Chapter 9: Cardiac Muscle Flashcards
Cardiac muscle is under the control by the ___ nervous system
autonomic nervous system
Is cardiac muscle neurogenic or myogenic
myogenic through pace maker potentials.
If cardiac muscle is myogenic, what is the role of the autonomic nervous system then?
although cardiac muscle can contract on its own, the nervous system modifies contraction, can excite or inhibit, and can contribute to gradation
What is the general speed of myosin ATPases in cardiac muscle? (and thus speed of contraction)
slow
What is the means by which cardiac gradation is accomplished`
varying length of fibers (depending on extent of the filling of the heart chambers) and varying cytosolic Ca2+ concentration through autonomic, hormonal and local metabolite influence.
2 Unique characteristics of cardiac muscle
1) cardiac fibers are joined together in a branching network 2) action potentials have a much longer duration before repolarizing due to calcium influx while K+ is effluxing, prevents the cell from going back to negative polarization as fast.
cardiac muscle fibers branch adn are interconnected by ___ ___
intercalated disks
Why do we need circulatory systems?
1) simple diffusion takes too long 2) larger animals have thicker bodies and higher metabolic rates 3) circulatory systems overcome the slowness of diffusion and allow for much faster bulk transport.
3 distinct components of a circulatory system
1) fluid: blood or hemolymph, which carries the molecules and cells than need to be transported 2) pump: dedicated pumps are called hearts; moves the fluid 3) vessels: vascular components that carry the fluid between the pump and body tissue.
2 broad categories of circulatory systems
1) open systems 2) closed system
explain an open system. What organisms use them?
a circulatory system in which HEMOLYMPH moves vvia pumping through vessels that open into an extracellular space among the tissues. Tissues are bathed in fluid and directly exchange molecules with cells. The fluid may be moved by cilia or hearts around the tissue, and vessels (arteries) typically drain the hemolymph back to starting point Found in most mollusks and all arthropods.
What is a hemocoel? what can it be divided into?
a hemocoel is used in an open circulatory system and is the entire space that is filled with hemolymph. It may be subdivided into sinuses.
In an open system, hemolymph flows from the pump through an ___ into the ___ (a space among the tissues), and drain from the _____ through a ___ back to the pump.
In an open system, hemolymph flows from the pump through an ARTERY into the HEMOCOEL (a space among the tissues), and drain from the HEMOCOEL through a VEIN back to the pump.
explain a closed circulatory system
BLOOD (rather than hemolymph) exits a heart throguh vessels that are continuous all the way back to the heart. -vessels branch and become smaller until they become tiny leaking capillaries and molecules can be directly exchanged with cells - vessel s that merge and become larger before going back to the heart.
2 primary components of a circulatory fluid (either blood or hemolymph)
1)plasma: mostly water containing dissolved and dispersed plasma proteins 2) cellular elements: hemolymph/blood cells, leukocytes etc.
Outline the four different types of pumping mechanisms
1) flagella 2) extrinsic/ skeletal muscle pumps 3) peristaltic musclar pumps 4) chamber muscle pumps.
How do flagella act as a pump
they portrude out of epithelial cells and beat slowly to create a slow current. seen in sponges.
How does extrinsic skeletal muscle act as a pump? Give an example. What must the animal be doing in order for skeletal muscle to act as a pump?
because motion of muscles or skeletal elements which are NOT apart of the normal circulatory system can move fluids. This can usually only occur during locomotion. Therefor, the animal usually needs to be moving. Seen in legs of tall animals: blood flow is aided by active skeletal muscles squeezing blood through one-way valves in veins, and by the action of the respiratory muscles in breathing.
How do peristaltic muscle pumps function? what is the other name for this type of pump?
perstaltic aka TUBULAR muscle pumps. Occurs when muscles in the WALLS of vessels contract in a moving wave that pushes fluid in FRONT of it. Allows for unidirectional fluid flow.
At what point are peristaltic muscle pumps called hearts?
they are called hearts if they occur in specialized sections of vessels.
compared to peristaltic muscle pumps, how to chambered muscle pumps prevent backflow?
peristaltic muscle pumps can contract in such a way that the fluid only moves one way. However, chambered pumps need VALVES to create flow in one direction to prevent back flow when the pump relaxes.
2 primary chambers in a chambered pump system
1) atrium: collects returning fluid 2) ventricle: provides the primary force for outgoing fluid.
most animals have a primary ____ heart that provides the initial force, and an auxillary pump, that does what?
most animals have a primary SYSTEMIC heart that provides the initial force, and an auxillary pump that AIDS FLOW RETURNING TO THE PRIMARY HEART OR FLOW GOING TO CRITICAL ORGANS.
Example of an auxillary pump
in bees, they have a PULSATILE ORGAN that boosts flow to their wings.
comparative heart anatomy: crustaceans, insects, and arachnids have hearts that are located in the ___ region of the body.
DORSAL.
In a graphical form, outline the ion movement during a pacemaker potential.
During the first part of the potenital, there is Na+ influx, followed by K+ efflux reduction, resulting in a growing of positive potential in the cell. Once at threshold, voltage gated Ca2+ channels open and Ca2+ moves into the cells, causing an action potential.
