A & P Chapter 6

anatomy

Anatomy

A field of study that focuses on the physical structure of the body and its systems.

Physiology

Examines the normal functions and activities of the body and its systems.

Pathophysiology

The study of functional changes that accompany a particular disease or syndrome.

Anatomic Position

Patient stands facing you, arms at side, palms forward.

Coronal (frontal) Plane

Divides the body front and back.

Sagittal (lateral) Plane

Divides the body left and right.

Midsagittal (midline) Plane

Divides the body into equal left and right halves.

Transverse (axial) Plane

Divides the body horizontally into top and bottom sections.

Cells

The foundation of the human body.

Tissue

Cells that share a common function form tissue.

Organs

Groups of tissue that perform similar or interrelated jobs form organs.

Body Systems

Organs with similar functions work together to comprise body systems.

Functions of the Skeletal System

1. Gives us our recognizable human form.

2. Protects vital internal organs.

3. Allows for movement.

4. Stores calcium.

5. Helps create blood cells.

Number of Bones in the Skeletal System

206 bones.

Axial Skeleton

Forms the longitudinal axis of the body from the skull to the coccyx. Includes the skull, facial bones, thoracic cage, and vertebral column.

Appendicular Skeleton

Comprises the upper and lower extremities and the points by which they connect to the axial skeleton.

Joints

Where two bones meet.

Ligaments

Fibrous tissues that connect bone to bone, helping to stabilize the joint.

Cartilage

A semirigid and flexible tissue that covers and cushions the ends of articulating bones.

Tendons

Attach bone to muscle.

Symphyses

Joints where only slight movement is possible.

Joint Capsule

A fibrous sac that holds the bone ends of a joint together.

Articular Cartilage

Allows the ends of bones to glide easily.

Synovial Membrane

The inner lining of the joint capsule.

Synovial Fluid

Produced by the synovial membrane, which allows the ends of bones to glide over each other.

Ball-and-Socket Joint

A type of joint that allows rotation and bending (e.g., the shoulder joint).

Hinge Joint

A type of joint where motion is restricted to flexion (bending) and extension (straightening).

Skull Bones

Consists of 28 bones divided into three groups: the cranium, the facial bones, and three small bones in the ear.

Cranium Bones

Protects the brain and consists of 4 bones: Occiput (posterior), Temporal bones (lateral), Parietal bone (between temporal and occiput), and Frontal bone (forehead).

Facial Bones

Consist of 14 bones, including the upper jawbones (maxillae), cheekbones (zygomas), lower jaw (mandible), orbits (eye sockets), and bones forming the bridge of the nose.

Spinal Column Components

Composed of 33 vertebrae divided into 5 sections:

1. Cervical spine (neck): 7 vertebrae

2. Thoracic spine (upper back): 12 vertebrae (each with a pair of ribs attached)

3. Lumbar spine (lower back): 5 vertebrae

4. Sacrum (back wall of pelvis): 5 fused vertebrae

5. Coccyx (tailbone): 4 fused vertebrae

Thorax Components

The thoracic cavity contains the heart, lungs, esophagus, and great vessels. It is formed by 12 thoracic vertebrae and 12 pairs of ribs. The sternum forms the midline of the chest.

Sternum Parts

Made up of the manubrium, body, and xiphoid process.

Shoulder Girdle

The point where the clavicle, scapula, and humerus come together.

Humerus

The supporting bone of the arm.

Forearm Bones

Consists of the radius (lateral, thumb side) and ulna (medial, little finger side).

Wrist and Hand Joints

A modified ball-and-socket joint formed by the ends of the radius and ulna and carpal bones. The hand is made up of five metacarpals, and the fingers are composed of phalanges.

Pelvic Girdle

Consists of two large hip bones (coxae), the sacrum, and the coccyx.

Coxa

Each hip bone formed by the fusion of the ilium, ischium, and pubis.

Pubic Symphysis

Cartilage that joins the left and right pubic bones and limits movement between them.

