The Respiratory System - Week 2

mean arterial pressure

volume of blood in the arterial system determines what?

arterial pressure increases

flow in > flow out

arterial pressure decreases

flow out > flow in

peripheral resistance

in the arterioles; determines the rate of blood flow out of the arteries

arterioles and capillaries

where resistance to blood flow is greatest because of narrow diameter

decreases

increased resistance does what to the rate of blood flow?

total peripheral resistance

the resistance to blood flow through he entire arteriole system

mean arterial blood pressure

cardiac output x total peripheral resistance =

cardiac output

stroke volume x heart rate

mean arterial pressure

modulated by altering stroke volume, heart rate, and total peripheral resistance

mechanoreceptors (barareceptors)

how the body detects change in blood pressure; stretch sensitive; located in walls of carotid artery and the aortic arch

baroreceptors

activate sensory nerves that return to cardiovascular control center

cardiovascular control center

integrates sensory input from the baroreceptors; module the ANS to regular blood pressure by altering HR, SV, & TPR

vascular smooth muscle cells

innervated by sympathetic nerve fibers only; express alpha adrenergic receptors with binds noradrenaline released by activated sympathetic nerves

counteract reduction in blood pressure

increased sympathetic nerve activity and reduction in vagus nerve activity

stimulation of vagus nerve activity

reduce cardiac output by slowing heart rate to counteract an elevation in blood pressure

inhibition of sympathetic nerve activity

reduce cardiac output buy slowing heart rate and stroke volume and cause relaxation of arterial smooth muscle to decrease peripheral resistance; to counteract elevation in blood pressure

baroreceptor reflex

counter changes in blood pressure and is very rapidly activated when pressure increases or decreases

baroreceptor reflex

more sensitive to decreases in blood pressure which causes a reduction in the stretch of arterial walls; more sensitive to rapid changes in pressure

venous pooling

from lying down to standing, 500-700ml of blood shifts immediately to lower extremities

thoracic cavity

in a lying position, venous blood pools in the veins here

orthostatic hypotension

venous pooling/drop in venous return/drop in cardiac output causes a resultant drop in arterial pressure and causes a sensation of dizziness or seeing stars

increases

if total blood volume increases, what happens to mean arterial pressure?

kidneys

play a vital role in regulating blood volume because urine is derived from blood plasma

glomeruli

what plasma is filtered through in the kidneys to form a filtrate

vascular system

where 99% of water and salts are reabsorbed back into

1.5 liters

how much urine is excreted daily

hypertension

chronically elevated blood pressure; 20% of adults have varying degrees

essential and secondary

two types of hypertension

essential hypertension

hypertension; unclear, multifactorial causes such as diet and genetics; accounts for 95% of cases

secondary hypertension

hypertension resulting from another condition such as chronic renal disease triggered by diabetes; chronically elevated slat and water reabsorption in the nephron will increase blood volume and chronically raise blood pressure

hypertension

cause long term damage to the heart and kidneys and is a risk factor for heart attach and stroke

diffusion

most important mechanism for trans capillary exchange

capillaries

walls contain pores which permit movement of fluid and small biomolecules

interstitial fluid (tissue fluid)

lies outside the cells and the circulatory system; directly bathes the cells of the tissues

capillary walls

act like a sieve, retaining blood cells and large proteins, but allowing plasma and interstitial fluid to mix

filtration

flow of plasma out of the capillaries into the tissues

absorption

flow of interstitial fluid into the capillaries

hydrostatic pressure

filtration is driven by blood pressure in the capillaries

38 mmHg

hydrostatic pressure at arterial end

16 mmHg

hydrostatic pressure at venous end

colloid osmotic pressure

pressure created by the diffusion of water from a fluid with a low osmolarity to a fluid with a higher osmolarity

osmolarity

the concentration of solutes in a fluid

colloid osmotic pressure/oncotic pressure

osmotic pressure created by plasma proteins

absorption

promotes movement of water out of tissue fluid into the capillaries

25 mmHg

net colloid osmotic pressure/oncotic pressure; constant across the length of capillaries

starling forces

opposing hydrostatic and osmotic pressures; direction of fluid motion at a specific region of a capillary is determined by the relative strength of these forces

higher

blood pressure at the arterial side of capillaries is WHAT; ensures that starling forces will promote net filtration of fluid from the capillaries

lower

blood pressure at the venous side of capillaries is WHAT; promotes net reabsorption of fluid back into the capillaries driven by colloid osmotic pressure

