respiratory & digestive system: Exam 3

nose

• only external portion of respiratory system

• moistens and warms entering air

• filters and cleans inspired air

• serves as resonating chamber for speech

• houses olfactory receptors

rhinitis

• inflammation of nasal mucosa

• spreads from nose to throat to chest

• also spread to tear ducts and paranasal sinuses, causing blockage of sinus passageways

respiratory zone

site of gas exchange

conducting zone

• conduits that transport gas to/and from gas exchange sites

• cleanses, warms, & humidifies air

larynx

• voice box

• provides patent airway

• routes air and food into proper channels

• houses vocal folds

epiglottis

prevents food & liquids from entering the trachea

laryngitits

• inflammation of vocal folds that causes swelling, interfering with vibrations

• results in changes to vocal tone or worst cases limited to a whisper

• caused by viral infections but also be due to overuse of voice, dry air, bacterial infections, tumors, or irritating chemicals

mucosa

ciliated pseudostratified epithelium with goblet cells

submucosa

• connective tissue with seromucous glands

• supported by C-shaped cartilage rings (prevent collapse of trachea)

alveolar pores

• connect adjacent alveoli

• equalize air pressure throughout lung

• provide alternate routes in case of blockages

alveolar macrophages

• keep alveolar surfaces sterile

• 2 million dead macrophages/ hour carried by cilia to throat & swallowed

pleural cavity

• between two pleurae

• provides lubrication & surface tension that assists in expansion & recoil of lungs

inspiration

• air flows INTO lungs down its pressure gradient

• pressure in the lungs is less than atmospheric pressure

expiration

• gases EXIT lungs

• pressure in the lungs is GREATER than atmospheric pressure

atmospheric pressure “P_atm”

• pressure exerted by air surrounding the body

• 760 mm Hg at sea level= 1 atm

intrapulmonary pressure “P_pul”

• pressure in ALVEOLI

• eventually equalizes with P_atm

intrapleural pressure “P_ip”

• pressure in PLEURAL CAVITY

• always a negative pressure

• fluid level must be kept at a minimum

  • excess pumped by lymphatic system

intrapleural pressure inward forces promoting lung collapse

1. lungs’ natural tendency to recoli

2. surface tension of alveolar fluid

atelectasis

• lung collapse from

  • plugged bronchioles → collapse of alveoli

  • pneumothorax: air in pleural cavity

pulmonary ventilation “breathing”

• inspiration & expiration

• depends on volume changes in thoracic cavity

  • volume changes = pressure changes

  • pressure changes = flow of gases to equalize pressure

boyle’s law

• relationship between pressure & volume of a gas

  • pressure varies inversely with volume

influence that ease air passage & amount of energy for ventilation

• airway resistance

• alveolar surface tension

• lung compliance

airway resistance

• friction (major nonelastic source of resistance to gas flow in airways)

• resistance in respiratory tree is insignificant

  • diameters of airways in conducting zone are huge

  • branching of airways as they get smaller lead to increase in total cross-sectional area

• usually occurs in medium-sized bronchi

• disappears at terminal bronchioles (diffusion drives gas movement)

alveolar surface tension

• attraction of liquid molecules to one another at a gas-liquid interface

• H₂O has very high surface tension, coats alveolar walls in a thin film

  • cause alveoli to shrink to smallest size

surfactant

• detergent-like lipid and protein complex that helps reduce surface tension of alveolar fluid by reducing H-bonds between H2O-molecules

  • prevent alveolar collapse

infant respiratory distress syndrome

• insufficient surfactant in premature infants

• collapse of alveoli after each breath

lung compliance

• measure of changes in lung volume that occurs with given change in transpulmonary pressure

  • measure of how much “stretch” the lung has

• normally high

• high = easier to expand lungs

diminishes lung compliance

• nonelastic scar tissue replacing lung tissue (fibrosis)

• reduced production of surfactant

• decreased flexibility of thoracic cage

alveolar ventilation rate

flow of gases into and out of alveoli during a particular time

dalton’s law of partial pressure

• total pressure exerted by mixture of gases is equal to sum of pressures exerted by each gas

  • pressure exerted by each gas in mixture

major gasses in the air we breathe in order of abundance

N- 78.6%

O- 20.9%

factors that influence external respiration

• Partial pressure gradients and gas solubilities

• Thickness and surface area of respiratory membrane

• Ventilation-perfusion coupling

Partial pressure gradients and gas solubilities

• venous blood P_O2 = 40 mm Hg

• alveolar P_O2= 104 mm Hg

• venous blood P_CO2 = 45 mm Hg

• alveolar P_CO2= 40 mm Hg

Thickness and surface area of respiratory membrane

• respiratory membranes are thin

• Large total surface area of the alveoli is 40x the surface area of the skin

ventilation-perfusion coupling

• P: blood flow reaching alveoli

• V: amount of gas reaching alveoli

• rates must be matched for optimal, efficient gas exchange

• controlled by local autoregulatory mechanisms

P_O2 in alveoli

• change cause changes in diameters of arterioles

• HIGH = arterioles dilate

• LOW = arterioles constrict

P_CO2 in alveoli

• change cause changes in diameter of bronchioles

• HIGH= bronchioles dilate

• LOW= bronchioles constrict

• allows elimination of CO₂ more rapidly

Tissue P_O2

• always lower than in arterial blood P_O2 (40 vs. 100 mm Hg)

