Transport in animals

Describe circulatory systems

Transport gases and nutrient around in a transport liquid

This liquid is transported around in vessels and there is a pump to move the liquid (heart)

describe open circulatory systems

Invertebrates have this (insects)

Transport medium (haemolymph) is pumped directly to open body cavity (haemocoel), few transports vessels

Transport medium is pumped at low pressure and transport food and nitrogenous waste - not gases, they are transported via teh tracheal system

Exchange takes place at cells and tissues, transport medium return to heart through through open ended vessel

Close circulatory system

Vertebrates and some invertebrates

Transport medium (blood) remains inside of vessels

Gases and small molecules leave blood by diffusion or high hydrostatic pressure

Transport oxygen and carbon dioxide , oxygen transported by a pigmented protein (hameoglobin)

Describe single closed circulatory systems

Blood only passes through heart once per cycle

Fish

Blood passes through two sets of capillaries

Immediately after pumped out of heart, blood flows through capillaries in gills to become oxygenated

Blood flows through capillaries delivery ig blood to body, then return to heart

Not enable efficient gas exchange for mammals, but work for fish due to counter current flow mechanism in gas exchange

Double closed circulatory system

Blood passes through heart twice per cycle

Birds and mammals

One circuit of blood vessels carry blood from heart to lungs for gas exchange

Second circuit carries blood from heart to rest of body to deliver oxygen and nutrients and collect waste

Describe the arteries

Collagen - provide strength to prevent vessel from bursting and to maintain vessel shape

Elastic fibres = elastin lets them stretch and recoil to minimise change in pressure

Thick smooth muscle layer = contracts/ relax to dilate lumen and control blood flow

Describe arterioles

Smaller than arteries, with larger lumen

Their walls have more smooth muscle and less elastin as they withstand less pressure

What is vasoconstriction and vasodilation?

Vasoconstriction = smooth muscle contracts, constricts blood vessel and decreases blood flow

Vasodilation = smooth muscle relaxed, dilate blood vessel and increasing blood flows

Describe capillaries

Form extensive networks between arterioles and venules, area between blood and tissue where exchange of substances occur

Narrow lumen = red blood cells close to body cells

Thin walls =- substances can be exchanged across a short distance by diffusion

Highly branched = large SA for diffusion

Describe veins

Carry blood towards heart at low pressure

Collagen = provide strength to prevent vessel from bursting and maintain vessel shape

Little smooth muscle and elastic fibre = low blood pressure, and thin walls allow veins to be compressed

Valves = pocket valves shut to prevent back flow of blood when wins are squashed by surrounding skeletal muscles

Pocket valves are the only type of value controlled by skeletal muscle

Describe venules:

Venules are smaller than veins

Thin walls, very little smooth muscle

They have valves

What does blood consists of?

Plasma = mostly water, transports substances

red blood cells = carry oxygen

White blood cells = immune cells

Platelets = blood clotting

Function of blood

Transport oxygen and carbon dioxide

Transports nutrients from digestion

Transports waste for excretion

Transports hormones

Transports food for storage

Transports clotting factors

What is tissue fluid?

Fills space between space

Site of diffusion between blood and body cells, provide cells with nutrients and oxygen while also removing waste products

Helps fight infection

Tissue fluid vs plasma

Tissue fluid has no red blood cells

Few proteins

Few white blood cells

How is tissue fluid formed from arterioles end?

High hydrostatic pressure exerted by force of heart pumping forces fluid out of capillaries

Forms fluid tissue surrounding body cells

How is tissue fluid formed at the venule end of capillaries?

Hydrostatic pressure is lower

Proteins in blood exert a high oncotic pressure, type of osmotic pressure in capillaries

The water potential is lower in capillaries than in tissue fluid due to fluid loss

Some tissue fluid move back into capillaries by osmosis

What is lymph and its composition comapred to tissue fluid?

Fluid that flows around the lymphatic system via lymph vessels

Has less oxygen and nutrients

More fatty acids

More white blood cells

How is lymph formed and transported?

Formed from tissue fluid

Some tissue fluid doesn’t re enter capillaries from tissue fluid

This fluid drains lymph vessels forming lymph

Lymph is transported through lymph vessels by muscles contractions

It passes through lymph nodes to filter pathogens

Lymph returned to blood

Describe the heart chambers:

Human heart has 4 chambers

Left and right atria, left and right ventricle

Atria = top chambers in heart that collect blood from blood vessels (veins)

Ventricles = bottom chambers in heart that pump blood into blood vessels (arteries)

Describe the pumping mechanisms in the heart:

Left side has oxygenated blood + Right side has deoxygenate blood = two seperate pumping machines beacuse:

Blood pressure drops in lungs as it flows through capillaries

Single pump would slow the blood flow to body cells

Two pumps increase the pressure before blood circulates

What does septum do?

Seperate two sides of heart, prevent oxygenated and deoxygenated blood from mixing

Describe the atrioventricular valve in heart:

Tricuspid valve - located between right atrium and right ventricle

Bicuspid = left atrium and left ventricle

Both valves prevent back flow of blood into atria when ventricles contract

Describe the semi lunar valves

Located between the ventricles and pulmonary artery and the aorta

Prevent back flow of blood into ventricle when they relax

Diagram of heart

Pulmonary vein = moves oxygenated blood into left atrium from lungs

Aorta = moves oxygenated blood from left ventricle to body

Vena cava = moves deoxygenated blood into right atrium from body

Pulmonary artery = moves dpexyganetd blood from right ventricle to lungs

Why are the ventricle walls thicker than the atria walls

They have more muscle beacuse:

Atria only need enough pressure to pump blood a short distance into ventricle

Ventricle need more pressure to pump blood a long distance out of heart to other organs

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

More muscle

Right ventricle needs enough pressure to pump deoxygenated blood a short distance to the lungs

Left ventricle needs a lot of pressure to pump oxygenated blood to other more distant organs of body

cardiac cycle - stage 1: atrial systole

• cardiac cycle is the sequence of contraction and relaxation of cardiac muscle in the walls of the heart -

Ventricle relax, atria contract = increases atrial pressure

Atrioventricular valanced open = blood flows into ventricle

Cardiac cycle - stage 2 = ventricular systole

Ventricles contract, atria relax

Ventricular pressure increases

Semi lunar valves open and atrioventricular valves close

Blood flows into arteries

Cardiac cycle - stage 3 - diastole

Ventricles and atria relax

Semi lunar valves close

Blood flows passively into atria