Transport In Animals :). Flashcards
Why can’t multicellular organisms diffuse everything they need in?
Relatively big
Low surface area to volume ratio
Higher metabolic rate
How does lots of multicellular organisms are very active mean they need a transport system more?
Large number of cells that are all respiring quickly so need constant rapid supply of glucose and oxygen
What do multicellular organisms need to ensure every cell has a good blood supply?
Transport system
What is the transport system in mammals?
The circularity system which uses blood to carry glucose and oxygen around the body as well as hormones, antibodies and waste. Of
Name the types of circularity systems?
Single- fish
Double-mammals
Open- some invertebrates
Closed- All vertebrates
How many times does heart pass through the heart in single and double?
Single- goes through once
Double- goes through twice
How does a fish heart pump?
To the gills and then on through rest of body in single circuit
How does a mammal heart pump?
Heart divided down middle so like 2 hearts joined together
Right side to lungs
From lungs travels to left side of heart which pumps it to rest of body
Blood returns to heart enters right side
What’s the loop in our circularity system going to the lungs called?
Pulmonary system
What’s the loop that goes to the rest of the body called?
Systemic
Give an advantage of the mammalian heart?
Can give blood extra push between lungs and rest of body.
Makes blood travel faster so oxygen is delivered to the tissues more quickly.
What’s an open circularity system?
Blood isn’t enclosed in blood vessels all time
Flows through body cavity.
How is a open circularity heart organised?
Segmented Heart contracts in a wave starting from back pumping blood in single main artery
Artery opens up into body cavity
Blood flows around insects organs gradually making way back through valves
What does the insect circularity system provide it with?
Nutrients
Hormones
What doesn’t the insect circularity system provide it with?
Oxygen
Oxygen is provided through tracheal system
How do single-celled organisms get substances needed?
Diffusion across outer membrane
Artery
Carry blood from heart
Thick and muscular elastic walls to stretch and recoil as heart beats helps maintain high pressure
Inner endothelium folded allowing artery to expand helps maintain high pressure
Artery carry oxygenated blood except pulmonary artery
Arterioles
Artery branches into Arterioles
Much smaller than arteries
Have layer of smooth tissue less elastic tissue
Smooth muscle allows them to expand/contract controlling amount of blood following to tissues
Capillaries
Smallest blood vessels
Substances like glucose and oxygen are exchanged between cells and capillaries
Adapted for efficient diffusion
Walls only one cell thick
Venule
Very thin walls contain muscle cells
Join together to form veins
Veins
Take blood back to heart under low pressure
Very little elastic/ muscle tissue
Contain valves stop blood flowing backwards
Blood flowed through vein helped by contractions of body lurked surrounding them
Carry deoxygenated blood except pulmonary veins carry oxygenated blood to heart from lungs
Tissue fluid
Fluid surrounds cells in tissue
Made from substances that leave blood plasma: oxygen, water and nutrients
What doesn’t tissue fluid contain that blood does?
Doesn’t contain red blood cells or big proteins because they’re too large to be pushed out through the capillary walls
Cells take in oxygen and nutrients from and what do they release?
From tissue fluid and release metabolic waste into it
What happens in capillary beds?
Substances move out of the capillaries into tissue fluid by pressure filtration
What are capillary beds?
The network of capillaries in an area of tissue
What happens at the start of the capillary bed nearest the arteries?
The hydrostatic (liquid) pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid. The difference in hydrostatic pressure forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid
What happens as fluid leaves the capillary bed?
The hydrostatic pressure reduced in the capillaries so the hydrostatic pressure is much lower at the end of the capillary bed that’s nearest to the Venules
What’s the other type of pressure involved in pressure filtration?
Oncotic pressure
How is oncotic pressure generated?
By plasma proteins present in the capillaries which lower the water potential
What happens at Venules end of the capillary bed?
The water potential in the capillaries is lower than the water potential in and the high oncotic pressure. Meaning some water re-enters the capillaries from the tissue fluid at the venule end by osmosis
Does all the tissue fluid re-enter the capillaries at the venule end of the capillary bed?
No some excess fluid is left over.
Extra fluid eventually gets returned to blood through lymphatic system
What’s the lymphatic system?
A kind of drainage system made up of lymph vessels
Smallest lymph vessels?
