Edexcel Biology GCSE - Topic 7: Homeostasis

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Questions and Answers

What role do FSH and LH hormones play in fertility treatments?

FSH and LH stimulate the maturation and release of eggs, increasing the chance of pregnancy.

What physiological changes occur in the body during the fight-or-flight response?

The body experiences increased heart rate, enhanced blood flow to muscles, and elevated adrenaline levels.

How does the copper intrauterine device prevent pregnancy?

The copper IUD kills sperm in the uterus and prevents fertilized embryos from implanting.

In what ways can homeostasis be disrupted?

Homeostasis can be disrupted by internal changes, like hormone levels, or external factors, such as temperature changes. Signup and view all the answers

What are the potential emotional impacts of undergoing IVF?

IVF can cause emotional stress, particularly due to the uncertainty of success and the physical toll of treatment. Signup and view all the answers

Describe the function of insulin in glucose metabolism.

Insulin helps regulate blood glucose levels by facilitating the uptake of glucose into cells. Signup and view all the answers

What are some risks associated with multiple births from IVF?

Multiple births can lead to complications for both the mother and the babies, such as premature birth and low birth weight. Signup and view all the answers

How does thyroxine affect metabolic rate?

Thyroxine increases metabolic rate by stimulating the activity of enzymes involved in metabolism. Signup and view all the answers

How does thyroxine regulate its own production?

Thyroxine regulates its production through negative feedback by inhibiting the release of TRH when its levels are normal, which subsequently stops TSH production from the pituitary gland. Signup and view all the answers

What role does TRH play in the hormonal regulation of thyroxine levels?

TRH, produced in the hypothalamus, stimulates the pituitary gland to release TSH, which then prompts the thyroid to produce thyroxine. Signup and view all the answers

During the menstrual cycle, what is the trigger for ovulation?

Ovulation is triggered by a surge in luteinising hormone (LH), which is produced as a response to increased levels of oestrogen. Signup and view all the answers

How does oestrogen affect the secretion of FSH during the menstrual cycle?

Oestrogen inhibits the secretion of FSH, preventing the maturation of multiple eggs in one cycle and promoting the maturation of a single dominant follicle. Signup and view all the answers

What initiates the growth of the uterine lining after menstruation?

The growth of the uterine lining following menstruation is initiated by oestrogen, which is secreted by the ovaries under the influence of FSH. Signup and view all the answers

Describe the pathway of an egg from the ovary to the uterus during the menstrual cycle.

After ovulation, the egg is released from the ovary and travels through the fallopian tube to reach the uterus. Signup and view all the answers

What happens to the menstrual cycle if a fertilized egg does not implant?

If the fertilized egg does not implant, the menstrual cycle continues and the uterine lining breaks down, leading to menstruation after roughly 28 days. Signup and view all the answers

What is the effect of progesterone during the second half of the menstrual cycle?

Progesterone helps maintain the uterine lining and prepares it for the implantation of a fertilized egg. Signup and view all the answers

What are the primary hormones involved in the mixed contraceptive pill and what is their role?

The mixed contraceptive pill contains oestrogen and progesterone, which inhibit FSH and prevent egg maturation. Signup and view all the answers

What is the main function of the contraceptive implant?

The contraceptive implant releases progesterone, preventing ovulation and thickening cervical mucus to block sperm. Signup and view all the answers

How does the contraceptive injection work and what is its duration?

The contraceptive injection is made of progesterone, preventing egg release and thickening cervical mucus, lasting for 2 to 3 months. Signup and view all the answers

Describe the effectiveness of barrier methods of contraception.

Barrier methods like condoms and diaphragms prevent sperm from fertilizing the egg but can be less reliable due to potential tearing. Signup and view all the answers

What is the role of the IUD, and how long can it be effective?

The IUD releases progesterone, preventing ovulation and sperm mobility, and can last for 5 to 10 years. Signup and view all the answers

What are the potential side effects of the mixed contraceptive pill?

Possible side effects include mood swings, depression, breast tenderness, and increased blood pressure. Signup and view all the answers

How do spermicides function as a contraceptive method?

Spermicides kill or disable sperm, achieving 70% to 80% efficacy in preventing fertilization. Signup and view all the answers

What are possible consequences of not taking the contraceptive pill regularly?

Failure to take the contraceptive pill regularly can result in the body's hormones being released, leading to egg maturation. Signup and view all the answers

Study Notes

Edexcel Biology GCSE - Topic 7: Animal Coordination, Control and Homeostasis

Animal coordination and control are studied as part of homeostasis.
Homeostasis is maintaining stable internal conditions.
The endocrine system and nervous system are involved in coordination and control.
Glands secrete hormones that travel in the bloodstream, affecting target organs.
The nervous system uses nerve impulses; hormonal action is slower but longer-lasting.

