SB7a-g Flashcards
(separated for semester 1 test 2)
What are hormones, where are they found and what is their purpose?
Hormones are chemical substances (chemical messengers). They are released by endocrine glands into the bloodstream and travel to their target organ. They give instructions to the target organ (stimulate) as to what to do.
What are the 6 different glands, what hormones do they release and what is their target organ (if they have a specific one)?
Pituitary: ACTH, FSH, LH, growth hormone
Adrenal: Adrenaline (target organs: muscles, heart, liver)
Pancreas: Insulin, Glucagon (target organs: liver)
Thyroid: Thyroxine
Ovaries : Sex hormones (e.g. oestrogen, progesterone)
Testes: Sex hormones (e.g. testosterone)
NOTE: target organs of oestrogen and testosterone is the pituitary gland.
Check teacher notes “Hormones”.
Explain the job of the adrenal glands and adrenaline, what organs they target and why.
Release adrenaline hormone which is responsible for the fight-or-flight response. Adrenaline works by vasodilating the blood vessels that lead to your legs and arms which allows more blood to flow, carrying oxygen and glucose for the muscles to respire and produce a lot of energy so they are ready to contract in order to either fight or run away. The blood vessels leading to the digestive system vasoconstrict so that the blood goes to the arms and legs.
Target organs:
Heart: pumps faster to increase blood pressure in order to send blood with oxygen and glucose faster to the muscles
Liver: glycogen in the liver converts to glucose in the blood used for respiration.
Explain the job of the thyroid gland, thyroxine and how it is released.
Releases thyroxine hormone into the bloodstream. Thyroxine affects the heart cells causing the heart to contract faster. This increases the rate at which proteins and carbohydrates are broken down.
In order for thyroxine to be released, many events must happen:
1. When thyroxine decreases in the blood, the hypothalamus in the brain gets a signal to release TRH.
2. TRH will stimulate the pituitary to release TSH.
3. TSH then stimulates the thyroid again to release thyroxine.
4. When too much thyroxine is released into the blood, the hypothalamus gets a signal to stop releasing TRH, stopping the events.
This is an example of negative feedback.
Check teacher notes “Hormonal control of metabolic rate”.
What is negative feedback?
A control mechanism that brings conditions back to normal in the body once they have changed. If the level of a substance in the body increases or decreases, then a control mechanism will be used to bring levels back to normal.
What is oestrogen, where is it released from and what does it do?
A sex hormone released from the ovaries. High levels of oestrogen triggers the release of LH which causes the uterus lining to build up again.
What is progesterone, where is it released from and what does it do?
A sex hormone released by the corpus luteum in the ovaries. High levels of progesterone inhibits the release of FSH and maintains the uterus lining thick.
During pregnancy it remains high so that the uterus wall does not break and lose the embryo. If there is no pregnancy, levels fall leading to the breakdown of the uterus lining leading to menstruation.
What is FSH and what does it do?
FSH (Follicle Stimulating Hormone) is released by the pituitary gland. High levels stimulate the maturation of the follicle.
What is LH and what does it do?
LH (Luteinising Hormone) is released by pituitary gland. High levels trigger ovulation.
How do hormones control the menstrual cycle?
During days 1-5, the uterus wall breaks down since the progesterone levels decrease causing menstruation.
During days 5-13, oestrogen levels increase (released from ovaries) causing the build up of the uterus wall. FSH levels also increase (released from pituitary) causing the maturation of the follicle.
Around day 14, oestrogen levels peak causing the release of LH from pituitary gland which causes ovulation.
From day 15-28, the corpus luteum releases progesterone and increases in levels maintaining the thickness of the uterus wall. If there is no fertilisation, then the progesterone levels decrease causing menstruation again.
Check book page 146-7, teacher notes “Hormones and the menstrual cycle” and notebook diagram “Menstrual Cycle”.
What are 3 different contraceptive methods and how do they prevent fertilisation?
Male condom (98% success rate): Placed over erect penis, prevents sperm entering the vagina.
Diaphragm/cap (92-96% success rate): Placed over the cervix (entrance to the uterus), prevents sperm in the vagina entering the uterus.
