bio 347 exam 2 cumulative

functions of respiratory system

* gas exchange (O2, CO2)
* protect respiratory surfaces from dehydration, temp changes, pathogens
* produce sounds
* detect odors

respiratory system

oxygen diffuses along surface of lungs → blood carries oxygen (O2 from lungs to peripheral tissues OR CO2 from peripheral tissues to lungs)

mucous and cilia

mucous traps particles from air breathed in → cilia in trachea brush it up → either coughed out or swallowed into esophagus

alveolar epithelium

lines exchange surfaces of alveoli

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made of very delicate, simple squamous epithelium

pharynx

a chamber shared by digestive and respiratory systems, either the digestive tract or respiratory tract

epiglottis

covers the glottis when swallowing; prevents foods and liquids from entering respiratory tract while swallowing

trachea

(windpipe), tough flexible tube that extends from cricoid cartilage to mediastinum → branches into right/left main bronchi

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contains 15-20 C-shaped tracheal cartilages

bronchial tree

right main bronchus and left main bronchus

terminal bronchiole

second to last bronchiole, end of conducting portion

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smooth muscle surrounding it allows bronchodilation and bronchoconstriction

capillaries and alveoli

capillaries bring deoxygenated blood to alveoli and reload on O2 before leaving

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autonomic nervous system

controls luminal diameter of bronchioles by regulating smooth muscle → controls airflow in lungs

bronchodilation

caused by sympathetic activation → enlarges luminal diameter of airway + reduces resistance to air flow

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more O2, produce more ATP, offload more CO2

bronchoconstriction

caused by parasympathetic activation or histamine release to allergic reaction → reduces luminal diameter of airway

alveolar cell layer

consists mainly of simple squamous epithelium formed by **pneumocystes type I**

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site of gas exchange and patrolled by alveolar macrophages

surfactant

oily secretion that coats alveolar surface and reduces surface tension so that the lungs can easily expand/contract

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produced by large, scattered **pneumocytes type II**

blood air barrier

alveolar cell layer, capillary endothelial layer, fused basement membrane between them

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if thickness is increased, ability to exchange gases is compromised

gas exchange

* across the blood air barrier, quick and efficient
* distance for diffusion is short
* O2/CO2 are small and lipid soluble

pulmonary embolism

a blocked branch of pulmonary artery that stops blood flow to alveoli

pulmonary circuit BP

lower than systemic circuit since it's smaller in size and less force is needed to push blood out

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pulmonary vessels are easily blocked by blood clots, fat or air bubbles

respiration

2 integrated processes: external and internal

external respiration

body breathing (between alveoli and blood)

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all process involved in exchange of O2 and CO2 with external environment

internal respiration

cell breathing; uptake of O2 and release of CO2 by cells

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result of cellular respiration

air flow

flows from an area of higher pressure to an area of lower pressure

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alveoli → blood → hemoglobin → tissue → capillaries → cell

what affects pulmonary ventilation?

* volume (increased lung space → low pressure → pulls air into lungs
* pressure
* thoracic cavity (muscles expand/contract the lungs)
* diaphragm/rib cage (contracts/pushes up → pushes on lungs → pushes air out → expiration)

resistance

force against which the lungs have to push to get air in/out

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adjusted with bronchodilation and bronchoconstriction

tidal volume

amount of air moved per breath

respiratory minute volume

amount of air moved per minute, measures pulmonary ventilation

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calculated as respiratory rate x tidal volume

anatomic dead space

volume of air remaining in conducting passages, doesn't exchange air

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mouth, trachea, bronchi

aleveolar ventilation

amount of air reaching alveoli each minute

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calculated as respiratory rate x (tidal volume - anatomic dead space)

gas exchange factors

depends on partial pressures of gases involved + diffusion of molecules between gas and liquid

expiratory reserve volume

additional amount of air capable of being exhaled

residual volume

amount of air in lungs after maximal exhalation, minimal volume in a collapsed lung

