Transport in animals

Why do multicellular animals need transport systems?

Size, metabolic rate and surface area to volume ratio

Open circulatory system

Blood flows freely in the body cavity and surrounds the organs.

Closed circulatory system

Blood is kept inside vessels, moving faster and more efficiently.

Single closed system

Blood passes through the heart one which is less efficient.

Double closed system

Blood passes through the heart twice for faster circulation.

Veins

Carry deoxygenated blood (except the pulmonary vein) towards the heart

Vein structure

Veins have walls containing less elastic fibre, less smooth muscle and valves

Arteries structure

Arteries have walls containing lots of elastic fibres and smooth muscle.

Capillaries

Are microscopic blood vessels that link the arterioles and venules.

Capillary structure

Capillaries have a small lumen, walls are one cell thick and there are fenestrations in the endothelium.

Cell

Makes up all living organisms and contains organelles.

Tissue

A group of cells working together to perform a shared function.

Organ

A structure made up of groups of different tissues working together to perform specific functions.

Organ system

A group of organs with related functions, working together to perform functions within the body.

Stem cells

Undifferentiated cells that are not adapted to a particular function and have the potential to differentiate to become a specialised cell.

Sources of animal stem cells

Embryonic stem cell and adult tissue stem cells (bone marrow)

Differentiation of erythrocytes (4)

Cells become smaller, are enucleated, they have a biconcave shape and are flexible

Differentiation of neutrophils (2)

Their nucleus is multi-lobed and contain granular cytoplasm containing lysosomes.

Tissue fluid composition

Water, oxygen, glucose, amino acids, small proteins and white blood cells.

Hydrostatic pressure

The blood is under high hydrostatic pressure from the heart contracting, forcing fluid out of the capillaries forming tissue fluid.

Oncotic pressure

Blood exerts osmotic pressure due to plasma proteins giving the blood a high solute potential.

Blood plasma composition

Water, oxygen, glucose, amino acids, large proteins, red blood cells, white blood cells and platelets.

Lymph production

The remaining tissue fluid is drained into lymph capillaries which return to the blood.

Lymph composition

Proteins, lipids and white blood cells.

Amino acid structure

Amine group, carboxyl group and R-group.

R-group

A range of chemical groups different in each amino acid

Amine group

NH2

Carboxyl group

COOH

Synthesis of peptides

Amino acids join when the amine (H) and carboxyl groups (OH) react in a condensation reaction to form a dipeptide.

Synthesis of proteins

Different R-groups interact forming hydrogen and ionic bonds and disulphide bridges.

Hydrogen bonds

Weak bonds between amine and carboxyl groups.

Ionic bonds

Strong bonds between oppositely charged R-groups

Disulphide bonds

Covalent bonds between R-groups containing sulphur atoms.

Primary protein structure

The sequence in which amino acids are joined by peptide bonds - directed by DNA

Secondary protein structure

The oxygen, hydrogen and nitrogen atoms interact forming 3D structures including an alpha helix and beta-pleated sheet.

Tertiary protein structure

The folding of a protein into its final shape as R-groups interact.

Quaternary structure

The association of 2 or more proteins called sub-units.

Globular protein structure

Compact, spherical and soluble

Conjugated protein structure

Globular proteins containing a non-protein (prosthetic) group.

Fibrous protein structure

Form longs strands and are insoluble in water.

Collagen

A fibrous protein made up of a triple helix of polypeptide chains used as a structural component in skin, bones and walls of blood vessels.

Haemoglobin structure

A conjugated protein made up of 4 polypeptide chains containing an iron-containing haem group.

Keratin

A group of fibrous proteins found in the hair and nails containing cysteine which allows disulphide bridges to form.

Elastin

A fibrous protein found in elastic connective tissue such as the walls of blood vessels.

Insulin structure

A globular protein known as a hormone used to regulate blood glucose concentration.

Amylase

A globular protein known as an enzyme responsible for the breakdown of starch into maltose made up of a single polypeptide chain.

Role of haemoglobin

Oxygen binds to iron in haem groups forming oxyhaemoglobin which can be transported via blood to respiring body tissues.

high partial pressure of oxygen

Haemoglobin has a high affinity for oxygen and binds with it so saturation is nearly 100%.

low partial pressure of oxygen

Haemoglobin has a low affinity for oxygen and releases it so saturation is low.

Cooperative nature of oxygen binding

When haemoglobin binds with one oxygen, it changes shape so it becomes easier to bind another oxygen.

Feral haemoglobin

Has a higher oxygen affinity than the mothers, allowing the oxygen to dissociate from the mother’s haemoglobin and bind with the fetal haemoglobin.

