Transport in Animals Flashcards Preview

OCR Biology AS H020 > Transport in Animals > Flashcards

Flashcards in Transport in Animals Deck (82):

Why are specialised transport systems needed in animals (5 things)...

The metabolic demands are high and diffusion won't supply the quantities needed. Small SA:V ratio. Hormones/enzymes are made in one place but needed in another. Food is digested in one organ system but is needed in every cell for respiration. Waste products of metabolism need to be removed.


What do most circulatory systems have in common?

A transport medium, vessels and a pumping mechanism.


What is the haemocel?

The open body cavity of an animal in a open circulatory system.


Describe the haemolymph...

There are very few vessels to contain the haemolymph, the haemolymph is pumped straight from the heart to the haemocel. The haemolymph comes into direct contact with cells and tissues. Haemolymph Flowing to a particular area cannot be controlled.


How does the haemolymph return back to the heart?

Through an open ended vessel.


What does the haemolymph carry?

Food, nitrogenous wasteland defence cells.


What pressure is the haemolymph under?



Where does the heart run through in an open circulatory system?

Through the thorax and abdomen


How is blood flowing to particular areas controlled in a closed circulatory system?

Vasoconstriction and vasodilation


Describe closed circulatory systems...

The blood is enclosed in vessels and does not come into direct contact with cells of the body. The heart pumps blood around the body under pressure and it returns to the heart. Substances enter /leave the blood by diffusion. Blood pigment carries the respiratory gases.


Describe single closed circulatory systems...

The blood flows through the heart and travels throughout the whole body before returning.


What type of animals have single closed circulatory systems...

Animals with low activity levels as blood is at low pressure and returns to the heart slowly as there are two sets of capillaries, the first for O2 and CO2 and the seconds for exchanges substances.


What is the exception for the type of animals that have single closed circulatory systems?

Fish have high activity levels but they have a countercurrent exchange system, their BMI is supported by the water and H2O regulates their body temperature.


What is a double closed circulatory system?

The blood travels through the heart twice for each circulatory of the body. Each circuit only passes through 1 capillary network maintaining high pressure and fast flow.


What are elastic fibres?

They are composed of elastin so can stretch hence they give vessel walls flexibility.


What is smooth muscle?

It contacts/relaxes changing the lumen size.


What is collagen?

It provides structural support to maintain vessel shape and volume.


What put of the 3 things do arteries contain?

Elastic fibres, smooth muscle and collagen.


What are the functions of arteries?

To carry blood away from the heart at high pressure


How do the 3 things work in an artery?

Elastic fibres enable arteries to withstand high blood pressure and stretch to limits maintained by collagen.


What is the purpose of elastic recoil in arteries?

To even out surges of blood, alas tic fibres return to their original length.


What do arteries have a smooth endothelium?

So blood flows easily over it


What do arterioles link?

Arteries and capillaries


What is the purpose of arterioles?

To constrict/dilate to control blood flow and pressure to capillary beds so Pitney don't get damaged.


What is the composition of arterioles?

More smooth muscle than elastic fibres.


What do capillaries link?

Arterioles and venules


What is the lumen size of a capillary?

Very small, to allow one RBC at a time


What is the structure of capillaries?

There are large gaps between endothelial cells (fenestrations) where substances are exchanged into tissue fluid or directly through tissue cells.


Name 3 ways capillaries are adapted to their role...

They provide a large SA for diffusion, their total CSA is larger than arterioles so blood flow drops allowing time for exchange, the walls are a single endothelial cell thick.


What is the function of veins and venules?

They carry deoxygenated blood from capillaries to the two main veins (superior and inferior vena cava) to the heart.


What is the pressure in the venules/veins?

Low, no pulse.


What adaption do veins have do to low pressure?

Valves to prevent back flow.


What is the composition of veins and venules?

Lots of collagen, little elastic fibres, thin walls with little smooth muscle, wide lumen, smooth endothelium.


Name 3 adaptions to overcome low pressure in the veins...

One way valves, they run between big active muscles so when they contact they move the blood, breathing movements act as a pump.


What is blood plasma?

A yellow transport liquid which makes up 55% of blood by volume


What does the plasma carry?

Dissolved glucose, amino acids, mineral ions, hormones, albumin, fibrinogen and globulins. RBCs, WBCs and platelets.


What is albumin?

Maintains the osmotic potential of blood


What are fibrinogens?

Blood clotting


What are globulins?

tRansport and the immune system


Describe platelets...

Fragments of large megakaryocytes found in bone marrow.


What is oncotic pressure?

The tendency of water to move into the blood by osmosis


What is the oncotic pressure of blood?



What is hydrostatic pressure?

The pressure from surges of blood


What is the hydrostatic pressure at the arterioles end?



