Comprehensive Human Body Systems & Medical Diagnosis Review

What is homeostasis?

Internal balance.

What organs make up the integumentary system and what are its functions?

Organs: Skin, hair, nails, sweat glands. Functions: Body external covering; protects deeper tissues from injury, synthesizes Vitamin D, helps regulate body temperature.

What organs make up the skeletal system and what are its functions?

Organs: Bones, cartilage, ligaments, joints. Functions: Structural framework for the body, protects vital organs, stores minerals, houses bone marrow where blood cells are formed.

What organs make up the muscular system and what are its functions?

Organs: Skeletal muscle, tendons. Functions: Allows physical manipulation of environment, locomotion, facial expression, maintains posture, generates heat.

What organs make up the nervous system and what are its functions?

Organs: Brain, spinal cord, peripheral nerves. Function: Body's fast-acting control system; responds to internal and external changes by activating muscles and glands.

What organs make up the endocrine system and what are its functions?

Organs: Pineal gland, pituitary gland, thyroid gland, thymus, adrenal glands, pancreas, testis/ovaries. Function: Body's slow-acting control system; glands secrete hormones that regulate growth, reproduction, and metabolism.

What organs make up the cardiovascular system and what are its functions?

Organs: Heart, blood vessels (arteries, veins, capillaries). Function: Blood vessels transport blood carrying oxygen, carbon dioxide, nutrients, wastes, and hormones throughout the body.

What organs make up the lymphatic/immune system and what are its functions?

Organs: Lymphatic vessels, lymph nodes, spleen, thymus, red bone marrow. Functions: Picks up leaked fluid from blood vessels and returns it to blood; houses white blood cells involved in immunity; mounts attack against foreign substances.

What organs make up the respiratory system and what are its functions?

Organs: Nasal cavity, pharynx, larynx, trachea, bronchi, lungs. Function: Keeps blood constantly supplied with oxygen and removes CO2. Gaseous exchange occurs through walls of alveoli.

What organs make up the digestive system and what are its functions?

Organs: Oral cavity, esophagus, stomach, small intestine, large intestine, rectum, anus, liver, gallbladder, pancreas. Function: Breaks down food into absorbable units that enter blood for distribution to body cells.

What organs make up the urinary system and what are its functions?

Organs: Kidneys, ureters, urinary bladder, urethra. Function: Eliminates nitrogenous wastes; master regulator of water, electrolyte, and acid-base balance of blood.

What organs make up the reproductive system?

Male: Prostate gland, penis, testes, scrotum, ductus deferens. Female: Mammary glands, ovaries, uterine tubes, uterus, vagina. Function: Produce offspring.

What is the sympathetic nervous system and what does it do?

"Fight or flight" response. Effects: Pupils dilate, heart rate increases, digestion stops, bronchioles dilate.

What is the parasympathetic nervous system and what does it do?

"Rest and digest" response. Effects: Pupils constrict, heart rate drops, GI tract activates.

What is the path of food through the GI tract?

Oral cavity → Pharynx → Esophagus → Stomach → Small Intestine (duodenum → jejunum → ileum) → Large Intestine → Rectum → Anus.

What happens in the mouth during digestion?

Mechanical digestion (teeth grind food to increase surface area) and chemical digestion (salivary glands secrete saliva with salivary amylase to break down carbohydrates). Tongue shapes food into a bolus.

How does food move through the esophagus?

The bolus moves to the pharynx; epiglottis covers the trachea during swallowing. Peristalsis (involuntary wave-like muscle contractions) pushes bolus to stomach. Lower esophageal sphincter prevents acid reflux (GERD if too relaxed).

What happens in the stomach during digestion?

Stomach acts as muscular blender. Secretes hydrochloric acid (HCl) to drop pH to 1.5-2.0 (kills pathogens, denatures proteins) and pepsin (enzyme that breaks down proteins). Bolus becomes acidic paste called chyme.

What is the function of the duodenum?

The short mixing chamber where chyme enters from stomach. Stomach acid is neutralized. Digestion intensifies with help from accessory organs (liver, gallbladder, pancreas).

