Anatomy & Physiology: Special Senses, Endocrine, Cardiovascular, Blood, and Lymphatic Systems Study Guide

Special Senses

General vs. Special Senses

The human body detects internal and external stimuli through senses, which are classified as general senses and special senses.

• General senses: Include touch, pain, temperature, pressure, vibration, and proprioception. These are distributed throughout the body.

• Special senses: Include vision, hearing, equilibrium, taste (gustation), and smell (olfaction). These are localized to specific organs.

Cranial Nerves Associated with Special Senses

• Olfactory nerve (I): Smell

• Optic nerve (II): Vision

• Facial (VII), Glossopharyngeal (IX), Vagus (X): Taste

• Vestibulocochlear nerve (VIII): Hearing and equilibrium

Olfactory & Gustation Main Parts

• Olfactory epithelium: Contains sensory receptors for smell, located in the nasal cavity.

• Taste buds: Sensory organs for taste, found on the tongue and oral cavity.

Layers of the Eye

• Fibrous tunic: Outermost layer; includes the sclera and cornea.

• Vascular tunic (uvea): Middle layer; includes the choroid, ciliary body, and iris.

• Neural tunic (retina): Innermost layer; contains photoreceptors (rods and cones).

Parts of the Eye and Their Functions

• Cornea: Refracts light entering the eye.

• Lens: Focuses light onto the retina.

• Iris: Controls pupil size and light entry.

• Retina: Contains photoreceptors for vision.

• Optic nerve: Transmits visual information to the brain.

Structures of the Ear

• External ear: Auricle (pinna), external auditory canal.

• Middle ear: Tympanic membrane, ossicles (malleus, incus, stapes).

• Inner ear: Cochlea (hearing), vestibule and semicircular canals (equilibrium).

Endocrine System

Endocrine System Organs & Glands

The endocrine system consists of glands that secrete hormones directly into the bloodstream to regulate body functions.

• Pituitary gland

• Thyroid gland

• Parathyroid glands

• Adrenal glands

• Pineal gland

• Pancreas (endocrine portion)

• Gonads (ovaries and testes)

Hormones Produced by Endocrine Glands

• Pituitary: Growth hormone (GH), antidiuretic hormone (ADH), oxytocin, etc.

• Thyroid: Thyroxine (T4), triiodothyronine (T3), calcitonin

• Adrenal: Cortisol, aldosterone, adrenaline (epinephrine)

• Pancreas: Insulin, glucagon

• Ovaries/Testes: Estrogen, progesterone, testosterone

Heart Anatomy

Heart Anatomy & Layers

• Epicardium: Outer layer (visceral pericardium)

• Myocardium: Middle, muscular layer responsible for contraction

• Endocardium: Inner lining of the heart chambers

Blood Flow Through the Heart

1. Deoxygenated blood enters right atrium via superior and inferior vena cava

2. Right atrium → right ventricle (via tricuspid valve)

3. Right ventricle → pulmonary trunk (via pulmonary valve) → lungs

4. Oxygenated blood returns to left atrium (via pulmonary veins)

5. Left atrium → left ventricle (via bicuspid/mitral valve)

6. Left ventricle → aorta (via aortic valve) → systemic circulation

Systemic vs. Pulmonary Circuits

• Pulmonary circuit: Right side of heart pumps blood to lungs for oxygenation.

• Systemic circuit: Left side of heart pumps oxygenated blood to the body.

Cardiac Conduction System

• Sinoatrial (SA) node: Pacemaker, initiates heartbeat

• Atrioventricular (AV) node

• Bundle of His (AV bundle)

• Right and left bundle branches

• Purkinje fibers

ECG Waveforms

• P wave: Atrial depolarization

• QRS complex: Ventricular depolarization

• T wave: Ventricular repolarization

Heart Rhythms

• Normal sinus rhythm: Regular rhythm originating from the SA node

• Arrhythmias: Abnormal heart rhythms (e.g., tachycardia, bradycardia)

Heart Physiology and Blood Vessels

Types of Blood Vessels

• Arteries: Carry blood away from the heart; thick, elastic walls

• Veins: Carry blood toward the heart; thinner walls, valves present

• Capillaries: Microscopic vessels for exchange of gases, nutrients, and wastes

Blood Flow Through Vessels

1. Arteries → arterioles → capillaries → venules → veins

Major Arteries and Veins

• Aorta: Main artery leaving the heart

• Vena cava: Main veins returning blood to the heart

• Pulmonary arteries and veins: Connect heart and lungs

Blood Pressure

• Definition: The force exerted by circulating blood on vessel walls

• Measured as: Systolic/diastolic pressure (e.g., 120/80 mmHg)

• Formula:

$\text{Blood Pressure} = \text{Cardiac Output} \times \text{Peripheral Resistance}$

Blood

Components of Blood

• Plasma: Liquid matrix (about 55% of blood volume)

• Formed elements: Red blood cells (erythrocytes), white blood cells (leukocytes), platelets (thrombocytes)

Red Blood Cells (Erythrocytes)

• Function: Transport oxygen and carbon dioxide

• Characteristic: Biconcave shape, no nucleus in mature cells

• Hemoglobin: Oxygen-carrying protein

White Blood Cells (Leukocytes)

• Types: Neutrophils, lymphocytes, monocytes, eosinophils, basophils

• Function: Immune defense

Blood Types

• ABO system: Based on presence of A and/or B antigens

• Rh system: Presence (+) or absence (−) of Rh antigen

Blood Type Determination

• Mix blood sample with anti-A, anti-B, and anti-Rh antibodies to observe agglutination

Lymphatic System

Organs and Glands of the Lymphatic System

• Lymph nodes: Filter lymph and house lymphocytes

• Spleen: Filters blood, recycles old red blood cells

• Thymus: Site of T cell maturation

• Tonsils: Protect against pathogens entering through mouth and nose

Functions of the Lymphatic/Immune System

• Return excess tissue fluid to the bloodstream

• Absorb dietary fats from the intestine

• Defend against pathogens and disease

Lines of Defense

• First line: Physical and chemical barriers (skin, mucous membranes)

• Second line: Innate immune responses (phagocytes, inflammation, fever)

• Third line: Adaptive immunity (T cells, B cells, antibodies)