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Questions and Answers
What is the primary function of the valves in the heart?
What is the primary function of the valves in the heart?
Which part of the heart generates electrical impulses to regulate heartbeat?
Which part of the heart generates electrical impulses to regulate heartbeat?
What is the primary reason why diffusion alone is not sufficient for larger organisms?
What is the primary reason why diffusion alone is not sufficient for larger organisms?
During exercise, blood flow is primarily directed to which part of the body?
During exercise, blood flow is primarily directed to which part of the body?
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What is the main advantage of a closed circulatory system?
What is the main advantage of a closed circulatory system?
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What determines the flow of blood in capillaries?
What determines the flow of blood in capillaries?
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What is the term for the contraction of the heart muscle?
What is the term for the contraction of the heart muscle?
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Which of the following animals has a 2-chambered heart?
Which of the following animals has a 2-chambered heart?
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What is the function of a circulatory system in maintaining homeostasis?
What is the function of a circulatory system in maintaining homeostasis?
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What is the term for the fluid that combines blood and interstitial fluid in open circulatory systems?
What is the term for the fluid that combines blood and interstitial fluid in open circulatory systems?
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Study Notes
Diffusion in Small Organisms
- Occurs across the surface of the organism
- Diffusion time is proportional to distance^2
- Surface area to volume ratio decreases with increased body size, making diffusion less efficient in larger organisms
Circulation Systems
- Transport nutrients, oxygen, and waste products to and from cells
- Facilitates movement of nutrients and oxygen to and from cells
- Allows for faster transport of substances over long distances
Animals Without a Circulatory System
- Turbellarians (flatworms): flat shape increases surface area and decreases diffusion distance
- Cnidarians: central gastrovascular cavity for digestion and transport, with a body wall only 2 cells thick
Functions of Circulatory Systems
- Transport: nutrients, wastes, respiratory gases, heat, and hormones
- Homeostasis: maintains a stable internal state despite changes in the external environment
Animals with Circulatory Systems
- Two types of systems: open and closed
- Open systems: arthropods and most molluscs, with no distinction between blood and interstitial fluid (haemolymph)
- Closed systems: annelids, echinoderms, cephalopods, and chordates, with blood distinct from interstitial fluid
Evolution of Vertebrate Circulatory System
- Adaptations of cardiovascular system in vertebrates through natural selection
- Common features: heart, blood vessels, and double circulation
- Fish: 2-chambered heart, 2 capillary beds
- Amphibians: 3-chambered heart, double circulation, and some mixing of oxygenated and deoxygenated blood
- Reptiles: 4-chambered heart, double circulation, and less mixing of oxygenated and deoxygenated blood
- Mammals and birds: 4-chambered heart, double circulation, and complete separation of oxygenated and deoxygenated blood
Mammalian Heart
- Sequential contractions of atria and ventricles
- Valves between atria, ventricles, and major arteries prevent backflow
- Contraction = systole, relaxation = diastole
How do the Heart Muscles Contract?
- Sinoatrial (SA) node or "pacemaker" sets the rate and timing of cardiac muscle cell contraction
- Generates electrical impulses relayed through atrioventricular (AV) node
Structure of Blood Vessels
- Blood flow in veins: interrelationship between blood flow velocity, cross-sectional area, and blood pressure
Blood Flow and Distribution
- Distribution of blood varies depending on the situation
- Always prioritizes the brain, kidneys, liver, and heart
- Also supplies the alimentary canal after a meal, and muscles during exercise
- Capillary flow controlled by muscle contraction and sphincters
Studying That Suits You
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Description
The learning content this week will help you to:
Interrelate biological structure, process and function in animals at organismal and organ levels Outline the structural systems of animals.
As you work through the activities and information in this module, think about how your own body achieves these tasks.