What is the function of the jejunum?

The primary site for absorbing nutrients (sugars, amino acids, fatty acids) into the bloodstream.

What is the function of the ileum?

Absorbs whatever the jejunum missed, notably vitamin B12 and bile salts.

What are the functions of the liver and gallbladder?

Liver: Produces bile (emulsifies dietary fats). Gallbladder: Stores and concentrates bile, releases it into duodenum when fatty meal is eaten.

What does the pancreas secrete during digestion?

Bicarbonate (neutralizes stomach acid) and digestive enzymes (lipases, proteases, amylases) to break down fats, proteins, and carbohydrates.

What is the function of the large intestine?

Absorbs water and electrolytes, turning liquid waste into solid stool. Also contains the gut microbiome.

What are the functions of the rectum and anus?

Storage and elimination. Rectum stores feces until stretch triggers the defecation reflex.

What is the function of the glomerulus in the nephron?

Acts like a coffee filter. Blood enters under high pressure. Filters: Water, salts, glucose, amino acids, small wastes (filtrate). Retains: Red blood cells, large proteins.

What is the function of the Proximal Convoluted Tubule (PCT)?

The "Bulk Recycler." Reabsorbs ~65% of water and sodium, and 100% of glucose and amino acids back into the blood.

What is the function of the Loop of Henle?

The "Salty Sponge." Creates a super salty environment in kidney tissue so water is naturally drawn out of the tube and back into the body (osmosis).

What is the function of the Distal Convoluted Tubule and Collecting Duct?

The "Fine-Tuners." Hormones make final adjustments.

What do hormones do in the body?

Hormones make final adjustments, such as ADH telling the collecting duct to pull water back into blood if dehydrated.

What is renin and when is it released?

Renin is released by the kidney when it senses low blood pressure to trigger a cascade that raises blood pressure.

What is erythropoietin and when is it released?

Erythropoietin is released by the kidney when it senses low oxygen to stimulate bone marrow to produce more red blood cells.

How does negative feedback work in the endocrine system?

When a hormone level drops, the body secretes more until the level is high enough to signal the body to stop making the hormone.

What is the innate immune system?

The innate immune system is a fast, non-specific response that includes macrophages and neutrophils.

What is the adaptive immune system?

The adaptive immune system is a slow, specific response involving T cells, B cells, and antibodies.

What is a Review of Systems (ROS)?

A systematic approach to asking questions about each body system to identify the source of a patient's complaint.

What organ systems can cause chest pain?

Cardiovascular, Respiratory, GI, and Musculoskeletal systems.

What questions help identify cardiac chest pain?

Questions include: 'Does the pain radiate to your jaw or left arm? Do you have palpitations?'

What questions help identify pulmonary chest pain?

Questions include: 'Does it hurt worse when you take a deep breath? Are you coughing?'

What questions help identify GI chest pain?

Questions include: 'Does it happen after you eat spicy food? Does it taste sour in your mouth?'

What is costochondritis?

Costochondritis is inflammation of the chest wall cartilage, causing pain that worsens with pressure.

What systems should be considered with fatigue?

Endocrine, Neurologic, Cardiovascular, and Hematologic systems.

What are signs and symptoms of hypothyroidism?

Fatigue, weight gain, feeling cold, dry skin, brittle hair, constipation, goiter.

What organs are in the right lower quadrant?

GI tract (appendix) and Renal/Ureters (kidneys/ureters).

How do you differentiate appendicitis from kidney stone?

Appendicitis: Patient lies still. Kidney stone: Patient writhes, can't sit still, often has hematuria.

What systems can cause dizziness?

Cardiovascular, Neurological, and ENT/Inner Ear systems.

What is orthostatic hypotension?

Lightheadedness and near-fainting when standing up due to insufficient blood pressure.

What systems are responsible for oxygen delivery?

Respiratory, Cardiovascular, Hematologic/Blood, and Psychiatric systems.

What are signs of a panic attack?

Sudden shortness of breath, chest tightness, tachycardia, dilated pupils, hyperventilation.

