circulation Flashcards
in multicellular animals are all cells engaged in metabolic activities
yes
every cell requires nutrients but which cells require oxygen
only those that carry out aerobic respiration
what are examples of cell waste products
nitrogenous compounds and carbon dioxide
why must every cell be bathed in aqueous solution
to allow for diffusion
what is diffusion proportional to
the square of distance
what is diffusion
the passive process of molecules moving from a high concentration to a low concentration over a semi permeable membrane
in terms o diffusion why do we need a complex transport system
diffusion alone is far too slow
diffusion plays an important role in movement of materials over what distance
<100um
do protistan, cnidarian and platyhelminthes require a complex transport system
no diffusion is sufficient because they are either small, thin or flat
What is the main purpose of the circulatory systems
to transport nutrients and oxygen to the tissues and remove waste products
what is a small artery called
arteriole
what is a small vein called
venule
do vertebrates have a closed or open circulatory system
closed
what does the circulatory system of vertebrates include
heart
arteries
veins
capillaries
do veins and arteries travel side by side
yes
how many chamber are in the heart
4 - 2 atria and 2 ventricles
which artery is the only one to carry deoxygenated blood
pulmonary artery
what direction do arteries travel
away from the heart
what direction do veins travel in
towards the heart
describe the circulatory system of a fish
single circulation
one atrium, one ventricle
blood reaches the tissues after passing over the gills to collect oxygen
blood has low pressure when flowing in the systemic part
what about the fish is in series
the gills and the systemic capillaries (tissues)
why is the fish circulatory system adequate
they have low metabolic rate as they are ectotherms
describe the circulatory system of amphibians
a partial double circulation
limited mixing
can redirect blood from the lungs to the skin - less blood goes to the lungs when the animal is not moving
as well as using the respiratory system how else do frogs respire
through their skin when they are in water
describe the circulatory system of reptiles
one ventricle partly divided by a septum
R-L shut occurs when submerged so blood by-passes the lungs
2 atria
in vertebrates which ventricle is thicker
the left ventricle
what are the pacemakers of the heart
the SA node primarily and the AV node is involved
How does the SA node set the pace of the heart
it sends out an electrical charge at a specific interval. this causes the right atrium to contract starting the whole string of events that gets blood pumping in waves through your body.
where do the SA and AV nodes sit in the heart
the right atrium
what is a pacemaker
it is a small device inserted into the chest of a recipient that mimics the electrical impulses of the SA and AV nodes
where is the pulmonary semilunar valve found
Between the right ventricle and the pulmonary artery
where is the aortic semilunar valve found
Between the left ventricle and the aorta
where is the tricuspid (atrioventricular) valve found
the right atrium
where is the bicuspid (atrioventricular) valve found
the left atrium
what process quickly follows the failure of the circulatory system
brain death - 3-4mins later
on average how many time does the heart beat per minute
70
how many times does an elephant heart beat per minute
25
how many times does a shrew heart beat per minute
25
what is the effect of mammal size on metabolic rate
smaller the mammal, greater the metabolic rate (due partly to their increased surface area to volume ratio)
the smaller the animal the …………. the heart rate
faster
life span ……………. with an decrease in heart rate
increases
what is the phrase that means the heart contracts spontaneously
myogenic property
what are the intercalated discs of the cardiac muscle
channels connecting cells
what occurs via the intercalated discs
cell-cell transmission
what is the rhythm of the cardiac muscle in the ventricles
slow
what is the rhythm of the cardiac muscle in the atria
faster than ventricles
what is the rhythm of the cardiac muscle in the SA (sino-atrial) node
the fastest - faster than atria and ventricles
describe what happens when the heart contracts
heartbeat is initiated by the SA node
it spreads over the atria
then it spreads over the ventricles
Excitation spreads slowly from the SA node over the atria to the AV node. why is this process slow
to ensure that atrial contraction is complete before ventricular contraction begins
cell-cell transmission is adequate for what size of heart
small
what is the order of excitation
SA Node > AV Node > Bundle of His > Purkinje Fibres
instead of cell-cell transmission what do larger hearts require
bundle of his and purkinje fibres which conduct rapidly to all parts of the ventricles including the apex (bottom tip of the heart in the left ventricle)
what is the bundle of his
a collection of heart muscle cells specialized for electrical conduction that transmits the electrical impulses from the AV node to the point of the apex of the fascicular branches via the bundle branches.
