Hormonal Conditions in Humans and Plants

Hormone - Hormones are chemical substances that help to regulate processes in the body.

Endocrine Gland - Endocrine Glands are glands of the endocrine system that secrete hormones directly into the blood rather than through a duct.

The Nervous System and Endocrine System 

Coordinates using   -  The Nervous system coordinates using nerve impulses along neurones, where as the Endocrine system uses hormones (chemicals) circulating in the  blood.

Transmission speed - The Nervous system has a faster transmission speed than Endocrine system.

Duration of Effects - The Nervous system has a short-lived duration of effects, where as the Endocrine system has a longer-lived duration of its effects.

Range of target - Nervous system targets much fewer organs where as the Endocrine system often affects many organs 

Pituitary Gland 

Placed in the Brain and is a 'Master Gland' which secretes several hormones into the blood in response to body conditions. These hormones in turn act onother glands to stimulate ther hormones to be released to bring about effects. 

Pancreas 

This produces insulin, which is used to regulate blood glucose levels.

Thyroid 

This produces Thyroxin, which is involved in regulating things like the rate of metabolism, heart rate and temperature. 

Andrenal Gland 

This produces Adrenaline, which is used to prepare the body for a 'fight or flight' response.

Ovary 

This produces Oestrogen, which is involved in the menstraul cycle.

Testes

Produces Testosterone, which controls puberty and sperm production in males.

At puberty, your body starts releasing sex hormones that trigger off secondary sexual characteristics and cause eggs to mature in women.

In men, the main reproductive hormone is testosterone.Its produced in the testies and stimulates sperm production. In women, the main reproductive hormone is Oestrogen. It is produced in the Ovaries. As well as carrying about physical changes, Oesrogen is involved in the menstraul cycle.

The menstrual cycle has FOUR stages 

Stage 1 - Day 1 - menstruation starts. The uterus lining breaks down for about 4 days. 

Stage 2 - The uterus lining builds up again, from day 4 to 14, into a thick, spongy layer full ofblood vessels, ready to recieve a fertillised egg.

Stage 3 - An egg develops and is released from the ovary at day 14 - this is Ovulation.

Stage 4 - The wall is then maintained for about 14 days until day 28, if no fertilised egg has landed on the uterus wall by day 28, the spongy layer starts to break down and thewhole cycle starts again.

FSH (Follicle-stimulating hormone)

1) Produced in the Pituitary Gland.

2) Caues an egg to mature in one of the ovaries, in a structure called a follicle.

3) Stimulates the Ovaries to produce Oestrogen.

Oestrogen 

1) Produced in the ovaries

 2) Causes the lining of the uterus to grow

3) Stimulates the release of LH (which causes the release of an egg) and inhibits release of FSH 

LH (Luteinising Hormone)

1) Produced by the Pituitary Gland.

2) Stimulates the release of an egg on day 14, Ovulation.

Progesterone 

1) Produced in the ovaries by the remains of the follicle after ovulation

2) Maintains the lining of the uterus during the second half of the cycle. When the level of Progesterone falls, the lining breaks down.

3) Inhibits release of LH and FSH 

Contreception or 'birth control' is used for a variety of reasons: 

• When pregnancy might harm the mental or physical stae of the mother 
• To limit the number of children people have to ensure they dont damage living standards or affect other children 
• To prevent pregnnancy in people who do not want a child  at this stage in their lives 

Oral contraceptives

Human fertility is controlled by hormones. This means that knowledge of hormones can be used to decide to increase, or reduce, the chances of fertilisation and pregnancy

The oral contraceptive, commonly known as the pill, greatly reduces the chances of mature eggs being produced. It contains oestrogen or progesterone (another hormone). These hormones inhibit the production of FSH, which in turn stops eggs maturing in the ovaries.

Oral contraceptives allow couples to choose the time they start a family, and choose the time they stop having children.

