Topic 5- Hormonal coordination in humans Flashcards
Give the name of the body’s coordination system which involves hormones
The endocrine system
What is a hormone?
A hormone is a chemical messenger secreted by a gland. It travels in the blood to a target organ, where it causes a response
What type of organ secretes hormones?
Glands
Which gland controls many other glans in the body, known as the “master gland”
The pituitary gland
Why is the pituitary gland considered a master gland?
It secretes a wide range of hormones, some of which may stimulate other endocrine glands
What os the role of the pituitary gland in the endocrine system
Secretes human growth hormone
Stimulates the thyroid gland
Stimulates ovulation and the production of oestrogen in the ovaries
Stimulates the production of sperm and testosterone in the testes
What is the role of the thyroid gland in the endocrine system?
Secretes the hormone thyroxine- controls metabolism, heart rate and body temperature
What is the role of the pancreas in the endocrine system?
Secretes the hormone insulin- controls blood glucose levels
What is the role of the adrenal gland in the endocrine system?
Secretes adrenaline- controls the body’s “flight or flight” response
What is the role of the ovaries in the endocrine system?
Secrete oestrogen which coordinates the menstrual cycle and the development of female sexual characteristics
What is the role of the testes in the endocrine system
Secrete testosterone, which coordinates the production of sperm and the development of male secondary sexual characteristics
Which organ monitors and controls blood glucose concentration
The pancreas
How does the pancreas respond when blood glucose levels are too high
The pancreas secretes the hormone insulin.
insulin binds to the receptors on the liver and muscles, causing excess glucose to be converted into glycogen and stored
Why does the pancreas respond when blood glucose levels are too low
The pancreas secretes the hormone glucagon. Glucagon binds to the liver cells, causing glycogen to be converted into glucose and released into the blood
How is blood glucose glucose concentration controlled using a negative feedback loop
-When the blood glucose concentration rises or falls below the optimum, a hormone is secreted by the pancreas
-The action of either hormone (insulin or glucagon) helps bring back the concentration to the correct level
What is type 1 diabetes
Type 1 diabetes is an autoimmune disorder in which the pancreas doesn’t produce sufficient insulin to control the blood glucose concentration
As a result, blood glucose levels are often very high, leading to excessive urination, tiredness and weight loss
How can Type 1 diabetes be treated?
Insulin injections before meals- allows glucose to be converted into glycogen
Limiting carbohydrate intake
-Attempts using pancreas and pancreatic cell transplants; investigations into genetic engineering of pancreatic cells
What is Type 2 diabetes
Type 2 diabetes is a disorder in which the body’s cells stop responding to insulin, leading to an uncontrolled blood glucose concentration. Its onset is linked with increasing age and obesity
How can Type 2 diabetes be treated
-Following a carefully controlled diet
-Doing regular excercise
-Loosing weight
-Use of drugs which increase insulin production and effectiveness
In what ways is water lost from the body
-During exhalation via lungs
-Sweating
-Urine (some reabsorbed in the kidney)
In what ways are ions lost from the body
-Sweating
-Urine (some reabsorbed in the kidney)
How are excess amino acids excreted from the body?
-Excess amino acids are deaminated in the liver to form ammonia
-Ammonia is toxic, therefore it is converted into urea
-Urea is excreted from the body via sweat and urine
How do the kidneys maintain the balance of water and other substances in the body
-Filter blood in order to remove waste products (like Urea)
-Selectively reabsorb useful molecules (like glucose, water, ions)
What is the full name of the hormone ADH
Anti-diuretic hormone
Where is ADH secreted in the body?
The pituitary gland of the brain
How does ADH affect the reabsorption of water in the kidneys?
-When the blood is too concentrated, the pituitary gland secretes more ADH
-ADH travels in the bloodstream to the kidney and increases the permeability of kidney tubules to water
-More water is reabsorbed in the kidneys, resulting in a smaller volume of more concentrated urine
Why is kidney failure dangerous?
When the kidneys are damaged, they may be unable to filter the blood properly. This may lead to:
- A build-up of toxic molecule (eg urea) in the body
-An uncontrolled ion and water balance and cells being damaged as a result of osmosis
What are the two main ways of treating kidney failure?
-Dialysis
-Transplant
What is kidney dialysis?
Kidney dialysis is the use of a specialist machine to carry out the function of kidneys. Dialysis fluid contains the same concentration of glucose and ions as healthy blood. As a result, only excess and waste molecules are lost from the blood, and glucose and ions remains
What is the function of reproductive hormones
Males: cause development of secondary sexual characteristics
Females: cause the development of secondary sexual characteristics and the maturation of eggs
What is the main male reproductive hormone?
Testosterone- produced by the testes and controls sperm production
What is the main female reproductive hormone?
Oestrogen- produced by the ovaries and is involved in the menstrual cycle
What is the menstrual cycle?
