Circulatory Systems And Cardiac Cycle Flashcards
Why cant big animals use diffusion
Need a circulatory system
Diffusion process is too inefficient to provide materials quickly to respiring cells
Describe an open circulatory system in insects
Insect blood not contained in blood vessels but fills up body cavity
The blood circulates slowly, tubes deliver air directly to respiring cells (not tissues)
Describe closed circulatory system in humans
Blood pumped by heart
Moves through blood vessels
Atriums receive blood from rest of body or lungs
The heart requires food substances for respiration
What delivers these to the heart (ventricles)
The coronary artery
single circulatory system
Eg fish 🐠
Blood flows around body in single circuit
Heart has TWO CHAMBERS: one atrium and one ventricle
Double circulatory system
Eg, humans and mammals
blood flows twice through heart on each complete circuit around the body
HEART HAS FOUR CHAMBERS
Describe how the double circulatory system uses the left and right chambers to pump blood around the body
One circuit:
deoxygenated blood pumped from RIGHT side of heart to lungs
Other circuit:
Oxygenated blood pumped from LEFT side of heart to respiring cells in body
Why is blood under higher pressure in a double circulatory system
Materials are transported quicker around the body
Describe Galen’s theory about the heart
Thought blood flowed like a tide between liver and heart
Describe Harvey’s discoveries about the heart
Showed heart pumped blood around body through blood vessels
Found arteries carried blood under high pressure away from heart and veins had valves to prevent backflow
What causes blood to move around the body
Contraction of heart moves blood
Describe the process of heart being supplied with glucose and oxygen by the coronary artery
Heart relaxes, blood enters both atria from veins
Atria contract to push blood into ventricles,opening atrioventricular valves
Ventricles contract from bottom pushing blood into arteries
Semi-lunar valves open and atrioventricular valves are forced to close as blood tries to flow backward into the atria
Describe the surge of blood known as the heart beat
When ventricles contract, blood is under pressure and sent to arteries in a surge of blood
Pressure of blood changes as it travels through blood vessels
Where is it under high pressure?
Blood is under high pressure as it flows through arteries
Pressure of blood changes as it travels through blood vessels
Where is it under mid pressure?
Blood pressure is medium when passing through capillaries
Pressure of blood changes as it travels through blood vessels
Where is it under low pressure?
Pressure of blood is lowest in veins that return blood to heart
Describe blood flow changes during exercise in the brain, heart and muscles
Brain blood flow remains the same
Muscle blood flow increased, more glucose and oxygen for respiartion
More blood passes through heart each minute
What is heartbeat controlled by (cells)
How do they work
Pacemaker cells produce small electrical impulses rhythmically which spread across the heart muscle, causing it to contract
Why does heart rate speed up in response to exercise
In order to supply oxygen and glucose to respiring muscles more efficiently
What can be done if pacemaker cells fail
Artificial pacemaker transplanted into chest and wired to keep heartbeat regular
What two methods can monitor and diagnose problems with the heart
Electrocardiogram (ECG) monitors electrical impulses from heart
Echocardiogram uses ultrasound to produce an image of beating heart
Why do some (small) animals eg, insects not need a circulatory system
Rely on diffusion to supply oxygen and nutrients to all parts of their body
Sinoatrial node (SAN)
Sinoatrial node (SAN) produces impulses that spread across the atria making them contract
Atrioventricular node (AVN)
Atrioventricular node (AVN) relays impulses that spread over the ventricles making them contract
What can increase or decrease the pace of the SAN (in order to regulate the heartbeat)
Nerves connecting the heart to the brain can increase or decrease pace of the SAN to regulate the heartbeat
Where are pacemaker cells located
Right atrium