arterial blood plasma

filtered into tissue fluid at the arterial end of the capillaries; then reabsorbed back into the capillaries at the venous end of the capillaries

lymphatic system

absorbs excess interstitial fluid and returns it to the vascular system (lymph/lymphatic fluid)

ventilation

mechanical process that moves air in (inspiration) and out of the lungs (expiration)

gas exchange

exchange of oxygen and carbon dioxide between air and blood in the lungs; exchange of oxygen and carbon dioxide between blood and cells in the circulatory system

oxgyen

moves from air to the blood

carbon dioxide

moves from blood to the air

oxygen

moves from blood to the cells

carbon dioxide

moves from cells to the blood

cellular respiration

utilization of the oxygen to oxidize organic molecules producing energy and carbon dioxide

conducting zone

airways connecting the external atmosphere to the gas exchange regions of the lung; primary bronchi transport air into each lung where they repeatedly divide into smaller and smaller bronchioles

the respiratory zone

regions of the lung where gas exchange occurs; occurs in 300 million air sacs (alveoli) that cluster

alveoli

air sacs that cluster at the ends of terminal bronchioles; contact with the capillaries of the pulmonary circulation

inspiration

occurs by reducing air pressure in the lungs to sub-atmospheric pressures; achieved by increasing volume in the lungs

expiration

occurs by increasing the air pressure in the lungs above atmospheric pressure; achieved by decreasing the volume in the lungs

Boyle’s law

pressure of a quantity of gas is inversely proportional to its volume

increases

what happens to pressure in the lungs when decreasing the volume compresses the air

decreases

what happens to pressure in the lungs when increasing the volume decompresses the air

diaphragm muscle

lies at the base of the thoracic cavity that contains the heart and lungs

2

amount of pleural membranes in the thoracic cavity; stick tightly to each other

parietal pleura

lines the inner wall of the thoracic cavity

visceral pleura

covers the outer surface of the lungs

normal inspiration

driven by contraction of the diaphragm which causes it to flatten; pulls on based of thoracic cavity increasing vertical volume

external intercostal muscles

simultaneous contraction of theses causes the rib-cage to increase thoracic volume laterally during normal inspiration

scalenes and pectoralis minor

muscles recruited to drive further thoracic expansion during forced inspiration

inspiration

as thoracic volume increases, the lung volumes correspondingly increase; air moves into the lungs

-3 mmHg

what intrapulmonary/intra-alveolar pressure drops to doing normal inspiration

-20 mmHg

what intrapulmonary/intra-alveolar pressure drops to during forced inspiration

passive

what kind of process is normal expiration

normal expiration

as muscles that drive thoracic expansion relax, the thorax and lungs recoil to their original state

+3 mmHg

what intrapulmonary pressure increases to in normal expiration that forces air out of the lungs

internal intercostal mules and abdominal muscles

muscles that become active and depress the thoracic cavity and lungs further during forced expiration

+30 mmHg

what intrapulmonary pressure increases to in forced expiration

intrapleural pressure

both pleural membranes are being pulled in opposite directions; assists in keeping lungs fully adhered to the thoracic cavity

outward

what type of force do walls of the thoracic cavity exert?

lower

intrapleural pressure is always WHAT compared to intra-alveolar pressure

pneumothorax

pleural membranes damaged by a broken rib or stab wound; entry of wire into the pleural fluid breaks the bond holding the membranes together; pleural space now exists

pneumothorax

collapsed lung

equalize

intrapleural and intra-alveolar pressure doe what in a pneumothorax

chest tube

suctions the air from the pleural space to allow lungs to re-expand after pneumothorax

surface tension

generated by the interaction of air and fluid secreted by spherical alveoli and

inward

what type of force is entered on the alveoli when surface tension pulls water molecules tightly together; opposes the expansion of lung tissue during inspiration

surfactant

produced by type II alveolar cells late in fetal development; composed of lipoprotein complexes; disrupts cohesive forces between water molecules

type II alveolar cells

produces surfactant

respiratory distress syndrome (RDS)

when premature infants are born without sufficient surfactant; difficulty in expanding lung volume during inspiration

artificial surfactant

treats RDS

radius of airways

primary determinant of resistance to air flow

bronchioles

contain smooth muscle innervated by sympathetic and parasympathetic nerves in airway resistance

bronchodilation

triggered by noradrenaline released from sympathetic nerves

bronchoconstriction

triggered by acetylcholine released from parasympathetic nerves

smoke, irritants, cold air

results in reflex stimulation of vagus nerve that causes inappropriate bronchoconstriction