Essential Medical Terminology: Endocrine, Blood, and Heart Systems

The Endocrine System: Signals and Outcomes

The endocrine system consists of signal senders, the chemical signals they transmit, and the resulting outcomes. The main signal senders are the endocrine glands, which include:

• Hypothalamus
• Pituitary gland
• Thyroid gland
• Parathyroid glands
• Adrenal glands
• Pancreas
• Gonads (Ovaries and Testicles)

Endocrine glands specifically send chemical signals (hormones) to different parts of the body. These hormonal signals generally cause slower, subtler changes compared to the nervous system, which uses electrical signals.

Hormones travel through the body via the bloodstream, but only the intended target cells respond. These cells are keyed with receptors that fit the hormone—much like matching puzzle pieces. The hormone then signals the cell to perform a desired job, such as releasing another hormone, releasing or taking in nutrients, or changing the speed at which the body synthesizes certain proteins.

Functions of Endocrine Hormones

The endocrine system adjusts nutrient levels in the blood, excretes excess nutrients, helps the body respond to its environment, and directs growth and development.

• The Pancreas secretes hormones that control blood sugar levels.
• The Adrenal, Thyroid, and Parathyroid Glands balance critical minerals like calcium and sodium.
• The Adrenal Glands also produce hormones for the fight-or-flight response to danger.
• Growth Hormone (GH) aids growth to adult height and affects metabolism.
• The Gonads produce hormones that drive sexual development.
• The endocrine system also stimulates milk production in new mothers.

Key Endocrine Glands and Their Roles

Hypothalamus and Pituitary Gland

The glands are linked to the nervous system via the Hypothalamus, located just below the thalamus in the brain. The hypothalamus acts as a gland by making and releasing hormones that direct other glands. Its main role is directing the Pituitary Gland, causing it to release chemical signals via releasing hormones (e.g., Gonadotropin-Releasing Hormone).

The pituitary gland has two parts: the anterior (front) and posterior (back) pituitary. The anterior pituitary is the source of many important hormones that travel by blood to stimulate other endocrine glands, including the thyroid, adrenal glands, and gonads.

Thyroid and Parathyroid Glands

The Thyroid Gland is located in the front of the neck, just below the Adam’s apple. It produces hormones (T3 and T4) that affect the body’s metabolism, as well as a hormone that helps control blood calcium levels.

The Parathyroid Glands are located just behind the thyroid. They produce a hormone that works with thyroid hormones to control blood calcium levels.

Pancreas: Endocrine and Exocrine Functions

The Pancreas, situated just under the stomach, is unique as it functions as both an endocrine gland and a gastrointestinal organ.

• Endocrine Function: Sends hormones directly into the bloodstream to maintain blood sugar balance.
• Exocrine Function: Secretes digestive enzymes via ducts into the intestines to aid digestion.

Adrenal Glands

The Adrenal Glands sit on top of the kidneys. They consist of two layers:

• The Inner Layer (Medulla) makes the fight-or-flight hormone, adrenaline.
• The Outer Layer (Cortex) makes two general types of hormones:
  • Hormones that maintain mineral levels (water and salt volume) in the blood.
  • Hormones that balance blood sugar levels and affect the body’s response to inflammation.

Endocrine Medical Terminology

Word Roots and Combining Forms

• aden/o: gland
• adren/o, adrenal/o: adrenal gland
• cortic/o: outer surface (cortex)
• gonad/o: gonads (sex organs)
• pancreat/o: pancreas
• pituitar/o, hypophys/o: pituitary gland
• thym/o: thymus
• thyr/o, thyroid/o: thyroid
• gluc/o, glucos/o, glyc/o: sugar
• crin/o: to secrete
• hormon/o: hormone
• ket/o, keton-: ketone body
• arche-: beginning
• meno-: menstrual
• phag-: eat
• acro-: extremities
• ex-: out
• acid-: acid
• alkal-: alkali
• chlor-: chloride
• eu-: good
• kal-: potassium
• natr-: sodium
• renal-: kidney
• epi-: upon
• trop-: stimulating
• chol-: bile
• angio-: vessel
• lith-: stone
• pan-: all
• toxic-: poison
• para-: beside

