Coordination and Control L2: Hormones Learning Objectives: 1.Describe what a hormone is. 2.Describe the menstrual cycle and the role of hormones. 3.Explain how hormones play a role in contraceptives and fertility treatments. 4.Describe the role of plant hormones in plant development. 5.Explain uses for plant hormones.

Hormones Hormone = chemical produced by organisms to stimulate a specific biological response They are considered “chemical messengers” telling parts of the organism to perform a certain function. Hormones are secreted by glands as well as other organs and cells in the endocrine system.

The Female Reproductive System Key Terms: Ovum = egg cell Ovary = organ where eggs are produced Uterus = organ where the foetus develops (also called the womb) Cervix = ring of muscle which at the entrance of the uterus, holds developing foetus in place Vagina = canal through which a baby is born Oviduct Lining of the Uterus

The Menstrual Cycle Day 1 – start of menstruation (period) Day 1-5 – Menstruation = lining of the uterus is shed if no pregnancy is detected. This is eliminated from the body along with the unfertilised egg. Day 5-14 – Uterus lining builds back up again in preparation for potential pregnancy. Day 14 – Ovulation = release of a new, mature egg from the ovaries. Day – Egg travels through the oviduct towards the uterus. Uterus lining continues to thicken. If the egg is not fertilised then the cycle repeats with menstruation.

Hormones and the Menstrual Cycle FSH (follicle stimulating hormone) Produced: pituitary gland (located in the brain) Targets: ovaries Function: stimulates egg to mature, stimulates oestrogen production Oestrogen Produced: ovaries Targets: pituitary gland and uterus Function: stops FSH production, stimulates LH production, and stimulates growth of lining of the uterus LH (luteinising hormone) Produced: pituitary gland Targets: ovaries Function: stimulates the release of the mature egg from the ovaries

Oral Contraceptive Contraceptive = drug that prevents pregnancy Oral contraceptives contain female hormones, particularly oestrogen and progesterone. Oestrogen prevents FSH production so no eggs mature in the ovaries. Progesterone (another female hormone) also prevents ovulation.

Modern contraceptives The first contraceptives contained high levels of oestrogen. Side effects of oestrogen only contraceptives: High blood pressure Headaches Modern contraceptives have fewer side effects Mixed pill: low levels of oestrogen and some progesterone Progesterone only pill: (even fewer side effects but not as effective)

Fertility Treatments Infertility = medical disorder of the reproductive system causing an individual have difficulty having children Infertility in women can be caused by the body not producing enough female hormones, such as FSH. Artificial FSH can be used as a fertility drug and can stimulate eggs in the ovaries to mature and produce oestrogen.

IVF (In Vitro Fertilisation) Infertility can also be caused by damaged oviducts (where fertilisation usually takes place). In IVF, fertilisation takes place in the laboratory. The fertilised egg develops into an embryo made of many cells. The embryos are then transferred into the uterus to develop.

IVF (In Vitro Fertilisation) 1.Fertility drugs used to cause many eggs to develop at once. 2.Eggs are collected from the ovaries and placed on a petri dish. 3.Sperm and eggs are mixed together. 4.Eggs are fertilised and develop into embryos. 5.Multiple embryos are placed into the uterus. 6.Hopefully, at least one embryo implants into the uterus.

Plant Hormones Plant hormones cause plants to respond to different stimuli. Stimuli that plants respond to: Light Gravity Moisture

Tropism Tropism = the turning of a plant in a particular direction in response to an external stimulus Phototropism = response to light, plants grow towards light Gravitropism = response to gravity, roots grow downwards, shoots grow upwards even if the plant/seed is tilted (also called geotropism)

Tropism is controlled by hormones Auxin = the plant hormone responsible for a plant’s response to light, gravity, and moisture How this works: Light, gravity, and moisture causes an uneven distribution of auxin in the shoot or root. Auxin causes an unequal growth rate, causing the plant to bend.

Phototropism Light affects the shoot of a plant. Auxin response to light: auxin moves away from light Auxin effect on shoot: increased auxin stimulates growth Effect Side away from the light grows more, causing the shoot to bend towards the light source. If light is even, both sides grow evenly and the plant does not bend.

Phototropism NOTE: Roots response to water is similar.

Gravitropism (Geotropism) Gravity affects the roots and the shoots differently. Auxin response to gravity: auxin moves to the lower side Auxin effect on shoot: increased auxin stimulates growth Auxin effect on root: decreased auxin stimulates growth Effect In shoots, auxin causes the lower side to grow, causing upward bend. In roots, auxin causes the top side to grow, causing downward bend.

Gravitropis m

Using Plant Hormones: Rooting Powder Cutting = technique to grow new plants from cutting a piece of an existing plant and causing it to grow into a new plant. Plant hormones can be used to stimulate the growth of new roots in a plant cutting allowing it to grow into a new plant.

Using Plant Hormones: Weed Killer High doses of plant hormones can be used to kill weeds. Weeds are broad leaved plants that absorb a lot of the hormone. This causes them to grow out of control, use up all nutrients, and die. Narrow leaved crop plants absorb less and are not affected.