The monthly cycle of physiological changes that occur in females, involving the shedding of the uterus lining (menstruation) and ovulation
Describe the events of the menstrual cycle
-Uterus lining thickens and eggs begin to mature in the ovaries
-An egg is released from one of the ovaries (ovulation) (uterus lining remains thick)
- If the egg is fertilised, pregnancy may occur. If not, both the egg and uterus lining are shed during menstruation
What is ovulation?
Ovulation, is the release of a mature egg from the ovaries, which occurs approximately every 28 days
Name the four main hormones involved in the menstrual cycle
-Oestrogen
-Progesterone
-Follicle stimulating hormone (FSH)
-Luteinising hormone (LH)
What is the role of FSH in the menstrual cycle?
FSH is secreted by the pituitary gland. It controls the maturation of eggs within the ovaries (inside a follicle) and triggers the production of oestrogen by the ovaries
What is the role of oestrogen in the menstrual cycle?
Oestrogen is produced by the ovaries and released due to the action of FSH - it causes the regrowth of the uterus lining.
It triggers the production of LH and restricts the release of more FSH
What is the role of LH in the menstrual cycle?
LH is produced in the pituitary gland as a result of oestrogen. Its release triggers ovulation
What is the role of progesterone in the menstrual cycle?
Progesterone is secreted from the follicle of the ovary. It sustains the uterus lining and inhibits FSH and LH
What is contraception?
Contraception refers to any method of preventing pregnancy
What are the two types of oral contraceptives?
-Combined contraceptive pill (contains oestrogen and progesterone)
-Mini pill (contains only progesterone)
How does the contraceptive pill prevent pregnancy?
-Inhibits FSH- eggs do not mature
-Prevents the development of the uterus lining- eggs cannot implant
-Increases the thickness of cervical mucus- immobilises sperm cells
What is the contraceptive patch?
-Contains both oestrogen and progesterone
-It is a patch that is placed onto the skin for 7 days at a time
What is the contraceptive implant?
A small rod inserted under the skin which continuously releases the hormone progesterone- lasts for 3 years
What is the contraceptive injection?
An injection containing the hormone progesterone- lasts for approximately 3 months
What is the IUS?
The IUS (intrauterine system) is a small plastic device that is inserted into the uterus. It releases progesterone which thickens cervical mucus and prevents the build-up of the uterine lining
What is the IUD?
The IUD (intrauterine device) is a small copper-containing device inserted into the uterus, which prevents the implantation of embryos
What is a spermicide
A spermicide is a chemical that kills or immobilises sperm cells- however, they are not very effective, and work better when combined with barrier methods
What is a barrier method of contraception?
A barrier method of contraception involves a physical separation between the sperm and the egg. They include:
-Condoms- thin sheath worn on the penis or inside the vagina- protects against STIs but may tear/break
-Diaphragms- a thin cap placed over the cervix- prevent entry of sperm
What surgical methods of contraception are available
Sterilisation- in males, the sperm ducts are tied (vasectomy) and in females, the oviducts are tied
What is abstinence?
Abstinence is the practice of not having sex, which also avoids pregnancy. Some people abstain from sex around the time of ovulation- known as the rhythm method, but its quite unreliable
How do fertility drugs increase the chance of pregnancy?
Many fertility drugs contain FSH- which stimulates oestrogen production and the maturation of eggs in the ovary. They also contain LH which triggers ovulation
What is IVF?
IVF (in vitro fertilisation) is type of fertility treatment:
-Mother is given FSH and LH- stimulates maturation of eggs and ovulation
-Eggs are fertilised using sperm in a laboratory- develop into embryos
-1 or 2 embryos are inserted into the mother’s womb
What are the advantages of fertility treatment
-Allows infertile couples to have children
-Can store a woman’s eggs for later
What are the disadvantages of fertility treatments?
-It can be very expensive
- It has a low success rate- especially for older couples
-Increases chance of multiple pregnancies- dangerous for mother and babies
-Side effects of fertility drugs
What is negative feedback?
Negative feedback is a type of control where the body responds to an increase or decrease in a factor by returning it to the optimum level
What is thyroxine?
Thyroxine is a hormone released by the thyroid gland. Its release is triggered by the thyroid stimulating hormone (TSH). Thyroxine controls the body’s metabolic rate, growth and development
How is the release of thyroxine controlled by negative feedback?
-Levels of blood thyroxine falls- detected by receptors in brain
-Pituitary gland releases more TSH
-More thyroxine produced and released by the thyroid gland
-Blood thyroxine level returns to normal
What is adrenaline?
Adrenaline is a hormone secreted by the adrenal gland in times of stress. It is responsible for the “fight or flight response”
What are the effects of adrenaline
-Increase in heart and breathing rate- delivers oxygen and glucose to the body
-Stored glycogen converted to glucose
-Dilation of pupils
-Increased mental awareness
-Blood diverted away from digestive system to muscles