What are the '3 Ps' of Type 1 Diabetes?

Polyuria, Polydipsia, Polyphagia.

Why does diabetes cause frequent urination?

High blood sugar overwhelms kidneys, causing glucose to spill into urine, dragging water out.

What does a CBC measure and what are its components?

A CBC measures blood cells, including WBC, Hemoglobin, and Platelets.

What is the normal WBC range and what do abnormal values indicate?

Normal: 4.5-11.0 × 10³/μL. High indicates infection or leukemia; low indicates bone marrow suppression.

What is the normal Hemoglobin range and what do abnormal values indicate?

Normal: 12-17 g/dL. High indicates dehydration; low indicates anemia or hemorrhage.

What is the normal Platelet range and what do abnormal values indicate?

Normal: 150,000-450,000/μL. High indicates inflammation; low indicates bleeding risk.

What does a CMP assess?

A CMP assesses electrolytes, kidney filtration, and liver processing.

What does Creatinine measure and what is the normal range?

Creatinine measures kidney function. Normal: 0.6-1.2 mg/dL.

What do ALT and AST measure and what is the normal range?

ALT and AST measure liver function. Normal: 10-40 U/L.

What is the normal Potassium range and what does high potassium cause?

Normal: 3.5-5.0 mEq/L. High potassium increases risk of cardiac arrhythmia.

What does the P-wave on an EKG represent?

Atrial depolarization.

What does the QRS complex represent?

Ventricular depolarization.

What does the T-wave represent?

Repolarization.

What is the classic EKG finding in a STEMI?

ST-segment elevation.

What appears white (radiopaque) on X-ray?

Denser objects like bone, fluid, and metal.

What appears black (radiolucent) on X-ray?

Air, as healthy lungs allow rays through.

What is X-ray best for?

Fractures, pneumonia, and screening for large masses.

What is a CT scan best for?

Fast, 3D imaging for trauma, bone, and internal bleeding.

What is an MRI best for?

Best for soft tissues like the brain, ligaments, and spinal cord.

How is pneumonia diagnosed?

CBC shows high WBC. Chest X-ray shows dense white consolidation/shadow (lungs should be black/air-filled). Clinical: productive cough, fever, shortness of breath.

How is iron deficiency anemia diagnosed?

CBC shows low Hemoglobin (RBCs), normal WBC and platelets. Clinical: fatigue, feeling cold, heavy periods.

How is acute liver injury diagnosed?

CMP shows ALT/AST astronomically high. Can be caused by acetaminophen toxicity, especially with alcohol.

How is a STEMI diagnosed?

EKG shows ST-segment elevation in leads. Clinical: crushing chest pain radiating to left arm, sweating, sense of doom.

What is the best imaging for trauma/splenic rupture?

CT Scan of abdomen/pelvis with IV contrast. Shows fluid (blood) collecting and organ damage. Fast, indicates if patient needs immediate surgery.

How is an ACL tear diagnosed?

X-ray first (normal, rules out fracture). MRI shows discontinuity/tear of ligament fibers in knee joint. Clinical: 'pop' sound, swelling, unable to bear weight.

What are the differences between the right and left heart?

Right heart: Deoxygenated blood → Lungs (pulmonary circuit), low pressure (25/10 mmHg), thin wall. Left heart: Oxygenated blood → Body (systemic circuit), high pressure (120/80 mmHg), thick massive wall.

What are the four chambers of the heart?

Right Atrium (RA), Right Ventricle (RV), Left Atrium (LA), Left Ventricle (LV).

What is the function of the atria?

Top chambers. Receive blood and give gentle squeeze ('atrial kick') to top off ventricles. Thin walls (only pumping a few centimeters).

What is the function of the ventricles?

Bottom chambers. Do the heavy lifting. Pump blood to lungs (right) or body (left).

What are the AV valves and where are they located?

Located between atria and ventricles. Tricuspid valve (Right - 'Tri to be Right'). Mitral/Bicuspid valve (Left). Chordae tendineae prevent valves from blowing backward.

What are the semilunar valves and where are they located?

