exam 3 (final)

functions of the respiratory system

functions of the respiratory system

-maintain a constant O₂ & CO₂ in blood

-acid-base balance

-provides a means of gas exchange b/n the environment & the body

ventilation

process of moving air in & out of lungs

respiration

ventilation & exchange of gases in lungs

internal respiration

at the cell

external respiration

at the lung

conducting zone

-10% of total lung volume

-air passed to the alveoli

-anatomical dead space

-nose, trachea, carina

respiratory zone

-90% of total lung volume

-where gas exchange (O₂ & CO₂) occurs

-alveolar ducts & capillaries

nose

-warms, humidifies & filters air (air conditioning)

-100% humidified (47 mmHg at body temp)

trachea

-surrounded by cartilage

-high resistance to airflow, slows done air

carina

-at base of trachea

-primary coughing reflex

type 1 alveoli

1 layer of epithelial cells

type 2 alveoli

surfactant secreting

surfactant

-lines surface of alveoli

-liquid containg lipoproteins

-↓ surface tension of alveolar membranes

-gives lungs good compliance

compliance

-change in volume for a change in pressure

-reason why we can inflate & deflate our lungs easily

O₂ cost of breathing

at rest= 6 mLO₂/min

inspiration at rest

diaphragm pulls down, lungs are expanded (active)

expiration at rest

diaphragm relaxes, lungs passively recoil

muscles of inspiration (exercise)

-pulls ribs up: scalenes & sternoclridomastoid

-pulls ribs out: external intercostal

-diaphragm

muscles of expiration (exercise)

-pulls ribs down & in: internal intercostal

-external oblique, rectus abdominis, internal oblique, transverse abdominis (abdominals push diaphragm up)

gas diffusion

moves from areas of high to low pressure

sites of gas diffusion in the body

-alveoli-capillary interface

-tissue-capillary interface

factors that affect gas exchange

↑ gas solubility, ↑ pressure gradient, ↑ diffusion space, ↑ surface area

Fick

Hartog Hamburger

gas solubility

-positively related

-how easily gas can dissolve into environment

pressure gradient

-positiviely related

-biggest driver of oxygen, high to low pressure

diffusion space

-inversly related

-tissue thickness

-connection with cells of capillaries & alveoli, want it to be very thin

surface area

positively related

ficks law of diffusion

-R= rate pf gas exchange

-D= solubility constant

-A= surface area

-∆p= difference in pressure gradient between capillaries & alveoli

-d= diffusion space/tissue thickness

atmospheric gas fractions at sea-level

-O₂= 0.2093

-CO₂= 0.0003

-N₂= 0.7904

change in atmospheric pressure

-↑ altitude= ↓ pressure

-due to gravity which causes gas molecules to be close to the ground

alveolar partial pressure of gases

-O₂= 0.146

-CO₂= 0.056

O₂ transport in blood

1)dissolved in blood

-3 mLO₂/L blood dissolved

-low dissolvability of O₂

-1.5%

2)bound to hemoglobin

-binds & carries O₂

-1.34 mLO₂/ gm Hb (when fully saturated)

-98.5 %

hemoglobin

-250 million Hb or 1 RBC

-binds 4 O₂ molecules

-men= 150 g Hb/L blood

-women= 130 g Hb/L blood

-1 g Hb can combine w/ 1.34 mLO₂

arterial-venous O₂ difference

-(a-v)O₂

-diffencene b/n CaO₂ & CvO₂

-amount of O₂ extracted by tissue

Fick equation VO₂

-(HR×SV)×(a-v)O₂ diffencene

-illustrated the factors determining VO₂

CO₂ transport

1)dissolved in plasma (10%)

2)bound to Hb (20%)

3)formed as HCO₃ on RBC (70%)

bicarbonate-CO₂ transport system

-CO₂ + H₂O→H₂CO₃→H⁺ + HCO₃⁻

-Cl⁻ shift/ Hamberger shift

rest-to-work transitions

1)rapid ↑ in ventilation

-proportional to intensity

2)rapid ↑ in pulmonary blood flow

3)airway dilation & ↓ resistance to air flow

-bronchioles

ventilatroy control during submax exercise

-higher brain center (primary drive to increase ventilation during exercise)

-chemoreceptors (↑ pCO₂ & ↓ pH) & mechanoreceptors (muscular movement)

-respiratory muscles (↑ ventilation)

-peripheral chemoreceptors carotid/aortic (↓ pO₂, ↑ pCO₂ & ↓ pH)

-↑ temp & catecholamines

ventrilation: incremental exercise

-sharp rise in Vε

-motor recruitment pattern

-propriceptive input

-↑ acidosis

-↑ body temp

-↑ epi/ne

anterior pituitary hormones

-thyroid stimulating hormone (TSH)

-adrenocorticotropin hormone (ACTH)

-LH & FSH (act on ovaries, regulate menstration)

-growth hormone

-prolactin (milk production when pregnant)

growth hormone (GH)

-signal for release: exercise & hypoglycemia

-acts on muscle, adipose, & liver

-releases from anterior pituitary

-essential for normal growth

-stimulated protein synthesis & bone growth

-decreases glucose uptake into muscle

-increases lipolysis

-stimulates gluconeogenesis in liver

anti-diuretic hormone

-released from posterior pituitary

-signal for release: sweating or dehydration & ↑ plasma osmolality

-acts on kidney (collecting duct)

