Chapter 6: The Human Body Notes

Topographic Anatomy

• Superficial landmarks serve as guides to structures that lie beneath.
• Topographic anatomy applies to a body in the anatomic position.
  • The patient stands facing you, arms at the side, palms forward.
• Planes of the body: Imaginary straight lines that divide the body
  • Coronal plane: front/back
  • Transverse plane: top/bottom
  • Sagittal (lateral) plane: left/right

The Axial Skeleton

• The axial skeleton is the foundation to which the arms and legs are attached.
  • It includes:
  • Skull
  • Spinal column
  • Thorax
• Skull
  • Cranium: made up of 4 bones
  • Face: made up of 14 bones
• Spinal column
  • Composed of 33 bones (vertebrae)
  • Divided into 5 sections:
  • 7 Cervical
  • 12 Thoracic
  • 5 Lumbar
  • Sacrum
  • Coccyx
  • Thorax
  • Formed by 12 thoracic vertebrae and 12 pairs of ribs
  • The thoracic cavity contains:
    • Heart
    • Lungs
    • Esophagus
    • Great vessels

The Appendicular Skeleton

• Arms, legs, their connection points, and pelvis
• Occur wherever bones come in contact
• Hinge joint
  • Motion restricted to one plane
• Ball-and-socket joint
  • Allows rotation and bending

The Upper Extremities

• Composed of arms, forearms, hands, and fingers
  • Shoulder girdle
  • Clavicle
  • Scapula
  • Humerus
• Arm
  • Humerus is the supporting bone
  • Forearm
  • Radius on the lateral side
  • Ulna on the medial side
• Wrist and hand
  • Ball-and-socket joint
  • Principal bones:
  • Carpals
  • Metacarpals
  • Phalanges

The Pelvis

• Closed bony ring consisting of three bones
• Sacrum
• Two pelvic bones
  • Each pelvic bone is formed by the fusion of the ilium, ischium, and pubis.
• Posteriorly, the ilium, ischium, and pubis bones are joined by the sacrum.
• Anteriorly, the pubic symphysis is where the right and left pubis are joined.

The Lower Extremities

• Main components: thigh, leg, and foot
  • Femur (thighbone)
  • Femur connects to the pelvic girdle by a ball-and-socket joint
• The knee connects the upper leg to the lower leg
  • Kneecap (patella)
• Lower leg
  • Tibia (shinbone)
  • Fibula
• Ankle
  • A hinge joint
  • Allows flexion/extension of the foot
• Foot
  • 7 tarsal bones
  • 5 metatarsal bones
  • Toes are formed by phalanges

The Skeletal System: Physiology

• Functions of the skeletal system
  • Gives the body its shape
  • Protects fragile organs
  • Allows for movement
  • Stores calcium
  • Helps create blood cells

The Musculoskeletal System: Anatomy

• The musculoskeletal system provides:

  • Form
  • Upright posture
  • Movement
  • Protection for vital internal organs

• 3 types of muscle

  • Skeletal (voluntary) muscle - not striated
  • Smooth muscle - digestive system
  • Cardiac muscle - the heart

  

The Musculoskeletal System: Physiology

• Contraction and relaxation of this system make it possible to move and manipulate the environment.
• A by-product of this movement is heat.
• Another function of the muscles is to protect the structures under them.

The Respiratory System: Anatomy

• Structures of the body that contribute to respiration (the process of breathing)

Muscles of Breathing

• The diaphragm and intercostal muscles are the primary muscles of breathing.
• Other muscles involved in breathing:
  • Neck (cervical muscles)
  • Abdominal muscles
  • Pectoral muscles

The Respiratory System: Physiology

• Functions to provide the body with oxygen and eliminate carbon dioxide
• Ventilation and respiration are two separate, interdependent functions of the respiratory system.
• Respiration: the exchange of oxygen and carbon dioxide in alveoli and tissues
  • Provides oxygen to the cells and removes waste carbon dioxide
  • Diffusion: the passive process in which oxygen molecules move from an area with a higher concentration of molecules to an area of lower concentration.
  • The brainstem controls breathing.
• Ventilation: simple air movement into and out of the lungs
  • Tidal volume
  • Residual volume
  • Dead space
  • Minute volume

Characteristics of Normal Breathing

• Normal rate and depth (tidal volume)
• Regular rhythm or pattern of inhalation and exhalation
• Clear, audible breath sounds on both sides of the chest
• Regular rise and fall movement on both sides of the chest
• Movement of the abdomen
• Inadequate breathing patterns in adults:
  • Labored breathing
  • Muscle retractions
  • Pale, cyanotic, cool, damp skin
  • Tripod position
  • Agonal gasps (gasping breaths)

