3.1.2 Transport in Animals COMPLETE Flashcards
Features of an effective transport system
- Fluid to carry O2 and nutrients around the body i.e. blood
- A pump to create pressure that’ll push the fluid around the body
- Exchange Surfaces that enable oxygen and nutrients to enter and leave the blood.
Closed Circulatory system
Blood enclosed in vessels all the time, called bleeding when its not. High pressure so is rapid, exchange surfaces are necessary.
Eg invertebrates/ mammals
Open Circulatory system
Blood not in vessels and it just fills the body cavity, heart pumps blood form the arteries directly into the haemocoel, no gases are contained in the blood. Lower pressure so less rapid
e.g. insects
Double circulatory system
Blood flows through the heart twice for each complete circuit of the body. Involves the pulmonary and systematic system. Moves rapidly due to the high pressure (Higher in the systematic as moving to rest of the body)
Single circulatory system
Blood flows through the heart once for each complete circuit of the body. Pressure is reduced as blood passes through tiny capillaries or gills, therefore rate of waste removal is slower
e.g. fish
Advantages of a double circulatory system
The blood doesn’t mix
A higher O2 conc leads to a steeper conc. gradient and faster diffusion.
Pressure can also be increased so blood flow to the tissues is much faster
Order of Blood flow
Heart -> Arteries -> Arterioles -> Capillaries -> Venules -> Veins -> Heart
Structure of Arteries
- High pressure blood
- Wall is thick to withstand pressure
- Narrow lumen to maintain pressure
- Inner wall folded to allow expansion
- Epithelium lines with squamous cells to make it smooth
Structure of Arterioles
Same as arteries but with more smooth muscle and less elastin. This is to allow vasodilation and vasoconstriction
Structure of Capillaries
- Very narrow (same as a RBC)
- Endothelium made of one layer of squamous cells
- Walls are porous to allow plasma and dissolved nutrients to leave the blood
- Form large networks to increase SA contact with tissues
Structure of Veins
- Low pressure blood
- Larger lumen
- Surrounding muscles move the blood
- Contain valves that only open when moving towards the heart to prevent back flow
Vessel layers
Inner Layer: Endothelium cells (reduce friction) and thin layer of elastin
Middle Layer: Smooth muscle (contracts to narrow lumen)
Outer Layer: Collagen and elastic tissue (stretch and recoil)
Internal Features of the Heart
- Septum separates the two sides
- Atrioventricular valves
- Tendinous chords
- Aorta and Pulmonary Artery
- Vena Cava and Pulmonary Vein
Atrioventricular Valves
Valves between the atria and ventricles
Tricuspid on the right
Bicuspid on the left
(drawings of the heart are in reverse)
The two arteries
Aorta from the left ventricle to the body
Pulmonary Artery from the right ventricle to lungs
The two veins
Vena Cava from the body to the left atrium
Pulmonary Vein from the lungs into the right atrium
Myogenic Muscle
Cardiac muscle that automatically contracts and relaxes without any stimulation from nerves. Have their own natural frequency.
How does the heart squeeze
Cardiac muscle consists of fibres that branch and produce cross bridges, these help spread the stimulus.
Intercalated disks help facilitate synchronised contraction
Semi Lunar Valves
Found in the aorta and pulmonary artery, prevents back flow into them, high pressure in the ventricles forces them open
Ventricular Septum
Separates the left and right ventricle, purkinje tissue is inside, stop the bloods from each chamber mixing
Coronary Arteries
First blood vessels to branch of the aorta, extend across the heart to supply oxygenated blood to the heart muscle.
Three phases of the Cardiac Cycle
- Atrial Systole
- Ventricular Systole
- Diastole
Atrial Systole
Muscle wall in the Atrial contracts, pressure created is limited due to the thin walls, but its enough to force blood into the ventricles through the AV valve. Valves prevent back backflow
Ventricular Systole
Thick muscle walls in the ventricle squeezes inwards to increase pressure and push blood out of the heart. Once pressure is greater in the ventricle than the atria AV valves shut. Semilunar valves are then forced open.
