The Lymphatic System and Immunity

Lymphatic System

• Lymphatic capillaries collect interstitial fluid through closed-ended tubes.
• Collecting vessels transport lymph through nodes using valves.
• Lymphatic trunks drain significant areas of the body.
• Lymphatic ducts (right lymphatic and thoracic) return lymph to the subclavian veins.
• The lymphatic system's main function is to return excess interstitial fluid to the bloodstream.
• Cervical lymph nodes drain the head and neck.
• Axillary lymph nodes drain the upper limbs and breast.
• Inguinal lymph nodes drain the lower limbs.

Immune Cells

• B cells mature in bone marrow and produce antibodies, providing humoral immunity.
• T cells mature in the thymus, including helper and cytotoxic T cells for cell-mediated immunity.
• Natural Killer (NK) cells non-specifically kill infected cells.
• Cytokines are chemical signals that coordinate immune responses.

Immune Organs

• Primary immune organs are the bone marrow and thymus.
• Secondary immune organs are lymph nodes, tonsils, and spleen.

Immune Processes

• Inflammation is characterized by redness, heat, swelling, and pain.
• Innate immunity is immediate and non-specific.
• Adaptive immunity is delayed, specific, and has memory.

Cardiovascular System - Heart Anatomy

• The heart has four chambers: Right Atrium (RA), Right Ventricle (RV), Left Atrium (LA), Left Ventricle (LV).
• Valves include: Tricuspid (RA→RV), Pulmonary (RV→lungs), Bicuspid/Mitral (LA→LV), Aortic (LV→aorta).
• Heart layers: endocardium (inner), myocardium (muscle), epicardium (outer); the pericardium surrounds the heart.
• During fetal circulation, the foramen ovale becomes the fossa ovalis, and the ductus arteriosus becomes the ligamentum arteriosum.
• Intercalated discs contain desmosomes that hold cells together and gap junctions that allow electrical communication.

Electrical Pathway of the Heart

• The electrical pathway is: SA Node → AV Node → Bundle of His → Bundle Branches → Purkinje Fibers.
• ECG waves: P wave indicates atrial depolarization, QRS complex indicates ventricular depolarization, and T wave indicates ventricular repolarization.
• Heart sounds: "Lub" is the sound of AV valves closing, and "Dub" is the sound of SL valves closing.
• Pulse points: Carotid, radial, brachial, femoral, dorsalis pedis, and posterior tibial.
• The brachiocephalic artery exists only on the right side of the body.

Blood Components

• Plasma (55%) consists of water and proteins like albumin, globulins, and fibrinogen.
• Formed elements (45%) include: RBCs for oxygen transport via hemoglobin, WBCs for immune defense, and platelets for clotting.
• Hemoglobin binds 4 oxygen molecules on iron sites.
• CO2 is mostly transported as bicarbonate.
• Erythropoietin (EPO), made in the kidneys, stimulates RBC production.
• Blood types: A, B, AB, O; Rh +/− (Know donor/recipient compatibility).

Respiratory System - Air Pathway

• The air pathway is: Nose → Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli.
• Includes head/nasal sinuses, vocal cords
• The lungs have 3 right lobes and 2 left lobes, covered by visceral and parietal pleura membranes.
• Surfactant prevents alveolar collapse.
• O2 binds to hemoglobin for transport.
• CO2 is transported: 70% as bicarbonate, 23% bound to hemoglobin, 7% dissolved.
• Obstructive conditions: asthma
• Restrictive conditions: fibrosis
• Acidosis and alkalosis are based on CO2 retention/exhalation.

Digestive System - Key Steps

• The digestive process involves ingestion (taking food in), propulsion (moving food), mechanical digestion (chewing, churning), chemical digestion (enzyme breakdown), absorption (nutrient uptake), and defecation (waste elimination).
• Oral cavity: salivary glands, teeth, tongue
• Stomach: rugae, gastric pits with chief and parietal cells
• Small intestine: duodenum, jejunum, ileum; villi, microvilli, folds
• Liver: bile production & detoxification
• Gallbladder: store bile
• Large intestine: water absorption
• Carbs break down into glucose via amylase.
• Proteins break down into amino acids via pepsin/trypsin.
• Lipids break down into fatty acids + glycerol via lipase/bile.
• Nucleic acids break down into nucleotides via nucleases.
• Deglutition refers to swallowing, peristalsis is the wave-like movement, and segmentation is the mixing of food.