what leads from the bundle of his to the purkinje fibres
fascicular branches
what happens when excitation reaches the purkinje fibres
electrical conduction to the ventricles, causing the cardiac muscle of the ventricles to contract at a paced interval.
what results when purkinje fibres become damaged
ventricular fibrillation - use a defibrillator to restart.
what regulates the frequency and strength of the heartbeat
autonomic nervous system - the part of the nervous system that controls things automatically
what does the sympathetic nervous system do
excitation of the heart
increase in heart rate
increase in stroke volume (greater force of contraction
what does the parasympathetic nervous system do
inhibition of heart
decrease in heart rate
decrease in stroke volume (weaker force of contraction)
what is stroke volume
the volume of blood pumped from the left ventricle per beat
what is epinephrine
adrenaline
what does excretion of epinephrine result in
increases heart rate and stroke volume
what is the stroke volume at rest
70ml/beat
5litres/min
what is the heart rate at rest
70beats/min
what is the heart rate during strenuous exercise
up to 180bpm
what is the stroke volume during strenuous exercise
25 litres/min
up to 35 litres/ min in a athlete
what happens to blood flow during exercise
cardiac output blood flow increases
brain blood flow is constant
skeletal muscle blood flow is increased
alimentary system blood flow is decreased
why shouldn’t you exercise straight after a meal
the blood flow of the alimentary system is decreased as the blood is diverted to the skeletal muscles and cardiac output so food won’t be digested as efficiently
what is systole
when the ventricle (left in example but can be either) contracts, blood is forced under high pressure into the aorta and blood surges forward in all arteries. the pressure waves stretch the walls of the arteries. this is a pulse
what is diastole
when the ventricle relaxes, the pressure falls and the elastic of the stretched arteries recoils, maintaining some pressure in the blood
what determines blood pressure
cardiac output and peripheral resistance met by the blood as it passes from the arteries into the arterioles and capillaries.
what is peripheral resistance
resistance to flow determined by the diameter of the tube – the smaller the diameter the greater the resistance
what is the cardiac cycle in terms of systole and diastole
atrial and ventricular diastole
atrial systole, ventricular diastole
ventricular systole, atrial diastole
what is the first sound of the heart beat
LUB
what is the second sound of the heart beat
DUB
which valves are open during atrial and ventricular diastole
atrioventricular valves (tricuspid and bicuspid (mitral) valves)
which valves are closed during atrial and ventricular diastole
semilunar valves (aortic and pulmonary valves)
what is the pulse pressure calculation
systolic-diastolic pressure difference
is there a pulse in veins
no
what are the 4 main functions of arteries
- To transport blood from the heart to the capillaries
- To act as pressure reservoir for forcing blood into small diameter capillaries – their thick walls withstand pressure
- To dampen oscillations in pressure and flow generated in the heart, so producing a more even flow of blood to the capillaries.
- The arterioles control flow to the capillary beds
what is vasoconstriction
smooth muscle in the arteriole wall contracts to decrease blood flow to capillary bed
what is vasodilation
smooth muscle in the arteriole wall relaxes to increase blood flow to capillary bed
what is vascular tone
the degree of constriction experienced by a blood vessel relative to its fully dilated state.
what controls the flow of blood between arterioles and venules
precapillary sphincters - rings of smooth muscle
what ultimately controls blood flow to the capillary beds
the sympathetic nervous system, hormones and local factors
is blood flow constant
yes
which organ have their capillaries filled to capacity
heart, brain, kidneys and liver
where is blood diverted to when body temperature increases
the skin - vasodilation occurs
what are the main functions of veins
- To transport blood from capillaries back to the heart
2. To act as a storage reservoir for blood (60% of blood volume is in veins).
blood pressure is very low in the veins, so how is blood returned to the heart?