Lymph capillaries
Where does excess tissue fluid go?
It passes into lymph vessels
Once inside its called lymph
What do valves in the lymph vessels do?
Stop the lymph going backwards
What does lymph do?
Gradually move towards the main lymph vessels in the thorax. Here it is returned to the blood near the heart
What’s the thorax?
The chest cavity
Red blood cells
Blood, tissue fluid, lymph
Blood has them
Tissue fluid doesn’t
Lymph doesn’t
Comment on red blood cells?
Red blood cells too big to get through capillary walks into tissue fluid
White blood cells
Blood, tissue fluid, lymph
Blood-yes
Tissue fluid-very few
Lymph-yes
White blood cell comment?
Most white blood cells are in the lymph system.
Only enter tissue fluid when there’s an infection
Platelets
Blood, tissue fluid, lymph
Blood-yes
Tissue fluid-no
Lymph-no
Protein
Blood, tissue fluid, lymph
Blood- yes
Tissue fluid-very few
Lymph-only antibodies
Comment on platelets
Only present in tissue fluid if capillaries are damaged
Proteins comment
Most plasma proteins are too big to get through capillary walls
Water
Blood tissue fluid lymph
Yes yes yes
Dissolved solutes
Blood lymph tissue fluid
Yes yes yes
Comment on water
Tissue fluid and lymph have higher water potential than blood
Dissolved solutes comment
Solutes e.g. Salt can move freely between blood, tissue fluid and lymph
What goes the right side and the left side of the heart pump
The right side of the heart pumps deoxygenated blood to the lungs
Left side pumps oxygenated blood to the rest of the body
What do the atrioventricular valves link?
The atria to the ventricles
What do the semi-lunar valves link?
The ventricles to the pulmonary artery and aorta
What do all the valves in the heart do?
Stop blood flowing the wrong way
How do valves work
Valves only open one way whether open or closed depends on relative pressure of heart chambers
If Higher pressure behind a valve its forced open
If higher pressure in front of valve its forces shut
Equipment needed to carry out a heart dissection?
Pig's or cow's heart Dissecting tray Scalpel Apron Lab gloves
What are two things you should look at during a heart dissection?
External examination
Internal examination
External examination of heart
Look at outside of heart and try to identify four main vessels attached to it
Feel inside vessels to help you.
Arteries are thick and rubbery whereas veins are much thinner
Identify right and left atria and right and left ventricles and coronary arteries. Draw sketch of outside of heart with labels
Internal examination
Cut along to look inside each ventricle. Measure and record thickness of ventricle walls and note any differences between them.
Cut open atria and look inside them. Note if atria are thicker or thinner than ventricle walls.
Find atrioventricular valves followed by semi-lunar valves. Look at valve structure.
Draw a sketch of valves and inside of ventricles and atria
Describe left ventricle?
Thicker and more muscular than right to push blood all around the body.
Describe ventricles?
Have thicker walls than atria because they have to push blood out of the heart
What is the cardiac cycle?
An ongoing sequence of contractions and relaxation of atria and ventricles that keeps blood continuously circulating round the body.
What happens to volumes of atria and ventricles in the cardiac cycle?
They change as they contract and relax altering the pressure in each chamber causing the valves to open and close directing blood flow through the heart
Three stages of cardiac cycle?
Ventricles relax, atria contract
Ventricles contract, atria relax
Ventricles relax atria relax
Explain ventricles relax, atria contract
Ventricles relaxed, atria contract decreasing their volume and increasing their pressure pushing blood into ventricles through atrioventricular valves. Slightly increasing ventricular pressure and volume as ventricles recurve ejected blood from contracting atria
Ventricles contract, atria relax
Atria relax, ventricles contract decreasing volume increasing pressure. Pressure becomes higher in ventricles than atria forcing atrioventricular valves shut to prevent black-flow. High pressure in ventricles open semi-lunar valves. Blood is forced out into pulmonary artery and aorta
Ventricles relax atria relax
Both ventricles and atria relax. Higher pressure in pulmonary artery and aorta cause semi-lunar valve to close preventing back-flow. Atria fill with blood increasing pressure due to higher pressure in vena cava and pulmonary vein. As ventricles continue to relax their pressure falls below pressure in atria. Atrioventricular valves to open and blood flow passively into ventricles from atria. Atria contacts and process begins again
Atria contract valves?
