module 3 - chapter 8 - transport and exchange in animals Flashcards
why might large, multicellular organisms need specialised transport systems?
-diffusion is too slow
-need to meet high metabolic demands and dispose of lots of metabolic waste
-SA:V ratio decreases as organism gets larger, less surface area to absorb or remove substances
-food can be digested in one organ system but needs to be transported to every cell for respiration etc.
what are the similarities between the different circulatory transport systems?
-have a liquid transport medium that circulates around the system (blood)
-have vessels that carry the transport medium
-have a pumping mechanism to move fluid around the system
outline an open circulatory system
- few vessels to contain transport medium
- pumped from heart directly to body cavity
open body cavity = haemocoel - in haemocoel, blood is under low pressure
- comes into direct contact with tissues and cells - exchange takes place
- transport medium returns to heart via an open ended vessel
- mainly in invertebrates (insects and molluscs)
what substance do insects have instead of blood?
describe this substance and what it transports
haemolymph - doesn’t carry oxygen or carbon dioxide
transports food, nitrogenous waste and immune cells
what is the major disadvantages or an open circulatory system?
slow - low blood pressure
unspecialised - amount of haemolymph flowing to a tissue cannot vary to meet specific demands
define vertebrate
animals that have a backbone
define invertebrate
animals that do not have a backbone
what is the difference between open and closed circulatory systems
closed - blood transported via vessels
open - blood released directly into body cavity (in insects)
define endotherm
give some examples
animal dependent on, or capable of generating their own heat (warm blooded)
mammals - humans and monkeys
define ectotherm
animal dependent on external sources of heat to regulate body temperature (cold blooded)
amphibians - snakes and frogs
what circulatory systems do:
1. humans
2. insects
3. amphibians
4. fish
have?
- double and closed
- open and single
- closed and incomplete double
- single and closed
describe the mammalian heart
- muscular double pump - thickest muscle on left ventricle
- divided in two by septum
- 4 chambers (2 atria and 2 ventricles)
- contains valves to prevent backflow of blood
what valves are present in the heart?
where are they?
what do they do?
atrio-ventricular valves - left and right
positioned separating the atria and the ventricles
semi-lunar valves - positioned between the ventricle and the arteries (pulmonary and aorta)
valves prevent backflow of blood
describe the 3 basic sections of the cardiac cycle
diastole - blood entering through the atria into the ventricle, through the atrioventricular valve
atrial systole - atria contracts forcing the last 30% of blood into the ventricles, pushing the AV valve open more
ventricular systole - AV valve closes, ventricle contracts beginning at the apex (bottom) forcing blood at high pressure through the semi-lunar valves and out of the heart (either to the lungs or to the rest of the body)
define ECG
what is it used for?
electrocardiogram - shows electrical activity in the heart
used to monitor heart beat and rhythm - outline any abnormalities
define cardiac cycle
the sequence of events in one full beat of the heart
what is haemolymph
the blood equivalent in invertebrates
what are the differences between blood and haemolymph
haemolymph does not carry oxygen or co2, transports food, nitrogenous waste and immune cells.
what is the name for irregular heart beat?
arrhythmia
what is the name for the “pace maker” and what does it do?
SAN - sinoatrial node
produces the wave of excitation - triggers electrical responses in the cardiac muscle
what is tachycardia
rapid heart beat - over 100bpm
what is a slow heart beat called?
what pace is this from/ below?
bradycardia
below 60bpm
what do we call early ventricular contractions
ectopic heart beat
what is atrial fibrillation?
when the atria beat faster than the ventricles
typically in humans, how long does the cardiac cycle take?
how much of this is taken up by systole
0.8 seconds
0.1 for atrial
0.3 for ventricular
how does the signal produced by the SAN travel through the heart?
rapidly across the atria intercalated discs spread impulse to the AVN - atrioventricular nodes
signal then conducted through the “bundle of His” down the length of the septum via the left and right bundle branches.
then up the purkinje/ purkyne fibres (specially adapted muscle fibres)
what is the function of the AVN in the cardiac cycle
picked up the “wave of excitation” and imposes a slight delay before stimulating the “Bundle of His”
what is the Bundle of His
a bundle of conducting tissue made up of purkinje/ purkyne fibres which penetrate through the septum between the ventricles
what separates the ventricles?
and why do we need this?
the septum
stops oxygenated and deoxygenated blood mixing
how thick are the walls on the
atria =
right ventricle =
left ventricle =
and why?
atria = 2mm - due to gravity, little blood pressure, only contracts to push 30% of blood to the ventricles
right ventricle = 9mm = thicker than atria as higher blood pressure to force blood to the lungs
left ventricle = 16mm = thickest as highest blood pressure to push blood all around the body
define myogenic
an organism that doesn’t need external electrical impulses to signal for an action or contraction
why is the SAN needed
to coordinate fibrillation (contraction) of the atria and ventricles
at what point are all the valves in the heart closed
after atrial systole, before ventricular systole - ventricles are 100% full but ventricles haven’t contracted yet
what are tendinous chords?
papillary muscles attached to valves to stop them from turning inside out (informally known as heart strings)
what is the name of the muscle that makes up the heart?
myocardium - cardiac muscle
how is cardiac muscle specialised for its function?
- contain fibres that branch producing cross-bridges - spread stimulus around the heart
- lots of mitochondria between myofibrils (muscle fibres) to supply energy for contraction
- muscle cells separated by intercalated discs - facilitate synchronised contraction
- each cell has a nucleus and is divided into contractile units called sarcomeres
what are the 5 types of blood vessels
arteries
arterioles
capillaries
venules
veins
describe the how arteries are adapted for their function
thick walls - withstand high blood pressure
lots of strong collagen for structural support - stop tearing under pressure
folded endothelium - enable expansion under high blood pressure
smaller lumen (channel) than veins - maintain pressure of blood
lots of elastin to allow recoil and expansion