module 3 - chapter 8 - transport and exchange in animals Flashcards
why might large, multicellular organisms need specialised transport systems?
-diffusion is too slow
-need to meet high metabolic demands and dispose of lots of metabolic waste
-SA:V ratio decreases as organism gets larger, less surface area to absorb or remove substances
-food can be digested in one organ system but needs to be transported to every cell for respiration etc.
what are the similarities between the different circulatory transport systems?
-have a liquid transport medium that circulates around the system (blood)
-have vessels that carry the transport medium
-have a pumping mechanism to move fluid around the system
outline an open circulatory system
- few vessels to contain transport medium
- pumped from heart directly to body cavity
open body cavity = haemocoel - in haemocoel, blood is under low pressure
- comes into direct contact with tissues and cells - exchange takes place
- transport medium returns to heart via an open ended vessel
- mainly in invertebrates (insects and molluscs)
what substance do insects have instead of blood?
describe this substance and what it transports
haemolymph - doesn’t carry oxygen or carbon dioxide
transports food, nitrogenous waste and immune cells
what is the major disadvantages or an open circulatory system?
slow - low blood pressure
unspecialised - amount of haemolymph flowing to a tissue cannot vary to meet specific demands
define vertebrate
animals that have a backbone
define invertebrate
animals that do not have a backbone
what is the difference between open and closed circulatory systems
closed - blood transported via vessels
open - blood released directly into body cavity (in insects)
define endotherm
give some examples
animal dependent on, or capable of generating their own heat (warm blooded)
mammals - humans and monkeys
define ectotherm
animal dependent on external sources of heat to regulate body temperature (cold blooded)
amphibians - snakes and frogs
what circulatory systems do:
1. humans
2. insects
3. amphibians
4. fish
have?
- double and closed
- open and single
- closed and incomplete double
- single and closed
describe the mammalian heart
- muscular double pump - thickest muscle on left ventricle
- divided in two by septum
- 4 chambers (2 atria and 2 ventricles)
- contains valves to prevent backflow of blood
what valves are present in the heart?
where are they?
what do they do?
atrio-ventricular valves - left and right
positioned separating the atria and the ventricles
semi-lunar valves - positioned between the ventricle and the arteries (pulmonary and aorta)
valves prevent backflow of blood
describe the 3 basic sections of the cardiac cycle
diastole - blood entering through the atria into the ventricle, through the atrioventricular valve
atrial systole - atria contracts forcing the last 30% of blood into the ventricles, pushing the AV valve open more
ventricular systole - AV valve closes, ventricle contracts beginning at the apex (bottom) forcing blood at high pressure through the semi-lunar valves and out of the heart (either to the lungs or to the rest of the body)
define ECG
what is it used for?
electrocardiogram - shows electrical activity in the heart
used to monitor heart beat and rhythm - outline any abnormalities
define cardiac cycle
the sequence of events in one full beat of the heart
what is haemolymph
the blood equivalent in invertebrates
what are the differences between blood and haemolymph
haemolymph does not carry oxygen or co2, transports food, nitrogenous waste and immune cells.
what is the name for irregular heart beat?
arrhythmia
what is the name for the “pace maker” and what does it do?
SAN - sinoatrial node
produces the wave of excitation - triggers electrical responses in the cardiac muscle
what is tachycardia
rapid heart beat - over 100bpm
what is a slow heart beat called?
what pace is this from/ below?
bradycardia
below 60bpm
what do we call early ventricular contractions
ectopic heart beat
what is atrial fibrillation?
when the atria beat faster than the ventricles
typically in humans, how long does the cardiac cycle take?
how much of this is taken up by systole
0.8 seconds
0.1 for atrial
0.3 for ventricular
how does the signal produced by the SAN travel through the heart?
rapidly across the atria intercalated discs spread impulse to the AVN - atrioventricular nodes
signal then conducted through the “bundle of His” down the length of the septum via the left and right bundle branches.
then up the purkinje/ purkyne fibres (specially adapted muscle fibres)
what is the function of the AVN in the cardiac cycle
picked up the “wave of excitation” and imposes a slight delay before stimulating the “Bundle of His”
what is the Bundle of His
a bundle of conducting tissue made up of purkinje/ purkyne fibres which penetrate through the septum between the ventricles
what separates the ventricles?
and why do we need this?
the septum
stops oxygenated and deoxygenated blood mixing
how thick are the walls on the
atria =
right ventricle =
left ventricle =
and why?