Exit doors of ventricles. Pulmonic valve (between RV and Pulmonary Artery). Aortic valve (between LV and Aorta). Three little cups that snap shut when ventricle relaxes.

Trace a drop of blood through the heart and lungs.

Vena Cava → Right Atrium → Tricuspid Valve → Right Ventricle → Pulmonic Valve → Pulmonary Artery → Lungs (oxygenated) → Pulmonary Veins → Left Atrium → Mitral Valve → Left Ventricle → Aortic Valve → Aorta → Body.

What is unique about the pulmonary artery and vein?

Pulmonary Artery carries deoxygenated blood (to lungs). Pulmonary Veins carry oxygenated blood (to heart). Opposite of typical arteries/veins.

What is the difference between arteries and veins?

Arteries carry blood AWAY from the heart. Veins carry blood TOWARD the heart.

How does the heart supply blood to itself?

Coronary arteries branch off the Aorta. Left Main: splits into LAD (Left Anterior Descending - feeds front of left ventricle) and LCx (Left Circumflex - wraps around back). Right Coronary Artery (RCA) feeds right side and bottom.

Where does infection from IV drug use affect the heart?

IV drugs → Superior Vena Cava → Right Atrium → Tricuspid Valve (first valve touched). Diagnosis: Tricuspid Endocarditis. Emboli travel → Right Ventricle → Pulmonic Valve → Pulmonary Artery → Lungs (Septic Pulmonary Emboli).

What is aortic stenosis and what are its effects?

Narrowing of aortic valve. Can be bicuspid (only 2 leaflets instead of 3). Heart must generate massive pressure to force blood through. Can cause syncope (fainting) during exercise when brain is deprived of blood.

What is a VSD and how does it affect blood flow?

Hole in septum between Right and Left Ventricles. Normally: Left (high pressure) → Right (low pressure). With crying: Pulmonary pressure spikes → Right → Left shunt. Deoxygenated blood bypasses lungs → cyanosis (turning blue).

What is the difference between ischemia and infarction?

Ischemia: Oxygen demand exceeds supply; reversible if caught early. Infarction: Irreversible cell death (necrosis) due to prolonged hypoxia.

What is the gold standard biomarker for heart attack?

Cardiac Troponin (cTn). Detects leakage from damaged heart muscle cells.

What is the difference between STEMI and NSTEMI?

STEMI: Transmural (full-wall) infarction, complete artery occlusion, ST-elevation on EKG, requires immediate PCI (catheterization). NSTEMI: Subendocardial (partial-wall), some flow remains, ST-depression or T-wave inversion, managed with meds then delayed PCI.

What are the symptoms of left-sided heart failure?

LV cannot eject blood to body → backs up into lungs. Symptoms: Crackles in lungs, Dyspnea, Pulmonary Edema.

What are the symptoms of right-sided heart failure?

RV cannot pump to lungs → backs up into venous system. Symptoms: JVD (Jugular Vein Distension), Pitting Edema (legs), Hepatomegaly.

What is HFREF (Systolic Heart Failure)?

Ejection Fraction ≤40%. The 'Baggy' heart. Muscle is too weak to squeeze effectively.

What is HFpEF (Diastolic Heart Failure)?

Ejection Fraction ≥50%. The 'Stiff' heart. Muscle is too thick to fill effectively. Fill pressure rises, leading to backup.

How does the cardiac pump model explain CPR?

Direct compression of the heart between sternum and spine creates pressure gradient to push blood forward.

How does the thoracic pump model explain CPR?

Increasing intrathoracic pressure forces blood out of the chest. Valves maintain one-way flow. High-quality recoil is mandatory for venous return.

What is the minimum coronary perfusion pressure for ROSC?

15 mmHg required for Return of Spontaneous Circulation. Uninterrupted compressions are vital; every pause drops CPP to zero.

What is the required mmHg for Return of Spontaneous Circulation?

15 mmHg

What is the ideal CPR compression rate?

100-120 compressions per minute

What is triage?

To sort; doing the greatest good for the greatest number of people