles contract and relax very quickly.
what happens to the skin when the body it too hot? (3 points)
The arterioles dilate, causing the sweat gland to make more sweat, more blood it brought to the surface capillaries where it loses heat. The hairs lie flat, this allows heat to leave the body and sweat production increases, as sweat evaporates it cools the body.
what is vasoconstriction?
narrowing of the arterioles
what happens to the sweat glands when the body is too cold?
The sweat gland reduces the quantity of sweat produced, sweat it to cool the body, hence it is not needed.
why do the muscles contract and relax when body is too cold?
so it warms the blood and as it flows the heat is distributed evenly.
what is vasodilation?
widening of arterioles
Where is urea formed?
in the liver
what do the kidneys produce?
urine
where does the urine flow after the kidneys?
from the ureter, to the bladder where it is stored and the urethra.
how is urea formed in the liver?
protein molecules are broken down to amino acids, amino acids are absorbed in the blood and taken to the liver, the needed amino acids are formed into proteins, the rest is deaminated, the carbohydrates are stored in the liver, the nitrogen containing part is converted to urea, urea is taken away by the blood.
what does the liver make urea out of?
excess proteins and amino acids.
How are amino acids taken to the liver?
in the hepatic portal vein
what is deamination?
the removal of nitrogen containing part of amino acids to form urea.
what is formed when amino acids are broken down?
Carbohydrates and nitrogen containing compound.
what are the 2 main parts of the kidney?
Medulla and cortex
what are the tiny tubules in the kidney called?
nephrons
which artery brings urea to the kidneys?
renal artery
what is the role of glomerulus?
filters the blood
what substances does the glomerulus filtrate?
water, glucose, ions and urea
what is reabsorption?
taking back the required substances into the body.
how much of each substance is taken back into the blood?
all of the glucose, most of the water and some of the ions
name the parts of the nephron.
glomerulus, proximal convoluted tubule, loop of Henle, Distal convoluted tubule and collecting tube.