The first birth-control pills contained higher amounts of oestrogen than the pills taken today. This caused women to have significant side effects, such as changes in weight, mood and blood pressure. Modern birth-control pills contain much less oestrogen. Some only contain progesterone, which also leads to fewer side effects.

Infertility refers to an inability to conceive after having regular unprotected sex. Infertilitycan also refer to the biological inability of an individual to contribute to conception, or to a female who cannot carry a pregnancy to full term.

The use of FSH and LH in 'fertility drugs' 

Some women have difficulty becoming pregnant because they dont produce enough FSH to allow their eggs to mature. Fertility drugs contain FSH and LH, which stimulate eggs to mature in the ovary.

1) IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.

2) The eggs are then collected from the mother and fertilised by sperm by the father in the               laboratory.

3) The fertilised eggs develop into embryos.

4) At the stage when they are tiny balls of cells, one or two of the embroyos are inserted into the       mothers womb.

Although fertility treatment gives a woman a chance to have a baby of her own:

• It is physically and emotionally very stessful
• The success rates are not high 
• It can lead to multiple births which are a risk to both the babies and the mother 

Auxin is a plant Growth hormone 

• Auxin is a plant hormone that controls growth near the tips and shoots.
• It controls the growth of the plant in respose to light (phototropism) and gravity (gravitropism or geotropism.)
• Auxin is produced in the tips and and moves backwards to stimulate the cell elongation (enlargement) process which occurs in the cells just behind the tips.
• If the tip of the shoot is removed, no auxin is available and the shoot may stop growing. 
• Extra Auxin promotes growth in the shoot but inhibits growth in the root - producing the desired result.

Shoots grow towards light 

1) When a shoot tip is exposed to light, more auxin accumulates on the side that is in the shade than theside that is in the light.                                                           2) This makes the cells grow (elongate) faster on the shaded side, so the shoot bends towards the light. 

Shoots grow away from Gravity and roots grow towards Gravity 

1) When a shoot is growing sideways, Gravity produces an unequal distribution of auxin in the tip, with more auxin on the lower side.                                                   2) This causes the lower side to grow faster, bending the shoot upwards.               3) A root growing sideways will also have more auxin on its lower side.                   4) But in the root extra auxin inhibits growth, this means that the cells on top elongates faster, and the root bends downwards 

1) WEED KILLING - Most weeds growing in fields of crops or in a lawn are broad-leaved, in contrast to cerials and grass which have very narrow leaves. Selective weedkillers have been developed using auxins, which only affact the broad-laved plants. They totally disrupt their normal growth patterns, which soon kills them, whilst leaving the grass and crops untouched. 

2) GROWING FROM CUTTINGS WITH ROOT POWER - A cutting is part of a plant that has been cut off it, like the end of a plant with some leaves on it. Normally, if you stick cuttings in soil they don't grow, but if you add rooting power, which contains auxins, they will produce roots rapidly and start growing as new plants. This enables growers to produce lots of clones of a good plant quickly. 

3) GROWING CELLS IN TISSUE CULTURE - Tissue culture can be used to grow clones of a plant from a few of its cells. To do this, hormones such as auxins need to be added to the growth medium (along with nutrients) to stimulate the cells to divide to form both roots and shoots.

Gibberellin stimultes plant stems to grow:

1) CONTROLLING DORMANCY - Lots of seeds won't germinate until they have been through certain conditions (e.g a period of cold or of dryness). This is called Dormancy. Seeds can be treated with Gibberellin to alter dormancy and make them germinate at times of year that they wouldnt normally. It also helps to make sure all the seeds in a batch geminate at the same time. 

2) INDUCING FLOWERING - Some flowers require certain conditions to flower, such as longer days or lower temperatures. If these plants are treated with gibberallin, they will flower without any change in their environment. Gibberellin can also be used to grow larger flowers. 

