hormones and homeostasis Flashcards
what is a hormone
chemical substance produced by one of 8 endocrine glands, carried by blood, and altering the activity of one or more target organs
what does the pituitary gland do and secrete
most of the hormones the pituitary glands secrete are stimulants for other glands to secrete their hormones:
Produces:
FSH
GH
Luteinizing Hormone - stimulates ovulation in females and testosterone production in males.
Thyroid-stimulating hormone - helps manage metabolism, energy levels and nervous system
what does FSH do and where is it produced
produced in the pituitary gland:
FSH (follicle stimulating hormone) stimulates sperm production in male babies and stimulates the ovaries to stimulate estrogen, which helps in egg development in females.
what does the growth hormone do and where is it produced
produced in the pituitary gland:
helps children grow and adults strengthen their muscles and bones
what is the luteinising hormone and where is it secreted
secreted in the pituitary gland:
stimulates ovulation in females and testosterone production in males
what is a thyroid stimulating hormone and where is it produced
produced in the pituitary gland:
as the name suggests the hormone stimulates thyroids to create thyroxine, also helps manage metabolism, energy levels and nervous system
what is the the thyroid gland and what does it do
the thyroid gland produces thyroxine
thyroxine increases the metabolic rate and hence regulating growth and development.
what are the pancreas and what do they do
the pancrease secrete many digestive enzymes (amylase, trypsin, lipase) but also play a major role in blood glucose level maintainence.
what is insulin
insulin is a hormone that is produced by the pancreas.
insulin acts in response to the blood glucose being too high. Insulin promotes glucose –> glycogen which reduces blood sugar levels.
glucose to glycogen conversion occurs in the liver and glucose once converted to glycogen is stored in the liver and muscles.
Inslulin is produced by beta cells
what is glucagon
produced by the pancreas, glucagon acts in response to the blood glucose level being too low.
glucagon promotes glycogen —> glucose which increases the glucose level in the blood.
glucagon is produced by alpha cells
what is the adrenal gland and what does it do
the adrenal gland produces adrenaline.
what is adrenaline and where is it produced
adrenaline is a hormone which is secreted in fight or flight situations.
major part of the sympathetic nervous system.
adrenaline stimulates increase in metabolism, heart rate, respiration, pupil dilation and blood glucose.
what is noradrenaline
noradrenaline is the main NEUROTRANSMITTER of the sympathetic nerves in the cardiovascular system. Noradrenaline can constrict blood vessels increasing blood pressure.
what is adrenaline used to treat
asthma attacks
cardiac arrest
what is noradrenaline used to treat
ADHD
septic shock
what are the testes and what do they do
testes produce testosterone (male sex hormone)
what are the ovaries and what do they do
produce estrogen (female sex hormone)
why does adrenaline increase pulse and breathing rate
so that in fight or flight situations glucose and oxygen can be delivered easily to the muscles
why does adrenaline increase blood glucose
for increased respiration in muscle cells
why does adrenaline dilate the pupils
so that more information can be processed by the brain
what is homeostasis
maintainence of a constant internal environment
what are the “internal environments” that is being referred to
Temperature
blood glucose concentration
water concentration
blood pressure
what is negative feedback
Negative feedback occurs when conditions change from the ideal or set point and returns conditions to this set point
how does negative feedback work
if the level of something rises, control systems are switched on to reduce it again
if the level of something falls, control systems are switched on to raise it again
what is the problem in patients with type-1 diabetes and how is it treated.
blood glucose is far too high as insulin secreting cells in the pancreas are not secreting enough insulin.
treated with insulin shots
how does the body regulate heat, when there is an increase in body temp
increase in body temp -> thermoreceptors in the hypothalamus and skin detect change -> increased sweating, vasodilation, hairs lie flat on skin -> decrease in body temp to normal temp (37C)
how does the body regulate heat, when there is a decrease in body temperature
decrease in body temp -> thermoreceptors in the hypothalamus and skin detect change -> vasoconstriction, shivering, hair on skin erect -> increase in body temp to regular temp (37C)
how does sweat help cool the body
sweat secreted by sweat glands evaporates off the skins surface leaving a cooling effect on the skin
how does shivering help heat up the body
skeletal muscles contract rapidly, the contractions need energy from respiration some of this energy is transferred as heat.
