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animal transport

need for a transport system is affected by

size
metabolic demand

activity level

surface area:volume ratio

as an organism gets larger, SA:V ratio decreases because, as size increases volume increases at a greater rate than SA

multicellular organism need transport system because

diffusion is not fast enough

efficient transport system

• a medium to transport substances
• mass flow of liquid

• mechanism for moving the liquid (heart)

• valves to maintain direction

• exchange surfaces

open circulatory system

invertebrates (insects)
transport medium is pumped by the heart directly into the body cavity at low pressure through open-ended vessels

diffusion is fast enough because body cells are all close to the heart

closed circulatory system

vertebrates (humans)
transport medium is contained within the vessels and never comes into contact with body cells

this allows blood to travel longer distance because it's kept at a high pressure

substances enter and leave the blood by diffusing through the walls of the vessel

single circulatory system

blood travels through the heart once for one circuit
e.g. fish

double circulatory system

blood travels through the heart twice for one circuit
under high pressure

e.g. birds and mammals as they have higher rates of metabolism

heart

4 chambers
found in thoracic cavity

made of cardiac muscle that contracts in regular rhythm and does not need nervous stimulation (called myogenic)

coronary arteries

supply the heart muscle with blood

atria

contract to push blood into the ventricles

ventricles

contract to push blood out of the heart to lungs or body

atrioventricular valves

between the atria and ventricles
prevent backflow

open to allow ventricles to fill with blood

shot when the ventricles contract

right atrioventricular valve

tricuspid (3 flaps)

left atrioventricular valve

bicuspid (2 flaps)
stronger as the contraction of the left ventricle is stronger than the right

semilunar valves

found between ventricles and blood vessels leaving the heart
open when the ventricles contract

shot when the ventricles relaxed to prevent backflow

attached to the ventricle walls by tendons (heart strings)

septum

wall of muscle that separates the left and right sides of the heart
stops oxygenated and deoxygenated blood mixing

cardiac cycle stages

diastole
atrial systole

ventricular systole

diastole

atria and ventricles relax and pressure in heart is low
blood trying to flow back into the ventricles causes semi-lunar valves to close

blood flows into heart through pulmonary vein and vena cava

pressure is low inside heart so atrioventricular valves open and blood flows through

atrial systole

atria contract causing atrial pressure to increase
valves close to prevent backflow

pressure in ventricles remains below that of the arteries

semi-lunar valves remain closed

ventricular systole

ventricles contract increasing pressure
causes semi lunar valves to open and blood to move out of the heart through aorta and pulmonary artery

atrio ventricular valves close preventing backflow

contraction occurs from bottom up and pushes blood up

heart will then return to diastole

cardiac muscle is

myogenic (it's stimulates its own contraction)

sinoatrial node

found in right atrium
stimulates contraction of atria

fires A wave of excitation causing them to contract

stopped from moving down to the ventricles because insulting layer of cells

atrioventricular node

between atria and ventricles
acts as a relay station and causes a slight delay after the contraction of the atria

after delay electrical stimulation has passed from the av node to a bundle of cells (bundle of His)

bundle of His splits into His branches

impulse and gets passed up sides of ventricles through purkyne fibres

normal heartbeat

beats evenly spaced

bradycardia

slow heart rate
below 60 bpm

tachycardia

fast heart rate
above 100 bpm

ectopic

irregular rhythm
two beats close together followed by a longer gap

fibrillation

abnormal rhythm
(loads of small ups and downs)

specialised blood vessels carry blood

Arteries (Away from heart)
veIn (In toward heart)

capillaries

arterioles (link arteries to capillaries)

venules (link capillaries to veins)

journey of blood around the body

vena cava
right atrium

tricuspid valve

right ventricle

right semi Lunar valve

pulmonary artery

arteriole

alveolar capillary

venule

pulmonary vein

left atrium

bicuspid valve

left ventricle

left semi Lunar valve

aorta

arteriole

capillaries in body

venule

vena cava

arteries

high pressure
thick wall

narrow lumen

found deeper in the body

structures in arteries

• endothelium - thin layer of cells, smooth to reduce friction
• elastic fibres - withstand the force of blood, stretch

• smooth muscle - allows vasoconstriction

• collagen - strong to stop artery over stretching or bursting

arterioles

smaller than arteries
contain more smooth muscle and less elastin

to allow for vasconstriction

capillaries

site of gas exchange
one cell thick

made of flat endothelial cells

a very narrow lumen

minimizes distance for diffusion

venules

carry deoxygenated blood away from tissues towards the heart
pressure is low

veins

carry blood towards the heart
lumen is wider than arteries

thinner wall, made of less elastic fiber and collagen

contains valves

blood components

plasma
erythrocytes

leucocytes

platelets

plasma

Carries other the substances in it around the body
water-based so good solvent

Carries nutrients, waste products, hormones

erythrocytes

don't contain nucleus mitochondria RER or Golgi
biconcave shape to increase SA

flexible to squeeze through capillaries

filled with hemoglobin to carry oxygen

leucocytes

phagocytes
lymphocytes

platelets

fragments of cells called megakaryocytes
found in bone marrow

stick together to clot blood

tissue fluid

fluid that fills the space between cells

formation of tissue fluid: hydrostatic pressure

occurs from the blood coming from when the heart beats
high the arterial end forcing fluid out capillaries

at venous end pressure is low as blood passes through capillaries

formation of tissue fluid: oncotic pressure

plasma proteins have an osmotic effect the lowering water potential
causes an osmotic gradient and water moves into capillary

plasma proteins do not leave the blood

is the tendency for water to move into the blood

lymph

fluid that does not re-enter the blood
drained into lymph vessels in the lymphatic system before eventually being returned to the blood

lymph fluid

last nutrients and more waste products than tissue fluid

haemoglobin

each sub-unit contains a haem group with an iron atom at the center
each haemoglobin molecule can bind 4 oxygens

transport of oxygen

transported from gas exchange service to respiring tissues by blood in plasma or associated with haemoglobin
binding is irreversible

association of oxygen to haemoglobin depends on

partial pressure of oxygen
at lungs, partial pressure is high, oxygen associates with haemoglobin


at respiring tissues, what should pressure is low, oxygen disassociates from haemoglobin

disassociation curve for oxygen on haemoglobin

steeper between 25% and 75%
because it's difficult for oxygen to bind

foetal haemoglobin

higher affinity for oxygen
at any partial pressure more oxygen is bound to haemoglobin

myoglobin

stores oxygen in your muscles
efficient at taking oxygen from the blood

transport of carbon dioxide

10 to 20% is carried by haemoglobin as carbonaminohaemoglobin
75 to 85% is transported as hydrogen carbonate ions

5% is transported dissolved in plasma

formation of hydrogen carbonate ions

CO2 enters the erythrocyte and reacts with water catalyzed by carbonic anhydrase forming carbonic acid
disassociates to form hydrogen carbonate ions and h+ ions

hydrogen carbonate ions diffuses out

h+ ion vines with haemoglobin to form haemoglobinic acid

bohr effect/bohr shift

in respiring tissues oxygen tension is lower so oxygen will dissociate away from hemoglobin
that will be more carbon dioxide which means more hydrogen ions

increase in hydrogen ions causes oxygen saturation of hemoglobin to decrease

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