Diastole
Heart muscles relax, elastic tissue in the walls recoils to stretch out the muscle. Pressure drops and the semilunar valves shut. Atrial systole begins as blood flows back into the atria
Fibrillation
When the frequency of contraction in the heart chambers is not properly coordinated leader to non synchronised contractions
Atrial Contraction
Initiated by the Sino- Atrial Node which is a small patch pf muscle in the wall of the right atrium. Contracts slightly faster so spreads a wave of electrical activity over the atrial walls. They respond by contracting in the same rhythm as the SAN
Ventricular Contraction
Collagen fibres between the Atria and Ventricles do not conduct the electrical wave. The only route is through the Atrioventricular Node. Electrical excitation is passed on to a bunch of connective tissue which runs down the septum (Purkinje tissue)
It rapidly travels to the apex and causes ventricles to contract upwards squeezing blood into the arteries
What affects Heart rate
- Cardiovascular fitness
- Underlying Medical Conditions
- Drugs
- Exercise
- Age
- Fear/shock
Electrocardiograms
The first small peak represents atrial systole P
The larger peak and small drop is ventricular systole QRS
The second smaller peak is ventricular diastole T
Bradycardia
When the heart rate slows down, can be due to fitness or a more severe when a pacemaker is then needed
Tachycardia
Heart beat is very rapid, normal during exercise or when scared, but if abnormal could be due to problems with eh electrical control in the heart and will need treatment
Ectopic Heartbeat
Extra heartbeats that are out of the normal rhythm, serious when they’re frequent
Atrial Fibrillation
No clear P wave, means there is an abnormal rhythm of the heart and rapid electrical pulses are generated in the atria
What is blood
Cells floating in a yellow fluid called plasma, contains hormones, urea and proteins. RBC carry the O2
Platelets cause clotting
WBC are part of the immune response
What is Tissue Fluid
Formed from the plasma that has leaked from capillary walls. very similar in composition to plasma but contains less proteins as they can’t pass through the capillary walls. Its essential for the exchange of materials i.e. CO2, Lactic acid
What is Lymph
90% of leaked fluids from the capillaries are returned. The remaining 10% is collected in lymph vessels, these are tiny blind endings or termination points.
Similar to tissue fluid but less O2 more CO2
Lymph Transportation
Its first transported to the subclavian veins, valves inside, pressure builds due to surrounding muscle contractions. Flow is slow through the thoracic duct. Lymphocytes are produced here and allow the filtering of bacteria and foreign particles.
How are RBC adapted
Biconcave disks increases SA
No nucleus so more room for haemoglobin
Same size as capillary to shorten diffusion path
Contain lots of haemoglobin for O2
Haemoglobin
A globular protein with 4 polypeptide chains each with a haem prosthetic group. Oxyhaemoglobin forms when a oxygen joins onto the Fe2+.
Reversible reaction, loading and unloading/ association and dissociation. Haem has an affinity for O2
Oxygen affinity
The tendency of a molecule to bind with oxygen, Hb affinity depends on the conditions.
Partial Pressure
PO2, as it increases so does Hb’s affinity. So oxygen is loaded where theres a high PO2
Hb cycle
- Hb is fully loaded in the lungs where theres a high pO2, almost all Hb forms OHb as it passes through the alveoli
- As blood flows through the tissue OHb responds to a lower PO2 by unloading some O2, it diffuses through capillaries
- As more oxygen is used up by respiration OHb dissociates more.
Fetal Haemoglobin
Fetal blood gains all oxygen from the mothers placenta. The PO2 in the placenta is relatively low so OHb unloads O2. The fatal blood can load the oxygen at the low PO2 because it has a higher oxygen affinity
CO2 Transportation Methods
- Dissolved in plasma
- Combines with Hb to form Carbaminohaemoglobin
- Forms Carbonic Acid
CO2 Removal with Carbonic Acid
Carbonic Acid formed by CO2 and water, catalysed by Carbonic anhydrase. The acid dissociates into H+ and HCO3-
H+ ions bind with Hb to form Haemoglobinic acid which leads to more O2 being released. HCO3 dissolved into plasma
Chloride Shift
LEFT
H+ ions lead to increase in cell acidity,Hb acts as a buffer. Therefore it unloads more O2. Charge is maintained by the movement of Cl- ions in to the cell from the plasma
Bohr Shift
RIGHT
Haemoglobinic acid causes the dissociation of O2, this is the Bohr effect as O2 released more readily in areas with more CO2. Means more O2 is delivered to respiring cells.
