4th Quarter Science: Endocrine and Nervous Systems

The Human Endocrine System

• The endocrine system, composed of glands, produces hormones that regulate various body processes
• The primary glands, hormones released, and their functions are key objectives of study

Objectives

• Identify endocrine system's primary glands and related hormones with their functions
• Understand hormones involved in male and female reproductive systems and their feedback mechanisms
• Identify different nervous system types and their underlying components

Endocrine System Components

• Pituitary Gland:
  • Located at the base of the brain
  • Releases hormones like oxytocin, vasopressin, prolactin, and somatotropin
  • Controls growth and functions of other glands
• Pineal Gland:
  • Situated at the base of the brain
  • Releases melatonin
  • Associated with circadian rhythm and light
• Thyroid Gland:
  • Located below the voice box
  • Releases thyroxin and calcitonin
  • Controls body metabolism and lowers calcium levels
  • Potential disorders: hypothyroidism, hyperthyroidism, and goiter
• Parathyroid Gland:
  • Located in the neck
  • Releases parathormone
  • Regulates calcium levels in the body and normalizes bone growth
  • Disorders can lead to abnormal calcium levels
• Thymus Gland:
  • Located in front of the heart
  • Releases thymosin
  • Produces certain antibodies
  • Plays a crucial role in the immune system's T lymphocytes
• Adrenal Gland:- Located on top of each kidney
  • Comprises two parts: the adrenal cortex and adrenal medulla
  • Produces hormones like cortisol, adrenaline, and aldosterone
  • Regulates metabolism, immune response, blood pressure, and stress responses
  • Disorders may include Addison's disease and Cushing's syndrome
  • Located atop the kidneys
  • Releases adrenaline
  • Prepares the body for action, controls heart rate and breathing in times of emergency; adrenaline also raises blood sugar
• Pancreas Gland:
  • Located between the kidneys
  • Releases insulin (lowers blood glucose levels) and glucagon (raises blood glucose levels)
  • Controls blood sugar levels
  • Disorders are associated with hypoglycemia or hyperglycemia (diabetes)
• Testes:
  • Located in the lower abdomen
  • Produces androgen and testosterone
  • Controls male maturation, characteristics and reproductive function.
• Ovaries:
  • Located in the lower abdomen
  • Produce estrogen and progesterone
  • Controls female maturation, characteristics, and reproductive function.

Reproductive Hormones and Feedback Mechanisms

• Hormones play a role in regulating reproductive function in both males and females.

Male Hormones

• GnRH: Produced in the hypothalamus, targets the pituitary gland, and influences production of gonadotropins and luteinizing hormone.
• FSH: Produced in the anterior pituitary gland; targets testes; influential in spermatogenesis
• LH: Produced in the anterior pituitary gland; targets testes; influential in androgen and testosterone production, maintains spermatogenesis
• Testosterone: Produced in testes; crucial for spermatogenesis and secondary sex characteristics.
• Inhibin: Produced by Sertoli cells in the testes; regulates FSH secretion

Female Hormones

• GnRH: Produced in hypothalamus, targets pituitary gland to trigger release of FSH and LH.
• FSH: Involved in egg production in ovaries
• LH: Involved in egg production and release in ovaries
• Estrogen: Produced in ovaries; regulates female secondary sex characteristics and uterine lining.
• Progesterone: Produced in ovaries; crucial for uterine lining and pregnancy

Menstrual Cycle

• Four key stages:

  Follicular Phase

  The follicular phase is the first half of the menstrual cycle, beginning on the first day of menstruation and lasting until ovulation. During this phase, the pituitary gland releases follicle-stimulating hormone (FSH), which stimulates the growth and maturation of ovarian follicles. These follicles produce estrogen, which helps to thicken the uterine lining in preparation for potential implantation of a fertilized egg.

  Ovulation

  Ovulation occurs around the midpoint of the menstrual cycle, typically on day 14 in a 28-day cycle. This pivotal event is triggered by a surge in luteinizing hormone (LH), which causes the dominant follicle to release an egg into the fallopian tube. The release of the egg marks the transition from the follicular phase to the luteal phase and is crucial for reproduction.