atria = 2mm - due to gravity, little blood pressure, only contracts to push 30% of blood to the ventricles
right ventricle = 9mm = thicker than atria as higher blood pressure to force blood to the lungs
left ventricle = 16mm = thickest as highest blood pressure to push blood all around the body
define myogenic
an organism that doesn’t need external electrical impulses to signal for an action or contraction
why is the SAN needed
to coordinate fibrillation (contraction) of the atria and ventricles
at what point are all the valves in the heart closed
after atrial systole, before ventricular systole - ventricles are 100% full but ventricles haven’t contracted yet
what are tendinous chords?
papillary muscles attached to valves to stop them from turning inside out (informally known as heart strings)
what is the name of the muscle that makes up the heart?
myocardium - cardiac muscle
how is cardiac muscle specialised for its function?
- contain fibres that branch producing cross-bridges - spread stimulus around the heart
- lots of mitochondria between myofibrils (muscle fibres) to supply energy for contraction
- muscle cells separated by intercalated discs - facilitate synchronised contraction
- each cell has a nucleus and is divided into contractile units called sarcomeres
what are the 5 types of blood vessels
arteries
arterioles
capillaries
venules
veins
describe the how arteries are adapted for their function
thick walls - withstand high blood pressure
lots of strong collagen for structural support - stop tearing under pressure
folded endothelium - enable expansion under high blood pressure
smaller lumen (channel) than veins - maintain pressure of blood
lots of elastin to allow recoil and expansion
what is the function of arterioles and how does their structure support this?
link arteries and capillaries
more smooth muscle and less elastin than arteries - able to respond to sympathetic innervation more efficiently (neurological system that helps your body activate its “fight or flight” response)
constrict or dilate to control the flow of blood to organs
what are the relative proportions of
elastic fibres : smooth muscle : collagen
in
a. aorta
b. medium-sized arteries
c. arteriole
from smallest to largest
arteries = smooth muscle < collagen < elastin fibres
medium-sized = collagen < smooth muscle = elastin fibres
arteriole = collagen = elastin fibres < smooth muscle
what are capillaries and how are they adapted for their function?
microscopic blood vessels linking arterioles and venules
lumen (10um) so small that R.B.C have to travel single file - effectively delivering oxygen to tissues
gaps between endothelial cells allow for diffusion between tissue cells and blood
(exception - central nervous system - tight junctions between cells)
numerous and highly branched - provide large surface area for diffusion
total cross-section area is greater than arteriole so slower movement of blood - more time for diffusion
single endothelial cell thick wall - short diffusion distance
what is the function of veins and venules
how are they adapted for this function
carry blood away from body cells towards the heart
several venules join to form a vein
as low blood pressure:
- one way valves - close to prevent backflow
- bigger veins run between big active muscles - muscles contract squeezing veins
- chest breathing movements - act as a pump, squeezing blood towards the heart
which two veins carry oxygenated blood?
where from and to?
pulmonary vein - from lungs to heart
umbilical vein - from placenta to foetus
why do veins need adaptations?
low blood pressure
no pulse - surges lost in capillaries
large volume of blood - up to 60% of blood in veins at one time
how are the veins structured for their function
large lumen and thin walls to maintain lower pressure
require valves to ensue blood doesn’t backflow
have less muscular and elastic tissue as they don’t have to control blood flow
which veins carry blood directly to the heart and where from?
inferior vena cava - from lower body
superior vena cava - from head and upper body
what are the relative proportions of
elastin : smooth muscle : collagen
from smallest to largest in:
a. large veins
b. medium sized veins
c. venules
large veins = elastin < smooth muscle = collagen
medium veins = elastin < smooth muscle < collagen
venules = only have a small amount of collagen
what are the diameters of the lumen in
1. aorta
2. medium-sized arteries
3. arterioles
aorta = 2.5cm
medium sized = 0.4cm
arteriole = 30um
what are the diameters of the lumen in
1. large veins
2. medium sized veins
3. venules
4. capillaries
large vein = >1cm
medium sized = <1cm
venule = 0.1mm
capillaries = 10um
what is the function of coronary arteries
supply blood to the tissues of the heart, which is made up of myocytes.
they supply the heart with oxygen and nutrients for respiration to occur
what are the consequences if the coronary arteries get blocked
oxygen and nutrients cannot access the heart tissue
therefore cannot respire
leads to: heart attacks, strokes, angina - painful heavy tightness - and heart failure - heart becomes too weak to pump blood to the lungs causing a build-up of fluid in the lungs making it hard to breathe
describe the process of CO2 leaving body cells and entering the blood
CO2 diffuses out of body cells into tissue fluid, then into the plasma. CO2 diffuses out of the plasma into the biconcave disc red blood cell.