Describe how tissue fluid is formed...

Hydrostatic pressure is higher than oncotic pressure so fluid is squeezed out of the capillaries through fenestrations filling spaces through the cells. Hydrostatic pressure falls to 2.3KPa at the venous end so fluid moves back in.


What is not in tissue fluid?

Red blood cells and plasma proteins


What percentage of tissue fluid moves back into the capillaries?



What happens to the remaining 10% of tissue fluid?

It drains into a system of blind ended tubes (lymph capillaries)


What is the composition of lymph?

Has less O2 and fewer nutrients


How is lymph transported through lymph vessels?

Squeezing of body muscles, one way valves.


Where does lymph return to the blood?

The right and left subclavian veins


Along lymph vessels, there are lymph. Does, what are their function?

Lymphocytes build up here and create antibodies which are passed into the blood.


What is the reversible reaction of oxygen binding to haemoglobin?

Hb + 4O2 -> Hb(O2)4


What is positive cooperatively?

As soon as one oxygen molecule binds to Hb it induces a shape change making it easier for the next one.


What do oxygen disassociation curves show?

The affinity of haemoglobin for oxygen


Describe the oxygen association curve...

At low partial pressure of oxygen, few haem groups are bound to oxygen so Hb does not carry much oxygen. At higher partial pressures of oxygen more game groups are bound to oxygen making it easier for oxygen to be picked up. Hb becomes very saturated at high partial pressures of oxygen as all the name groups are bound.


What is the Bohr effect?

At higher partial pressures of CO2, Hb gives up O2 more easily


Why is the Bohr effect important?

Active tissues produce more CO2 and require more O2. In the Kings the % of acO2 is low so O2 binds easily.


On a graph how is the Bohr shift shown?

The curve moves to the right


Describe foetal haemoglobin

Fetal haemoglobin has a higher affinity for oxygen so moves O2 from its mother when it runs close to the placenta.


How is foetal hamoglobin show on A graph

The curve moves to the left


When CO2 diffuses into the blood stream where does it go?

5% is dissolved in the plasma and 95% diffuses into RBCs.


What happens to CO2 in RBCs?

10-20% binds to Hb forming carbaminohaemoglobin and 75-85% reacts with H20 with catalytic action from carbonic anhydrase to form carbonic acid (H2CO3).


What does carbonic acid disassociate into?

H+ ions and HCO3- ions.


What happens to H+ ions?

H+ ions are removed by haemoglobin buffers to form haemoglobinic acid.


What happens to HCO3- ions?

Hess diffuse out of the RBC as chlorine enters maintaining an electrochemical balance, this is called the chloride shift.


State the route of blood starting with the vena cava...

Vena cava, right atrium, tricuspid valve, right ventricle, semilunar valves, pulmonary artery, pulmonary vein, left atrium, bicuspid valve, left ventricle, semilunar valves, aorta.


Describe the structure of the the heart...

The heart is made of cardiac muscle that does. It get fatigued, it is supplied with oxygen by the coronary artery, it is surrounded by I elastic pericardial membranes which prevent the heart over-dis tending with blood. The septum separates the let and right side.


Why is the muscular wall of the left side of the heart thicker?

Blood has to travel further at a higher pressure.


How long is the cardiac cycle?



What are the 2 stages of the cardiac cycle?

Diastole and systole


What happens during diastole?

The heart relaxes, the atria and ventricles fill. The atria have thin muscular walls pressure builds up in the tricuspid valves until it opens, it closes when the ventricles contract.


What happens during systole?

The atria contract (atrial systole)' closely followed by ventricular systole, the volume and pressure is low in the heart and high in the arteries.


What does the lub-dub of the heart represent?

The atrioventricular valves closing then the semilunar valves closing.


Cardiac muscle is myogenic, what does this mean?

It has an intrinsic rhythm, 60bpm.


Describe the heart rhythm...

In the sino-atrial node. A wave of electrical excitement causes the atria to contract, non conducting tissue prevents it reaching the ventricles immediately. The atrioventricular node picks up the impulse and imposes a slight delay to allow the atria to stop contracting before stimulating the bundle of His (made of Purkyne Fibres) which penetrates through the septum to the apex which finally spreads out through the ventricles causing them to contract from the base upwards.


What does ECG stand for?



What do PQRST waves mean in an ECG?

P = contraction of the atria
QRS = contraction of the ventricles
T = relaxation of the ventricles


What is tachycardia?

Too fast


What us bradycardia?

Too slow


What is an ectopic heartbeat?

A heartbeat out of normal rhythm


What is atrial fibrillation?

An example of arrhythmia, atria beat too quickly but only some implies are caught on by the ventricles leading to ineffective emptying if the heart.