Bohr effect

At higher partial pressures of CO2 haemoglobin has a lower affinity for oxygen and releases it to respiring tissue.

Carbon dioxide to ions in red blood cells

CO2 reacts with water to form carbonic acid by the enzyme carbonic anhydrase. Carbonic acid dissociates to hydrogen and hydrogen carbonate ions.

Ions to CO2

Hydrogen ions bind with haemoglobin to form haemoglobinic acid causing oxygen to be released. When blood reaches the lungs, the low partial pressure of CO2 causes ions to reform CO2.

Chloride shift

Hydrogen carbonate ions leave red blood cells while chloride ions enter to maintain the charge balance.

Biological catalyst

Increase the rate of a chemical reaction without being used up in the reaction itself

How catalysts work

Enzymes work by lowering the activation energy for a chemical reaction

Intracellular enzymes

Act within the cell that produce them (catalyse for hydrogen peroxide)

Extracellular enzymes

Act outside the cell that produce and secrete them (amylase)

How enzymes work

Enzymes have unique tertiary structures which determine the shape of their active site which is complementary to the substrate it binds to (bonds between R-groups).

Lock and key model

The substrate fits perfectly into the enzyme’s active site

Induced fit model

As the substrate enters the enzyme, the active site changes shape slightly which puts a strain on the substrate’s bonds, lowering the activation energy.

How temperature affects the rate of enzyme-controlled reactions

As temperature increases, rate of reaction increases (more KE). Maximum rate is reached at the optimum temperature. As temperature increases past optimum, rate decreases.

How pH affects rate of enzyme-controlled reactions

Below or above the optimum pH the rate is low or zero. The maximum rate of reaction is reached at the optimum pH.

How enzyme/substrate concentration affects rate of enzyme-controlled reactions

As there are more enzyme/substrate molecules rate of reaction increases. At the saturation point, all active sites are occupied and the rate of reaction plateaus.

Inhibitors

Molecules that bind to enzymes to reduce their activity

Competitive inhibitors

Bind to the active site of an enzyme to prevent enzyme-substrate complexes from forming. Most competitive inhibitors are reversible and temporary.

Non-competitive inhibitors

Non-competitive inhibitors bind to enzymes at an allosteric site, changing its tertiary structure, cause the active site to permanently no longer be complementary to the substrate.

Cofactors

Non-protein substances that bind to enzymes to increase their activity - Cl- is a cofactor for amylase.

Coenzymes

Organic cofactors that are usually derived from vitamins

Prosthetic groups

Cofactors that are tightly bound to enzyme - Zn2+ is a prosthetic group for carbonic anhydrase.

Atria

The top chambers in the heart that collect blood from veins

Ventricles

The bottom chambers in the heart that pump blood into arteries

Atrioventricular valves

The bicuspid (right) and tricuspid (left) prevent backflow of blood into the atria when the ventricles contract.

Semi-lunar valves

Prevent backflow of blood into the ventricles when they relax

Why are the ventricle walls thicker than atria walls?

The atria only need enough pressure to pump blood a short distance into the ventricles. The ventricles need lots of pressure to pump blood out of the heart.

Why is the left ventricle walls thicker than the right ventricle wall?

The right ventricle only needs enough pressure to pump deoxygenated blood to the lungs and the left ventricle needs a lot of pressure to pump blood around the body.

Atrial systole

Ventricles relax and atria contract. This increases atrial pressure causing the atrioventricular valves to open. Blood flows into the ventricles.

Ventricular systole

The ventricles contract and atria relax and ventricular pressure increases. The semilunar valves open and the atrioventricular valves close so blood flows into the arteries.

Diastole

The ventricles and atria relax and the semilunar valves close. Blood flows passively into the atria.

Stroke volume

The volume of blood that is pumped out of the left ventricle during ventricular systole.

Sinoatrial node (SAN)

Initiates the heartbeat by stimulating the atria to contract. A layer of collagen fibres prevents direct electrical flow form the atria to the ventricles.

Atrioventricular node (AVN)

Picks up the electrical activity from the SAN and imposes a slight delay in the impulse.

Bundle of His

Receives electrical activity from the AVN and conducts the wave of excitation to the heart’s apex.

Purkyne fibres

Branch of the bundle of His, causing the right and left ventricles to contract from the bottom upwards.

Electrocardiograms (ECGs)

Record the heart’s electrical activity using electrodes.

P wave

Atrial systole

QRS wave

Ventricular systole

T wave

Diastole

Tachycardia

An abnormally rapid heart rate

Bradycardia

An abnormally slow heart rate

Ectopic heartbeats

Extra heartbeats out of the normal rhythm

Atrial fibrillation

Abnormally rapid and ineffective contraction of the atria.