Femur

The longest and one of the strongest bones in the body. Its femoral head articulates with the acetabulum by a ball-and-socket joint. The greater and lesser trochanters serve as anchor points for thigh muscles.

Knee Joint

A hinge joint connecting the femur to the bones of the lower leg.

Lower Leg Bones

Tibia and Fibula.

Ankle and Foot Structure

The foot comprises the tarsals, metatarsals, and phalanges. The distal ends of the tibia and fibula articulate with the talus to form the ankle.

Musculoskeletal System Functions

Provides form, upright posture, movement, and protection for vital internal organs.

Types of Muscle Tissue

1. Skeletal muscle (voluntary)
2. Smooth muscle (involuntary)
3. Cardiac muscle (involuntary)

Skeletal Muscle

Attaches to the bones of the skeleton and forms the major muscle mass of the body. It is known as voluntary muscle because it is under direct voluntary control of the brain.

Smooth Muscle

Found within blood vessels and intestines; its movement does not require conscious thought.

Cardiac Muscle

Found only within the heart; its movement does not require conscious thought.

Physiology of Musculoskeletal System Movement

Contraction and relaxation of the system make it possible to move and manipulate the environment. A by-product of this movement is heat.

Respiratory System Function

Responsible for breathing (respiration) and the exchange of oxygen and carbon dioxide within the lungs.

Upper Airway Components

Nose, Mouth (oral cavity), Tongue, Jaw (mandible), Larynx, Pharynx (Nasopharynx, Oropharynx, Laryngopharynx), Trachea (windpipe), Epiglottis.

Larynx

The dividing line between the upper and lower airways.

Epiglottis

A thin, leaf-shaped flap that prevents food and liquid from entering the trachea.

Lower Airway Components

Thyroid cartilage (Adam’s apple), Cricoid cartilage, Cricothyroid membrane, Trachea, Carina, Right and left main stem bronchi, Bronchioles, Alveoli.

Alveoli

Tiny air sacs within the lungs that allow for gas exchange (oxygen and carbon dioxide).

Pleura

Serous membranes surrounding the lungs. The visceral pleura covers the lungs, and the parietal pleura lines the chest wall. A thin layer of fluid between them facilitates lung movement.

Diaphragm

The primary muscle of breathing, containing both voluntary and involuntary muscle fibers.

Inhalation (Mechanics of Breathing)

An active part of the respiratory cycle where the diaphragm and intercostal muscles contract, enlarging the thoracic cage. Pressure within the thoracic cavity decreases, and the lungs fill (negative-pressure ventilation).

Exhalation (Mechanics of Breathing)

A passive portion of the respiratory cycle where the diaphragm and intercostal muscles relax, and the thoracic cavity returns to its normal shape and volume.

Ventilation

The movement of air between the lungs and the environment.

Respiration

The exchange of oxygen and carbon dioxide in the alveoli and in tissues of the body.

Diffusion (Respiration)

A passive process in which molecules move from an area with a higher concentration to an area of lower concentration, facilitating oxygen and carbon dioxide movement across membranes.

Chemical Control of Breathing

The brainstem controls breathing by monitoring levels of carbon dioxide in the blood and spinal fluid. Breathing is primarily stimulated by a buildup of carbon dioxide in the cerebrospinal fluid, which causes the pH to decrease.

Primary Stimulus for Breathing

To lower carbon dioxide levels, not to increase oxygen levels.

Hypoxic Drive

A 'backup' system to control respiration, where the stimulus to breathe comes from low oxygen levels.

Medulla Oblongata (Respiratory Control)

Responsible for initiating the ventilation cycle, primarily stimulated by high carbon dioxide levels, helps control the rhythm of breathing, initiate inspiration, set the base pattern for respiration, and send the signal to the diaphragm via the phrenic nerve.

Pons (Respiratory Control)

Has two areas which help augment respirations during emotional or physical stress and helps change the depth of inspiration, expiration, or both.

Tidal Volume

The amount of air that is moved into or out of the lung in a single breath, generally 500 \text{ mL} in an adult.