• oxygen moves from blood to tissues

Tissue P_CO2

• always higher than arterial blood P_CO2 (45 vs. 40 mm Hg)

• CO2 moves from tissues into blood

molecular O2 transportation

• dissolved in plasma (1.5%)

• loosely bound to each Fe of hemoglobin (Hb) in RBC (98.5%)

  • carry 4 O molecules

Oxyhemoglobin (HbO₂ )

• hemoglobin-O2 combination

• O2 is bound to hemoglobin

Reduced hemoglobin (deoxyhemoglobin) (HHb):

hemoglobin that has released O2

change in shape of Hb

• facilitates loading & unloading of O₂

  • O₂ BINDS= affinity for O₂ increases

  • O₂ RELEASED= affinity for O₂ decreases

factors that influence hemoglobin saturation

• P_O2

• Temperature

• Blood pH

• P_CO2

• Concentration of BPG

arterial blood

• P_O2 is 100mm Hg

• 20 ml of O₂/ 100 ml blood

• Hb is 98% saturated

venous blood

• P_O2 is 40 mm Hg

• contains 15 volume % oxygen

• Hb is 75% saturated at rest

BPG

• produced by RBC during glycolysis

• levels rise when oxygen levels are low

modify structure of hemoglobin

• Increases in temperature, H+ , PCO2 , and BPG\

• Results in a decrease for Hb’s affinity for O2

• Occurs in systemic capillaries

• Enhances O2 unloading (curve to right)

glucose metabolism using O₂ cause

• increases in P_CO2 & H⁺ in capillary blood

• declining blood pH (acidosis) & increasing P_CO2 cause HB-O₂ bond to weaken (Bohr effect)

hypoxia

inadequate O₂ delivery to tissues; can result in cyanosis

ischemic hypoxia

impaired or blocked circulation

histotoxic hypoxia

cells unable to use O_2, as in metabolic poisons

hypoxemic hypoxia

abnormal ventilation; pulmonary disease

CO₂ transportation in blood

• 7-10% is dissolved in plasma as P_co2

• 20% is bound to the globin in hemoglobin (carbaminohemoglobin)

• 70% is transported as bicarbonate ions (HCO₃) in plasma

HCO^-₃ in systemic capillaries

• after created it diffuses from RBCs into plasma

• Outrush from RBC is balanced as Cl moves into RBCs from plasma

  • Chloride shift

HCO₃^- in pulmonary capillaries

• moves into RBCs while Cl moves out of RBCs back into plasma -

• binds with H+ to form H₂CO₃

• H₂CO₃ is split by carbonic anhydrase into CO₂ and H₂O

• CO2 diffuses into alveoli

Haldane effect

• Increased blood O2 decreases ability to carry CO2

  • CO2 release in lungs

• Decreased blood O2 increases ability to carry CO2

  • CO2 pick up in tissues

bohr effect

• Increased blood CO2 decreases ability to carry oxygen

  • ↑blood CO2 = ↓ blood pH

    • decreased affinity of hemoglobin for O2

  • O2 release in tissues

• Decreased blood CO2 increases ability to carry oxygen

  • ↓ blood CO2 = ↑ blood pH

    • increased affinity of hemoglobin for O2

  • O2 pick up in lungs

Carbonic acid–bicarbonate buffer system

• helps blood resist changes in pH

• If H+ concentration in blood rises

  • excess is removed by combining with HCO3 to form H2CO3 which dissociates into CO2 and H2O

• If H+ concentration drops

  • H2CO3 dissociates, releasing H+

• HCO3 – is the alkaline reserve

Slow shallow breathing

causes an increase in CO2 in blood, resulting in a drop in pH

Rapid deep breathing

causes a decrease in CO2 in blood, resulting in a rise in pH

affect respiratory centers

• Chemical factors

• Influence of higher brain centers

• Pulmonary irritant reflexes

• Inflation reflex

chemical factors influence respiratory rate

• changing levels of P_CO2, P_O2, pH

  • Pco2 & pH are most potent and closely controlled

• levels are sensed by central & peripheral chemoreceptors

• rising CO2 levels

  • most powerful respiratory stimulant

influence of P_CO2

• if blood levels decrease, respiration becomes slow and shallow

• Declining P_O2 normally has only slight effect on ventilation because of huge O2 reservoir bound to Hb

  • Requires substantial drop in arterial P_O2 (below 60 mm Hg) to stimulate increased ventilation

Apnea

breathing cessation that may occur when P_CO2 levels drop abnormally low

Hyperventilation

• increased depth and rate of breathing that exceeds body’s need to remove CO2

• Leads to decreased blood CO2 levels (hypocapnia)

influence of arterial pH

• can modify respiratory rate and rhythm even if CO2 and O2 levels are normal

• Mediated by peripheral chemoreceptors

• Decrease may reflect CO2 retention, accumulation of lactic acid, or excess ketone bodies