Suffixes and Prefixes

• -tropin: stimulating hormone
• -emia: blood condition
• -uria: urine condition
• a-: no, without
• em-: blood
• -ic: pertaining to
• -ine: chemical substance
• -megaly: enlargement
• -genesis: formation
• neo-: new
• meta-: over, beyond
• dys-: bad, difficult
• -plasia: formation
• con-: with
• genit-: birth
• -iasis: presence of

Endocrine Abbreviations

• ACTH: Adrenocorticotropic Hormone
• BS: Blood Sugar
• CGM: Continuous Glucose Monitor
• DI: Diabetes Insipidus
• DM: Diabetes Mellitus
• ERCP: Endoscopic Retrograde Cholangiopancreatography
• FBS: Fasting Blood Sugar
• GDM: Gestational Diabetes Mellitus
• GH: Growth Hormone
• GTT: Glucose Tolerance Test
• HgA1C: Hemoglobin A1C test (monitors blood sugar levels)
• HRT: Hormone Replacement Therapy
• TFT: Thyroid Function Test
• TSH: Thyroid-Stimulating Hormone (Thyrotropin)
• T3: Triiodothyronine (primary thyroid hormone)
• T4: Thyroxine (primary thyroid hormone)

Hematology: Components of Blood

Blood contains three main types of cells (cytes):

1. Red Blood Cells (Erythrocytes): Transport oxygen to all body cells and carry away waste.
2. White Blood Cells (Leukocytes): Fight infection and protect the body from invasion.
3. Platelets (Thrombocytes): Small cells responsible for clotting and patching injured vessels.

Red Blood Cells and Hemoglobin

Red blood cells (RBCs) are the most common cells in the blood (hemo/hemato). They contain hemoglobin, a substance that binds to oxygen when levels are high and releases it when ambient oxygen levels are low. This mechanism ensures fresh oxygen is carried from the lungs to all parts of the body that need it.

White Blood Cells and Immunity

White blood cells (WBCs) protect the body from invasion. The blood contains different types of WBCs that fight specific infections, including neutrophils, lymphocytes, basophils, and eosinophils. Each type performs a specialized immune function.

Platelets and Clotting

Platelets are the smallest blood cells. Their primary job is to repair broken blood vessels. When a vessel is injured, it attracts platelets that clump together to form a sticky patch. They also send signals that help further form a permanent clot.

Hematology Terminology and Abbreviations

Word Roots and Combining Forms

• thromb/o, trombo-: clot
• hem/o, hemat/o: blood
• cyt/o, cyte: cell
• leuk/o: white
• phleb/o, ven/o: vein
• lymph/o: lymph
• tonsill/o: tonsils
• iso-: equal
• ellipto-: oval-shaped
• embol-: embolus
• erythro-: red
• macro-: large
• myelo-: bone marrow
• globin: globe, protein
• immuno-: immune system
• bili-: bile
• septic-: rotting, infection
• nephr/o: kidney

Suffixes and Prefixes

• -emia: blood condition
• edema: swelling
• em-: in
• -poiesis: formation
• -lysis: breakdown
• -malacia: softening
• -gram: record
• per-: through
• tom-: cut
• mano-: thin
• sphygmo-: strangle, pulse
• isch-: hold back
• -ectasia: dilatation
• -static: standing, stopping
• apheresis: separation

Hematology Abbreviations

• AIDS: Acquired Immunodeficiency Syndrome
• ALL: Acute Lymphoblastic Leukemia
• AML: Acute Myeloid Leukemia
• BMT: Bone Marrow Transplant
• CBC: Complete Blood Count
• CML: Chronic Myeloid Leukemia
• DIC: Disseminated Intravascular Coagulopathy
• EBV: Epstein-Barr Virus
• ESR: Erythrocyte Sedimentation Rate
• Hct: Hematocrit
• Hgb: Hemoglobin
• HIV: Human Immunodeficiency Virus
• HSM: Hepatosplenomegaly
• HUS: Hemolytic Uremic Syndrome
• INR: International Normalized Ratio
• ITP: Idiopathic Thrombocytopenic Purpura
• IVIG: Intravenous Immunoglobulin
• LAD: Lymphadenopathy
• PLT: Platelet Count
• PTT: Partial Thromboplastin Time
• RBC: Red Blood Count; Red Blood Cell
• TTP: Thrombotic Thrombocytopenic Purpura
• WBC: White Blood Count; White Blood Cell