-↑ H₂O reabsorption

-maintain plasma volume

osmolality

-decreased water in plasma

-concentration of solutes

adrenal medulla

-part of the SNS

-secretes catecholamines (epi/ne)

adrenal cortex

-secretes steroid hormones

~mineralocorticoids: aldosterone, corticosterone, deoxycorticosterone

~glucocorticoids: cortisol

~androgens

aldosterone

-releases from adrenal cortex

-signal for release:

~decreased blood volume/pressure

~decreased plasma sodium

~angiotensin II: potent vasoconstricter

-acts on kidney (distal convoluted tubule)

-actions:

~maintain plasma Na⁺ & volume

~↑ H₂O reabsorption

~BP regulation

~stimulate thirst

erythropoietin (EPO)

-released from the kidney

-signal for release: hypoxia, anemia, & blood loss

-ergogenic aid alert

-action: stimulates RBC production

insulin

-released from pancreas (β cells)

-signal for release: ↑ BG & AA’s in blood

-acts on muscle & adipose

-actions:

~untake of FFA’s, AA, & glucose

~inhibits gluconeogenesis, lypolysis, & protein breakdown

glucagon

-released from the pancreas (α cells)

-signal for release: ↓ BG/AA’s in blood & prolonged exercise

-acts on liver

-actions:

~↑ gluconeogenesis & glycogen breakdown

~↑ lypolysis & protein breakdown

~inhibits TG & glycogen synthesis

epi/norepi

-released by adrenal medulla

-↑ linearly with exercise

-acts on liver, muscle, & adipose

-actions: ↑ lipolysis, gluconeogenesis in liver, & glycogenolysis in muscle

athletic amenorrhea

-FSH & LH have altered release from pituitary

-↓ estrogen

-causes female athletes to lose period

temperature homeostasis

to maintain a constant core temp, heat lost must match heat gain

heat gain

-PA

-TEF: thermic effect of food

-hormonal responses

-warm environment

heat loss

-radiation

-conduction

-convection

-evaporation

conduction

transfer of heat via direct contact with another surface (cold bleacher)

convection

transfer of heat via movement of molecules within fluids or gases (air)

evaporation

-transfer of heat when liquids change physical state becoming gas

-80% heat loss during exercise

-20% heat loss at rest

radiation

-transfer of electromagnetic heat waves

-60% heat loss at rest

-5% heat loss during exercise

evaporative cooling rate depends on

-temp & relative humidity

-convective current around the body

-amount of skin surface exposed

factors related to heat injury

-aclimatization

-hydration

-wind

-temp

-humidity

-clothing

-fitness

-exercise intensity

acclimatization

-earlier onsent of sweating

-↑ sweat rate, ↓ body temp

-9-14 days, > 1 hr exercise

hydration

↑ sweat rate, ↓ body temp

wind

-↑ heat loss by convection

-↑ rate of evaporation

temp

-↑ temp=heat gain

-evaporative cooling

humidity

-↑ humidity=heat gain

-lose evaporative cooling

clothing

need skin exposure

fitness

↑ fitness=↓ risk of injury

exercise intensity

-↑ intensity=↑ risk of injury

-monitor intensity closely

sweat rate

2-3 L/hr

dehydration: CV function

-↓ skin BF, SV, & Q

-↑ HR & (a-v)O₂, maintain O₂ supply to muscle

hyperthermia: CNS

-motivation & motor control

-hypothalamus can be damaged

hyperthermia: neuromuscular

↓ neural activation of muscle (MU recruitment)

signs of heat acclimatization

-↑ plasma volume & VR

-early onset of sweating during exercise

-more dilute sweat (less Na⁺ lost)

-↑ SV & ↓ HR, Q is maintained

-↑ capacity for sustained sweat response

-↓ core temp for given workload

-↓ glycogenolysis

dehydration

-1%: rapid ↑ in temp

-2%: ↓ performance

-3%: ↓ coordination

-4%: headache/nausea

-5%: failure of thermoreg

-6%: serious risk for collapse, permanent injury, & organ failure

dehydration calculation

[(pre-exercise kg−post-exercise kg)÷pre-exercise kg]×100

gastric emptying rates affected by

-temp

-pH (acidity)

-volume of fluid

-CHO (6%), ↓ fat, ↓ protein, ↓ fructose

max gastric emptying rate

1.2 L/hr

water replacement before exercise

-300-500 mL H₂O, 2 hrs prior (based on hydration status)

-more H₂O w/ glycerol (“hyperhydration”)

-1.2 g glycerol/kg w/ 26 mL water/kg for 2 hrs prior

water replacement during exercise

-< 1 hr: H₂O only

->1 hr: H₂O & CHO

-> 2 hrs: add Na⁺ (40 mmol/L)

rehydration is improved by

-volume ingested > 1.5 times body weight loss

-CHO-electrolyte solution is ingested

-glycerol is added to drink

severe hypohydration

-> 4% body weight loss

-can require >24 hrs for complete rehydration