Circulation Flashcards
Why do animals need a circulatory system?
- oxygen and nutrients must be transported around the body to tissues and organs
- waste products must be removed
- communications via hormones
- temperature regulation and reproduction
Describe the SA:V ratio of animals without a circulatory system.
Very high. They will be very flat with a thin body wall
What happens if oxygen is provided by diffusion only?
No oxygen will reach centre of animal
What process allows animals with a circulatory system to transport oxygen?
Convection
What is convection?
Bulk movement of fluid
What does convection usually assist?
Usually assists diffusion
Is a concentration always maintained by convection? Why or why not?
Yes, due to continual motion.
Which is faster: diffusion or convection?
Convection is much faster, .
Describe an open circulatory system. In what types of animals are there open circulation systems?
- open vessels, cells bathed directly in blood plasma (haemolymph)
- found in invertebrates, e.g crab, beetle, moth
What is a disadvantage of an open circulatory system?
It is non-selective.
Describe a closed circulatory system. In what animals are these present?
-blood remains in closed vessels
- extracellular fluid bathes cells
- limited exchange between blood and extracellular fluid
- blood and extracellular fluid are SEPARATE
— commonly in vertebrates and earthworm
What is an advantage of closed circulation?
Very selective, blood flows in preferential direction
What separates blood from cells in a closed circulatory system?
Vessels and extracellular fluid
What processes work together in closed circulation?
Convection and diffusion
What powers the convection of blood in closed circulation?
The heart.
What forms of energy are needed and transferred by the heart?
- requires metabolic (chemical) energy for muscle contraction
- potential energy contributes to blood pressure
- kinetic energy contributes to blood flow
What are the general features of hearts?
- several chambers in sequence
- sequential contraction
- one way flow using valves
Describe the pressure changes in blood flow in the heart.
Blood flows from high to low pressure.
What drives movement of blood through heart?
Pressure changes
Atrium always does the ____ to the ventricle?
Opposite
What is the function of the valves in the heart?
Prevent backflow of blood.
What is systole and diastole?
Systole - contraction of heart, expels blood
Diastole - relaxation of heart, refills with blood
What are the two sources of heart contraction?
- Muscle: myogenic. Can contract without nerve input
2. Nerves: neurogenic. Requires electric signal
Are myogenic or neurogenic hearts allowed to be transplanted? Explain why.
Only myogenic as they can keep beating regardless of cut off nerves.
What type of muscle is vertebrate cardiac muscle?
Striated muscle consisting of stripes that are actin and myosin ready to contract.
What are heart muscle cells interconnected?
Via intercalated discs.
What are desmosomes and gpa junctions in the heart?
Desmosomes - strong connections
Gap junctions - electrical connections
What is the sinoatrial node in the heart?
The pacemaker.
Describe the process of action potential conduction in the mammalian heart in steps.
- Action potential starts in sinoatrial node (pacemaker), causing contraction over both atrium.
- This action potential triggers atrioventricular node (0.1 sec delay)
- Rapid conduction of AP down AV bundle (middle of ventricles) and to Purkinje fibres (on far side of ventricles).
- Ventricular contraction propagated from apex expels blood: systole
In the body, what does blood pick up and lose?
Picks up CO2
Loses O2
In the lungs, what does blood pick up and lose?
Picks up O2
Loses CO2
Where does blood flowing into the right and left atrium come from?
Blood entering right atrium comes form body
Blood entering left atrium comes from lungs
Where does blood from the right and left ventricle flow to?
right: Flows to lungs
Left: flows to body
Which ventricle has higher pressure?
Right ventricle has low pressure, left ventricle has high pressure
Describe the process of fish blood circulation with the heart.
Blood picks up O2 and loses CO2 in gills.
This blood is transferred to the body where O2 is lost and CO2 is picked up.
Blood from the body is transferred into the heart.
Blood coming from the heart has higher pressure than blood coming from the gills.
Predict the structure of a fish heart.
Single atrium, single ventricle
Describe the properties of arteries.
- elastic which dampens flow pulse and prevents absence of blood
- high pressure and velocity
Describe the muscle of arterioles.
- smooth muscle which regulates blood flow and pressure
Describe the properties of capillaries.
- exchange vessels
- low pressure, low velocity
- very thin wall only comprised of endothelium
- very high SA:V ratio
Describe the properties of veins.
- low pressure, relatively high velocity
- some smooth muscle, small resistance changes and large volumes of blood
- veins contain valves to ensure that blood flows in one direction.
Why don’t arteries have valves?
Because blood pressure from the heart is so strong that it already flows in one direction
Describe two diseases associated with the arteries. What do both diseases reduce?
Arteriosclerosis: hardening of arteries
Atherosclerosis: fatty deposits
Both diseases reduce elasticity of arteries
What are capillaries? What is it formed by?
- site of exchange
Formed by a rolled endothelial cell.
Name the locations where capillaries don’t leak vs do leak.
Where is leaked fluid transported to?
Don’t leak: blood, brain barrier
Do leak: kidney, spleen, bone marrow,
Leaked fluid is transported back to heart via lymphatic system
What processes enable exchange across capillaries?
- diffusion
- filtration
- pinocytosis
Active transport in placenta
What are baroreceptors? Explain what they do when there is high nad low pressure.
Regulate blood pressure.
High pressure causes lower heart rate and lower resistance
Low pressure causes higher heart rate and higher resistance
What are chemoreceptors? Explain what they do in situations where there is low O2 and low pH, high CO2. AND high O2 and high pH, low CO2.
Regulate O2 in carotid body and CO2 and pH in aortic body.
Low O2- increase breathing rate
High O2- decrease breathing rate
What do baroreceptors and chemoreceptors feed into? What do they regulate?
Feed into vasomotor centre in brain stem Regulation of: - respiration - heart rate, cardiac output - blood pressure - vascular tone (constriction of blood vessel walls)
