Heart stuff Flashcards
what type of circulatory system do fish have ?
single
what type of circulatory mammals do fish have ?
double
what type of circulatory system do insects have ?
open
what is the difference between single / double circulatory system ?
single - blood passes through heart once for each complete circuit of body, double passes twice
describe the circulation of blood in fish
heart pumps blood to gills, then to rest of the body
what to remember when labeling heart …
left is right, right is left
what is the pulmonary system ?
blood moving to / from the heart and lungs
what is the systemic system ?
blood moving to / from the heart and the rest of the body
what is the advantage of mammals having double circulatory system ?
blood gets extra push between lungs and rest of body, blood travels faster, oxygen delivered faster
what is a closed circulatory system ?
blood is enclosed inside blood vessels
what is an open circulatory system ?
blood isn’t enclosed in blood vessels (all the time), instead flows freely through body cavity
Describe how an open circulatory system works
- heart is segmented, and contracts in waves, pumping blood into a single main artery
- artery opens up into body cavity
- blood flows around organs, and makes it back to heart segments through valves
what does the blood of an insect supply ?
its nutrients / hormones … (not oxygen)
what system in an insect supplies its oxygen ?
tracheal system
where do arteries carry blood from / to ?
from heart / to rest of body
describe the structure of walls of arteries and how it helps function
- thick muscular walls, with elastic tissue to stretch and recoil, which helps maintain high pressure
- endothelium is folded, allowing arteries to expand (maintain high pressure)
what is the endothelium ?
the inner lining
what type of blood do arteries carry ?
oxygenated (except pulmonary, which takes deoxygenated to lungs)
what are arterioles ?
small branches of arteries
describe the structure of walls of arterioles and how it helps function
- less elastic tissue than arteries
- have smooth muscle, which allows to expand / contract, thus control amount of blood flowing through
describe the structure of walls of capillaries and how it helps function
- one cell thick for quick diffusion (glucose / oxygen)
what are venules ?
- formed from capillaries
- thin walls with some muscle cells
- join to form veins
where do veins take blood from / to ?
from respiring tissues / to heart
describe the structure of walls of veins and how it helps function
- wide lumen (so low pressure)
- pocket valves prevent back flow
- blow flow helped by contraction of surrounding body muscles
what type of blood do veins carry ?
deoxygenated (except pulmonary veins)
what is tissue fluid?
fluid surrounding cells (consists of substances that leave the plasma e.g. oxygen / water / nutrients)
how do substances move out of the capillaries ?
pressure filtration
Describe the movement of fluid at start of capillary bed
fluid forced out of capillaries and into spaces around cells - due to higher hydrostatic pressure in the capillaries than in tissue fluid
what is hydrostatic pressure ?
liquid pressure
Describe the movement of fluid at end of capillary bed
water re-renters capillaries by osmosis - due to low water potential in capillaries - due to fluid loss and high oncotic pressure
what is oncotic pressure ?
pressure generated by plasma proteins which lower the water potential
what is lymph?
excess tissue fluid that passes into lymph vessels
what substances are in tissue fluid ?
water / dissolved substances / (very few) white blood cells / (very few) proteins
what substances are in lymph ?
white blood cells / antibodies (protein) / water / dissolved substances
why are red blood cells / plasma proteins not in tissue fluid ?
too big to fit through capillary walls
when would white blood cells enter tissue fluid ?
when there’s an infection
when would platelets be in tissue fluid ?
capillaries are damaged
do tissue fluid and lymph have higher or lower water potential than blood ?
higher
where do lymph vessels lead to ?
thorax
what special structure feature do lymph vessels have ?
valves
what valves link the atria and the ventricles ?
atrioventricular valves
what valves link the ventricles and the pulmonary artery / aorta ?
semi - lunar valves
if there’s a high pressure behind a valve, what does it do ?
forced open
if there’s a low pressure behind a valve, what does it do ?
forced shut
what is the cardiac cycle?
ongoing sequence of contraction and relaxation of atria and ventricles to keep blood continuously circulating
what is the lub sound from the lub-dub sound caused by ? (heart)
atrioventricular valves closing
what is the dub sound from the lub-dub sound caused by ? (heart)
semi-lunar valves closing
what does it mean that cardiac muscle is myogenic ?
contracts and relaxes without receiving signals from nerves
where is the sino-atrial node ? (SAN)
wall of right atrium
what does the SAN do ?
sets the rhythm of the heart beat by sending out regular waves of electrical activity to atrial walls - causing both atria to contract at same time
what is the machine that records electrical activity in heart called ?
electrocardiograph
what happens to electrical charge of heart when it contracts ?
depolarizes (loses charge)
what happens to electrical charge of heart when it relaxes ?
repolarizes (regains charge)
what does an electrocardiograph use ?
electrodes placed on the chest
what is the trace produced by an electrocardiograph called ?
electrocardiogram / ECG
what are the letters of an electrocardiogram ?
PQRST
what is the P wave caused by ?
contraction of the atria
what is the QRS complex ? what is it caused by ?
main peak of heartbeat, caused by contraction of ventricles
what is the T wave caused by ?
relaxation of ventricles
what is a tachycardia heart beat ?
fast heartbeat (over 120bpm)
what is a bradycardia heart beat?
slow heartbeat (less 60bpm)
what is an ectopic heartbeat and what is it caused by ?
‘extra’ heartbeat, caused by early contraction of atria / ventricles
what is a really irregular heartbeat called ?
fibrillation
what is an irregular heart beat caused by ?
atria / ventricles lose their rhythm and stop contracting properly
what can irregular heartbeat result in ?
chest pain / fainting / death
what does a tachycardia heartbeat suggest at rest ?
heart isn’t pumping blood efficiently
what does affinity for oxygen mean ?
tendency to combine with oxygen
state the path of the signal for a heart beat
SAN - (atrium) - AVN - bundle of His - Purkyne tissue - (ventricle)
what is the haemoglobin + oxygen equation?
Hb + 4O2 — HbO8
high pO2 means …
high [O2]
high affinity for oxygen means …
more readily combines with oxygen - high saturation
low affinity for oxygen means …
releases oxygen rather than combine - low saturation
how does carbon dioxide affect haemoglobin ?
Hb offloads oxygen more readily at higher p(CO2)
what happens to carbon dioxide and water in erythrocytes ?
- combine to form carbonic acid (catalyst - carbonic anhydrase)
- carbonic acid dissociates to H+ and HCO3- ions
what happens to the H+ ions in erythrocytes ?
Increase in H+ causes HbO8 to offload oxygen to take up H+ ions
HAEMOGLOBINIC ACID formed
what happens to the HCO3- ions in erythrocytes ?
- HCO3- diffuses into blood plasma
- ## Cl- ions diffuse in to maintain charge balance (chloride shift)
how are HCO3- and H+ removed from body?
- recombine at low pCO2 in lungs w/ water to form carbon dioxide
- breathed out