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(never pushed out or leaves the lung)

inspiratory reserve volume

additional amount of air that can be inhaled

inspiratory capacity

tidal volume + inspiratory reserve volume

functional residual capacity

expiratory reserve volume + residual volume

vital capacity

expiratory reserve volume + tidal volume + inspiratory reserve volume

total lung capacity

vital capacity + residual volume

diffusion of gases

occurs in response to concentration gradients

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rate depends on physical principles, or gas laws like Boyle's direction (air into blood vs. blood into air)

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also determined by partial pressures and solubilities

efficiency of gas exchange

* differences in partial pressure across blood air barrier are substantial
* distances involved in gas exchange are short
* O2 and CO2 are lipid soluble
* total surface area is large (more gas exchange)
* blood flow and airflow are coordinated

differences in partial pressure

acts like a concentration gradient; high partial pressure of O2 in alveoli, low partial pressure of O2 in blood arriving to lungs O2 moves to oxygenate blood

ventilation-perfusion

V/Q, ideally equal to 1 but usually about 1.1 varies at different parts of lungs (more air at bottom of lungs)

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measures how coordinated blood flow and air flow are

external respiration

blood arriving in pulmonary arteries have low PO2 and high PCO2

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concentration gradient causes O2 to enter blood and CO2 to leave blood

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rapid exchange allows blood and alveolar air to reach equilibrium

internal respiration

concentration of gradient in peripheral capillaries is opposite of lungs (high PO2, low PCO2)

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CO2 diffuses into blood, O2 diffuses out of blood

oxygen transport

O2 binds to iron ions in hemoglobin molecules (reversible reaction)

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each Hb can bind bind 4 oxygen molecules

hemoglobin saturation

% of heme units containing bound oxygen at any given movement saturated when all units are bond to O2

Hb saturation factors

* PO2 of blood → if high, drives O2 into Hb
* blood pH (low)
* temperature
* metabolic activity within RBCs

oxygen-hemoglobin saturation curve

a graph relating hemoglobin saturation to partial pressure of oxygen at pH 7.4 and 37 C

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higher PO2 → greater Hb saturation

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curve not straight line because Hb changes shape each time a molecule of O2 binds → each O2 bound makes next O2 bind more easily (strength for wanting O2 decreases as heme units start binding)

when pH drops or temperature rises

more oxygen is released, oxygen-hemoglobin saturation curve shifts to **right**

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ex: exercising → muscle gets warm → build up of lactic acid → cause Hb to offload O2

when pH rises or temperature drops

less oxygen is released or Hb holds onto oxygen more, oxygen-hemoglobin saturation curve shifts to the **left**

Bohr effect

the effect of pH on hemoglobin saturation curve, caused by CO2 which diffuses int RBC

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more CO2 = lower pH

BPG

product of RBCs' ATP production, directly affects O2 binding and release

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more = more O2 released

PCO2 levels

control bronchoconstriction and bronchodilation

respiratory centers of brain

more responsive to CO2 than O2

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when O2 demand rises, respiratory rate increases under neural control (voluntary and involuntary components) aka breathe more

respiratory centers

regulate frequency and depth of pulmonary ventilation in response to sensory information

hypercapnia homeostasis

increasing arterial PCO2 → chemoreceptors in arteries/medulla oblongata stimulated → respiratory muscles stimulated → increased respiratory rate → decreased arterial PCO2

hypocapnia homeostasis

decreasing arterial PCO2 → chemoreceptors in arteries/medulla oblongata inhibited → respiratory muscles inhibited → decreased respiratory rate → increased arterial PCO2

major organs of digestive tract

* oral cavity
* pharynx
* esophagus
* stomach
* small intestine
* large intestine

accessory organs of digestive system

not on main path

* teeth
* tongue
* salivary glands
* liver
* gallbladder
* pancreas

integrated processes of digestive system

* ingestion
* mechanical digestion and propulsion
* chemical digestion
* secretion
* absorption
* defecation

oral cavity

responsible for

* ingestion
* mechanical digestion with accessory organs (teeth, tongue)
* moistening and mixing food with salivary secretions

pharynx

common passageway for food, liquid, air

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muscular propulsion of materials into esophagus

esophagus

tube from pharynx to stomach, transports materials to stomach

stomach

chemical digestion of materials by acid and enzymes

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mechanical digestion through muscular contractions

small intestine

long muscular tube where chemical digestion is completed and 90% of nutrient absorption occurs

