B11. Hormonal Coordination Flashcards
What is homeostasis?
The regulation of the internal environment in order to maintain optimum conditions for function
Why is homeostasis important?
Homeostasis maintains optimal conditions for enzyme action and all cell functions
What conditions are regulated inside the human body as part of homeostasis?
Blood glucose concentration
Body temperature
Water levels
What is the endocrine system?
The endocrine system is composed of glands that secrete hormones directly into the bloodstream
How are hormones transported around the body?
Hormones are carried around the body in the blood
Compare the effects of hormones and the nervous system
Compared to the nervous system, the effects of hormones are slower but they act for longer
What is the endocrine system?
A system composed of glands that secrete hormones directly into the bloodstream, when they reach a target cell/organ, they produce an effect
Define the term hormone
A chemical messenger molecule released from glands and transported in the blood. Hormones bring about changes in specific target cells
Name the gland that produces and secretes insulin.
The pancreas
What hormone does the pancreas produce when blood glucose is too high?
The pancreas produces the hormone insulin to bring it back down
What happens to excess glucose in liver and muscle cells?
Excess glucose is converted into glycogen for storage
Define Type 1 diabetes
Tyle1 diabetes is a disorder in which the pancreas fail to produce sufficient insulin to control blood glucose levels
Define Type 2 diabetes
Type 2 diabetes is a disorder where the body cells no longer respond to insulin produced by the pancreas
How is Type 2 diabetes treated?
A carbohydrate-controlled diet and an exercise regime are common treatments for Type 2 diabetes.
What is a major risk factor for Type 2 diabetes?
Obesity is a major risk factor for Type 2 diabetes
What is the role of the hormone glucagon?
The hormone glucagon is produced when the blood glucose concentration is too low. It causes glycogen to be converted into glucose and released into the blood
What is the menstrual cycle?
The sequence of events that include the thickening of the uterus lining, ovulation and menstruation; it is controlled by a series of hormones
What is the role of oestrogen in the menstrual cycle?
Oestrogen is required to stimulate the thickening of the uterus lining
What happens to oestrogen levels during the menstrual cycle
Oestrogen levels rise from day 1 and peak just before day 14. The peak in oestrogen occurs just before the egg cell is released
What happens to progesterone levels during the menstrual cycle?
Progesterone levels are low from day 1-14 and starts to rise once ovulation has occurred. Levels then decrease towards the end of the cycle
What s the role of FSH (follicle-stimulating hormone) in the menstrual cycle?
FSH is released by the pituitary gland and cause an egg to start maturing in the ovary
What hormone is released by the pituitary gland to stimulate ovulation?
The pituitary gland is stimulated to release LH (luteinising hormone) which triggers ovulation
Define secondary sexual characteristics?
Secondary sexual characteristics are features that are not present at birth but that develop during puberty
What are the two hormones that control the development of secondary sexual characteristics?
Oestrogen (females)
Testosterone (males)
Give examples of secondary sexual characteristics that develop in females
Breasts develop
Body hair grows
Widening of hips
Menstruation begins
Growth of sex organs
What causes the sudden peak in LH seen at day 14 in a graph?
The peak in LH occurs as a result of oestrogen levels reaching a threshold, the release of LH then stimulates ovulation
Describe the hormonal changes leading the menstrual cycle into stage 1 (Day 1-7)
This is because progesterone is responsible for maintain the lining of the uterus, so when levels drop, the lining starts to break away
Name two hormonal methods of contraception
Injection
Implant
Oral contraceptives
Skin patch
Hormonal coil/intrauterine device
What is an example of a barrier method of contraception?
Condoms
Diaphragms
How does a spermicide prevent pregnancy?
Spermicide kills or disables the sperm so it is unable to fertilise the egg
Why might a woman in her 20’s be discouraged from sterilisation as contraception?
A woman who is 20 years old may be discouraged from sterilisation as she is young and may decide to have children at a later time
Why might it sometimes be recommended to use barrier methods of contraception over hormonal options?
Barrier methods of contraception might be recommended as they provide protection against sexually transmitted diseases
Define the term infertitlity
Infertility refers to the difficulty or inability of a couple to naturally conceive
What hormones found in a fertility drug may stimulate the production of eggs in the ovaries?
A fertility drug may contain FSH to stimulate maturation of an egg, and LH to trigger ovulation
What are the main steps of IVF treatment?
- IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs
- The eggs are collected from the mother and fertilised by sperm from the father in the laboratory
- The fertilised eggs develop into embryos
- At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother’s uterus
What is an embryo?
Embryos are tiny balls of cells which develop from mitotic division of a fertilised egg
What is the risk associated with implanting several embryos during IVF?
The risk associated with implanting several embryos is the high likelihood of multiple births, which increase the risk of miscarriage or stillbirths
Why do some people oppose the production of more embryos than are used in IVF?
Some people oppose the practice of more embryos than are used because it raises ethical concerns about the ownership and potential destruction of unused embryos, which are considered potential life
What is one potential benefit of fertility treatments?
One potential benefit of fertility treatments is that they provide couples with the chance to have a baby of their own
Define ‘negative feedback’
Negative feedback refers to the mechanisms by which homeostasis maintains conditions within an optimal range
A move away from the optimum results in mechanisms which return the conditions back towards the optimum
Where is adrenaline released from?
The adrenal glands found just above the kidneys
What is the function of adrenaline in the human body?
Adrenaline is a hormone produced by the adrenal glands in times of fear or stress, which increases heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’
How is the level of thyroxine controlled in the body?
The level of thyroxine is controlled by negative feedback where high levels of thyroxine leads to a series of events which results in a reduction thyroxine production. Low levels of thyroxine leads to a series of events which results in an increase in thyroxine production.
Define ‘basal metabolic rate (BMR)’?
The basal metabolic rate is the speed at which chemical reactions occur in the body when it is at rest
How is the endocrine system responsible for the fight-or-flight response?
The endocrine system is the system of glands which are responsible for hormone release. This includes the releases of the hormone adrenaline which prepares the body for fight or flight
Why do plants produce plant hormones?
Plants produces hormones in order to coordinate and control growth responses
Define the term phototropism
The directional growth of plants in response to light allowing shoots to grow towards the light to optimise photosynthesis
Define the term geotropism (or gravitropism)
Geotropism, also known as gravitropism, is the directional growth response of plants in relation to gravity; roots grow downwards and shoots grow upwards
What effect does auxin have on cells in the shoots of plants?
Auxins stimulate cell elongation in plant shoots
How does auxin distribution in response to light lead to phototropism?
Auxin accumulation on the shaded side of a shoot causes cells on the shady side to elongate at faster rate than cells on the light side; this leads to bending of the shoot towards the light
What role do gibberellins have in seeds?
Gibberelins initiate seed germination
Which variables need to be controlled in an investigation into the effect of light on newly germinated seedlings?
Direction of gravity
Temperature
Water availability/ how damp the cotton wool is
Type / size / age of seedlings
Why is a clinostat used to investigate the effect of light or gravity on newly germinated seedlings?
A clinostat is used to investigate the effect of light gravity on newly germinated seedlings because it cancels out the effects if gravity
When investigating light this means that the variable of gravity can be controlled so that it does not affect results
When investigating gravity this means that it is possible to study seedling growth in the presence and absence of gravity
How can auxins aid the production of new plants?
Auxins can aid the production of new plants when it is added to:
rooting powder that encourages plant cuttings to grow new roots
cells in a tissue culture to promote growth
What is the use of ethene?
Fruit ripening
How are gibberellins used in the plant growing industry?
Initiate seed germination by ending seed dormancy
Promote flowering
Increase fruit size