• Respiratory system controls attempt to raise pH by increasing respiratory rate and depth

arterial P_O2

if falls below 60 mm Hg, it becomes major stimulus for respiration (via peripheral chemoreceptors

Hering-Breuer reflex (inflation reflex)

• Stretch receptors in pleurae and airways are stimulated by lung inflation

  • Send inhibitory signals to medullary respiratory centers to end inhalation and allow expiration

• can be a protective response

hypernea

• increased ventilation in response to metabolic needs

  • Pco2, Po2, & pH remain constant

alimentary canal “GI tract”

• Muscular tube that runs from the mouth to anus

• Digests food

• Absorbs fragments through lining into blood

• Organs: mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus

accessory digestive organs

• organs: Teeth, Tongue, Gallbladder, Digestive glands

• produce secretions that help break down food

  • Salivary glands, Liver, Pancreas

Processing of food

• ingestion

• Propulsion

• Mechanical breakdown

• Digestion

• Absorption

• Defecation

mechanical breakdown- digestion

• chewing, mixing food with saliva, churning food, & segmentation

• segmentation: alimentary canal organs contract and relax to mix and mechanically break down food

chemical digestion

catabolic steps that involves enzymes

propulsion

• movement of food through the alimentary canal

  • swallowing

  • peristalsis: alimentary canal organs alternately contract and relax to move food along the tract

peritoneum

• serous membranes of abdominal cavity

  • visceral & parietal

mesentery

• double layer of peritoneum; layers fuse back to back

• provides routes for blood vessels, lymphatics, & nerves

• holds organs in place & stores fat

digestive organs layes “tunics”

1. mucosa

2. submucosa

3. muscularis externa

4. serosa

mucosa

• lines lumen

• function: secretes, absorbs, & protects

  • secretes mucus, digestive enzymes, & hormones

  • absorbs end products of digestion

  • protects against infectious disease

• made up of epithelium, lamina propria, & muscularis mucosae

epithelium

• secretes mucus

  • protects digestive organs from enzymes

  • eases food passages

• may secrete enzymes & hormones

lamina propria

• rich supply of capillaries for nourishment & absorption

• lymphoid follicles that help defend against microorganisms

Muscularis mucosae

Smooth muscle that produces local movements of mucosa

submucosa

• consists of areolar connective tissue

• contains blood & lymphatic vessels, lymphoid follicles, & submucosal nerve plexus which supply surrounding GI tract tissues

• has abundant elastic tissue that helps organs to regain shape

muscularis externa

• muscle layer responsible for segmentation & peristalsis

• contains inner circular muscle layer & outer longitudinal layers

enteric nervous system

• intrinsic nerve supply to the alimentary canal

• contains more neurons than spinal cord

• their neurons communicate extensively with each other

• participates in short & long reflex arcs

submucosal nerve plexus

• regulates glands and smooth muscle in mucosa

• made up by enteric neurons

myenteric nerve plexus

• controls GI tract motility

• made up by enteric neurons

long reflexes

• respond to stimuli arising inside/outside of gut

  • parasympathetic system ENANCES digestion

  • sympathetic system INHIBITS digestion

tongue

• Form bolus (mixture of food and saliva)

• Intrinsic muscles change shape of tongue

• Extrinsic muscles alter tongue’s position

filiform papaillae

• gives tongue roughness to provide friction

• only one that does not contain taste buds

ankyloglossia “tongue-tied” "fused tongue”

• congenital condition in which children are born with an extremely short lingual frenulum

• restricted movement distorts speech

saliva

• compacts into bolus

• begins breakdown of starch with enzyme amylase

• produced by major (extrinsic) glands located outside oral cavity

• mostly water

• slightly acidic

mumps

• inflammation of parotid glands caused by myxovirus

• common children’s disease

salivation

• 1500 ml/day can be produced

• Intrinsic glands keep mouth moist

• Extrinsic salivary glands are activated by parasympathetic nervous system

• Strong sympathetic stimulation inhibits it and results in dry mouth (xerostomia)

teeth

• Crown: exposed part above gingiva (gum)

• Covered by enamel, the hardest substance in body

• Heavily mineralized with calcium salts and hydroxyapatite crystals

• Enamel-producing cells degenerate when tooth erupts

• Root: portion embedded in jawbone; connected to crown by neck

gastroesophageal sphincter

• junction of the esophagus and the stomach

• Prevents heartburn

gingivitis

• Plaque calcifies to form calculus (tartar)

• Calculus disrupts seal between gingivae and teeth

• Anaerobic bacteria infect gums

• Infection is reversible if calculus removed

periodontitis (periodontal disease)

• Neglected gingivitis can escalate to disease

• Immune cells attack bacterial intruders & body tissues

• May increase heart disease and stroke

esophagus

• Flat muscular tube that runs from laryngopharynx to stomach

• joins stomach at cardial orifice

• alimentary canal that transitions from skeletal muscle to smooth muscle

  • From stratified squamous to simple columnar epithelium?