Year 9 Response to Stimuli Part 2

Endocrine System

• Composed of various glands releasing hormones into the bloodstream, influencing target cells.
• Functions primarily through a key and lock system: only specific cells have receptors for certain hormones.
• Hormones can be water-soluble (faster action, shorter effect) or lipid-soluble (slower action, longer effect).
• Major endocrine glands include the hypothalamus, pituitary, thyroid, parathyroids, adrenal glands, pancreas, ovaries, and testes.

Hormonal Response

• Stimulus response model consists of: stimulus, receptor, modulator, effector, response, essential for homeostasis.
• Negative feedback loops are crucial; they help maintain balance by modifying responses to stimuli.
  • Example: Thermoregulation and blood glucose management.

Menstrual Cycle Overview

• A monthly series of physiological changes in preparation for potential pregnancy.
• Duration typically ranges from 21 to 35 days, varying by individual.

Female Reproductive System

• Ovaries: Produce eggs (ova) and hormones (progesterone and estrogen), regulating the cycle and supporting pregnancy.
• Fallopian Tubes: Transport eggs to the uterus; fertilization typically occurs here.
• Uterus: Pear-shaped organ housing developing fetus; thickens and sheds its lining (endometrium) during the cycle.

Phases of the Menstrual Cycle

• Menstruation (Days 1-5): Shedding of the uterine lining occurs; commonly referred to as a period. Symptoms may include cramps, fatigue, and mood changes.
• Follicular Phase (Days 1-13): Following menstruation, hormones prepare a new egg for release, while the uterine lining thickens. Individuals often feel energetic during this phase.
• Ovulation: Release of the mature egg from the ovary.
• Luteal Phase: Prepares the body for a potential pregnancy after ovulation.

Hormonal Regulation in the Cycle

• Progesterone and estrogen are vital for regulating the menstrual cycle.
• Feedback mechanisms ensure the cycle progresses smoothly, adapting to potential pregnancy needs or initiating menstruation when pregnancy does not occur.

This quiz examines key concepts from Year 9 biology, focusing on the endocrine system and the menstrual cycle. Students will review how hormones function within the body and the stimulus response model essential for homeostasis. Test your understanding of these crucial physiological processes.