In the red blood cell, CO2 reacts with water in a reversible reaction forming carbonic acid (H2CO3), catalysed by the enzyme carbonic anhydrase.
carbonic acid then dissociates into H+ ions and HCO3- ions.
the H+ ions bind to haemoglobin forming haemoglobinic acid (HHb).
the hydrogen carbonate (HCO3-) ions diffuse out of the red blood cell into the plasma but as this reaction is much quicker than the H+ ions, it creates a charge imbalance.
to balance this out, chloride ions (Cl-) diffuse into the red blood cell - Chloride shift
how is tissue fluid formed
capillaries have gaps in the walls.
as blood enters the capillaries from arteriole end
hydrostatic pressure is greater than oncotic pressure, so water and other elements are forces out of the capillaries - ultrafiltration
red blood cells, platelets and large proteins remain in the capillaries (maintaining oncotic pressure)
what is re-absorbed into the capillaries after ultrafiltration
large molecules remain in capillaries creating a lower water potential
towards the venule end of capillaries the hydrostatic pressure is lowered due to loss of liquid but the water potential is very low so water re-enters the capillaries by osmosis
what are the functions of the blood
transports:
oxygen to and from the respiring cells
digested food from the smaller intestine
nitrogenous waste products from the cells to excretory organs
chemical messengers (hormones)
food molecules from storage compounds to the cells that need them
platelets to damaged areas
cells and antibodies involved in the immune response
blood also contributes to the maintenance of a steady body temperature and acts as a buffer, minimising pH changes
define oncotic pressure
and what is the value in the human body?
the tendency of water to move into the blood by osmosis (changing water potential of the capillaries as water moves out)
value = around 3.3 kPa
what causes oncotic pressure
the large proteins in the blood can’t leave so maintain a pressure in capillaries
what is hydrostatic pressure
and where is it highest in capillaries
the pushing force on the water due to presence of more fluid in one region than another
higher at arteriole end than venous end
define osmotic pressure
the pulling force on the water due to presence of solutes in a solution
what tissues carry the wave of excitation
purkinje/ purkyne tissues
where does carbon dioxide diffuse into out of the capillary
into the tissue fluid
why is pressure higher at the arteriole end of the capillary than the venule end
because there is a higher water potential at the arteriole end as water has not diffused out of the capillary via osmosis
describe the trend in the oxy-haemoglobin dissociation curve
s shape due because of conformational change - as haemoglobin binds to oxygen, the shape changes to accept more oxygen until it “gives O2 up” to respiring cells.
how does adult and fetal haemoglobin differ
fetal haemoglobin has a higher affinity for oxygen so it can absorb more of the oxygen available.
in fetal haemoglobin, the two beta sub-units are replaced by 2 gamma sub-units
why is fetal haemoglobin different to
sadult
because when the blood reaches the placenta, its oxygen saturation has decreased because some has been used by the mother’s body.
so fetal haemoglobin needs to be better at absorbing oxygen
how are organisms’ haemoglobin altered to adapt to environment
left shift - higher affinity to oxygen
more loading of oxygen into the lungs at a lower O2 saturation
eg. organisms at higher altitudes, under ground or fetuses
right shift - lower affinity for oxygen
more offloading of oxygen into respiring cells
eg. organisms with higher metabolic rate need more O2
what is the difference between the haemoglobin in the lungs and tissues
lungs = higher affinity for oxygen, readily loads oxygen, haemoglobin is more saturated with oxygen
tissues - lower affinity for oxygen, readily unloads oxygen into respiring cells, haemoglobin is less saturated with oxygen
what is the Bohr Effect
the effect of CO2 on the oxyhaemoglobin curve
increased CO2 eg. during exercise,
lowers the pH - haemoglobin changes shape
reduces affinity for O2,
more O2 unloading into respiring tissues/ cells
what does carbonic acid dissociate in the red blood cell
dissociates into H+ and HCO3- ions
what causes the charge imbalance in red blood cells
and how is this resolved
HCO3- diffusing out of the red blood cells faster than H+ ions bind to haemoglobin
chloride ions diffuse into the red blood cells to balance the charge - chloride shift
what is lymph
the 10% of liquid that leaves the capillaries that does not return (reabsorption)
drains into a system of blind-ended tubes called lymph capillaries where it is known as lymph
how does the composition of lymph differ to that of tissue fluid?
