Vertebrate heart structure and function Flashcards
Why do animals need a circulatory system?
- O2, nutrients must be transported around the body to tissues and organs
- waste products removed
- communication via hormones
- temperature regulation & reproduction
Open circulatory system
- Blood flows freely with body cavities making direct contact with all tissues and organs
- vessels are open ended - blood flows out and bathes tissue
Closed circulatory system
- circulating blood contained in a continuous series of vessels
- specific components of the fluid filter out of blood vessel and penetrate tissues
- blood kept separate to interstitial fluid
What are the advantages of a closed circulatory system?
- faster, more efficient delivery of fluid to tissues
- ability to control distribution
- assists in the delivery of larger molecules to specific tissue
- enabled the evolution of circulatory system that keeps oxygenated and deoxygenated blood separate
Fish heart structure
- one atrium and one ventricle, one circulation
- specialisation of vessels (Arteries and veins)
- Blood pumped over gills to become oxygenated but leaves under very low pressures
- very low pressure in capillary bed - limits efficiency of delivery of nutrients and O2 to tissues
Air-breathing fish hearts
- 2 circulations (pulmonary and systemic)
- partially divided atrium and ventricle
- oxygenated (right) and deoxygenated (left) blood is kept separate
- Gill specialisation:
- low-resistance by-pass to lung
- direct link to aorta
Amphibians (i.e. frog) hearts
- 3 chambered heart
- Left atrium - oxygenated blood, right atrium - deoxygenated blood
- single ventricle - potential for some mixing of blood but septum directs blood movements and maintain separation
- partial separation of pulmonary and systemic circuits allow for different pressures
What are the similarities of a closed and open circulatory system?
• hearts pump the fluid to different regions of the body via blood vessels
• fluid drains back to the heart
- via veins for closed
- via ostia (openings) for open system (Act as valves)
• Valves ensure one-way flow of fluid
What is the bulbus arteriosus in fish hearts?
• In teleosts
• elastic
• works to reduce extreme pulsing of blood leaving the ventricle, giving a more constant, even flow
(like water passing through a balloon)
What is the Sinus venosus in fish hearts?
Preliminary collecting chamber
What does the septum do in amphibian hearts?
Directs blood movement & maintains separation of oxygenated and deoxygenated blood
Reptiles heart structure
• 3/4 chambered hearts
• 2 aortae
Left: oxygenated blood from left ventricle to body
Right: mixed - receives blood from both ventricles
• reptiles dont always breathe - blood by-passes lungs and flows directly to the systemic circuit via the right aorta
• direction of blood is controlled by resistance in the pulmonary circuit
Birds and Mammal heart structure
- 4 chambered heart
* separate pulmonary and systemic circuits
What are the advantaged of having separate pulmonary and systemic circuits?
- pulmonary and systemic circuits can operate at different pressures
- systemic circuit always receives blood with higher O2 content
- gas exchange is maximised
What change occur in the heart immediately after birth?
• fetal heart: foramen ovale and ductus arteriosus is open
In the newborn heart, both these structures are closed
What is Atrial Septal Defect (ASD)
- Hole in the septum
- congenital
- deoxygenated and oxygenated blood mix and the heart does not work efficiently
- shortness of breath, fainting, irregular heart rhythm and fatigue after regular activity
- no treatment - surgery needed
What is the septum?
Muscle wall between atria
Define congenital
Present at birth
Difference between arteries and veins
- Arteries: carry blood away from the heart
* veins: return blood to the heart
What are the 4 main valves in the human heart and where are they found?
- Tricuspid valve - right
- bicuspid valve - left
- Aortic semilunar valve - aorta
- pulmonary semilunar valve - pulmonary artery
Briefly describe the blood flow through a mammalian heart
DEOXYGENATED
• from the body, enters via the vena cava to the right atrium, to right ventricle
• passes pulmonary valve and through pulmonary artery to the lungs
GETS OXYGENATED
• through pulmonary vein to left atrium
• through atrioventricular valves to left ventricle
• passes aortic valve and through aorta to the body
Summarise the blood flow of the mammalian heart
DEOXYGENATED (from body)
• vena cava, into right atrium
• pulmonary artery to lung
OXYGENATED
• lung to pulmonary vein, to left atrium
• from left ventricle through aorta (to body)
Function of valves
Prevent backflow of blood
Difference between the pulmonary and systemic circuits?
- PULMONARY: blood takes up oxygen in the lungs
* SYSTEMIC: oxygenated body is distributed to body tissues
