B11 - Hormonal coordination Flashcards
What is a hormone?
chemical molecule (protein/lipid) secreted into the blood by a gland which is carried to a target organ to produce an effect
What is the endocrine system?
system of glands that secrete hormones directly into the bloodstream
Draw the endocrine system, then name the 6 organs in it and their hormones:
-pituitary, master gland (releases hormones to stimulate other glands, eg: TSH)
-thyroid (thyroxine)
-adrenal (adrenaline)
-pancreas (insulin/glucagon)
-testes (testosterone)
-ovaries (oestrogen)
Describe some differences between the endocrine and nervous system:
endocrine
-hormones through blood
-longer lasting
-slower
nervous
-electrical impulses through neurones
-short lasting
-faster
Don’t say the nervous system acts more precisely than endocrine
How does the pancreas restore optimum blood glucose concentrations if they are too high?
-pancreas detects rise and secretes insulin
-glucose moves from blood into cells for respiration
-in liver/muscle cells, excess glucose is converted to glycogen for storage
-BGC reduces
Interacts with glucagon in a negative feedback cycle
How does the pancreas restore optimum blood glucose concentrations if they are too low?
-pancreas detects decrease and secretes glucagon
-glycogen converted to glucose and is released into blood
-BGC increases
Interacts with insulin in a negative feedback cycle
When might the blood’s glucose concentration come out of its normal levels?
increased -eating excess carbs
decrease - exercising/fasting, or not eating for a while after a meal
Describe T1 diabetes:
-T1 is a disorder where the pancreas fails to produce sufficient insulin
-characterised by uncontrolled high blood glucose levels
-usually treated with insulin injections.
Describe T2 diabetes:
-T2 is where the body cells no longer respond to insulin, so the BGC remains high
-treated with carb-controlled diet + exercise regime
-obesity is a risk factor
Suggest why a blood test is more reliable than a urine test for diagnosing diabetes:
-there isn’t always glucose in urine
-could be other reasons for glucose in urine
-blood test gives current result, urine’s glucose levels might be older
Why might a person with T2 diabetes have a high concentration of insulin in the blood?
-cells don’t respond to the insulin produced by the pancreas
-cells absorb less glucose and conversion of glucose to glycogen is reduced
-BGC remains high
-stimulates the pancreas to produce even more insulin
What does negative feedback do?
negative feedback responds to a change in internal conditions, and aims to restore conditions back to ideal levels for optimum enzyme action and cell functions
What is adrenaline released by and when? What does it do?
-produced by adrenal glands in times of fear/stress
-increases HR
-boosts delivery of glucose/oxygen to brain and muscles (prepares the body for fight/flight)
Adrenaline levels are controlled by positive feedback
Describe the role of thyroxine, and how thyroxine levels are controlled:
-released by thyroid
-stimulates basal metabolic rate (BMR), and plays an important role in growth and development
-negative feedback loop
TSH from pituitary gland causes thyroxine to be secreted, but then thyroxine inhibits TSH, forming a loop
What would happen inside the body of someone with an overactive thyroid?
-excess thyroxine released into blood, raising BMR
-causes increase in formation of glycogen/lipids/proteins
-increase in rate of respiration
-increase in breakdown of excess proteins
Generally, what do reproductive hormones do? Describe the male and female sex hormones:
-causes secondary sex characteristics to develop during puberty
-oestrogen (from ovary) stimulates the preparation of the uterus lining for pregnancy by thickening it
-testosterone (from testes) stimulates sperm production
How and when does ovulation start to happen?
at puberty, eggs start to mature and 1 is released from the ovary roughly every 28 days
Describe the hormone interactions during menstruation with a diagram:
oestrogen also helps to maintain the lining
Mature
Thicken (stimulates the preparation of the uterus lining for pregnancy by thickening it)
Ovulation
Maintain
Describe how hormones control the menstrual cycle:
-FSH is released from pit. gland and stimulates the maturation of egg, and the secretion of oestrogen
-oestrogen is released from ovary and stimulates LH production whilst inhibiting FSH production
-LH is released by pit. gland, and stimulates ovulation
-progesterone is released from ovary and inhibits FSH and LH production
-oestrogen and progesterone maintain the uterus lining
Name 3 hormonal methods of contraception:
-oral contraceptive to inhibit FSH production so eggs can’t mature
-injection/implant/skin patch for a slow release of progesterone to stop egg maturation and ovulation
-intrauterine devices to prevent the implantation of embryo, or to release a hormone
Name 4 non-hormonal methods of contraception:
-barrier (condom/diaphragm/cap) prevents sperm reaching egg
-spermicidal agents to kill/disable sperm
-abstinence when egg may be in oviduct
-surgical methods of male/female sterilisation
Only barrier method can prevent an STD
Describe 2 methods of treating infertility:
-FSH/LH in a “fertility drug” so the female can become pregnant normally
-IVF (in vitro fertilisation)
Describe the process of IVF:
-give mother FSH and LH to stimulate the maturation of several eggs
-collect several eggs from mother and fertilise with father’s sperm in lab
-fertilised eggs develop into embryos
-at the stage when they are tiny balls of cells, insert one or two into mother’s uterus
Give some disadvantages of IVF:
-emotionally/physically stressful
-low success rates
-may lead to multiple births (risk to babies and mother)
Why do plants produce hormones?
to coordinate and control their growth in response to changes in light (phototropism) and gravity (gravitropism/geotropism)
What is a tropism?
tropisms are growth responses to a plant’s environment through hormones
Describe the responses the shoots and roots have to light and gravity:
-shoots are positively phototropic and negatively geotropic
-roots are negatively phototropic and positively geotropic
Name 3 plant hormones:
-auxins
-ethene
-gibberellins
Where are auxins produced and what do they do to plants?
auxins are produced in meristems, and uneven distributions of it stimulate cell growth in shoots, but inhibit it in roots
Which part of the meristems do auxins accumulate on?
-the shaded side
-the lower side
Name some agricultural/horticultural uses of auxins:
-weed killers
-rooting powders
-promoting growth in tissue culture
What does ethene do for plants and in agriculture?
-controls cell division
-controls ripening of fruits (can be used during storage/transportation)
What do gibberellins do for plants and in agriculture?
-initiating seed germination (by ending seed dormancy)
-promotes flowering
-increase fruit size
RP8 - How would you prepare germinated seeds for investigating the effect of light/gravity on plant growth?
-pour fixed volume of water into 3 petri dishes and add cotton wool
-put 10 seeds (cress/mustard) into each dish
-put dishes in warm location and allow them to germinate for 3 days
-if some haven’t germinated, remove excess so each dish has equal amounts of germinated seedlings
RP8 - How would you use the prepared petri dishes of seedlings to investigate the effect of light intensity on growth?
-place one dish in each conditions of full sunlight by a window, partial light, and in darkness in a cupboard
-control temperature/wind
-leave for several days
-measure something about the plant depending on the experiment (eg: vertical height, angle from vertical, length)
RP8 - What would happen to the seedling left in the dark?
-grows very tall and yellow
-it tries to find light (like how a seedling in soil would do)
-BUT they aren’t actually growing faster, they are undergoing rapid cell elongation and stretch
