Chapter 6 - The Human Body

DEFINE (3): anatomy, physiology, pathophysiology

anatomy: physical structure of the body and its systems physiology: normal function of those structures pathophysiology: functional changes that accompany disease or injury

DEFINE (3): anatomic position

patient standing, facing forward, arms at sides, palms forward frame of reference for all providers directional terms are from the patient's perspective, not the EMT's

LIST (4): planes of the body

coronal (frontal): front and back sagittal (lateral): left and right midsagittal (midline): equal left and right halves (nose and umbilicus) transverse (axial): top and bottom

DEFINE (2): topographic anatomy

surface landmarks that guide you to internal structures beneath them example: umbilicus, lower tip of breastbone

LIST (7): skeletal system - functions

gives body shape supports and bears weight framework for soft tissue and organs protects vital organs allows movement stores calcium red marrow makes blood cells

COMPARE (3): axial vs appendicular skeleton (206 bones)

axial: skull, facial bones, thoracic cage, vertebral column (skull to coccyx) appendicular: upper and lower extremities, shoulder girdle, pelvis attachments pelvis includes parts of both

COMPARE (3): ligament, tendon, cartilage

ligament: bone to bone tendon: muscle to bone cartilage: semirigid cushion covering bone ends

LIST (4): joint structure

joint capsule: fibrous sac holding bone ends together articular cartilage: smooth cover on bone ends synovial membrane: lines capsule, makes synovial fluid synovial fluid: lubricant so bones glide

LIST (4): joint types

ball-and-socket: shoulder, hip - rotation and bending hinge: fingers, elbow, knee, ankle - flexion and extension only symphyses: slight motion (pubic symphysis) fused: cranial bones

LIST (3): the skull

28 bones: cranium, 14 facial bones, ear bones cranium: frontal, temporal, parietal, occipital, ethmoid, sphenoid foramen magnum: opening at base where spinal cord meets brain

VALUES (5): vertebral column (33)

cervical: 7 (C1 atlas, C2 axis) thoracic: 12 (each has a pair of ribs) lumbar: 5 sacral: 5 fused (sacrum) coccygeal: 4 fused (coccyx)

EXPLAIN (4): spinal column protection

ligaments and intervertebral disks allow limited motion disks are shock absorbers spinal injury: mishandling may damage cord or nerves spinal cord ends at L2

LIST (3): the thorax

contains heart, lungs, esophagus, great vessels 12 thoracic vertebrae and 12 pairs of ribs great vessels: aorta, superior and inferior venae cavae

LIST (3): the sternum

manubrium: top (sternal notch at upper edge) body: largest section xiphoid process: narrow cartilaginous tip

LIST (4): shoulder girdle

clavicle + scapula sternoclavicular joint: only direct link between shoulder girdle and axial skeleton clavicle lateral end meets scapula (A/C joint) scapula held by muscle only

LIST (6): upper extremity bones

humerus: upper arm radius: forearm, thumb (lateral) side ulna: forearm, little finger (medial) side carpals (8): wrist metacarpals (5): palm phalanges: thumb 2, other digits 3 each

LIST (5): pelvis

two coxae (hip bones) + sacrum + coccyx each coxa = ilium + ischium + pubis pubic symphysis: joins pubic bones acetabulum: hip socket for femoral head sacroiliac joint: sacrum to ilium

LIST (4): femur

thighbone: longest, one of strongest bones femoral head fits acetabulum (ball-and-socket) femoral neck below head greater trochanter (lateral), lesser trochanter (medial)

LIST (5): lower leg and knee

patella: kneecap tibia: shinbone, larger, medial fibula: smaller, lateral knee: hinge joint lateral malleolus (fibula), medial malleolus (tibia)

LIST (5): ankle and foot

tarsals (7): include calcaneus (heel) and talus metatarsals (5): middle foot phalanges (14): 2 in great toe, 3 in others plantar: bottom of foot; dorsal: top of foot ankle: hinge joint of talus with tibia and fibula

COMPARE (3): three muscle types

skeletal: voluntary, striated, attaches to bone smooth: involuntary, blood vessels and intestines cardiac: involuntary, generates its own electrical impulses

EXPLAIN (4): skeletal muscle action

muscles work in antagonistic pairs for control biceps: flexes elbow (anterior humerus) triceps: extends elbow (posterior humerus) more than 600 muscles

