Animal Transport

Factors that mean that multicellular animals need transport systems

Large size, high metabolic rate, low surface area to volume ratio, rate of diffusion is not enough, large distance between where molecules are produced and where they are needed

Types of circulatory system

Single, double, open, closed

Features different circulatory systems have in common

Liquid transport medium, vessels that carry the transport medium, of pumping mechanism

Open circulatory system

Few blood vessels, haemocoel (Open body cavity), low pressure

Circulatory system in insects

Open, haemolymph doesn't carry oxygen and carbon dioxide, haemolymph transports nitrogenous waste, body cavity split by membrane, heart extends along length of thorax and abdomen

Disadvantages of open circulatory systems

No steep diffusion gradients, amount of fluid flowing to a tissue can't be changed

Closed circulatory system

Blood enclosed in vessels, blood returns directly to the heart, substances leave and enter thro ugh walls of blood vessels

Examples of organisms with closed circulatory systems

Echinoderms, cephalopod molluscs, mammals

Single circulatory system

When the blood travels once through the heart for each complete circulation of the body

How a single circulatory system works

Oxygen and carbon dioxide diffuse through set of capillaries, substances exchanged through other capillaries to organ systems

Disadvantages of single circulatory system

Low blood pressure, low speed

Circulatory system in fish

Single circulatory system, countercurrent gaseous exchange system, body weight supported by water so can be active without efficiency

Double circulatory system

The blood travels twice through the heart for each circuit of the body

Two circuits in the double circulatory system

Heart to lungs, heart to body

Advantages of doubl circulatory system

High pressure, fast flow of blood

Examples of blood vessels (Types)

Arteries, arterioles, capillaries, veins, venules

Function of arteries

To carry oxygenated blood away from th heart to tissues in the body

Structure of arteries

Elastic fibres, smooth muscle, collagen, order of layers from smallest to largest is lumen endothelium elastic muscle tough outer

Role of elastin fibres in blood vessels

Stretching and recoiling, flexibility

Role of smooth muscle in blood vessels

Contracts or relaxes to change the size of the lumen

Role of collagen in the blood vessels

To provide structural support, to maintain the shape and volume of the vessel

Role of endothelium in the blood vessels

Smooth so blood flows over it

Function of arterioles

To link arteries and capillaries

Structure of arterioles

More smooth muscle, less elastin

Why do arterioles constrict and dilate?

To control the flow of blood to organs and capillary beds

Function of capillaries

To link arterioles to venules

Structure of capillaries

Narrow lumen to squeeze oxygen out of red blood cells, gaps between endothelial cells in capillary wall,

Adaptations of capillaries

Narrow diameter so short diffusion distance, thin wall for rapid diffusion, smooth endothelium, large surface area to allow more exchange

Function of veins

To carry deoxygenated blood from the cells of the body towards the heart

Structure of veins

Lots of collagen, little elastic fibre, wide lumen, valves, smooth endothelium, sequence of layers is lumen endothelium elastic muscle tough

Function of venules

To link capillaries with veins

Structure of venules

Thin walls, little smooth muscle

Disadvantage to structure of veins

Low pressure when having to work against gravity

Adaptations to structure of veins

Valves, bigger veins run between active muscles, breathing movement during of chest act as a pump

How tissue fluid is formed

Plasma proteins in capillaries decrease water potential, water moves into capillaries by oncotic pressure, blood still under pressure due to hydrostatic pressure, hydrostatic pressure greater than oncotic pressure so fluid squeezed out of capillaries at the arterial end, fluid fills spaces between cells

Oncotic pressure

Pressure created by the osmotic effect of solutes

Hydrostatic pressure

Pressure exerted by a fluid

Differences between composition of blood and tissue fluid

No red blood cells, no plasma proteins

How tissue fluid gets back into blood vessels

Hydrostatic pressure falls, oncotic pressure is greater than hydrostatic pressure, water moves back into the capillaries by osmosis at the venous end

Lymph

Liquid that leaves the blood vessels and drains into the lymph capillaries

Differences between composition of lymph and blood/tissue fluid

Less oxygen, fewer nutrients, fatty acids

Explanation for the difference in composition between blood and tissue fluid

Red blood cells and white blood cells are too large to be pushed out of the capillaries as tissue fluid is formed

Explanation for the difference in composition between lymph and blood/tissue fluid

Fatty acids come from the vili of the small intestines, oxygen and nutrients have been used up by cells by the time lymph is formed

External structure of the heart

Made of cardiac muscle, coronary arteries supply cardiac muscle with oxygen and glucose, surrounded by inelastic pericardial membranes

Role of inelastic pericardial membranes

TO stop the heart over-distening with blood

How deoxygenated blood flows through the heart

Deoxygenated enters the right atrium through the superior and inferior vena cava, tricuspid valve opens, blood goes into right ventricle, tricuspid valve closes, blood enters pulmonary artery

How oxygenated blood flows through the heart

Enters left atria through pulmonary vein, bicuspid valve opens, blood goes into left ventricle, blood enters the aorta

What causes atrioventricular valves to open?