They return blood to the heart by the mechanism of having valves (blood may only flow in 1D) and skeletal muscular activity.
what is thrombophlebitis
the pooling of blood, leading to blood clot formation in bedridden patients - why people are encouraged to walk soon after operation
what increases the likelihood deep vein thrombosis (blood clot in the leg)
Immobility for long periods of time e.g. long flight
what is thrombosis
formation of a blood clot or thrombus in a blood vessel.
where can a blood clot block a vessel
in the vessel in which it forms or it may become dislodged and be carried to some other location in the circulatory system, in which case it is called an embolus. can be very dangerous e.g. in the lung
what is a stroke
When an embolus or thrombus blocks a blood vessel in the brain
what are symptoms of a stroke
depending on which part of the brain has been damaged (due to lack of blood supply) – e.g. paralysis, speech impairment, emotional disturbance.
where do capillaries run from
arterioles to venules
what are endothelial cells
Endothelial cells are the thin layer of cells that line the interior surface of all blood vessels. these cells line the entire circulatory system
what are the 2 ways that materials can move in and out of capillaries
passively and actively
how do materials move in/out capillaries passively
through capillary endothelial cell wall
e.g. O2, CO2
How do materials move in/out capillaries actively
by bulk flow through the intercellular spaces between the endothelial cells. happens in most capillaries (not the brain) active transport (especially in brain) there are tight junctions in the brain that close the intercellular spaces forming a blood brain barrier
how do nutrients get from capillaries to cell tissues
the nutrients diffuse into the interstitial fluid around the cells
define cardiac output
the volume of blood each ventricle pumps per minute
define heart rate
number of beats per minute
define stroke volume
the volume of blood pumped by a ventricle in a single contraction
what creates the lub sound
recoil of blood against the closed AV valves
what creates the dub sound
the closing of the semilunar valves
what happens when impulses are released from the SA node
both atria contract in unison
the impulse reaches the AV node
signals from the AV node a re conducted to the heart apex and throughout the ventricular walls by bundle of his branches and purkinje fibres
which two systems regulate the pacemaker function of the SA node
the sympathetic and parasympathetic nervous system
which nervous system speeds up the pacemaker when you walk
sympathetic
which nervous system slows down the pacemaker when you sit down
parasympathetic
which gland secretes epinephrine that induces fight or flight (speeds up the pacemaker)
adrenal glands
what else other than the sympathetic and parasympathetic nervous system affects the pacemaker
body temperature - increase in temperature increases heart rate
what is a heart murmur
when blood squirts back through a defective valve
what is a an endothelium
single layer of flattened epithelial cells
what part of the blood vessel is lined with an endothelium
the central lumen (cavity)
how does endothelium affect resistance
it decreases the resistance
what surrounds the endothelium in a capillary
basal lamina
what layers surround the endothelium of arteries and veins
smooth muscle and connective tissue (elastin allow stretch and collagen allows strength)
why can arteries accommodate blood pumped at high pressure
because they have thick walls
what controls modulation of blood flow by constriction or dilation
signals from the nervous system and circulating hormones act on the smooth muscle of the vessels
do veins contain valves
yes
do arteries contain valves
no
what happens to the velocity of blood flow when blood flows between the arteries and arterioles
decreases
what is the connection between total cross sectional area and velocity of blood flow
increase in cross sectional area = decrease in blood flow velocity
Blood, like all fluids flows from areas of …………….pressure to areas of ………..pressure
higher to lower
contraction of a …………… generates blood pressure
ventricle
when is arterial blood pressure highest
when the heart contracts during ventricular systole
what is the blood pressure called when the heart contracts
systolic pressure
what is the blood pressure called during diastole
diastolic pressure
why is blood always under pressure
so that their is a continuous flow
how is a continuous flow of blood maintained
during diastole, before enough blood has flowed into the arterioles to completely relieve pressure in the arteries, the heart contracts again (systole)
Smooth muscles of the arteriole wall contracts. vasoconstriction …………….. blood pressure upstream in the arteries
increase
smooth muscles of the arteriole walls relax. vasodilation ………………. blood pressure in the arteries
decrease
how is blood pressure measured
systole pressure/diastole pressure (mm Hg)
what is osmotic pressure
the pressure produced by the difference in solute concentration across a membrane
the difference in osmotic pressure between the blood and the interstitial fluid ………….. fluid movement out of the capillaries
opposes
generally, blood pressure is …………. than opposing forces leading to net loss of fluid from the capillaries
greater
how is the fluid lost from the capillaries brought back to the blood
via the lymphatic system
what is the fluid recovered to the lymphatic system called
lymph
do lymph vessels have valves
yes
disruption in the movement of lymph can result in fluid accumulation in affected tissues. what is this called
edema
edema is responsible for what in starving children
bloated bellies (kwashiorkor)
Pregnant women get swollen ankles because their …….…….…. pressures become higher than the norm.