Endocrine System

• The hypothalamus controls the pituitary gland.
• Anterior pituitary hormones: TSH, ACTH, GH, LH, FSH, prolactin.
• Posterior pituitary hormones: ADH, oxytocin.
• Thyroid hormones: T3, T4, calcitonin.
• Parathyroid hormone: PTH.
• Adrenal cortex hormones: aldosterone, cortisol, androgens.
• Adrenal medulla hormones: epinephrine, norepinephrine.
• Pancreas hormones: insulin, glucagon.
• Gonad hormones: estrogen, progesterone, testosterone.
• Tropic hormones target other glands.
• Anabolism refers to building up, and catabolism refers to breaking down.
• Type 1 Diabetes Mellitus involves no insulin production, while Type 2 involves resistance to insulin.
• Diabetes Insipidus involves an ADH problem.
• Three signs of diabetes include polyuria, polydipsia, and polyphagia.

Urinary System

• Structures: kidneys, ureters, bladder, urethra
• Nephron flow:
  • Blood: Renal artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries → renal vein
  • Filtrate: Bowman's capsule → PCT → Loop of Henle → DCT → Collecting duct → Papilla → Minor calyx → Major calyx → Renal pelvis → Ureter
• Processes: Filtration, Reabsorption, Secretion
• Urine abnormalities: Ketoneuria, nitrites, bilirubinuria
• Hormones: ADH retains water, and aldosterone retains sodium.

Reproductive & Developmental Systems

• Male:
  • Testes produce sperm in seminiferous tubules.
  • Sperm Path: epididymis → vas deferens → ejaculatory duct → urethra.
  • Seminal fluid provides an alkaline environment, nutrients, and enzymes.
• Female:
  • Ovaries produce eggs.
  • Uterine cycle: menstrual, proliferative, secretory phases
  • Ovarian cycle: follicular, ovulation, luteal phases
  • Hormones: FSH, LH, estrogen, progesterone
• Gamete Development:
  • Spermatogenesis vs. Spermiogenesis
  • Oogenesis produces polar bodies.
• Embryo Development:
  • Zygote → Morula → Blastocyst → Embryo → Fetus
  • Inner cell mass becomes the embryo.
  • Trophoblast becomes the placenta.
  • Germ layers: ectoderm, mesoderm, endoderm
• Key Terms:
  • Gastrulation and neurulation are key developmental processes.
  • hCG maintains the corpus luteum during early pregnancy.
  • Knowledge of dominant, recessive, and codominance is essential, as well as Punnett squares.

Blood Flow - Heart to Body

• Deoxygenated blood enters the right atrium via the superior and inferior vena cava.
• Blood flows through the tricuspid valve to the right ventricle.
• Blood is pumped through the pulmonary valve into the pulmonary arteries to the lungs.
• In the lungs, blood becomes oxygenated.
• Oxygenated blood returns via pulmonary veins to the left atrium.
• Blood passes through the bicuspid/mitral valve into the left ventricle.
• Blood is pumped through the aortic valve into the aorta and out to the body.

Blood Flow - Head to Toe

• From the aorta:
  • Brachiocephalic artery serves the right head and arm.
  • Left common carotid serves the left head.
  • Left subclavian serves the left arm.
  • Descending aorta branches into thoracic and abdominal sections.
  • Branches to renal, mesenteric, and iliac arteries.
• To the legs:
  • Iliac → femoral → popliteal → anterior and posterior tibial arteries
• Returning via veins:
  • Tibial → femoral → iliac → inferior vena cava (from legs/body)
  • Jugular → subclavian → superior vena cava (from head/arms)