Slight pressure builds up

When do atrioventricular valves close?

When ventricles start to contract

How to stop valves from turning inside out

Tendinous cords

Septum

Inner dividing wall of the heart

Function of the septum

To prevent the mixture of oxygenated and deoxygenated blood

Events in diastole

Heart relaxes, atria and ventricles fill with blood, volume and pressure of blood in the heart increases, pressure in arteries is at a minimum

Events in systole

Atria contract and the ventricles quickly afterwards, pressure inside heart increases, blood forced out of the heart, volume and pressure of heart decrease, blood pressure in arteries at maximum

How aortic pressure changes

Rises when ventricles contract as blood forced into the aorta, falls but remains relatively high because of elastic recoil, recoil slightly increases pressure at the start of relaxation

How atrial pressure changes

Low generally because of thin walls, highest when contracting, drops when atrioventricular valves close, pressure builds as they fill with blood, drops when atrioventricular valves open

How ventricular pressure changes

Low, increases as ventricles fill with blood, atrioventricular valves close and pressure builds massively as walls contract, pressure rises above that in the aorta, blood forced into aorta, pressure falls

How ventricular volume changes

Atria contract and it increases, drops as blood forced into the aorta

Sequence of valves opening and closing

Atrioventricular valves close, semilunar valves open, semilunar valves close, atrioventricular valves open

Myogenic

Muscle with its own intrinsic rhythm of contraction

How heart action is coordinated

SAN impulse, atria contract, heartbeat initiates, picked up by AVN, bundle of His stimulated, signal conducted in two parts to apex of the heart, spread of excitation through Purkyne fibres causes ventricles to contract from the apex

How does the signal from the SAN not get through to the ventricles?

Layer of non-conducting tissue

Bundle of His

Bundle of conducting tissue made of Purkyne fibres which penetrate through the septum between ventricles

Why does contraction start at the ventricles?

More efficient emptying of ventricles

Why is the AVN delay good?

Make sure the atria stop contracting before the ventricles start

Tachycardia

Rapid heartbeat

Normal causes of tachycardia

Fear, anger, fever (The worst new emotion in Inside Out 2)

Bradycardia

Very slow heartbeat

Normal cause of bradycardia

Fitness

Ectopic Heartbeats

Extra heartbeats that are outside of the normal rhythm

Atrial fibrillation

Rapid electrical impulses in the atria cause fast contraction of the atria so don't contract properly

How haemoglobin transports oxygen

Steep concentration gradient between erythrocytes and air in alveoli, oxygen diffuses in and binds with haemoglobin, positive cooperativity, at respiring tissues the concentration of oxygen is lower, diffuses out of erythrocytes

Positive cooperativity of haemoglobin

Once binded to one oxygen, the haemoglobin will change shape to better be able to bind to another oxygen

Axis labels on an oxygen dissociation curve

Percentage saturation of oxygen, partial pressure of oxygen

Shape of oxygen dissociation curve

Sigmoid

Explanation for sigmoid shape of oxygen dissociation curve

Small changes to partial pressure of surroundings will increase or decrease the percentage saturation very quickly, levels out at highest because reaches maximum saturation

Is the binding of oxygen reversible?

Yes

Bohr Effect

As the partial pressure of carbon dioxide rises, haemoglobin gives up oxygen more easily

Importance of the Bohr Effect

Gives up oxygen more readily in respiring tissues, oxygen binds to haemoglobin tissues easily in the lungs

Difference between maternal and foetal haemoglobin

Foetal haemoglobin has a higher oxygen affinity

Why foetal haemoglobin must have a higher oxygen affinity than maternal haemoglobin

Oxygenated maternal blood runs close to deoxygenated foetal blood, there would be no oxygen transferred if same affinities, high affinity allows oxygen to be removed at every point on the curve

Ways carbon dioxide is transported

Blood plasma, carbaminohaemoglobin, hydrogen carbonate ions

How is carbon dioxide transported as carbaminohaemoglobin?

Combines with amine groups in the haemoglobin

Process of carbon dioxide being transported

CO2 reacts with water to form carbonic acid, reaction catalysed in red blood cells by carbonic anhydrase, carbonic acid dissociates into hydrogen ions and hydrogen carbonate ions, hydrogen carbonate ions diffuse out of red blood cell, chloride ions diffuse into cell to even out gradient, haemoglobin can be a buffer

Chloride shift

When negatively charged chloride ions go into the erythrocyte to provide electrical balance

How carbon dioxide is released from hydrogen carbonate ions

Hydrogencarbonate ions diffuse back into red blood cell, react with hydrogen ions to form carbonic acid, breakdown into carbon dioxide and water catalysed by carbonic anhydrase, carbon dioxide released

How the Bohr Effect changes the oxygen dissociation curve

Moves it to the right

Why does hydrostatic pressure decrease as you move away from the heart?

More blood vessels so larger cross sectional area

How does the Bohr Effect work?

More CO2 leads to more H+ being released, haemoglobin acts as a buffer by mopping up the H+ to form haemoglobinic acid, leads to haemoglobin releasing more O2