LIST (4): musculoskeletal system - other functions

heat production (shivering) protects organs (rectus abdominis protects intestines) movement homeostasis: internal balance

LIST (11): the respiratory system anatomy

nose mouth throat larynx trachea bronchi bronchioles lungs diaphragm chest wall muscles accessory muscles

LIST (5): upper airway (descending)

nasopharynx oropharynx laryngopharynx larynx vocal cords (glottis) = transition to lower airway

LIST (4): lower airway

trachea bronchial tree (main stem bronchi, bronchioles) alveoli lungs

EXPLAIN (3): epiglottis

leaf-shaped flap covers larynx during swallowing lifts open for breathing

LIST (4): larynx landmarks

thyroid cartilage: Adam's apple cricoid cartilage: just below thyroid cartilage cricothyroid membrane: depression between them vocal cords: vibrate to make sound

EXPLAIN (4): lungs and bronchi

right lung: 3 lobes left lung: 2 lobes trachea splits at carina into right and left main stem bronchi bronchi branch into bronchioles

EXPLAIN (4): alveoli

about 700 million air sacs functional units of respiratory system surrounded by pulmonary capillaries oxygen and CO2 exchanged here

EXPLAIN (4): pleura

visceral pleura: covers lungs parietal pleura: lines chest wall fluid film between them lets tissues glide pleural space: potential space (blood or air leaking in separates the layers)

EXPLAIN (4): the diaphragm

primary muscle of breathing dome-shaped, separates thorax from abdomen skeletal and involuntary traits - works automatically pierced by great vessels and esophagus

STEPS (3): mechanics of breathing - inhalation

diaphragm and intercostal muscles contract, enlarging chest cavity pressure falls, air rushes into lungs - negative pressure breathing active

STEPS (4): mechanics of breathing - exhalation

diaphragm and intercostal muscles relax chest cavity dimensions decrease, pressure is increased air is pushed through trachea passive

LIST (2): accessory muscles of breathing

neck (cervical), intercostal, abdominal, pectoral used when airway resistance increases

COMPARE (3): ventilation vs respiration

ventilation: movement of air between lungs and environment respiration: gas exchange (O2 to cells, CO2 removed) also helps control blood pH

EXPLAIN (4): diffusion

passive movement from higher to lower concentration O2: alveoli → blood CO2: blood → alveoli at tissues: O2 leaves capillary into cells, CO2 enters capillary

VALUES (3): air composition

inhaled: 21% oxygen exhaled: 16% oxygen, 3-5% CO2, rest nitrogen only 5% margin of safety for oxygen in air

STEPS (4): chemical control of breathing

CO2 rises → CSF pH falls medulla senses it → phrenic nerve → diaphragm contracts faster rate and tidal volume increase primary reason you breathe: lower CO2, not raise O2

EXPLAIN (4): hypoxic drive

backup breathing control sensors in aortic arch and carotid arteries low oxygen stimulates breathing much less sensitive and powerful than CO2 sensors

COMPARE (2): brainstem control of breathing

medulla oblongata: starts inspiration, sets rhythm, signals phrenic nerve pons: adjusts depth of inspiration and expiration during stress

VALUES (5): lung volumes (adult)

tidal volume: 500 mL inspiratory reserve volume: 3,000 mL expiratory reserve volume: 1,200 mL residual volume: 1,200 mL total lung capacity: about 6,000 mL (men); women about one-third less

DEFINE (3): minute volume

air moved in 1 minute minute volume = respiratory rate × tidal volume normal rate with shallow breaths = inadequate

LIST (6): normal breathing

normal rate and depth regular rhythm clear breath sounds both sides equal chest rise and fall abdominal movement easy, not labored

VALUES (4): normal respiratory rates

adults: 12-20 children: 12-40 infants: 30-60 breaths per minute

LIST (6): inadequate breathing - adult

labored, accessory muscle use rate under 12 or over 20 retractions (above clavicles, between ribs, below rib cage) pale or cyanotic skin cool, clammy skin tripod position

LIST (5): inadequate breathing - infant/child extras

retractions nasal flaring seesaw respirations (infants) grunting exhalation becomes active, may wheeze

LIST (6): pediatric airway differences

smaller, softer, more flexible airway larger tongue relative to mouth smaller larynx obstructs easily softer chest wall, rely on diaphragm under 1 month: do not breathe through mouth large head affects spinal care

