3.1 Flashcards
Define single circulatory system
Blood passes through the heart once per complete circuit, for example, in fish
Define double circulatory system
Blood passes through the heart twice per complete circuit, for example, in mammals
What factors are effected by a single circulation system?
Reduced blood pressure, which limits the rate of O2 and nutrients to cells
What are the benefits of a double circulatory system for mammals?
Maintains high blood pressure, this allows more O2 to reach cells so they can respire faster to support the level of activity for mammals, and maintain a body temperature
What is the pulmonary system?
The deoxygenated blood is tranferred from the heart to the lungs through the pulmonary artery. When the blood is oxygenated, it is pumped back to the heart through the pulmonary vein.
What is the systemic system?
The oxygenated blood is pumped through arteries around the body and then the deoxygenated blood is pumped back towards the heart through veins
Define an open circulatory system
Blood is not contained in vessels and instead circulates through the body’s cavity, so tissues and cells are bathed directly in blood (haemocoel)
Why do open circulatory systems work in insects
The oxygen from the air is carried directly tissues through an arrangment of traches , diffusion is enough to suit there demands.
Describe the route of blood around a fish
atrium, ventricle, gilles, body, atrium …
Describe a veins features and give there reasons
wide lumen as it only needs to pump at low pressure
thin walls that are less elastic and muscular
valves (semilunar): prevent backflow (so keep it going in one direction
don’t pulsate due to the smooth flow of blood
Describe a capillary’s features and give reasons
wall is one cell thick for short diffusion distances
the capillary is just the endothilium with a large surface area
Describe the feature of an artery and give there reasons
narrow lumen to keep high pressure
highly elastic to expand and recoil
thick muscular walls to whitstand force
no valves as blood is at higher pressure
pulsate
What do all blood vessels have in common?
Have an inner lining made of a single layer of cells called the endothelium
Why is the endothelium particulary smooth?
To reduce friction with blood
Describe the tunica interna/intima, media and externa in an artery
tunica interna/intima: endothilium made from squamous cells, very smooth to reduce friction
tunica media: contains smooth muscle, collagen and elastic fibres
tunica externa: elastic fibres and collagen
Why does the arteriole walls contain smooth muscle
to contract to constrict flow and limit it allowing it to go elsewhere
Describe the tunica interna/intima, media and externa in an vein
tunica interna/intima: endothilium made from squamous cells, very smooth to reduce friction
tunica media: very thin containing some smooth muscles and elastic fibres
tunica externa: mostly collagen fibres
Why do veins have valves?
To prevent backflow of blood and keep it flowing in one direction
Describe the lumen of a capillary and give a reason for this
Very narrow around the same diameter of a erythrocyte, this ensures they are squeezed as they pass along the capillarys helping them give up there oxygen
Decribe plasma and it’s function in the blood
liquid part, makes up 55% of the blood, made up of 90% water and 10% substances and transports substances around the body (CO2 from cells to lungs, urea from liverto kidneys, hormones and enzymes)
Describe leucocytes and their function in the blood
5000-7000 per ml of blood, your bodys defence system against pathogens, many types such as: neutrophils (phagocytosis) and lymphocytes (produce antibodies and antitoxins)
Describe thrombocytes (platelets) and their functions in the blood
200,000 to 300,000 per ml of blood. allow for blood clotting by initiating a reaction that turns soluble blood protein fribinogen into insoluble protein fibrin to form a blood clot. prevent loss of blood and entry of microorganisms
Describe erythrocytes and their functions in the blood
4 - 6 million per ml of blood, 45% of blood volume, transport oxygen from lungs to cells
What is the role of tissue fluid?
It is the fluid that allows the exchange of substances between the blood and cells
What is hydrostatic pressure (blood pressure) in capillaries and what does it do?
As capillaries are narrow a pressure builds up which forces tissue fluid out of the blood plasma aswell as small molecules leaving cells and large proteins behind.
What does (high) osmotic pressure do?
Return fluid of the blood at the veniole as blood still contains proteins which tissue fluid lack
What is oncotic pressure?
Form of osmotic pressure exerted by proteins which pulls fluid into the circulatory system.
Where is the overall net flow of fluid and what are the percentages?
out of the circulatory system into the tissues
90% returns back to the capillaries, 10% drains into lympth vessels
Where is lymph moved towards and why?
The thorax to be returned to the blood
What is the difference between tissue fluid and lymph fluid?
Lymph fluid contains less Oxygen, more CO2, less nutrients and more white blood cells which are lymphocytes
Where are lymphocytes produced?
Lymph nodes
What are lymph nodes and what do they do?
Swellings found at intervals along the lymphatic system that filter bacteria which lymphocytes engulf through phagocytosis and destroy
What route does blood take through the heart (major veins and arteries, chambers and valves) starting with the vena cava?
vena cava, right atrium, tricuspid valve, right ventricle, semilunar valve, pulmanory artery, lungs, pulmanory vein, left atrium, bicuspid valve, left ventricle, semi lunar valve, aorta, body
How are cardiac muscles joined?
intercolated discs
What are the 3 stages of the cardiac cycle?
atrial systole, ventricular systole and diastole
What happens in atrial systole?
atria contract, ventricles are relaxed, blood goes from atria to ventricles, bicuspid and tricuspid valves are open, semi lunar valves are closed
What happens in ventricular systole?
ventricles contract, atrials relax, blood goes from ventricles to the pulmonary artery and aorta, tricuspid and bicuspid valves are closed and semi-lunar valves are open
What happens in diastole (filling time)?
everything is relaxed, blood goes from pulmonary vein and vena cava into atria, valves in the vena cava and pulmonary vein are open, bicuspid and tricuspid valves and partially open, semi-lunar valves are closed.
Where is the first electrical wave released from?
The sino-atrial node (SAN)
When the SAN releases an electrical wave where does it go and what is casued?
Across the atriums causing them to contract and goes to the AVN
What stops the initial wave from the SAN from going to the ventricles?
Layer of non-conducting collagen tissue
What relays the initial electrical wave to the bundle of His?
The atrioventricular node (AVN)
Where does the bundle of His pass the wave of charge on to?
Purkyne tissue
What happens before the AVN released a wave of electrical charge to the bundle of His and why?
a slight delay to make sure the atria is empty
What happens when charge reaches the purkyne tissue?
The ventricles are contractes simultaneously from the bottom up
What is the simplified electrical activity of a heartbeat
SAN sends an electrical wave, atria contract, AVN recieves this, after a slight delay the AVN releases a charged wave to the bundle of His the wave up muscular walls and the ventricle contracts
Where is the SAN?
In the right atrium
What happens during polarization in the heart?
Gain of charge
What happens during depolarization in the heart?
Loss of charge
On a ECG: what does the P peak show
Contraction of the atrium
On an ECG: what does the QPR peak show?
The contraction of the ventricle and the main heartbeat
On an ECG: what causes the T wave?
Relaxation of ventricles
What is brachycardia?
A resting hearbeat that is to fast, over 100bpm
What is tachycardia?
A heartbeat that is to slow, under 60 bpm
What is an ectopic heartbeat and what is it shown by on an ECG and what causes it?
An extra heartbeat caused by the early ontraction of the atria or ventricles, shown by an early P wave
What does elavation of P-T show on an ECG?
Heart attack
What is atrial fibrillation and what is it shown by on an ECG?
Irregular and abnormal heart rate where the atria and ventricles lose their rhythum shown by a small and unclear P wave