The Circulatory System: Anatomy

• A complex arrangement of connected tubes
  • Arteries, arterioles, capillaries, venules, veins
• Two circuits
  • Systemic circulation (body)
  • Pulmonary circulation (lungs)

The Heart

• Made of specialized cardiac muscle
• Works as two paired pumps
  • The septum divides the right and left sides
  • Each side is divided into:
  • Atrium (upper chamber)
  • Ventricle (lower chamber)
• Circulation
  • The heart receives its blood from the aorta.
  • The right side receives deoxygenated blood from the veins.
  • The left side receives oxygenated blood from the lungs.
• Normal adult resting heart rate (HR): 60–100 beats/min
• Stroke volume (SV)
  • Amount of blood moved by one beat
• Cardiac output (CO)
  • Amount of blood moved in 1 minute
  • HR × SV = CO
• Electrical conduction system
  • Causes smooth, coordinated contractions
  • Contractions produce the pumping action

Arteries

• Arteries carry blood from the heart to all body tissues.
• Pulmonary artery
  • Carries oxygen-poor blood to the lungs
• Arteries branch into smaller arteries and then into arterioles.
  • Arterioles branch into smaller vessels until they connect to the capillaries.
• Pulse
  • Created by the forceful pumping of blood out of the left ventricle and into major arteries
  • Palpated most easily at the neck, wrist, or groin

Capillaries & Veins

• Capillaries connect arterioles to venules
• Capillaries allow contact between blood and cells
• Veins return oxygen-depleted blood to the heart
  • The superior vena cava carries blood returning from the head, neck, shoulders, and upper extremities
  • The inferior vena cava carries blood from the abdomen, pelvis, and lower extremities

Spleen

• A solid organ located under the rib cage
• Filters blood
• Particularly susceptible to injury from blunt trauma
  • This can lead to severe internal bleeding
• Solids do not rupture, but hollow organs can
• Solid organs → internal bleeding, infection, sepsis, death
• Hollow organs → rupture of the organ, internal bleeding, sepsis

The Blood

• Blood composition
  • Plasma (liquid)
  • Red blood cells (erythrocytes)
  • White blood cells (leukocytes)
  • Platelets
• Blood pressure: the pressure blood exerts against the walls of the arteries
  • Systole occurs when the left ventricle contracts
  • Diastole occurs when the left ventricle relaxes
• Blood pressure readings
  • Systolic blood pressure: high point of wave
  • Diastolic blood pressure: low point of wave
• Normal circulation in adults
  • Automatically adjusted and controlled
  • Perfusion: circulation of blood in an organ or tissue in adequate amounts to meet the needs of its cells
  • Blood enters organs and tissues through arteries.
  • Blood leaves organs and tissues through veins.
• Inadequate Circulation in Adults
  • The system can adjust to small blood loss.
  • With a large loss, adjustment fails, and the patient goes into shock.
• Functions of blood
  • Perfusion
  • Transporting oxygen
  • Transporting carbon dioxide
  • Transporting wastes and nutrients
  • Clotting (coagulation)

The Nervous System

• The nervous system is perhaps the most complex organ in the body
• Divided into two main portions:
  • Central nervous system (CNS)
  • Peripheral nervous system
• Brain
• Controlling organs of the body
• Subdivisions
  • Cerebrum
  • Cerebellum
  • Brain stem
• Spinal cord
  • Continuation of the brain
  • Transmits messages between brain and body

Peripheral Nervous System

• Somatic nervous system
  • Transmits signals from the brain to voluntary muscles
• Autonomic nervous system
  • Involuntary actions
  • Split into two areas
  • Sympathetic nervous system (fight-or-flight)
  • Parasympathetic nervous system (slows body)

The Integumentary System: Physiology

• Two layers
  • Epidermis (superficial)
  • Dermis (deeper)
• Below the skin lies subcutaneous tissue.
  • Fat that insulates and serves as an energy reservoir
• The skin is the largest single organ in the body.
• Three major functions
  • Protect the body in the environment
  • Regulate body temperature
  • Transmit the information from the environment to the brain

The Digestive System: Anatomy

• Digestion: processing of food that nourishes the cells
• Abdomen: the second major body cavity
  • Contains major organs of digestion and excretion
  • Quadrants are the easiest way to identify areas:
  • Right upper
  • Lower upper
  • Right lower
  • Left lower
• Mouth
  • Lips, cheeks, gums, teeth, tongue
  • Salivary glands
• Oropharynx
• Esophagus
• Stomach
• Pancreas
• Liver
  • Bile ducts
• Small intestine
• Large intestine
• Appendix
• Rectum

The Digestive System: Physiology

• Enzymes are added to food.
  • By salivary glands, stomach, liver, pancreas, and small intestine
• Enzymes convert food into basic sugars, fatty acids, and amino acids.
  • Further processed by the liver
  • Circulated via blood throughout the body