Endocrine, Blood, Heart, Lymphatic, and Respiratory System Study Notes

Posterior Pituitary Hormones

• Hormones stored in posterior pituitary and produced by hypothalamus: ADH (antidiuretic hormone) and oxytocin.

• These are not synthesized in the posterior pituitary itself; they are made in the hypothalamus and transported/stored in the posterior pituitary for release when needed.

Anterior Pituitary Hormones

• Anterior pituitary secretes six major hormones:

  • TSH (thyroid-stimulating hormone)

  • ACTH (adrenocorticotropic hormone)

  • LH (luteinizing hormone)

  • FSH (follicle-stimulating hormone)

  • GH (growth hormone)

  • PRL (prolactin)

    TINY ANTS LOVE FRESH GREEN PLANTS

• Hypothalamic releasing hormones (examples mentioned): GnRH (gonadotropin-releasing hormone; GRH in the talk), TRH, CRH, GHRH, somatostatin (not listed in talk but relevant for regulation).

• LH and FSH are gonadotropins; they are stimulated by GnRH from the hypothalamus.

Adrenal Glands: Cortex vs Medulla

• Adrenal medulla (inside) produces catecholamines:

  • Epinephrine (adrenaline)

  • Norepinephrine (noradrenaline)

  • These medullary hormones mediate fight-or-flight effects: ↑ heart rate, bronchodilation, vasodilation in some vessels, etc.

• Adrenal cortex (outside) produces steroid hormones:

  • Mineralocorticoids (e.g., aldosterone): promotes Na+ reabsorption and shifts water retention, leading to increased blood pressure.

  • Glucocorticoids (e.g., cortisol): regulates glucose metabolism, interacts with insulin, affects blood sugar; stress response; anti-inflammatory actions.

  • Androgens/sex hormones (gonadocorticoids).

• Key regulatory hormone: ACTH (from anterior pituitary) stimulates cortisol production in the cortex; ACTH is activated by CRH from hypothalamus.

• Clinical connections: excessive or deficient cortisol leading to Cushing’s syndrome or Addison’s disease.

Thyroid, Parathyroid, and Calcium Regulation

• Calcitonin (from thyroid) and parathyroid hormone (PTH) regulate blood calcium in opposition (antagonists):

  • PTH raises blood calcium (hypocalcemic to hypercalcemic balance via bone resorption, kidney reabsorption, and vitamin D activation).

  • Calcitonin lowers blood calcium.

• Note from transcript: there was a quick mix-up naming the regulator source; standard physiology is PTH from parathyroids and calcitonin from thyroid, not hypothalamus.

• Other calcium-related hormones often discussed with thyroid include TSH (thyroid-stimulating hormone) and its role in thyroid hormone production, which indirectly affects metabolism and calcium handling via overall systemic effects.

Blood: Composition, Cells, and Blood Types

• Blood composition: Plasma is the liquid component and is the most abundant portion of blood; typically about 55% of whole blood; the remaining ~45% are formed elements (red cells, white cells, platelets).

  • Representation from transcript: plasma is the largest component; percentage discussions reflect typical hematology knowledge.

• Red blood cells (RBCs) carry oxygen via hemoglobin (Hb). The molecule responsible for oxygen transport on RBCs is hemoglobin.

• Leukocytes (white blood cells) are involved in immune defense.

• Coagulation cascade (blood clotting): Involves intrinsic and extrinsic pathways converging on the common pathway.

  • Common pathway components include factors X, II (prothrombin), V, and I (fibrinogen), leading to formation of thrombin and fibrin.

  • A representative schematic:
    ext{Prothrombin (II)} o ext{Thrombin (IIa)} ext{ via } ext{Prothrombinase}(Xa+Va)
    ext{Fibrinogen (I)} o ext{Fibrin} (Ia) ext{ via } ext{Thrombin}

• ABO blood types (antigens and antibodies):

  • Type O: has antibodies against A and B; no A/B antigens.

  • Type AB: has all A and B antigens; no anti-A or anti-B antibodies; universal recipient for RBCs.

  • Type A: has A antigens; anti-B antibodies.

  • Type B: has B antigens; anti-A antibodies.

Heart: Anatomy, Conduction, and Vessels

• Cardiac apex location: commonly taught as the left 5th intercostal space at the midclavicular line; the transcript shows a student answer of “bottom left,” which is a simplified memory cue but not the precise anatomical landmark.

• Sulci (grooves) of the heart:

  • Interventricular sulcus (groove between left and right ventricles).

  • Interatrial sulcus/atrioventricular grooves separate atria from ventricles and mark coronary vessels.

• Atria and auricles (ears): the atrial appendages are called auricles (horseshoe-shaped pockets).

• Foramen ovale: fetal opening between the right and left atria that normally closes after birth.

• Electrical conduction order (pacemaker-to-pump):

  • SA node → AV node → AV bundle (bundle of His) → bundle branches → Purkinje fibers.

  • The transcript shows student confusion; the correct sequence is SA node -> AV node -> AV bundle -> bundle branches -> Purkinje fibers.

• Blood flow vs. electrical system interplay is emphasized for nursing practice; nurses often monitor or manage devices that interact with these conduction pathways.

• Major vessels and heart vessels:

  • Elastic (conducting) arteries near the heart (e.g., the aorta) are large and elastic.

  • As arteries move away from the heart, they become smaller (arterioles).

