Chapter 7 - Animal Coordination Flashcards
Hormones
- Chemical messengers released directly into the bloodstream
- Carried to other parts of the body and trigger a gradual response in their target response
- Porduced/secreted by various glands called endocrine glands
- These make up the endocrine system
The Pituitary Gland
- Produce many hormones that are invloved in regulating body conditions
- It produces hormones that make other glands produce hormones
Ovaries
Produced oestrogen used in the memstrual cycle
Testes
Produce testosterone which is involved in puberty and sperm production
Thyroid Gland
Produces thyroxine which is involved in regulation of metabolism, temperature and heart rate
Adrenal Glands
Produces adrenaline which is used to prepare the body for the fight or flight response
The pancreas
Produces insulin which regulates the blood glucose level
Neurones and hormones
- Hormones have slow action, act for a long time and act in a more general way
- Neurones act fast, act for a short time and act in a precise area
Adrenalin
- Prepares the body for the fight or flight response in which you stand your ground or run away in front of danger
Process of adrenalin
- Binds to specific recrptors in the heart. This causes the heart muscle to contract more frequently with more force so heart rate and blood pressure increase
- This increases blood flow to the muscles which increases oxygen and glucose
- Adrenalin binds to the liver causing it to break down its glycogen stores and increase glucose in the blood stream
Hormone release
- Controlled by a negative feedback loop
- The body detects if the levels of a substance are too high or too low and a response is triggered to bring the levels back to normal
Thyroxine
- Released by hryoid glsnd
- Regulated metablosim
- Metabloic rate is the speed at which chemical reactions occur in the body
- Uses a negative feedback loop
Process of thyroxine
- When the blood thryoxine level is lower than normal, the hypothalamus is stimulated to release thyrotropin releasing hormone (TRH)
- TRH stimulates the release of Thyroid stimulating hormone (TSH) from the pituitary gland
- TSH stimulates the release of thyroxine so the blood thyroxine level rises back to normal
- This is is the opposite if the blood thyroxine level is detected to be too high
Four stages of the menstrual cycle
- Day 1 is when menstruation starts and the uterus lining begins to break down
- From day 4 to 14, the uterus lining builds back up until it becomes a thick spongy layer of blood vessels ready for a fertilised egg to be implanted there
- An egg develops in the ovary and is released (ovulation)
- From day 14 to 28, the lining is maintained so the egg has place to be fertilised. It then begins to break down again
The four hormones that cobtrol the menstrual cycle
- FSH (Follicle stimulating hormone)
- Oestrogen
- LH (Lutenising hormone)
- Progesterone
FSH (Follicle stimulating hormone)
- Released by pituitary gland
- Causes a follicle (an egg and its surrounding cells) to mature in the ovaries
- Stimulates oestrogen production
Oestrogen
- Released by the ovaries
- Causes the lining of the uterus to thicken and grow
- A high level causes an LH surge
LH (lutenising hormone)
- Released by pituitary gland
- Stimulates ovulation and causes the follicle to breach and the egg to be released
- Stimulates the remains of the Follicle to develop into a corpus luteum which secretes progesterone
Progesterone
- Released by the coropus luteum after ovulation
- Maintains the lining of the uterus
- Inhibits the releases of FSH and LH
- When the level of progesterone falls and there is a low oestrogen level, the uterus lining breaks down
- A low progesterone level causes a surge in FSH which restarts the whole process
Clomifene therapy
- Some women are infertile because they do not ovulate
- Clomifene is a drug that causes a surge in LH and FSH which stimulates egg maturity and ovulation
- These increases the chance of pregnancy during this time
IVF
- In vitro fertilisation
- Involves collecting eggs from the woman’s ovaries and fertilising them using the male’s sperm
- Thses are grown into embryos
- These embryos are then transferred to the uterus
- FSH and LH are also given
Contraceptives
Methods of preventing pregnancy either natural or artifical
Hormones as a contraceptive
- Oestrogen can be used to prevent the release of an egg because a high level inhibits the production of FSH which will stop egg development
- Progesterone can reduce fertility as it can stimulate the production of thick cervical mucus,this will prevent the sperm entering the uterus
- These can be put into pills such as the mini pill which contains progesterone
Barrier methods
- These methods put a barrier between the sperm and the egg
- Examples are condoms and diaphragms