  Corpus Luteum

  After the egg is released, the ruptured follicle transforms into the corpus luteum, which secretes progesterone and some estrogen. These hormones are essential for maintaining the uterine lining, making it receptive for implantation. If fertilization does not occur, the corpus luteum degenerates, leading to a decrease in hormone levels.

  Menstrual Flow

  Menstrual flow, or menstruation, occurs if fertilization does not happen. The decline in progesterone leads to the breakdown of the uterine lining, which is expelled through the vagina. This process typically lasts between 3 to 7 days and marks the beginning of a new menstrual cycle.

Nervous System and Homeostasis

Homeostasis - refers to the dynamic process through which organisms regulate and maintain a stable internal environment, despite changes in external conditions. This concept is crucial for the survival of living organisms, as it ensures that vital parameters such as temperature, pH, hydration levels, and concentrations of ions and nutrients remain within specific limits.

In humans and other mammals, homeostasis is achieved through various feedback mechanisms involving the endocrine and nervous systems. For example, when body temperature rises, mechanisms such as sweating and vasodilation (widening of blood vessels) are activated to cool the body down. Conversely, if the body temperature drops, shivering and vasoconstriction help to conserve heat.

Maintaining homeostasis is essential for metabolic processes, as deviations from normal ranges can lead to dysfunction and disease. Various systems work in concert, such as the hypothalamus regulating body temperature, the kidneys managing fluid balance, and the endocrine system controlling hormone levels. Overall, homeostasis is foundational for health and functionality in biological systems.

• The nervous system is crucial for coordinating body processes, and maintaining homeostasis
• The nervous system includes the The Central Nervous System (CNS) comprises the brain and spinal cord, which process information and coordinate responses, while the Peripheral Nervous System (PNS) connects the CNS to limbs and organs.

CNS Divisions

• Brain:
  • Controls most body reactions
  • Left Hemisphere: skill based: speaking, writing, numerical skills, and language.
  • Right Hemisphere: spatial intelligence, pattern recognition, and music ability.
  • Different Lobes:
  • Frontal- voluntary functions, different moods, and smell;
  • Parietal- touch and taste;
  • Occipital- sight;
  • Temporal- hearing and memory.
• Cerebrum: Largest portion, controlling several abilities
• Cerebellum: Controls movement coordination
• Brain Stem: Connects brain to spinal cord
• Three Regions of Brain Stem:
  • Medulla Oblongata: Controls heartbeat, breathing, swallowing, vomiting, coughing and sneezing.
  • Midbrain: Coordinates muscular movements and reflexes for eye and head movements
  • Pons: Connects brain parts and controls breathing

PNS

• Somatic Nervous System:
  • Controls voluntary body movements
  • The two divisions of the Somatic Nervous System (SNS) are the afferent division, which transmits sensory information to the CNS, and the efferent division, which carries motor commands from the CNS to muscles.
• Autonomic Nervous System:
  • Regulates involuntary movements
  • Two divisions:
    • Sympathetic (active, stressful situations, increases metabolic rate)
    • Parasympathetic (returns body to normal state)

Recall Questions

• Key questions about the endocrine system and how hormones regulate the body.

Homeostasis

• The process of maintaining internal stability while adjusting to external changes
• Nervous system and endocrine system work together to uphold homeostasis

Generalization Questions

• Questions for discussion, including working together in a community, the relevance of balance, and the relationship between the nervous and endocrine systems in sustaining homeostasis.
• Cortisol, often referred to as the "stress hormone," plays a crucial role in regulating a variety of functions within the body, including metabolism, immune response, and blood pressure. It helps manage how the body utilizes carbohydrates, fats, and proteins, ensuring energy availability during stressful situations. Additionally, cortisol assists in maintaining homeostasis, influencing inflammation, and modulating the body's response to stress by increasing glucose in the bloodstream, thus providing energy.

This quiz covers the key concepts of the 4th Quarter Science curriculum, focusing on the human endocrine and nervous systems. Participants will explore the primary glands, hormones, and their functions, as well as different types of the nervous system. Test your knowledge through trivia and review sessions.