Chapter 8 - Transports Systems In Multicellular Animals Flashcards
Why are specialised transport systems needed
High metabolic demands
- diffusion over long distances is not enough to supply with needed quantities
- make lots of waste products, require lots of oxygen + food
SA:V is low
- not enough surface to transport required quantities
Hormones need to be transported
Waste products removed l
Food digested in one organ needs to be transported to every single cell
What features do circulatory systems have in common
- liquid transport medium that circulates around the system
- have vessels that Carr the transport medium
- pumping mechanism to move the liquid around
What is a
Mass transport system
When substances are transported in a mass of fluid with a mechanism for moving the fluid around the body
What are open circulatory systems
Blood isn’t enclosed in blood vessels all the time
It flows freely through the body cavity (haemocoel)
returns to heart through an open ended vessel
Example of open circulatory system in insect
Heart is segmented and contracts a wave, starting from the back pumping the blood into a single main artery
Artery opens up in haemocoel
Insect haemolymph transports food and nitrogenous waste
Haemolymph circulates but steep diffusion gradients can’t be maintained - can’t control the amount of haemolymph flowing to a particular tissue
Makes its way back to heart through open ended vessel
What is a closed circulatory system
The blood is enclosed inside blood vessels
Single circulatory systems definition
Single
- blood only passes through the heart once for each complete circuit of the body
Why single closed circulation is less efficient than double
Blood has to pass through 2 sets of capillaries , to exchange:
- O2 + CO2
- substances between blood and cells in organ systems
After passing through theses capillaries, blood pressure is very low, returns to heart slowly
Why is double closed circulatory efficient
Blood travels twice through the heart for each circuit of the body
Each circuit only passes through one capillary network
Which means
- High pressure and fast flow
Similarities between open and coded systems
Liquid transport medium
Vessels to transport the medium
Pumping mechanism to move fluid
Differences between open and closed systems
Open has few vessels
Closed has transport medium enclosed by vessels
Open isn’t enclosed
Closed can target specific tissues and cells
Open - transport medium pumped into body cavity (low pressure)
Closed - transport pumped by heart into artery (high pressure)
Arteries
- Thick muscular walls
- Have elastic tissue to stretch and recoil
- Inner lining is folded - allows expansion
- smooth muscle
Arteriole
-More smooth muscle than elastic
Capillaries (adaptations)
- large surface area for diffusion of substances
- single endothelial cell thick
- cross sectional area greater than arterioles so rate of blood flow falls, more time for exchange of materials
- substances pass out of fenestrations
Veins
- Wide lumen
- Collagen - but little elastic/smooth
- Valves
Venules
- Thin walls
- Smooth muscle
Adaptations that enable the body to overcome blood flow against gravity
- one way valves
- big veins run between active muscles so when muscles contract the blood is squeezed up the veins
- breathing movements and pressure changes cause blood in veins of chest and abdomen to move towards the heart
What does blood consist of
Plasma
- dissolves glucose, amino acids, mineral ions, hormones, large plasma proteins: albumin (maintaining osmotic potential), fibrinogen (blood clotting), globulins
Red blood cells / white blood cells
- carry oxygen
Platelets
- clotting mechanism
Functions of blood
Transport of:
- O2 + CO2
- digested food
- nitrogenous waste
- hormones
- cells and antibodies involved in immune response
- platelets to damaged areas
Maintains a steady body temperature
Minimising pH changes
How are substances transports between the capillaries and tissue fluid
- at start of capillary bed nearest to arterioles
- the hydrostatic pressure forcing fluid out of the capillaries is greater then the oncotic pressure attracting water in by osmosis
- so fluid is squeezed out of capillary into tissue fluid
- capillaries towards venules
- have a lower hydrostatic pressure than oncotic pressure because the pulse is lost
- water moves back into the capillaries by osmosis
What causes oncotic pressure
Plasma proteins in blood give capillaries high solute potential
Water has a tendency to move into capillaries by osmosis
What is tissue fluid
Fluid surrounding cells in tissues
Exchanges Oxygen water nutrients
Same components as blood but without:
- red blood cells
- plasma proteins
What are lymph vessels
Lymph transports excess tissue fluid to the heart
Has less oxygen and nutrients than tissue fluid and plasma
Contains fatty acids absorbed from villi on small intestine
How does the cardiac cycle pump blood round the body
Atrial systole
- ventricles are relaxed
- atria contract - decreases volume - increases pressure
- pushes blood into ventricle by atrioventricular valves
Ventricular systole
- atria relax
- ventricles contract - increase pressure - valves to close
- opens semi lunar valves
- blood forced into aorta/ pulmonary artery
Diastole
- ventricles and atria relax
- semi lunar valves close
- atria fill with blood
- atrioventricular valve opens
Calculate cardiac output
Heart rate
X
Stroke volume
Cardiac muscle is myogenic
Myogenic definition
Can contract and relax without signals from nerves
How does the heart beat
- sinoatrial node sends wave of electrical activity to atrial walls
- left and right atria contract at the same time
- non conducting collagen tissue prevents wave from ventricles