EXPLAIN (4): agonal gasps

occasional slow, shallow gasps in cardiac arrest respiratory center still firing inadequate needs ventilations and likely compressions

VALUES (3): FIO2

fraction of inspired oxygen, as a decimal room air: 0.21 nonrebreather at 15 L/min: about 0.9 (90%)

DEFINE (3): respiratory compromise

inability to move gas effectively hypoxia (low O2), hypercapnia (high CO2), or both caused by impaired ventilation or respiration

LIST (7): impaired ventilation - causes

airway blockage (tongue is most common) foreign body, swelling, trauma, blood, vomit neuromuscular disease phrenic nerve or brainstem injury low level of consciousness drug overdose, chest wall trauma asthma, allergic reaction

LIST (5): impaired respiration - causes

low oxygen in air (fire, altitude) fluid in alveoli (pulmonary edema) mucus and pus (pneumonia) fluid in interstitial space blocked pulmonary blood flow (pulmonary embolism)

EXPLAIN (4): V/Q mismatch

V = ventilation, Q = perfusion mismatch when either is abnormal pulmonary embolism: ventilated, no blood flow pulmonary contusion: blood flow, no ventilation

STEPS (5): effects of respiratory compromise

O2 falls, CO2 rises brain increases breathing if ineffective: blood turns acidic cells shift to anaerobic metabolism lactic acid builds, pH drops, cells die

COMPARE (2): systemic vs pulmonary circulation

systemic: left ventricle → body → right atrium (O2-rich out) pulmonary: right ventricle → lungs → left atrium (O2-poor out)

EXPLAIN (5): the heart

size of a clenched fist cardiac muscle (myocardium) septum divides right and left left side: high pressure, more muscular right side: low pressure

EXPLAIN (4): coronary arteries

branch from base of aorta left and right supply heart muscle with oxygenated blood heart cannot function anaerobically

STEPS (6): blood flow through the heart

venae cavae → right atrium tricuspid valve → right ventricle pulmonic valve → pulmonary artery → lungs pulmonary veins → left atrium mitral valve → left ventricle aortic valve → aorta → body

LIST (6): heart valves

one-way valves prevent backflow tricuspid: R atrium/R ventricle pulmonic: R ventricle/pulmonary artery mitral: L atrium/L ventricle aortic: L ventricle/aorta chordae tendineae stop valves from inverting

STEPS (5): electrical conduction

sinoatrial (SA) node atrioventricular (AV) node bundle of His Purkinje fibers ventricles contract

VALUES (4): cardiac values

resting HR: 60-100; athlete 45-60 stroke volume: 70-80 mL cardiac output = HR × SV (about 5-6 L/min) blood volume 5-6 L circulates each minute

EXPLAIN (5): arteries

carry blood away from heart muscular wall; middle layer = tunica media constrict and dilate to change diameter bright red blood bleeding spurts

LIST (7): aorta and branches

carries oxygenated blood to the body coronary: heart carotid: head hepatic: liver renal: kidneys mesenteric: digestive system divides into common iliac arteries at umbilicus

EXPLAIN (5): capillaries

smallest vessels blood passes one cell at a time exchange O2, CO2, nutrients, wastes connect arterioles and venules bleeding oozes

EXPLAIN (6): veins

venules → larger veins → venae cavae thinner walls, larger diameter, low pressure one-way valves dark blue-red blood bleeding flows steadily return aided by gravity, muscle contraction, breathing pressure changes

COMPARE (3): venae cavae

superior: head, neck, shoulders, upper extremities inferior: abdomen, pelvis, lower extremities both empty into right atrium

LIST (4): great vessels

venae cavae aorta pulmonary arteries pulmonary veins

LIST (2): central pulses

carotid: upper neck femoral: groin

LIST (4): peripheral pulses

radial: wrist at base of thumb brachial: medial arm midway between elbow and shoulder posterior tibial: behind medial malleolus dorsalis pedis: top of foot

LIST (5): blood composition

plasma red blood cells white blood cells platelets protein molecules

LIST (4): blood components - functions

red blood cells: carry O2 (hemoglobin) white blood cells: fight infection platelets: start clot plasma: carries cells, nutrients, wastes, hormones; CO2 as bicarbonate; buffers pH

EXPLAIN (5): spleen

solid organ, LUQ under left ribs lymphatic organ that supports circulation filters old red blood cells (life span about 120 days) highly vascular, delicate frequently injured in blunt trauma → major bleeding