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enzymatic digestion and absorption of water, organic substrates, vitamins and ions

large intestine

horseshoe shaped, extends from end of ileum → anus

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dehydration and compaction of indigestible materials in preparation for elimination

teeth

mechanical digestion by chewing

tongue

assists teeth with mechanical digestion and responsible for sensory analysis

salivary glands

secretion of lubricating fluid containing enzymes that break down carbohydrates

liver

secretion of bile (important for lipid digestion), storage of nutrients, many other vital functions

gallbladder

hollow, pear-shaped muscular sac

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storage and concentration of bile prior to secretion into small intestine

pancreas

exocrine cells secrete buffers and digestive enzymes; endocrine cells secrete hormones

ingestion

intake of food

mechanical digestion/propulsion

physically crushing and shredding food

chemical digestion

molecularly breaking down foods through acids/enzymes

secretion

accessory organs secrete enzymes/acids for chemical digestion

absorption

nutrients move from the digestive system into the bloodstream

defecation

elimination of feces

adipose tissue functions

* pads and protects surfaces of abdomen
* provides insulation to reduce heat loss
* stores lipid energy reserves

stratified squamous epithelium

found in oral cavity, pharynx, esophagus, anal canal

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necessary to withstand physical stresses and trauma

simple columnar epithelium

found in stomach, small intestine and most of large intestine necessary for absorption

villi

finger like projections that increase surface area for absorption in the intestines

peristalsis

waves of muscular contractions that move a bolus along length of digestive tract (starts at esophagus)

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squeezing moves food down the digestive tract

segmentation

cycles of contraction that churn and fragment the bolus (mechanical digestion of food)

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mixing contents with intestinal secretions random pattern aka not pushing materials in one specific direction

oral cavity functions

* sensory analysis
* mechanical digestion
* lubrication
* limited chemical digestion

sensory analysis

tasting of food before swallowing

lubrication

mixing food with mucus and saliva

amylase

secreted by salivary glands for start of carbohydrate digestion in mouth

tongue functions

* mechanical digestion by compression, abrasion, distortion
* sensory analysis by touch, temperature and taste receptors

saliva functions

* clean oral surfaces
* moisten and lubricate food
* keep pH of mouth near 7.0
* control populations of bacteria and limiting acids that they produce
* dissolve chemicals that stimulate taste buds
* initiate digestion of complex carbohydrates with salivary amylase

mastication

chewing food which is forced from oral cavity to vestibule and back across occlusal surfaces of teeth

bolus

moist, rounded ball of food compacted by tongue fairly easy to swallow

stomach functions

* temporary storage of ingested food (1-2 hrs)
* mechanical digestion with muscular contractions
* chemical digestions of food with acid and enzymes (specific)

chyme

partially digested food mixed with acidic secretions of stomach

parietal cells

secrete intrinsic factor to absorb B12 and indirectly secrete hydrochloric acid

chief cells

secrete pepsinogen that's activated into pepsin by HCl in gastric lumen

pepsin

an active proteolytic enzyme or protein-digesting enzyme

duodenal papilla

the raised bump/hole where the common bile duct and pancreatic duct enter the duodenum

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allows pancreas and gallbladder to dump their digestive enzymes

pancreatic endocrine cells

secrete insulin and glucagon into bloodstream

pancreatic exocrine cells

acinar and epithelial cells of duct system

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secrete 1L basic/alkaline pancreatic juice into small intestine per day

pancreatic juice

alkaline mixture of digestive enzymes, water and ions