Hormone pill/implant placed under skin (>99% success rate): Release hormones to prevent ovulation and thickens mucus at the cervix, making it difficult for sperm cells to pass through.
Check teacher notes “Hormones and the menstrual cycle”.
What are different types of hormone therapy?
Assisted Reproductive Technology (ART):
1. Clomifene therapy
2. IVF (in vitro fertilisation)
What is ART?
Assisted Reproductive Technology (ART) is the use of hormones and other techniques in order to increase the chance of pregnancy.
What is clomifene and when is it used?
A drug that increases the concentrations of LH and FSH in the blood. It is given to a women that cannot release eggs or rarely releases eggs.
How is IVF carried out?
- Hormones are given to a woman to mature plenty of eggs.
- The eggs are harvested and transferred to petri dishes.
- The eggs are fertilised by sperm cells in the petri dishes.
- Embryos are formed.
- Usually 2 healthy embryos are implanted into the uterus of the mother.
Check teacher notes “Hormones and the menstrual cycle”.
What is glucose?
Soluble form of sugar in blood.
What is glycogen?
Insoluble form of sugar in liver.
What is the pancreas and what hormones does it release?
Gland that releases 2 hormones:
Insulin - converts glucose into glycogen in the liver
Glucagon - converts glycogen into glucose
What changes glucose levels in the blood?
- Eating a meal causes glucose level to increase
- Skipping a meal or exercising causes glucose level to decrease
How does the body control the glucose level in the blood when it increases?
- Pancreas releases insulin into the blood
- Insulin will take the glucose to the liver which is the target organ
- Converts glucose into glycogen and gets stored in the liver
- This causes the glucose concentration in the blood to decrease back to normal
This is an example of negative feedback.
Check notebook diagram “Blood Glucose”.
How does the body control the glucose level in the blood when it decreases?
- Pancreas releases glucagon
- Glucagon will travel to the liver in the bloodstream and convert the glycogen back into glucose
- Glucose will enter the bloodstream
- This causes the glucose concentration in the blood to increase back to normal
This is an example of negative feedback.
Check notebook diagram “Blood Glucose”.
What happens if a person has Type I Diabetes?
- Pancreas does not release enough insulin or does not release insulin at all
- Inject insulin 3 times a day before or after a meal
- Have a low carbohydrate diet
What happens if a person has Type II Diabetes?
- Pancreas produces the correct amount of insulin but the cells in the body are resistant to insulin
- Obese people have a higher chance of getting it
- Take special medication and exercise
- Have a low carbohydrate diet
What is correlation?
When one variable changes, the other variable appears to change as well which shows a relationship.
What causation?
When one variable changes, causes the other variable to change as well.
What is homeostasis?
The control of all internal conditions and keeping them constant.
What controls thermoregulation?
The hypothalamus in the brain.
What is the normal body temperature?
36.5-37°C
How does the body control changes in the body temperature when it increases?
- Thermoreceptors in the blood/skin detect this increase and send a signal to the hypothalamus
- The hypothalamus sends a signal to the sweat glands which release sweat
- The sweat evaporates and heat will be lost, cooling the body down
- Shunt vessels deep in the body will vasoconstrict
- Blood vessels near the skin surface vasodilate so most blood flows near surface and more heat is lost by radiation
- These mechanisms cause the body temperature to decrease back to normal
Check notebook diagram “Thermoregulation”.
How does the body control changes in the body temperature when it decrease?
- Thermoreceptors in the blood/skin detect this decrease and send a signal to the hypothalamus
- The hypothalamus sends a signal to the muscles of the hair to erect
- This traps a layer of air between the skin and the environment and air acts as an insulator, stopping the heat to be lost by radiation
- Muscles start to contract causing shivering and release heat by respiration
- Shunt vessels vasodilate so more blood flows deeper into the body to stop any heat loss
- Blood vessels near the skin vasoconstrict so less blood flows through them and less heat is lost by radiation
- These mechanisms cause the body temperature to increase back to normal
Check notebook diagram “Thermoregulation”.