DEFINE (4): blood pressure terms

systolic: pressure when ventricle contracts diastolic: pressure when heart is at rest pulse pressure: systolic minus diastolic measured in mm Hg with sphygmomanometer

DEFINE (3): preload and afterload

preload: blood returning to heart afterload: pressure left ventricle must overcome (aortic pressure) textbook: diastolic pressure = afterload

EXPLAIN (3): systemic vascular resistance (SVR)

resistance in all vessels except pulmonary constricted vessels: smaller container, higher pressure dilated vessels: larger container, lower pressure

VALUES (4): blood volume by age

adult: about 6 L child: 2-3 L infant: about 300 mL small loss can be fatal in an infant

DEFINE (3): perfusion

circulation of blood through an organ or tissue to meet cell needs in through arteries, out through veins good BP does not guarantee blood reaches all tissues

COMPARE (2): shock vs hypoperfusion

hypoperfusion: inadequate perfusion, can be regional shock: always systemic hypoperfusion

STEPS (3): compensation for blood loss

vessels constrict (smaller container) heart rate rises to keep cardiac output constant if loss too great, compensation fails → shock

EXPLAIN (3): clotting and bleeding

platelets and clotting factors form fibers trapping red cells venous or capillary bleeding clots in 6-10 minutes arterial: spurts; venous: steady; capillary: ooze

EXPLAIN (3): baroreceptors

pressure sensors in aortic arch and carotid arteries signal brain about blood pressure brain adjusts sympathetic and parasympathetic output

STEPS (3): response to a drop in blood pressure

baroreceptors signal brain sympathetic on: vessels constrict, rate rises, stronger beats BP returns to normal

EXPLAIN (4): alpha-1 receptors

blood vessels vasoconstriction raises BP pale, cool, clammy skin

EXPLAIN (4): beta-1 receptors

heart increased heart rate increased force of contraction raises cardiac output

EXPLAIN (2): beta-2 receptors

lungs bronchodilation

EXPLAIN (3): parasympathetic stimulation of the heart

muscarinic receptors decreased heart rate decreased force of contraction

LIST (4): divisions of the nervous system

CNS: brain and spinal cord PNS: nerves outside the CNS PNS → somatic (voluntary) and autonomic (automatic) autonomic → sympathetic and parasympathetic

COMPARE (4): sympathetic vs parasympathetic

sympathetic: fight or flight, increases activity heart rate up, airways dilate, pupils dilate, sweating, blood to muscles parasympathetic: rest and digest heart rate down, pupils constrict, airways constrict, digestion promoted

LIST (3): the brain - three parts

cerebrum: about three-fourths of brain cerebellum: balance, coordination, posture brainstem: life-sustaining functions

EXPLAIN (3): cerebrum

higher functions: thought, speech, reasoning, emotions, fine motor control left and right hemispheres each hemisphere controls the opposite side of the body

LIST (4): lobes of the cerebrum

frontal: personality, judgment, planning parietal: touch, spatial relationships temporal: hearing, language occipital: vision

LIST (3): brainstem parts - functions

midbrain: level of consciousness, RAS, muscle tone pons: respiratory pattern and depth medulla: heart rate, blood pressure, respiratory rate

EXPLAIN (4): cerebrospinal fluid (CSF)

cushions brain and spinal cord absorbs shock filters impurities and toxins leak from ears or nose = significant finding (skull fracture)

EXPLAIN (4): spinal cord

extension of brainstem through foramen magnum runs in spinal canal, ends at L2 relays messages between brain and body nerve fibers cross sides before reaching brain

EXPLAIN (4): sensory nerves

carry information to brain heat, cold, pressure, pain, position, taste, smell, light most go through spinal cord to parietal lobe optic nerve goes directly to occipital lobe

EXPLAIN (3): motor nerves

carry commands from brain to muscles every skeletal muscle has one cell bodies in spinal cord

LIST (3): skin layers

epidermis (outer) dermis subcutaneous tissue (below)

EXPLAIN (4): epidermis

watertight barrier germinal layer: innermost, makes new cells and pigment stratum corneum: outer dead layer, shed continually cells reach surface in about 4 weeks

LIST (5): dermis

sweat glands sebaceous glands (sebum waterproofs) hair follicles blood vessels nerve endings