similar but lymph contains less oxygen and fewer nutrients, also containing fatty acids
what are the functions of lymph nodes
where lymphocytes build up and produce antibodies when necessary, which are then passed into the blood
lymph nodes also intercept bacteria and other debris - major role in defence mechanisms
why do doctors look for enlarged lymph nodes
they are a sign that the body is fighting off an invading pathogen
what result does the Bohr effect have on the body?
in active tissues with a high partial pressure of carbon dioxide, haemoglobin gives up its oxygen more easily
in the lungs, the proportion of carbon dioxide in the air is relatively low, the oxygen binds to the haemoglobin easily
how is carbon dioxide transported from the tissues to the lungs? (3 ways)
- about 5% is carried in dissolved plasma
- 10-20% is combined with amino groups in polypeptide chains of haemoglobin to form carbaminohamoglobin
- 75-85% is converted into hydrogen carbonate ions (HC03-) in the cytoplasm of red blood cells
how does tissue fluid differ from blood and lymph
tissue fluid is formed from blood but does not contain red blood cells, platelets, and various other solutes usually present in the blood
after tissue fluid has bathed cells, it becomes lymph and therefore contains less oxygen and nutrients and more waste products
how do you calculate cardiac output
cardiac output = heart rate x stroke volume
how does partial pressure of oxygen affect oxygen-haemoglobin binding
as partial pressure of oxygen increases, the affinity of haemoglobin for oxygen also increases so oxygen binds tightly to haemoglobin.
when partial pressure is low, oxygen is released from the haemoglobin
what do oxyhaemoglobin dissociation curves show?
saturation of haemoglobin with oxygen in % against partial pressure of oxygen (kPa)
curves further to the left show the haemoglobin has a higher affinity for oxygen
describe the Bohr effect
as partial pressure of carbon dioxide increases , the conditions become acidic causing haemoglobin to change shape.
the affinity of haemoglobin to oxygen therefore decreases and oxygen is released
explain the role of carbonic anhydrase in the Bohr effect
carbonic anhydrase is present in red blood cells
converts carbon dioxide to carbonic acid, which dissociates to produce H+ ions
these combine with the haemoglobin to form haemoglobinic acid
encorages oxygen to dissociate from haemoglobin
explain the role of hydrogen carbonate ions (HCO3-) in gas exchange
produced alongside carbonic acid
70% of carbon dioxide is carried in this form
in the lungs, hydrogen carbonate ions are converted back into carbon dioxide which we breathe out
explain the advantage, in terms of oxygen supply, of the fact the dissociation curve of oxy-haemoglobin is “S” shaped
small change in partial pressure of oxygen leads to a large decrease in % saturation of haemoglobin. large amounts of oxygen are unloaded in the tissues. unloaded in capillaries where needed.
which features out of:
contains nucleus
produces antibodies
has endoplasmic reticulum
contains haemoglobin
do red blood cells
lymphocytes
phagocytes
possess
RBC = only contains haemoglobin
lymphocyte = has nucleus, produces antibodies and possesses endoplasmic reticulum
phagocyte = has nucleus and possesses endoplasmic reticulum
do tissue fluids contain:
large proteins
neutrophils
erythrocytes
large protein = no
neutrophils = yes
erythrocytes = no
does lymph contain
large proteins
neutrophils
erythrocytes
no
no
no
suggest the advantages of a closed circulatory system
maintain higher blood pressure
increase rate of flow/ delivery
flow can be diverted/ directed
how does the artery withstand pressure
how does the artery maintain pressure
withstand: wall is thick with collagen which provides strength. endothelium is folded - no damage to artery wall
maintain: thick layer of elastin - cause recoil
thick layer of smooth muscle - constricts lumen
how is hydrostatic pressure generated in the heart
contraction of ventricular muscle
what are neutrophils
a type of white blood cell
What are some advantages of keeping blood inside vessels
Blood is transported at a faster rate
Maintain/ higher blood pressure
Flow can be diverted/ directed
How are arteries adapted to withstand pressure
Thick wall
Collagen for strength
Endothelium folded to avoid damage
Why is the wave of excitation carried to the apex
Because contraction starts at the apex, to push blood upwards
Describe what happens to blood plasma as it moves along the capillary from arteriole to venular end
Plasma moves out of capillary/ blood
Enters/ forms tissue fluid
Large proteins remain in capillary - too large
Fluid moves down concentration gradient
Hydrostatic pressure greater than water potential
What effect is caused by the opening of the semilunar valve
Increase in aortic pressure
Which organ system absorbs tissue fluid in order to destroy potential pathogens
Lymphatic system