3) GROWING LARGER FRUIT - Seedless varieties of fruit (e.g seedless grapes) often do not grow as large as seeded fruit. However, if these are treated with gibberellin, they will grow larger to match the normal types.                                                                                                    

Ethane is used in the food industry to control ripening of fruit during transport and storage.

Some examlples of plant organs include:

• Roots  
• Stems 
• and Leaves 

Transport 

Stems transport materials between a plants roots and its leaves and flowers. They also provide support. In some plants, stems store food and water. The stem contains Xylem and Phloem. 

Roots have a large surface area to collect as much water from the surrounding soil as possible. this is then taken to the xylem by osmosis. 

Leaves transport water to the stomata, where water can evaporate from the plant, about 90% of water that is collected from the roots is lost via evaporation. 

1) The Epidermal Tissue is covered in a waxy cuticle, which helps to reduce water loss by evaporation.

2) The Upper epidemis is transparent so that light can pass through it to the pallisade layer. 

3) The Pallisade layer has lots of chloroplasts (the little structures where photosynthesis takes place.) This means that they are near the top of the leaf where they can get the most light.

4) The Xylem and Phloem for a network of vascular bundles, which deliver water and other nutrients to the entire leaf and take away the glucose produced by photosynthesis. They also help support the structure.

5) Under the Pallisade layer is the Spongy Mesophyll, this contains some chloroplasts so that, if some light gets through the Pallisade cells it can be photosynthesised. In the Spongy mesophyll there are large air spaces, which is needed for easy gas exchange, this is placed near the lower epidermis, which has stomata, where these gases can enter and exit the leaf. 

Xylem tubes takewater UP:

1) Made of dead cells joined end to end with no end walls between them and a hole down the middle. They are strengthened with a material called lignin.

2) They carry water and mineral ions from the roots to the stem to the leaves.

3) The movement of water from the roots, through the xylem and out of the leaves is called the transpiration stream. 

Phloem tubes transport food:

1) Made of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through, these ends can be referred to as seive plates

2) They transport food substances (mainly dissolved sugars) made in the leaves to the rest of the plant for immediate use (e.g in growing regions) or for storage 

3) Ths transport goes in both directions 

4) This process is called translocation

Light In bright light transpiration increases The stomata (openings in the leaf) open wider to allow more carbon dioxide into the leaf for photosynthesis Temperature Transpiration is faster in higher temperatures Evaporation and diffusion are faster at higher temperatures Wind Transpiration is faster in windy conditions Water vapour is removed quickly by air movement, speeding up diffusion of more water vapour out of the leaf Humidity Transpiration is slower in humid conditions Diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air

Transpiration explains how water moves up the plant against gravity in tubes made of dead xylem cells without the use of a pump.

Water on the surface of spongy and palisade cells (inside the leaf) evaporates and then diffuses out of the leaf. This is called transpiration. More water is drawn out of the xylem cells inside the leaf to replace what's lost. As the xylem cells make a continuous tube from the leaf, down the stem to the roots, this acts like a drinking straw, producing a flow of water and dissolved minerals from roots to leaves.

Phloem transports sucrose and amino acids up and down the plant. This is called Translocation. In general, this happens between where these substances are made (the sources) and where they are used or stored (the sinks).

UNITS - cm(3) hour(-1)

                     Rate of Transport =      Difference in Weight                                                                                      Hours taken

Carbon dioxide + Water -> Oxygen + Glucose

Photosynthesis is an endothermic reaction inwhich energy is transferred from the environment to the chloroplasts by light. 

• Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis.

• Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide.

• Temperature can effect Photosynthesis. If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot.

• The concentration of chlorophyll affects the rate of reaction as they absorb the light energy without which the reactions cannot proceed. Lack of chlorophyll or deficiency of chlorophyll results in chlorosis or yellowing of leaves. It can occur due to disease, mineral deficiency or the natural process of aging (senescence). Lack of iron, magnesium, nitrogen and light affect the formation of chlorophyll and thereby causes chlorosis.