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
heart relaxes
pressure in ventricles and atria drop
av valves open - pressure in atria is greater than ventricles
semilunar valves closed
atrial systole
av valves open - pressure is higher in atria than ventricles
semilunar valves closed
blood moved into heart
atria contract - pushes blood into ventricles
ventricular systole
ventricles contract
av valves close - pressure in vebtricles is higher than atria
pressure in ventricles rises
semi lunar valves open - pressure is greater in ventricles than aorta
semi lunar valves close - pressure in greater in aorta than ventricles
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
no nucleus or mitochondria - more space for harmoglobin
made in the bone marrow from stem cells
flexible - to squeeze through capillaries
biconcage shape - increases surface area
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
oxygen is released by the haemoglobin
some carbon dioxide is dissolved in the plasma
rest of co2 diffuses into rbc
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 than adult haemoglobin at the same ppO2
in placenta- low oxygen so because the fetal haemoglobin has a higher affinity
myoglobin
stores oxygen in your muscles
efficient at taking oxygen from the blood
transport of carbon dioxide
respiring tissues release co2
carbonic acud dissociates to form H+ and HCO3-
H+ combine with harmoglobin to form haemoglobinic acid
HCO3- move into plasma
Cl- move from plasma into rbc - chloride shift
in lungs, co2 is reformed and exhaled
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