  • Veins generally increase in size as they return to the heart.

  • Tunica layers: tunica media (muscular middle layer), tunica intima (innermost), tunica externa/adventitia.

  • The hilum (MIDDLE) of the lungs is the mediastinal region where bronchi, pulmonary arteries, and veins enter/exit the lungs.

      

    Lungs and respiration anatomy:

  • Right lung has three lobes; left lung has two lobes (heart occupies space on left side).

  • Apex of the lung is located high near the clavicle; the apex is susceptible to injury around the collarbone area.

  • The diaphragm separates thoracic and abdominal cavities; lungs are largely in the thoracic cavity.

    

• Larynx, trachea, bronchi, and zones:

  • Larynx (voice box) sits above the trachea.

  • Trachea leads to bronchi; terminal bronchioles lead into respiratory zones.

  • Conducting zone: from nose down to terminal bronchioles; no gas exchange.

  • Respiratory zone: respiratory bronchioles, alveolar ducts, and alveoli where gas exchange occurs.

• Lung structure and perfusion concepts:

  • Alveoli are more numerous at the bases due to gravity-driven perfusion differences; upright individuals have better perfusion at the bases than the apices.

  • Smoking or inactivity can reduce perfusion efficiency and alveolar ventilation distribution.

• Ear-to-nose connection: the auditory (Eustachian) tube connects the middle ear to the nasopharynx; risk of middle ear infections increases with swimming and nasopharyngeal pressure changes.

Lymphatic System and Immunity

• Lymph basics: lymph is mostly water-based, with proteins and occasional pathogens; it can contain lipids in chyle.

• Lymphatic vessels are closed-ended tubes; lacteals are lymphatic vessels in the small intestine that absorb dietary lipids (fat absorption).

• Peyer’s patches (referred to as parapatches in the transcript) are lymphoid tissues in the small intestine that contribute to gut immunity.

• MALT: Mucosa-associated lymphoid tissue; lymphoid tissue associated with mucosal surfaces (any mucus membranes).

• Lymphatic function: lymphatic drainage is driven by hydrostatic/pressure gradients and tissue dynamics.

• Thymus: location and anatomy: located in the mediastinum; typically described as having two lobes.

• Lymphocyte maturation: standard immunology states that B cells mature in bone marrow and T cells mature in the thymus.

• Immune defense structure: 3 tiers often discussed in nursing:

  • First line of defense: physical barriers (skin) and mucous membranes.

  • Second line of defense: innate immune responses (complement system, inflammation).

  • Third line of defense: adaptive immunity (antigen-specific responses).

• Complement pathways:

  • Classical pathway requires antigen presentation to initiate.

  • Alternative pathway can activate more directly to promote effector functions.

• Inflammation: classic cardinal signs are redness, heat, swelling, pain, and loss of function.

• Immunity types:

  • Innate vs adaptive; acquired (active) immunity vs passive immunity.

  • Vaccines provide acquired immunity and training of the immune system to recognize specific antigens.

Respiratory System: Conducting vs Respiratory Zones

• Upper vs lower respiratory tract definitions:

  • Upper tract includes nasal cavity, pharynx, larynx up to the vocal cords.

  • Lower tract includes trachea, bronchi, bronchioles, and lungs.

• Conducting zone vs respiratory zone:

  • Conducting zone: cleans, humidifies, and transports air; no gas exchange.

  • Respiratory zone: sites of gas exchange (alveoli and respiratory bronchioles).

• Larynx and pharyngeal anatomy: the larynx is the voice box; following it is the trachea.

• Lung lobes and mediastinal context: as noted, right lung has three lobes; left lung has two due to heart position.

• Pleura and lung support fundamentals (briefly implied): lungs are encased within pleural cavity, separated from the chest wall by pleurae.

• Practical nursing notes:

  • Understanding apex vs base, lobes, hilum, and major vessels is essential for interpreting imaging and planning procedures (e.g., catheterization, chest tube placement).

Quick Connections and Clinical Takeaways (Integrated insights)

• Endocrine–metabolic links:

  • Cortisol and glucose metabolism interact with insulin; cortisol elevation can raise blood glucose; stress affects glucose control.

  • Aldosterone’s mineralocorticoid action increases Na+ retention, which can elevate blood pressure; relevant in hypertension management.

  • ADH/vasopressin: excess (SIADH) causes water retention and potential hyponatremia; deficiency leads to polyuria and dehydration risk.

• Blood and clotting relevance:

  • ABO compatibility is critical for transfusions; mismatches can trigger severe immune reactions.

  • The coagulation cascade converges on the common pathway (X, II, I, V) to form a fibrin clot; proper balance prevents bleeding or thrombosis.

• Cardiac and pulmonary integration:

  • The left ventricle’s apex and ventricular wall mechanics relate to electrical conduction and mechanical pumping; conduction system integrity ensures synchronized contraction.

  • Gas exchange depends on alveolar surface area and perfusion distribution; bases typically have higher perfusion than apices in upright individuals.

• Immunology and infection control:

  • Distinguishing innate vs adaptive immunity helps in understanding vaccines, infections, and inflammatory responses.

  • Lymphatic drainage and lymphoid tissues (MALT, Peyer’s patches, thymus) are central to mucosal defense and systemic immunity.

• Fetal vs postnatal circulation:

  • Foramen ovale is a fetal opening that normally closes after birth; persistence can affect hemodynamics.