osmotic
by what method of transport does gas exchange occur
by diffusion
what factors does rate of transfer depend upon
area
distance
concentration difference
area should be as large/small as possible
diffusion distance should be as small/large as possible
large
small
describe the anatomy of the lungs
trachea, bronchus, bronchioles, alveoli
what hormone secreted by the kidneys stimulates generation of erythrocytes
erythropoietin
what is coagulation
liquid blood going to solid blood
the enzyme thrombin converts what to what
fibrinogen to fibrin - this forms a clot
what is a heart attack caused by
a blockage in one of the coronary arteries
what is partial pressure
the pressure exerted by a particular gas in a mixture of gases
in what direction does a gas move
from a high partial pressure to a lower partial pressure
what makes an alveoli
capillary endothelium
interstitial space
alveolar epithelium
what about alveoli maximises gas exchange
moist walls
thin walls
large surface area
what are the walls lined with
moist epithelium cells
what are the lungs
localised respiratory organs
run through the process of breathing
inhale through nostrils
air goes to pharynx
trachea opens and air passes through into bronchi then bronchioles then alveolidissol
what lines the epithelium that line the major branches in the lung tree
cilia
what do cilia do in the lungs
they brush up mucous into the pharynx where it is swallowed into the oesophagus
where does gas exchange in mammals occur
alveoili
how is oxygen taken up
oxygen in the air entering the alveoili dissolves in the moist film lining their inner surfaces and rapidly diffuses across the epithelium into a web of capillaries that surrounds each alveoli
how is carbon dioxide removed from the capillaries
net diffusion of carbon dioxide occurs from the capillaries across the epithelium of the alveoli and into the air space
As the oxygen passes through the airways it ………….pressure.
loses
mammals employ negative/positive pressure breathing
negative - it means pulling rather than pushing air into the lungs
air pressure is lowered by muscle contraction which expands the thoracic cavity, causing what
influx of air into the lungs
inhalation
The diaphragm …………..and is pulled down
The rib cage expands and the rib muscles contract
contracts
exhalation
rib cage gets ……………
rib muscles ………..
elasticity of lungs drives air out of them
smaller
relax
what is tidal volume
volume of air inhaled and exhaled with each breath
what is vital capacity
tidal volume during maximal inhalation and exhalation
what is residual volume
air that remains after a forced exhalation
because the lungs of mammals don’t completely empty with each breath fresh and oxygen depleted residual air mix slightly. what results
concentration of oxygen in alveoili is always less than in the atmosphere
how is CO2 transported
5% as dissolved CO2
5% attached to haemoglobin and other blood proteins
90% as bicarbonate ions
describe cooperativity of haemoglobin
when one oxygen binds affinity of other sites increases
when one oxygen is released affinity of other sites decreased
where is the foramen Ovale located (allows blood to bypass the lungs)
between the right and left atrium
what coats the lining of the alveoli
pulmonary surfactant
