Human Body

Introduction

  • Importance of knowledge of anatomy for understanding the human body.

Key Terminology

  • Anatomy: Study of the structure of the body.

  • Physiology: Study of the functions of the body systems.

  • Pathophysiology: Study of the changes in body function due to disease.

  • Topographic Anatomy: Refers to the body's position with arms at the side, palms forward, as a reference point.

Planes of the Body

  • Imaginary lines that divide the body into sections:

    • Coronal (Frontal) Plane: Divides the body into front (anterior) and back (posterior).

    • Sagittal (Lateral) Plane: Divides the body into left and right.

    • Midsagittal Plane: Divides the body into equal left and right halves.

    • Transverse (Axial) Plane: Divides the body into top (superior) and bottom (inferior).

Levels of Organization

  • Cells: Basic building blocks of the body.

  • Tissues: Groups of cells working together for a common function.

  • Organs: Composed of different tissues performing specific jobs.

  • Body Systems: Groups of organs that work together to perform complex functions.

The Skeletal System: Anatomy

  • Total Bones: 206 in the adult human body.

    • Axial Skeleton: Forms the core structure of the body, includes:

    • Skull

    • Thoracic cage

    • Vertebral column

    • Appendicular Skeleton: Comprises limbs and their attachments to the axial skeleton, includes:

    • Pelvis

Musculoskeletal System: Physiology

  • Functions of muscles:

    • Enable movement and manipulation of the environment.

    • Produce heat as a by-product of movement.

    • Protect underlying structures.

Respiratory System: Anatomy

  • Responsible for breathing and gas exchange; consists of:

    • Upper Airway: Nose, mouth, tongue, jaw, larynx, pharynx.

    • Lower Airway: Includes cranial structures, trachea, bronchi, and bronchioles.

Lower Extremities

  • Knee: Connects upper leg (thigh) to lower leg (shin).

    • Components:

    • Kneecap (Patella): Protects the knee joint.

    • Tibia: Main bone of the lower leg (shin bone).

    • Fibula: Smaller bone located on the lateral side of the lower leg.

  • Foot:

    • Consists of 7 tarsal bones, 5 metatarsals, and toes composed of phalanges.

Skeletal System: Physiology

  • Functions include:

    • Providing shape to the body.

    • Protecting vital organs.

    • Enabling movement through muscle attachment.

    • Storing calcium and producing blood cells.

Musculoskeletal System: Anatomy

  • Provides:

    • Form: Supports upright posture.

    • Movement: Facilitates bodily motion.

    • Protection: Shields vital internal organs.

  • Types of Muscles:

    • Skeletal Muscle: Under voluntary control.

    • Smooth Muscle: Involuntary muscle found in walls of organs.

    • Cardiac Muscle: Involuntary muscle found in the heart.

Upper Extremities

  • Arm:

    • Composed of the Humerus (supporting bone) and forearm bones (Radius on lateral side, Ulna on medial side).

  • Wrist and Hand:

    • Carpals, Metacarpals, and Phalanges make up this region.

The Pelvis

  • Composed of two Coxae (hip bones) and the Sacrum and Coccyx.

  • Formed by fusion of the Ilium, Ischium, and Pubis bones.

  • Pubic Symphysis: Connection point of the right and left pubis.

Lower Extremities Continued

  • Femur: Longest and strongest bone, connects to the pelvic girdle via a ball-and-socket joint.

    • Major muscle connections occur at the greater and lesser trochanters.

Joints

  • Formed where bones meet; include:

    • Ball-and-Socket Joints: Allow rotational movement (e.g., shoulder and hip).

    • Hinge Joints: Allow movement in one direction (flexion and extension, e.g., elbow and knee).

Axial Skeleton Details

  • Skull: Comprised of the cranial bones (8) and facial bones (14).

  • Spinal Column: Composed of 33 vertebrae divided into five sections:

    • Cervical region

    • Thoracic region

    • Lumbar region

    • Sacrum

    • Coccyx (tailbone)

  • Thorax: Formed by 12 thoracic vertebrae and 12 pairs of ribs, housing critical organs (heart, lungs, etc.).