Inspiratory Reserve Volume

The deepest breath you can take after a normal breath.

Expiratory Reserve Volume

The maximum amount of air you can forcibly breathe out after a normal breath.

Residual Volume

The gas remaining in the lungs after exhalation.

Dead Space

The portion of the respiratory system that has no alveoli and little to no gas exchange.

Minute Ventilation (Minute Volume)

The amount of air that moves in and out of the lungs in one minute. Calculated as: Minute volume = respiratory rate \times tidal volume.

Characteristics of Normal Breathing

1. Normal rate and depth.
2. Regular rhythm or pattern of inhalation and exhalation.
3. Clear, audible breath sounds on both sides of the chest.
4. Regular rise and fall movement on both sides of the chest.
5. Movement of the abdomen.

Signs of Inadequate Breathing in Adults

1. Labored breathing (significant effort using accessory muscles).

2. Breathing slower than 12 \text{ breaths/min} or more than 20 \text{ breaths/min}.

3. Additional signs: Muscle retractions (above clavicles, between ribs, below rib cage), pale or cyanotic skin, cool/damp skin, tripod position.

Circulatory System Components

A complex arrangement of connected tubes including arteries, arterioles, capillaries, venules, and veins.

Systemic Circulation

Carries oxygen-rich blood from the left ventricle through the body and back to the right atrium.

Pulmonary Circulation

Carries oxygen-poor blood from the right ventricle through the lungs and back to the left atrium.

Heart Structure

An involuntary muscle made of specialized cardiac muscle (myocardium) that works as two paired pumps. The left side is a muscular high-pressure pump, and the right side is a thinner low-pressure pump. Each side is divided into an atrium (upper chamber) and a ventricle (lower chamber).

Cardiac Circulation

The heart receives its blood from the aorta via coronary arteries. The right side receives deoxygenated blood from body veins. Oxygenated blood returns from the lungs through pulmonary veins into the left side and is pumped into the aorta to the body's arteries.

Normal Adult Pulse Rate

60 \text{–} 100 \text{ beats/min}.

Stroke Volume (SV)

The amount of blood moved by one beat of the heart.

Cardiac Output (CO)

The amount of blood moved in 1 minute. Calculated as: \text{CO} = \text {HR} \times \text{SV} .

Heart's Electrical Conduction System

A network of specialized tissue (SA node, AV node, bundle of His, Purkinje fibers) that initiates and conducts electrical current throughout the heart, producing a coordinated pumping action.

Arteries (Function)

Carry blood from the heart to all body tissues.

Aorta

The main artery leaving the left side of the heart and carrying freshly oxygenated blood to the body. It has many branches that supply vital organs.

Pulmonary Artery

Originates at the right ventricle and carries oxygen-poor blood to the lungs.

Pulse

Created by the forceful pumping of blood out of the left ventricle and into the major arteries. It is most easily palpated at the neck, wrist, or groin.

Capillaries

Tiny blood vessels that connect arterioles to venules. They allow oxygen and nutrients to pass from blood cells and plasma to individual tissue cells, and blood moves through them one cell at a time.

Veins (Function)

Return oxygen-depleted blood to the heart. They have thinner walls than arteries and are generally larger in diameter.

Major Veins

1. Superior vena cava: Carries blood returning from the head, neck, shoulders, and upper extremities.
2. Inferior vena cava: Carries blood from the abdomen, pelvis, and lower extremities.

Systemic Vascular Resistance (SVR)

The resistance to blood flow within all blood vessels except the pulmonary vessels.

Spleen

A solid organ located under the rib cage in the left upper part of the abdomen that filters worn-out blood cells, foreign substances, and bacteria from the blood. It is highly vascular and susceptible to injury from blunt trauma.

Plasma (Blood Composition)

The liquid portion of blood, containing water (primary component), proteins (primary component), oxygen, carbon dioxide, nitrogen, nutrients, and cellular wastes.

Red Blood Cells (Erythrocytes)

Contain hemoglobin, which carries oxygen.