Semi-lunar valves closed
Atrioventricular valves open
Ventricles contract?
Semi-lunar valves forced open
Atrioventricular valves forced closed
Atria and ventricles relax
Semi-lunar valves close
Atrioventricular valves forced open
What sound does a heart make?
Lub-dub
What is the lub sound made by?
Atrioventricular valves closing
What is the dub sound made by?
Semi-lunar valves closing
Cardiac muscle is special why?
Myogenic
Can contact and relax without receiving signals from nerves,
Pattern of contraction controls regular heartbeat
Electrical signals of heart?
Sino-atrial node (SAN) send electrical valves out to atrial walls.
Right and left atria contact at same time
Atrioventricular node (AVN) send electrical activity to bundle of his which leads to purkyne tissue carrying signal to ventricles causing them to contract simultaneously from bottom up
Where is sino-atrial node?
In wall of right atrium
What is the sino-atrial node like?
A pacemaker
Sets rhythm of heartbeat by sending out regular waves of electrical activity to atrial walls
What stops the electrical signal travelling from the atria straight to the ventricles?
A non-conducting collagen tissue preventing waves of electrical activity from being passed directly from atria to the ventricles
What is the AVN responsible for?
Passing waves of electrical activity in to bundle of his but there’s a slight delay before the AVN reacts to make sure the ventricles contract after the atria have emptied
What are the bundle of his ?
Group of muscular fibres responsible for conducting the waves of electrical activity the finer fibres
What can a electrocardiograph do?
Record the electrical activity of the heart
How can a doctor check someone’s heart function?
Using an electrocardiograph
How does a electrocardiograph work?
Machine records electrical activity of the heart
Heart muscle depolarises (loses electrical charge)
When contracts and repolarises (regains charge) when it relaxes. An electrocardiograph records these changes in electrical charge using electrodes placed in the chest
What does a electrocardiograph produce?
A traced called an electrocardiogram or ECG
What’s the P wave caused by?
Contraction (depolarisation) of the atria
QRS complex
Caused by contractions (depolarisation) of the ventricles
T wave caused by
Relaxation (depolarisation of the ventricles)
What does the height of the wave indicate?
How much electrical charge is passing through the heart
A bigger wave means more electrical charge so (P and R waves) a bigger wave means a stronger contraction
What do doctors do to help them diagnose any heart problem?
Compare patients ECG with a normal trace
Too fast!!!!
Tachycardia
Heartbeat is too fast around 120 beats per minute
tachycardia
Okay for exercise not for rest shoes heart isn’t pumping blood efficiently
Tachycardia
Slooooow
Bradycardia
Heartbeat can be too slow
Below 60 beats per minutes at rest
Bradycardia
Ectopic heartbeat?
Extra heartbeat
Can be caused by earlier contraction of atria than previous heartbeats
Can be caused by early contraction of ventricles too
Occasional ectopic heartbeats in a healthy person don’t cause a problem
What’s fibrillation
Really irregular heartbeat
Atria or ventricles completely lose their rhythm and stop contracting properly
Can result in anything from chest pain and fainting to lack of pulse and death
What do red blood cells contain?
Haemoglobin
Haemoglobin describe
Large protein with quaternary structure
Made from more than one polypeptide chain
Each chain had haem group containing iron giving haemoglobin it’s red colour
Explain haemoglobin’s and oxygen relationship?
Haemoglobin has a high affinity for oxygen-each molecule can carry four oxygen molecules
What do oxygen and haemoglobin do together in the lungs?
Join to form oxyhaemoglobin
Equation for oxyhaemoglobin production
Hb+4O2 HbO8
Haemoglobin+ oxygenoxyhaemoglobin
What is oxygen and haemoglobin making haemoglobin?
Reversible reaction
When oxygen leaves oxyhaemoglobin (dissociates from it) near the body cells, it turns back to haemoglobin
Affinity for oxygen?
Tendency to combine with oxygen
What does haemoglobin saturation depend on?
The partial pressure of oxygen
What is the partial pressure of oxygen (pO2)?
A measure of oxygen concentration.
Relationship between partial pressure and oxygen concentration?
