Types of Circulatory Systems Flashcards
Why would animals have a circulatory system?
Diffusion is efficient over short distances, but larger animals need to move large amounts of fluid by bulk flow to get the oxygen closer to their cells
What is bulk flow?
A pressure increase in one area of the system drives the flow of the fluid/gas to an area with lower pressure
What are the 3 features of a circulatory system?
- Propulsive organ
- Circulating fluid
- System of tubes or channels
What are the 3 possible forms of a pumping organ?
- Contractile chambers
- External pump from contractions of skeletal muscles
- Peristaltic contractions
What are the 4 types of circulatory fluids?
- Blood
- Hemolymph
- Lymph
- Interstitial fluid
What are the 2 types of circulatory system?
Open and closed
What animals have an open circulatory system?
Arthropods and some molluscs
What are the characteristics of open circulatory systems?
The circulatory fluid is not enclosed in vessels, but is circulated in the spaces between cells and organs. The blood pressure is relatively low
What are lacunae?
Small spaces between cells
What are sinuses?
Large spaces between organs
What is a hemocoel?
Central body cavity
What is the structure of the circulatory system in brachiopod crustaceans?
They have a long tubular heart that extends the whole length of their body with lots of ostia. The type and number of vessels vary according to the organism
What is the structure of the heart of decapod crustaceans?
Muscular, chambered heart with valves to provide unidirectional blood flow
How does circulation work in decapods?
The heart pumps hemolymph through the arteries and smaller tubes until it pool around the head and tissues then back to the heart
What type of pacemaker is seen in decapod hearts?
Neurogenic. Contractions are controlled by nerve impulses from the cardiac ganglion
What happens in decapod hearts during systole?
The heart contracts, valves open, ostia close, the suspensory ligaments tighten. Hemolymph gets pushed into the arteries (pressure pump)
What happens in decapod hearts during diastole?
The heart relaxes, valves close, ostia open, suspensory ligaments relax. Hemolymph gets sucked in through the ostia (suction pump)
What is the cavity where the heart is located in decapods?
Pericardial sinus
What is the “vein” that brings hemolymph into the pericardial cavity in decapods?
Branchiopericardial vein
Is hemolymph coming into the pericardial cavity oxygenated or deoxygenated?
Oxygenated
What is a closed circulatory system?
Circulatory fluid is enclosed in vessels and always physically separated from the tissues. Pressure is higher
What are the 3 blood vessel systems in a closed circulatory system? What is the function of each one?
Arterial system: distribute blood and act as pressure reservoir
Capillaries: transfer of materials
Venous system: act as blood reservoir and carries blood back to the heart
What are the 4 layers that make up arteries and veins?
Tunica externa, tunica media, tunica intima, and endothelium
What is the tunica externa made of?
Collagen
What is the tunica media made of?
Smooth muscle
What are the 3 types of capillaries?
Continuous, fenestrated, sinusoidal
What are continuous capillaries? Where are they found?
Endothelial cells are connected with tight junctions, allowing passage of small molecules. Found in skin and muscles
What are fenestrated capillaries? Where are they found?
The endothelial cells are full of pores that allows easy passage of small molecules. Found in kidneys, intestines and some endocrine organs
What are sinusoidal capillaries? Where are they found?
The endothelial cells are loosely linked and have passages for large molecules and proteins. Found in bone marrow, liver, and some endocrine organs
How do the 3 hearts in cephalopods work?
The 2 branchial hearts pump deoxygenated blood across the gills, and the systematic heart pumps oxygenated blood to the body
How many circuits are present in water breathing fish? How does it work?
Single circuit. Blood is pumped to the gills, becomes oxygenated, then circulates around the body and back to the heart
How is the blood pressure different between pulmonary and systemic circuits?
Lower in the pulmonary circuit
