Endocrine System and Hypothalamus Role

Endocrine System Overview

• The endocrine system functions as a command center, crucial for maintaining homeostasis, which involves balancing various bodily conditions.
• Homeostasis examples include maintaining a body temperature of 98.6°F, blood pressure at 120/80 mmHg, and glucose levels between 70-100 mg/dL.
• Endocrine glands control bodily functions through hormones, which are chemical messengers distributed via the bloodstream.

Hypothalamus Role

• The hypothalamus controls the pituitary gland and regulates temperature, hunger, emotions, and stress responses.
• The hypothalamus controls the adrenal medulla, thus influencing the fight-or-flight response.
• TRH stimulates TSH production for thyroid activation.
• CRH stimulates ACTH production, activating stress hormones.
• GnRH stimulates FSH and LH production, which are involved in reproductive functions.
• GHRH stimulates GH production, promoting growth.
• PIH (dopamine) inhibits prolactin production.

Pituitary Gland Functions

• The pituitary gland has two sections: the posterior pituitary (neurohypophysis) and the anterior pituitary (adenohypophysis).
• The posterior pituitary releases oxytocin for bonding, childbirth, and milk ejection
• The posterior pituitary also releases antidiuretic hormone (ADH) to promote hydration by signaling the kidneys to retain water.
• The anterior pituitary releases TSH, which stimulates the thyroid.
• ACTH, released from the anterior pituitary, is central to stress hormone regulation.
• FSH and LH from the anterior pituitary regulate the reproductive system.
• Prolactin (PRL), released by the anterior pituitary, stimulates milk production.
• Growth hormone (GH), also from the anterior pituitary, is essential for growth and repair, with levels spiking during sleep and exercise.

Thyroid Gland Responsibilities

• The thyroid gland, located in the neck, influences energy levels, metabolism, and mood.
• T3 and T4 hormones regulate metabolism and calorie burning.
• Insufficient T3 and T4 lead to hypothyroidism, causing sluggishness and weight gain.
• Excessive T3 and T4 lead to hyperthyroidism, causing nervousness, weight loss, and a rapid heart rate.
• Calcitonin promotes calcium storage in bones.

Adrenal Glands Actions

• The adrenal glands, located atop the kidneys, consist of the cortex and medulla.
• The adrenal cortex includes the zona glomerulosa, which produces aldosterone to regulate sodium and blood pressure.
• The zona fasciculata produces cortisol, the stress hormone.
• The zona reticularis produces backup sex hormones.
• The adrenal medulla produces epinephrine and norepinephrine, mediating the fight-or-flight response.

Reproductive Glands Activity

• The ovaries produce estrogen and progesterone, which regulate menstrual cycles, pregnancy, and mood.
• The testes produce testosterone, which supports muscle growth, libido, and sperm production.
• Both ovaries and testes produce inhibin, which inhibits FSH production.

Pancreas: The Sugar Regulator

• The pancreas regulates energy levels through hormone secretion.
• Alpha cells secrete glucagon to increase blood sugar levels.
• Beta cells secrete insulin to decrease blood sugar levels.
• Delta cells secrete somatostatin which inhibits hormone production.
• Type 1 diabetes results from the pancreas ceasing insulin production.
• Type 2 diabetes occurs when the body becomes resistant to insulin.

Other Endocrine System Components

• The pineal gland secretes melatonin to regulate sleep.
• The heart produces ANP to lower high blood pressure.
• The kidneys release EPO to stimulate red blood cell production and activate vitamin D.
• The lungs convert angiotensin I to angiotensin II to increase blood pressure.

Endocrine System Disorders

• Hypothyroidism symptoms include sluggishness, weight gain, and feeling cold.
• Hyperthyroidism symptoms include nervousness, weight loss, and a rapid heart rate.
• Cushing’s syndrome involves excessive cortisol, leading to a puffy face, weight gain, and a compromised immune system.
• Addison’s disease involves insufficient cortisol, causing fatigue, low blood pressure, and salt cravings.
• Diabetes mellitus is characterized by dysregulated blood sugar levels.

Circulatory System Overview

• Transports oxygen, hormones, and nutrients.
• Removes waste.

Heart: The Pumping Force

• The heart pumps blood continuously.
• Blood carries oxygen and hormones, and removes waste

Blood Components

• Blood consists of plasma, cells, and other substances.
• Plasma (50-60%) is primarily water and transports hormones, proteins, nutrients, and waste.
• Albumin maintains blood thickness, transports hormones, and prevents fluid accumulation.
• Globulins support the immune system.
• Fibrinogen aids in blood clot formation.

Red Blood Cells: Oxygen Transport

• Red blood cells (RBCs) transport oxygen from the lungs to the body's tissues.
• RBCs lack a nucleus.
• RBCs survive for 120 days.
• Too many RBCs can thicken blood, increasing stroke risk.
• Too few RBCs can cause anemia, leading to exhaustion and dizziness.

White Blood Cells: The Body's Defense

• White blood cells (WBCs) defend the body against bacteria, viruses, and parasites.
• There are two types of WBCs: granulocytes and agranulocytes.
• Neutrophils (60-70%) are granulocytes and act as first responders, consuming bacteria.
• Eosinophils (2-4%) are granulocytes that defend against allergies and parasites.
• Basophils (

Overview of the endocrine system's role in maintaining homeostasis through hormones. Focus on the hypothalamus and its control over the pituitary gland, regulating temperature, hunger, emotions, and stress responses. Includes details on TRH, CRH, GnRH, GHRH, and PIH functions.