7.1 - Hormones

The human body has two communication systems: nervous and endocrine.
Hormones are chemical messengers in the endocrine system.
Hormones, produced by glands, directly enter the bloodstream, reaching target tissues or organs causing responses.
Pituitary gland: the "master gland", influencing other glands.
Pancreas: secretes insulin (regulates blood glucose).
Thyroid: secretes thyroxine (controls metabolic rate).
Adrenal gland: secretes adrenaline (fight-or-flight response).
Ovary: secretes oestrogen (female sex hormone).
Testes: secretes testosterone (male sex hormone).

7.2 - Adrenaline and the Fight-or-Flight Response

Adrenaline is released by the adrenal glands during stressful situations.
It prepares the body for a fight or flight response. This involves increased heart rate, blood pressure, and blood flow to muscles.
Blood sugar levels also increase, releasing glycogen into glucose to power muscles for rapid action.

7.3 - Thyroxine and Metabolic Rate

Thyroxine regulates metabolic rate (how quickly reactions occur).
Low thyroxine levels trigger TRH release in the hypothalamus, then TSH release from the pituitary gland, which stimulates thyroxine production from the thyroid.
Increased thyroxine inhibits further TRH and TSH production via negative feedback.
Thyroxine is vital for growth and development.

7.4 and 7.5 - The Menstrual Cycle

The menstrual cycle is a monthly process preparing the body for pregnancy.
Four hormones are involved: FSH, LH, oestrogen, and progesterone.
The cycle involves stages of uterine lining buildup, ovulation, and menstruation if not fertilised.
FSH triggers egg maturation in the ovary, oestrogen prepares the uterus, LH triggers ovulation. Progesterone maintains the uterine lining.

7.6 and 7.7 - Hormonal Contraception

Hormonal contraceptives like the combined pill or progesterone-only pill prevent pregnancy by suppressing the hormones involved in the menstrual cycle.
They can affect egg maturation, uterine lining and mucus production.

7.8 - IVF and Assisted Reproductive Therapy (ART)

Treatments like IVF use fertility drugs (FSH, LH) to stimulate egg production.
Eggs are extracted from the mother, fertilised in a lab, then embryos are inserted into the uterus.
This technique is used when natural conception is difficult or not possible.

7.9 and 7.10B - Homeostasis and its Importance

Homeostasis maintains stable internal body conditions despite external changes.
Homeostasis is essential for enzyme functions, growth, and cellular processes.
Key factors of homeostasis include blood glucose, body temperature, and water levels.

7.11B - Thermoregulation (Biology Only)

Thermoregulation maintains a constant internal body temperature (usually 37°C).
Key mechanisms include sweating (evaporation to cool down) and vasodilation (widening of blood vessels to release heat).
The opposite reactions (shivering, vasoconstriction) occur when temperature is too low.

7.12B - Thermoregulation and Blood Vessels (Higher and Biology Only)

The hypothalamus has temperature receptors, regulating thermoregulation activities.
Receptors in the skin also influence the process; they send impulses to the hypothalamus to adjust temperature-regulating mechanisms.

7.13 - Insulin

Elevated blood glucose levels cause the pancreas to release insulin.
Insulin stimulates the uptake of glucose from the blood into cells for respiration or conversion to glycogen, reducing blood glucose levels.

7.14 - Glucagon (Higher Only)

If blood glucose levels fall too low, the pancreas releases glucagon.
Glucagon stimulates the liver to convert glycogen to glucose and release it into the bloodstream.

7.15 and 7.16 - Causes and Control of Diabetes

Type 1 diabetes: the pancreas doesn't produce enough insulin.
Type 2 diabetes: body cells are resistant to insulin.
Management involves managing diet, exercise, and medication.

7.17 - Body Mass and Diabetes Risk

Obesity and being overweight increase the risk of developing Type 2 Diabetes.
Risk assessment can include BMI and waist-to-hip measurements.

7.18B - Urinary System Structure (Biology Only)

Kidneys are the main organs of the urinary system, filtering waste from the blood, producing urine.
Blood containing impurities travels via renal arteries into the kidneys, and back to circulation through renal veins.
The kidneys manage salt, ions and urea levels in blood; excess is sent to the bladder.

7.19B - Nephron Structure and Function (Biology Only)

Urine production occurs in millions of nephrons within each kidney.
Key steps involve filtration (removing substances from blood in the glomerulus), selective reabsorption (taking back useful materials), and excretion (removing waste).

7.20B - ADH and the Collecting Duct (Higher and Biology Only)

ADH, released from the pituitary gland, regulates water reabsorption in the kidney.
ADH affects the permeability of the collecting duct, adjusting water loss in urine.
ADH increases water reabsorption when blood becomes too concentrated and vice versa.

7.21B and 7.22B - Treatments for Kidney Failure and Urea (Biology Only)

Dialysis: a machine filters and cleanses blood when the kidneys falter.
Transplantation: a kidney from a donor is a long-term solution but raises immune rejection concerns, tissue typing checks compatibility.
Urea: a waste product of protein breakdown, removed by the kidneys.

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Explore the intricate systems of animal coordination and control, focusing on homeostasis. Delve into the roles of the endocrine and nervous systems, and understand the functions of key hormones and glands like the pituitary and pancreas. This quiz will test your knowledge of how these systems work together to maintain stable internal conditions.