Appendicular Skeleton Details

  • Comprises limbs and their attachment points (pelvis, joints, upper and lower extremities).

  • Upper extremities include arms, forearms, hands, and fingers, originating from the pectoral girdle (composed of the clavicle, scapula, and humerus).

The Human Body: Lungs

  • Lungs Structure

    • Two lungs held in place by:

    • Trachea

    • Arteries & veins

    • Pulmonary ligaments

    • Lobes:

    • Right Lung: Upper, Middle, Lower Lobes

    • Left Lung: Upper, Lower Lobes

  • Gas Exchange

    • Within the lobes: bronchi, bronchioles, alveoli

    • Alveoli allow for gas exchange

  • Pleura:

    • Smooth tissue covering each lung

    • Lines the chest cavity

    • Contains a small amount of fluid for smooth gliding

Muscles of Breathing

  • Primary Muscle: Diaphragm

  • Other Involved Muscles:

    • Neck (cervical muscles)

    • Intercostal Muscles

    • Abdominal Muscles

    • Pectoral Muscles

  • Inhalation Process:

    • Diaphragm & intercostal muscles contract

    • Decreases pressure in thoracic cavity, allowing lungs to fill with air

  • Exhalation Process:

    • Diaphragm & intercostal muscles relax

    • Thoracic cavity returns to normal shape & volume

The Heart

  • Electrical Conduction System:

    • Specialized tissue that initiates/conducts electrical current

    • Causes smooth, coordinated contractions to produce pumping action

  • Arteries:

    • Carry blood from the heart to body tissues

    • Major Branches of Aorta:

    • Coronary arteries

    • Carotid arteries

    • Hepatic arteries

    • Renal arteries

    • Mesenteric arteries

    • Pulmonary artery (carries oxygen-poor blood to lungs)

    • Arterial Branching: Arteries → Arterioles → Capillaries

  • Pulse:

    • Palpated at neck, wrist, groin

    • Created by blood pumped from the left ventricle into arteries

  • Capillaries:

    • Connect arterioles to venules

    • Fine divisions allowing contact between blood & cells

  • Veins:

    • Return oxygen-depleted blood to the heart

    • Major Veins:

    • Inferior vena cava (from abdomen, pelvis, lower extremities)

    • Superior vena cava (from head, neck, upper extremities)

    • Drains into the right atrium

Structure of the Heart

  • Characteristics:

    • Hollow muscular organ of specialized cardiac muscle

    • Functions as paired pumps (right & left sides)

    • Each side consists of an atrium (upper) and ventricle (lower)

  • Circulation:

    • Right side receives deoxygenated blood (via inferior/superior vena cava)

    • Left side receives oxygenated blood from lungs (via pulmonary veins)

    • Normal Heart Rate: 60-100 BPM

    • Stroke Volume (SV): Amount of blood pumped in one beat

    • Cardiac Output (CO): Amount of blood pumped in one minute

    • Formula: CO = HR × SV

Breathing Patterns in Adults

  • Symptoms of Inadequate Breathing:

    • Labored breathing

    • Muscle retractions

    • Pale, cyanotic (blue), cool, damp skin

    • Tripod position

    • Agonal gasps

Circulatory System

  • Anatomy:

    • Connected tubes: arteries, arterioles, capillaries, venules, veins

    • Two Circuits:

    • Systemic Circulation: Supplies body

    • Pulmonary Circulation: Supplies lungs

  • Blood Flow:

    • Pulmonary arteries → carry oxygen-poor blood from heart to lungs

    • Pulmonary veins → carry oxygen-rich blood from lungs to heart

Respiratory System Physiology

  • Function: Provide oxygen & remove carbon dioxide

    • Ventilation & Respiration: Two interdependent functions

  • Respiration:

    • Gas exchange of oxygen and carbon dioxide in alveoli & tissues

    • Diffusion: Passive process moving molecules from high to low concentration

  • Control of Breathing:

    • Brainstem: Monitors CO₂ in blood & spinal fluid

    • Main driver: Lower CO₂ levels

    • Hypoxic drive when oxygen levels drop

    • Medulla: Initiates ventilation cycles, stimulated by high CO₂ levels

    • Pons: Augments respiration during stress

  • Ventilation:

    • Air movement into/out of lungs

    • Tidal Volume: Volume of air per breath

    • Residual Volume: Remaining gas to keep lungs open

    • Dead Space: Air without gas exchange

  • Normal Breathing Characteristics:

    • Regular rate & depth

    • Clear breath sounds

    • Regular rise/fall of chest & abdomen

The Spleen

  • Location: Solid organ beneath the rib cage.

  • Function: Filters blood and is particularly vulnerable to injuries from blunt trauma.

Blood Composition

  • Components:

    • Plasma (liquid portion)

    • Red Blood Cells (Erythrocytes)

    • White Blood Cells (Leukocytes)

    • Platelets

The Circulatory System: Physiology

  • Blood Pressure: The pressure blood exerts on arterial walls.

  • Systole: Contraction phase of the left ventricle; pumps blood into the aorta.

  • Diastole: Relaxation phase; allows ventricle to fill with blood.

Blood Pressure Readings

  • Systolic Blood Pressure: High point of blood pressure wave.

  • Diastolic Blood Pressure: Low point of blood pressure wave.

Normal Circulation in Adults

  • Automatically adjusted and controlled.

  • Perfusion: Adequate blood circulation in organs/tissues.

  • Hypoperfusion: Inadequate blood supply to organs/tissues.

Inadequate Circulation in Adults

  • Minor blood loss adjustments can occur (e.g. vessel constriction, increased heart rate).

  • Significant loss leads to shock; mean arterial pressure is useful for detecting shock.

The Endocrine System: Anatomy & Physiology

  • Function: Integrates various body functions via hormones released into the bloodstream.

  • Control: Brain regulates hormone secretion.

  • Diseases: Can result from hormone excess or deficiency (e.g. Epinephrine, Norepinephrine, Insulin).

The Urinary System: Anatomy & Physiology

  • Functions: Discharge waste, fluid balance, pH balance.

  • Components: Kidneys, Ureter, Urinary Bladder.

The Genital System: Anatomy & Physiology

  • Male System: Testicles, Epididymis, Vasa deferentia, Prostate gland, Seminal vesicles, Penis.

  • Female System: Ovaries, Fallopian tubes, Uterus, Cervix, Vagina.

Life Support Chain

  • Necessities for Cells: Oxygen, nutrients, waste removal.

  • Impact of Interference: Damage and death of cells if supply is compromised.

  • Metabolism: Cells use Oxygen for aerobic metabolism and switch to anaerobic if Oxygen is low.

  • Diffusion: Key mechanism for moving O2, wastes, and nutrients. pH is crucial for diffusion efficiency.

The Human Body: The Digestive System

Anatomy

  • System: Gastrointestinal system located in the abdomen, divided into 4 quadrants.

  • Components: Salivary glands, Oropharynx, Liver, Bile ducts, Appendix, Esophagus, Stomach, Small intestine, Large intestine, Pancreas, Rectum, Mouth and its components (lips, cheeks, gums, teeth, tongue).

Physiology

  • Enzymatic Action: Food is processed using enzymes from the salivary glands, stomach, liver, pancreas, and small intestine, converting food into basic sugars, fatty acids, and amino acids for circulation.

The Lymphatic System

  • Components: Spleen, lymph nodes, lymph, lymph vessels, Thymus gland.

  • Function: Supports circulatory and immune systems by transporting oxygen and nutrients to cells and removing waste products; helps eliminate toxins.

Central Nervous System

  • Primary Component: Spinal cord (extension of the brainstem), transmits messages between brain and body.

Peripheral Nervous System

  • Divided into two main portions:

    • Somatic Nervous System: Transmits signals from brain to voluntary muscles.

