Edexcel iGCSE Biology-3.44- 3.45B Sources, Roles and effects of Hormones- Study Notes- New Syllabus
Edexcel iGCSE Biology-3.44- 3.45B Sources, Roles and effects of Hormones- Study Notes- New syllabus
Edexcel iGCSE Biology-3.44- 3.45B Sources, Roles and effects of Hormones- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
3.44 understand the sources, roles and effects of the following hormones: adrenaline, insulin, testosterone, progesterone and oestrogen
3.45B understand the sources, roles and effects of the following hormones: ADH, FSH and LH
Hormones: Sources, Roles, and Effects
🌱 Introduction
Hormones are chemical messengers secreted by endocrine glands.
They travel through the bloodstream to target organs and control specific body processes.
1️⃣ Adrenaline
- Source: Adrenal glands (on top of kidneys)
- Role: Prepares body for “fight or flight” response
- Effects:
- Increases heart rate and blood pressure
- Dilates airways → more oxygen to muscles
- Converts glycogen to glucose in liver → more energy
- Example: Escaping from danger or sudden stress
2️⃣ Insulin
- Source: Pancreas (beta cells of islets of Langerhans)
- Role: Lowers blood glucose levels
- Effects:
- Promotes glucose uptake by cells
- Stimulates glycogen formation in liver and muscles
- Example: After eating, insulin prevents hyperglycemia
3️⃣ Testosterone
- Source: Testes (male reproductive glands)
- Role: Controls development of male secondary sexual characteristics
- Effects:
- Growth of facial and body hair
- Deepening of voice
- Muscle development and increased strength
- Stimulates sperm production
- Example: Male puberty changes
4️⃣ Progesterone
- Source: Ovaries (corpus luteum)
- Role: Maintains pregnancy and regulates menstrual cycle
- Effects:
- Prepares uterus lining for implantation of fertilized egg
- Prevents uterine contractions during early pregnancy
- Example: Supports early stages of pregnancy
5️⃣ Oestrogen
- Source: Ovaries
- Role: Controls female secondary sexual characteristics and menstrual cycle
- Effects:
- Development of breasts
- Widening of hips
- Regulates menstrual cycle by stimulating uterus lining growth
- Example: Female puberty changes
📊 Summary Table
| Hormone | Source | Role | Key Effects / Example |
|---|---|---|---|
| Adrenaline | Adrenal glands | Fight or flight | ↑ heart rate, dilates airways, glycogen → glucose |
| Insulin | Pancreas | Lowers blood glucose | ↑ glucose uptake, glycogen formation |
| Testosterone | Testes | Male secondary sexual characteristics | Facial hair, deep voice, muscle growth, sperm production |
| Progesterone | Ovaries | Pregnancy maintenance | Prepares uterus lining, prevents contractions |
| Oestrogen | Ovaries | Female secondary sexual characteristics | Breasts development, menstrual cycle regulation |
📌 Quick Recap
Hormones are chemical messengers controlling growth, metabolism, reproduction, and stress response.
– Adrenaline → emergency response
– Insulin → blood sugar control
– Testosterone → male puberty & fertility
– Progesterone → pregnancy support
– Oestrogen → female puberty & menstrual cycle
Hormones: ADH, FSH, and LH
🌱 Introduction
Hormones are chemical messengers secreted by endocrine glands.
They travel in the bloodstream to control specific body functions.
1. ADH (Antidiuretic Hormone)
- Source: Pituitary gland (posterior lobe)
- Role: Regulates water balance in the body
- Effects:
- Makes kidneys reabsorb more water → less urine is produced
- Helps maintain blood water content and osmotic balance
- Example: When dehydrated, ADH levels rise → body conserves water
2. FSH (Follicle Stimulating Hormone)
- Source: Pituitary gland (anterior lobe)
- Role: Controls reproductive processes
- Effects in females:
- Stimulates growth and maturation of ovarian follicles
- Follicles start producing oestrogen
- Effects in males:
- Stimulates sperm production in testes
- Example: Initiates menstrual cycle in females and spermatogenesis in males
3. LH (Luteinising Hormone)
- Source: Pituitary gland (anterior lobe)
- Role: Triggers reproductive events
- Effects in females:
- Causes ovulation → release of an egg from ovary
- Stimulates formation of corpus luteum, which produces progesterone
- Effects in males:
- Stimulates testosterone production in testes
- Example: LH surge triggers ovulation in menstrual cycle
📊 Summary Table
| Hormone | Source | Role | Key Effects / Example |
|---|---|---|---|
| ADH | Pituitary gland (posterior) | Water regulation | Kidneys reabsorb water → less urine |
| FSH | Pituitary gland (anterior) | Reproduction | Females: follicle growth, oestrogen ↑; Males: sperm production |
| LH | Pituitary gland (anterior) | Reproduction | Females: ovulation, corpus luteum formation; Males: testosterone production |
📌 Quick Recap
– ADH → water balance, kidney reabsorption
– FSH → egg/sperm production, follicle growth
– LH → ovulation & corpus luteum in females, testosterone in males