Cardiovascular System: Heart and Circulation

Heart Structure and Valves

The heart is divided by the septum, a thick muscular wall. The left side handles oxygen-rich blood, while the right side handles oxygen-poor blood.

Heart Valves

• Left Side:
  • Mitral Valve: Connects the left atrium and left ventricle.
  • Aortic Valve: Connects the left ventricle to the outgoing blood vessel, the Aorta.
• Right Side:
  • Tricuspid Valve: Connects the right atrium and right ventricle.
  • Pulmonary Valve: Connects the right ventricle to the outgoing blood vessel, the Pulmonary Artery.

The Closed Loop of Circulation

The body contains miles of blood vessels, ranging from large arteries to tiny capillaries. This network acts as a closed-loop transportation system.

Systemic Circulation (Body)

1. The left ventricle forces oxygenated blood into the main outgoing vessel, the Aorta.
2. The Aorta branches into smaller Arteries, which further divide until they reach target tissues (brain, stomach, muscles, etc.).
3. Blood flows through tiny Capillaries, where oxygen and nutrients pass into the tissues, and waste is collected.
4. Deoxygenated blood returns to the heart through Veins.
5. Smaller veins collect into larger veins, eventually forming the Superior (upper) and Inferior (lower) Vena Cava, which return blood to the right atrium.

Pulmonary Circulation (Lungs)

Simultaneously, the right ventricle pumps deoxygenated blood into the Pulmonary Artery, which carries it to the lungs. Here, gases are exchanged: carbon dioxide is discarded, and oxygen is attained. The oxygen-rich blood returns to the heart via the main Pulmonary Vein, dumping into the left atrium, restarting the cycle.

Cardiac Symptoms and Evaluation

The most common cardiac complaint is chest pain (Pectoralgia), which can range from minor muscle soreness to the severe pain associated with a heart attack (Angina Pectoris). Pain in blood vessels (Phlebalgia) is occasionally reported, often associated with enlarged surface veins.

A patient may feel a jumping sensation (Palpitation) if the heart beats out of pace. A sustained irregular rhythm is known as Arrhythmia or Dysrhythmia.

Understanding Blood Pressure

Blood pressure readings consist of two numbers:

• Systole: The first number. This is the highest arterial pressure, occurring when the heart muscle contracts and sends blood out of the ventricles.
• Diastole: The second number. This refers to the pressure on the vessels when the heart is relaxed and filling with blood.

Heart Sounds (S1 and S2)

Evaluating the heart often involves listening directly to the heartbeat. The two primary heart sounds are caused by the closing of the heart valves:

• First Heart Sound (S1): Caused by the closing of the valves between the atria and ventricles, marking the beginning of systole.
• Second Heart Sound (S2): Caused by the closing of the pulmonary and aortic valves, marking the end of systole.

During auscultation, the examiner listens for abnormal sounds (murmurs) or disturbances in the rhythm.

Cardiology Terminology

Word Roots and Combining Forms

• valvul/o: valve
• angi/o, vas/o, vascul/o: vessel
• aort/o: aorta
• ather/o: fatty plaque
• card-: heart
• myo-: muscle
• cyan-: blue
• cava-: hollow
• scler-: hard
• arterio-: artery
• sono-: sound
• thorac-: chest
• varico-: swollen

Suffixes and Prefixes

• -rrhythm: rhythm
• phoresis: carry
• dia-: through
• -rrhage: burst forth
• -ium: tissue
• epi-: upon
• brady-: slow
• sys-: together
• stol-: send, contraction
• re-: back
• an-: up, not
• tens-: stretch
• ton-: tone
• vers-: turn
• -stom: mouth, opening
• -rraphy: suture