    • Autonomic Nervous System: Involuntary actions, split into Sympathetic (fight-or-flight) and Parasympathetic (rest and digest) systems.

Types of Nerves

  • Sensory Nerves: Carry information from the body to the CNS.

  • Motor Nerves: Carry commands from the CNS to muscles.

Integumentary System (Skin): Anatomy

  • Layers: 2 layers - Epidermis (superficial), Dermis (deeper); Subcutaneous tissue beneath the skin acts as insulation and energy reservoir.

Integumentary System (Skin): Physiology

  • Functions: Protects body from environment, regulates body temperature, transmits external information to the brain.

Fighting Infection: Functions of Blood

  • Roles:

    • Transporting oxygen

    • Transporting waste & nutrients

    • Controlling pH

    • Clotting (coagulation)

Nervous System Control of the Cardiovascular System

  • Sympathetic nervous system: Triggers fight-or-flight response, commands adrenal glands to release Epinephrine and Norepinephrine, enhancing heart and vascular function.

  • Receptors:

    • Alpha-adrenergic for blood vessels.

    • Beta-adrenergic for heart and lungs.

  • Baroreceptors: Sense blood pressure variations, balancing sympathetic and parasympathetic nervous systems.

Nervous System: Anatomy & Physiology

  • Complexity: The nervous system is one of the body's most intricate systems, composed of the CNS (brain and spinal cord) and PNS.

  • Cerebrospinal Fluid: Cushions and protects the brain and spinal cord, while oxygenated blood is supplied through carotid arteries and the deoxygenated blood is drained through jugular veins.

Overview of Pathophysiology

  • Definition: Study of functional changes in the body due to disease.

Respiratory Compromise

  • Definition: Inability of the body to move gas effectively.

    • Key Terms:

    • Hypoxia: Insufficient oxygen reaching the tissues.

    • Hypercarbia: Elevated carbon dioxide levels in the blood.

Factors Impairing Ventilation

  • Blocked Airway: Obstruction that prevents airflow.

    • Example: Asthma-induced airway obstruction.

  • Impairment of Breathing Muscles: Weakness affecting the muscles used for respiration.

Factors Impairing Respiration

  • Atmospheric Changes: High altitudes can reduce oxygen availability.

  • Impaired Gas Movement: Difficulty in gas exchange across cell membranes.

V/Q Ratio (Ventilation/Perfusion Ratio)

  • Definition: Measures efficiency in gas movement through lungs and blood flow around alveoli.

    • Normal function requires balance between ventilation (gas movement) and perfusion (blood flow).

    • Mismatch: Occurs when either ventilation or perfusion is abnormal, leading to reduced gas exchange.

Effects of Respiratory Compromise on the Body

  • Oxygen Levels: Decrease (hypoxia).

  • Carbon Dioxide Levels: Increase (hypercarbia).

  • Respiratory Rate: Increases as the body attempts to compensate.

  • Blood pH: Becomes more acidic (due to CO2 retention).

  • Cellular Metabolism:

    • Switches from aerobic to anaerobic metabolism, leading to less efficient energy production.

Shock

  • Definition: A state where organs and tissues do not receive adequate oxygen (O₂).

    • Effects:

    • Impaired O₂ delivery leads to cellular hypoxia.

    • Types of shock categorized based on underlying cause.

    • Consequences: Shift to anaerobic metabolism, resulting in:

      • Severe metabolic acidosis.

      • Increased heart rate due to baroreceptor activation and release of epinephrine/norepinephrine.

      • Interstitial fluid shifts into capillaries, potentially leading to edema.

Impairment of Cellular Metabolism

  • Consequences: Inability to effectively use O₂ and glucose at the cellular level.

    • Anaerobic Metabolism: Cells rely on this less efficient energy production method.

    • Metabolic acidosis may occur as a result.

    • Brain Cells: Cannot utilize alternative energy sources, increasing vulnerability to injury.

    • Cellular Injury: Can become irreversible if impaired for an extended period.