The greater the concentration of dissolved oxygen in cells, the higher the partial pressure
What is the partial pressure of carbon dioxide (pCO2)?
Measure of concentration of CO2 in a cell
What does haemoglobin’s affinity for oxygen vary depending on?
The partial pressure of oxygen
What does oxygen do when there’s high pO2?
Load onto haemoglobin to form oxyhaemoglobin
What does oxygen to when there’s low pO2?
Oxyhaemoglobin unloads its oxygen where there’s a lower pO2
Where does oxygen enter and what happens as a result?
Oxygen enters blood capillaries at the alveoli in the lungs.
Alveoli have a high pO2 so oxygen load onto haemoglobin to form oxyhaemoglobin
What happens when cell respire?
They use up energy lowering pO2. Red blood cells deliver oxyhaemoglobin to respiring tissues where it unloads its oxygen.
When haemoglobin has unloaded its oxygen where does it go?
Returns to lungs to pick up more oxygen
What does an oxygen dissociation curve show?
How saturated the haemoglobin is with oxygen at any given partial pressure
What does 100% saturation mean?
Every haemoglobin molecule is carrying the maximum of 4 molecules of oxygen
0% saturation means?
Means none of the haemoglobin molecule are carrying any oxygen
Where pO2 is high (in lungs)?
Haemoglobin has a high affinity for oxygen (will readily combine with oxygen) so has high saturation of oxygen
Where pO2 is low (respiring tissues)?
Haemoglobin has a low affinity for oxygen meaning it releases oxygen rather than combine it
It’s why it has a low saturation of oxygen
Why is the dissociation curve S shaped?
When haemoglobin (Hb) combine with the first O2 molecule its shape alters making it easier for the other molecules to join As Hb starts become more saturated it gets harder for more oxygen to join.
What’s the dissociation curve made up of?
A steep bit in the middle where it’s easy for oxygen to join and shallow bits at each end where’s its hard.
When curve is steep, a small change in pO2 causes a big change in the amount of oxygen carried by the Hb
Adult haemoglobin fetal haemoglobin affinities?
Different affinities.
Fetal haemoglobin has a higher affinity for oxygen (fetus’s blood is better at absorbing oxygen than mother’s blood) at same partial pressure for oxygen.
Why does it matter that fetal haemoglobin has a higher affinity than adult haemoglobin?
Fetus gets oxygen from mothers blood across the placenta
By the time, the mothers blood reached the placenta its oxygen saturation has decreased.
For fetus to get enough oxygen to survive its own haemoglobin has to have a higher affinity for oxygen.
If haemoglobin had same affinity for oxygen as adult haemoglobin its blood wouldn’t be saturated enough.
When would haemoglobin be more readily give up oxygen?
At higher partial pressures of carbon dioxide pCO2
What’s is the body cunning way of getting more oxygen to cells during activity?
When cells respire they produce carbon dioxide which raises pCO2 increasing the rate of oxygen unloading. Reason for this is linked to how CO2 affects blood pH.
Where does most of the CO2 from respiring tissues go?
It diffuses into red blood cells
What does CO2 do when it’s diffused into red blood cells?
React with water to form carbonic acid catalyses by enzyme anhydrase
What does the rest of the CO2 do?
Around 10% bonds directly to haemoglobin and is carried back to the lungs
What does the carbonic acid formed do?
Dissociate to give hydrogen ions (H+) ions and hydrogencarbonate (HCO3-) ions
What does the increase in H+ ions do?
Causes oxyhaemoglobin to unload its oxygen so haemoglobin can take up H+ ions forming haemoglobinic acid
Process also stops hydrogen ions from increasing the cell’s acidity
What do the HCO3- ions do?
Diffuse out of the red blood cells and are transported in the blood plasma
What happens to compensate the loss of HCO3- ions from the red blood cells?
Chloride ions (Cl-) diffuse into red blood cells (chloride shift) and prevents any changes in pH that could affect the cells
When the blood reaches the lungs what happens?
Low pCO2 causes some of HCO3- and H+ ions to recombine into CO2 and water
CO2 then diffuses into alveoli and is breathed out
What happens in the bone effect if the carbon dioxide level decreases?
The dissociation curve shifts right showing more oxygen is released from blood (because lower saturation of haemoglobin with O2, the more O2 is released) Bohr effect