what is the effect of strenuous exercise on the volume of water lost by the skin and the kidneys
volume of water lost by the skin:- increases
volume of water lost by the kidney:- decreases
why does vasoconstriction make us feel warmer
capilaries get narrower, less blood flow to the surface of the skin, less heat lost by radiaton from blood travel
why does vasodilation make us feel colder
arterioles relax, more blood is flown to the surface of the skin, more heat is lost by radiation making us feel cooler.
what is gravitropism
+ve response
-ve response
growth in plants towards/away from gravity
positive response: growth towars gravity (towards the ground)
negative response: growth away from gravity (away from the ground)
what is phototropism
+ve response
-ve response
growth towards/away from light
positive response: growth towards light (towards shoot)
negative response: growth away from light (towards root)
what are shoots photopic and gravitropic
positively phototropic
negatively gravitropic
what is a clinostat
a device that revolves slowly and repeatedly so the shoots are evenly exposed to light. Allows all the sides of the seedlings to get an equal amount of light so they dont curve towards the light but grow straight up
What is auxin
growth hormone in plants which controls the direction of the plant growth
how do plants control their growth
chemically
where is auxin made
and how does it spread
in the tips of growing stems and roots, diffuses to the other parts of the stem/roots spreading from high concentration to low concentration
what does auxin stimulate
auxin stimulates the cell behind the tip to elongate. the more auxin present the more they will grow
How does auxin affect phototropism
if light is shone all around the tip then auxin is distributed evenly and equally and the cells in the meristem grow at the same rate.
when light shines on the shoot predominantly from one side then the auxin produced in the tip concentrates on the shaded side (side with no light), making cells on the shaded side elongate and grow faster than the side facing the light.
how does auxin affect gravitropism
Auxin collects on the lower side of the plant making it grow faster than the upper side causing it to curve upwards
where does auxin collect in plants exposed to light and plants under the force of gravity
how does the plant grow accordingly
gravity: bottom. grows upwards
light: shaded side. grows towards the light
in which organ do the breakdown of hormones first appear
liver
which target organ releases glucose into the blood as a result of adrenaline
liver
what part of the eye prevents total internal reflection
choroid
explain how a decrease in water potential of the blood may damage the red blood cells
water diffuses out of the rbc
through a partially permeable membrane
down the water potential gradient
which part of the brain is key in maintaining homeostasis
hypothalamus
why must internal body temperatures remain below 37 degrees C
If body temperature increases over this temperature, enzymes will denature and become less effective at catalysing reactions such as respiration
Describe how the nervous system coordinates the response of the skin to cold weather.
change in temperature acts as a stimulus
thermo receptors in the hypothalamus and skin detect change
electric impulse travels through sensory neurone to brain
relay neurone to motor neurone to effector (eg arteriole)
Explain how negative feedback is involved in the control of body temperature.
change in temperature is detected and acts as a stimulus
to keep temperature constant
corrective action by body is taken
body temperature returns back to normal (37 deg C)
homeostasis is maintained
Explain how the liver lowers blood glucose concentration when it is too high.
responds to insulin (from the pancreas)
increased uptake of glucose
glucose converted to glycogen
insoluble glycogen is stored in the liver
Explain how an increase in glucose concentration is controlled in the body.
pancreas detect increase in glucose concentration
pancreas secrete insulin
liver converts glucose to glycogen
stores in liver
homeostasis maintained
Explain how a decrease in water potential of the blood may damage red blood cells.
water, diffuses out of red blood cells
through partially permeable membrane
by osmosis
down water potential gradient
red cells decrease in volume
The organs of the human body are coordinated by the nervous system.
Outline one other way in which these organs are coordinated.
hormones
secreted in the blood
stimulate target organ