- SAN transfers waves of electrical conductivity (WOEA) to atrioventricular node
- slight delay before AVN passes wave to bundle of HIS
- HIS conducts wave of electrical actively to purkyne tissue
- cause ventricles to contract at same time
Double circulatory systems definition
Double
- blood only passes through the heart twice for each complete circuit of the body
Components utilised in blood vessels
elastic fibres
smooth muscle
collagen
How are elastic fibres utilised in vessels
Composed of elastin
Can stretch and recoil
Providing vessel walls with flexibility
Helps withstand force of blood
Evens the surges of blood - continuous flow
How are smooth muscle utilised in vessels
Contracts or relaxes
Changes the size of lumen
Controls the flow of blood to individual organs
How are collagen utilised in vessels
Provides structural support to maintain the shape and volume of the vessel
Smooth muscles role in vasoconstriction of arterioles
- smooth muscle contracts
- constricts the vessel
- prevents flowing into capillary bed
Smooth muscles role in vasodilation of arterioles
- smooth muscle relaxes
- dilates
- blood flows through capillary bed
How is the fluid in the lymph capillaries transported
Squeezing of body muscles
Has valves - prevent backflow
Lymph returns to blood
What do the lymph nodes on the lymph vessels do
Lymphocytes build up in nodes
Produce antibodies
Passed into blood
Intercept bacteria and other debris from lymph - is digested by phagocytes
What is hydrostatic pressure
The pressure from heart beat forcing liquid out through fenestrations in capillaries
What is oncotic pressure
Result of water potential in capillary from the plasma proteins moving water into the capillary by osmosis
What is the heart made of
Cardiac muscle
What do the coronary arteries do
Supply cardiac muscle with the oxygenated blood in needs to keep contracting and relaxing
What is the heart surrounded by to prevent itself from over dispensing with blood
Inelastic pericardial membranes
How does blood move throughout the heart
- Heart is relaxed (diastole) and atria fill
- Tricuspid valve opens (atrioventricular right)
- Atrium and ventricle fills
- Atrial systole
- Ventricles contract
- Tricuspid valve closes
- Pumps blood into aorta/pulmonary artery
- Semi lunar valve closes
What is diastole
Heart relaxes
Atria and ventricles fill with blood
Volume and pressure in heart builds
What is atrial systole
Atria contracts
What is ventricular systole
Ventricles contract
Pressure increases
Blood forced out
What do the tendinitis chords do in valves
Make sure valves are not turned inside out by pressures exerted when the ventricles contract
What is an electrocardiogram
Technique for measuring tiny changes in the electrical conductivity of the skin
That result does the electrical activity of the heart
Produces a trace which can be used to analyse the health of the heart
How to get an ECG reading
Electrodes stuck to clean skin
Electrodes pick up tiny changes and feed to machine
Tachycardia
Heartbeat is rapid
Over 100bpm
Shows the heart isn’t pumping blood efficiently
Bradycardia
Heart beat is slow
Below 60bpm
Ectopic heartbeat
Extra heartbeats that are out of normal rhythm
Early contraction of the atria or ventricles depending on graph
Atrial fibrillation
Rapid impulses in the atria
But do not contract properly
Atria and ventricles loss rhythm
Stop contracting
P wave caused by
Contraction (dépolarisation) of the atria
QRS peak caused by
Dépolarisation of ventricles
T wave caused by
Relaxation (repolarisation) of ventricles
Height of the wave means
More electrical charge
Stronger contraction
What is the role of haemoglobin
Binds to and transports oxygen at carbon dioxide from
Lungs - cells
Cells - lungs
What is the reversible binding of oxygen in haemoglobin
Haemoglobin + 4O2 oxyhaemoglobin HbO8
Is reversible
When oxygen leaves oxyhaemoglobin disassociates
How does haemoglobin saturation depend on partial pressure of oxygen
Oxygen loads into haemoglobin = high partial pressure of oxygen
Oxygen unloads = where = low partial pressure of oxygen
What does the
Partial pressure of oxygen mean
Measure of oxygen concentration in cells
What happen to o2 when affinity is low
Releases oxygen
Why is the graph s shaped
Steep
- when first O2 molecule joins, shape changes, to make easier for other oxygens to join
Plateaus
- when haemoglobin is saturated - harder to pick up more oxygen
Why is fetal haemoglobin have a higher affinity
Fetus blood is better at absorbing oxygen than mothers blood
Fetus gets blood from placenta when OXYGEN SATURATION has decreased
For fétus to get enough oxygen to survive it needs to have a higher affinity
Otherwise it’s haemoglobin would not be saturated enough
When does haemoglobin release oxygen more readily
At high partial pressures of CO2
Made by respiration
This is where O2 is being used up
How is CO2 transported
CO2 diffuses into red blood cell
Dissociates into H+ and HCO3-
H+ make haemoglobin release O2 to carry H+
HCO3 diffuses out into plasma
To make up for this loss Cl- diffuse into red blood cell = chloride shift
Maintains the balance between plasma and blood
At low pCO2, HCO3- + H+ rejoin to make CO2
Diffuses into alveoli breathed out
What is the Bohr shift
The shift in the oxygen dissociation curve
Caused by changes in carbon dioxide levels
What happens when carbon dioxide increases to
Dissociation curve
Shifts to the left
To show oxygen is release more form the blood
Because there’s a lower concentration of haemoglobin
What does the fetal adult dissociation curve look like
Fetal is shifted to the left
To show more oxygen is loaded on to the haemoglobin
Has a higher affinity that’s adult
