Endocrine Glands: Thyroid, Parathyroid & Pituitary

• Study notes generated from the provided lecture material

Thyroid and Parathyroid Glands

• The thyroid gland produces thyroid hormones (T3, T4) and calcitonin, regulating metabolism, growth, and body temperature.
• The parathyroid glands produce parathyroid hormone (PTH), which increases blood calcium levels.
• The anterior pituitary secretes growth hormone (GH) to stimulate growth, cell reproduction, and metabolism.
• Excess GH causes gigantism in children and acromegaly in adults.

Adrenal Cortex Regions and Hormones

• The zona glomerulosa produces aldosterone to regulate sodium and potassium levels.
• The zona fasciculata produces cortisol, a stress hormone involved in glucose metabolism.
• The zona reticularis produces androgens, which are sex hormones.

Anterior and Posterior Pituitary Glands

• The anterior pituitary produces and releases hormones including GH, TSH, ACTH, FSH, LH, and PRL.
• The posterior pituitary stores and releases hormones from the hypothalamus, specifically ADH and oxytocin.
• Releasing hormones from the hypothalamus signal the anterior pituitary to release its hormones.

Insulin and Glucagon in Blood Sugar Regulation

• Insulin, produced by β-cells in the pancreas, lowers blood sugar levels
• Glucagon, produced by α-cells in the pancreas, raises blood sugar levels
• Symptoms of excess thyroid hormone are weight loss, heat intolerance, and rapid heartbeat.
• Deficiency in thyroid hormone leads to weight gain, cold intolerance, and slow metabolism.

Hormone Targeting and Endocrine Organs in the Brain

• Hormones affect target cells through specific receptors.
• The hypothalamus regulates the pituitary gland
• The pineal gland produces melatonin

EKG and Heart Sounds

• The P wave represents atrial depolarization
• S1 ("lub") corresponds to the closing of the AV valves.
• S2 ("dub") corresponds to the closing of the semilunar valves.

Hemodynamics and Blood Flow Basics

• Blood pressure equals cardiac output multiplied by total peripheral resistance (BP = CO × TPR).
• Arteries carry mostly oxygenated blood, with the exception of the pulmonary artery.
• Veins carry mostly deoxygenated blood, with the exception of the pulmonary vein.
• The myocardium receives blood through the coronary arteries.

Blood Flow Regulation and Pathway

• Blood flow is regulated by autoregulation, hormones, and neural control.
• The pathway of blood flow through the heart is: right atrium → right ventricle → pulmonary artery → lungs → pulmonary veins → left atrium → left ventricle → aorta → body.

Heart Valves and Endocardium

• The heart valves are the tricuspid, pulmonary, mitral (bicuspid), and aortic valves.
• AV valves close via chordae tendineae and papillary muscles.
• Both the endocardium and endothelium are smooth, but the endocardium lines the heart chambers.

Autonomic Nervous System and the Heart

• The sympathetic nervous system increases heart rate via norepinephrine.
• The parasympathetic nervous system decreases heart rate via acetylcholine.
• The SA node serves as the heart's pacemaker.
• The AV node delays the signal before the ventricles contract.
• Blood vessel tunics consist of intima, media, and externa layers.

Steroid Hormones

• Steroid hormones work inside the cell by binding to intracellular receptors.
• Examples of steroid hormones include cortisol, estrogen, and testosterone.

Hormone Acronyms and Iodine

• Key hormone acronyms include TSH, ACTH, ADH, GH, FSH, LH, and PRL.
• Iodine is essential for thyroid hormone synthesis.

Hypothalamus and Pituitary Relationship

• The anterior pituitary is controlled by releasing hormones from the hypothalamus.
• The posterior pituitary stores and releases hormones produced by the hypothalamus.

Endocrine, Paracrine, and Autocrine Signaling

• In endocrine signaling, hormones travel via the bloodstream to reach target cells.
• In paracrine signaling, hormones affect nearby cells
• In autocrine signaling, hormones affect the same cell that releases them.

Cardiac Cycle Events

• The cardiac cycle consists of atrial systole, ventricular systole, and diastole.

Preload, Afterload, and Orthostatic Hypotension

• Preload refers to the blood filling the ventricles, representing the end-diastolic volume.
• Afterload is the pressure the heart must overcome to eject blood.
• Orthostatic hypotension is a sudden drop in blood pressure upon standing.

Capillary Types

• Continuous capillaries are found in the brain and muscles.
• Fenestrated capillaries are found in the kidneys and intestines.
• Sinusoidal capillaries are found in the liver and bone marrow.

Cardiac Action Potential and Refractory Period

• The refractory period prevents tetanus (continuous contractions) in the heart.

Capillary Exchange Forces

• Hydrostatic pressure pushes fluid out of capillaries
• Osmotic pressure pulls fluid into capillaries.
• The related terms are filtration and reabsorption.

Blood Pressure and Vessel Structure

• Blood pressure is not constant; it is higher in arteries and lower in veins.
• Arteries have thick walls and are elastic
• Veins have thinner walls and valves.

Osmotic and Hydrostatic Pressure

• Net Filtration Pressure (NFP) = Hydrostatic Pressure (HP) - Osmotic Pressure (OP).
• Fight-or-flight hormones include epinephrine and norepinephrine.

Blood Calcium, Sodium, and Diabetes

• Blood calcium levels are increased by PTH and decreased by calcitonin.
• Aldosterone regulates both sodium and potassium levels.
• Type 1 diabetes is an autoimmune disease characterized by no insulin production
• Type 2 diabetes is characterized by insulin resistance.

Shock, Heart Issues, and Electrical Pathway

• Hypovolemic shock results from blood loss.
• Myocardial infarction (MI or heart attack) occurs when a coronary artery is blocked.
• Cerebrovascular accident (CVA or stroke) occurs when the brain's blood supply is blocked.
• The electrical pathway of the heart is: SA node → AV node → Bundle of His → Purkinje fibers.

Heart and Adrenergic Receptors

• Trabeculae carneae are internal ridges in the ventricles.
• Adrenergic receptors include α1 (found in vessels) and β1 (found in the heart).

Blood Pressure, Valves, and SA vs. AV Node

• Normal blood pressure is 120/80 mmHg
• Backflow of blood is prevented by valves and the skeletal muscle pump.
• The SA node is the heart's pacemaker.
• The AV node delays conduction.

Pulse Pressure and MAP

• Pulse Pressure = Systolic Blood Pressure (SBP) - Diastolic Blood Pressure (DBP).
• Mean Arterial Pressure (MAP) = Diastolic Blood Pressure (DBP) + (Pulse Pressure (PP)/3), with the division by 3 because time spent in diastole is longer than systole.

Baroreceptors and Aldosterone Pathway

• Baroreceptors detect changes in blood pressure.
• The RAAS pathway is: Angiotensin I → Angiotensin II → Aldosterone.

Vessel Diameter and Resistance

• Smaller vessel diameter results in more resistance to blood flow.
• The lumen is the hollow space inside the vessel.

Systemic vs. Pulmonary Circulation

• Systemic circulation involves blood flow from the heart to the body and back to the heart.
• Pulmonary circulation involves blood flow from the heart to the lungs and back to the heart.

Overview of the thyroid, parathyroid, anterior and posterior pituitary glands. Covers hormone production, regulation of metabolism, growth, body temperature, and calcium levels. Discusses the adrenal cortex regions and related hormones.