The Heart

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  • Created by: Alex
  • Created on: 08-05-13 11:27
purpose of a heart
Delivers 02 to the body by aqueous medium. (water has low O2 solubility so plasma solution needed)
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Open system
Heart pumps blood into open ended vessels
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Hemolymph
Fluid that bathes tissues of an animal with an open circulatory system
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Closed System
Blood flows through continuous circuit of blood vessels.
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Purpose of closed system
Transports nutrients, 02, metabolic wate, hormones, metabolic heat, maintains ph & defends against microorganisms
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Vertebrate circulatory system components
Heart, blood vessels, blood, lymph and lymph vessels
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How many circuits in typical closed system
2, one thorugh heart, one through body. allow low pressure in lungs and high in remainder of body
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Features of evolution
Single central pump, unidirectional flow and one way valves to maintian pressure
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Location of heart
Between sternum and vertebre in upper part of throax
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Size and weight of heart
12cm long, 8cm diameter, 250-300g in weight
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4 chambers of heart
Left and right ventricle and atrium
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4 vessels of heart
Pulmonary artery, pulmonary vein, aorta and vena cava
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4 valves of heart
left and right AV valve, pulmonary valve and aortic valve
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Whats's the tricuspid valve
The three-segmented valve of the heart that keeps blood in the right ventricle from flowing back into the right atrium. - right AV valve
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What's the bicuspid valve
two segmented valve - 2 flaps/cusps. between the left atrium and the left ventricle. It permits blood to flow one way only, from the left atrium into the left ventricle (Left AV valve)
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what are chordae tendineae
Heart strings - cord-like tendons that connect the papillary muscles to the tricuspid valve and the mitral valve in the heart. Prevent Eversion (turning inside out)
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Purpose of semi-lunar valves
Prevent backflow. forced open when pressure is greater on non-lunar side. close when pressure changes. on at opening of aorta,, on at opening of pulmonary artery
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Type of muscle is cardiac?
Striated
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Diastole
When heart muscle relaxes and allows chambers to fill with blood - expansion
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Systole
The phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries.- Relaxation
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What makes the Heart beat (lub-dub)
1. Upper &lower chambers fill & the pulmonary & aortic valves close. 2. upper chambers contract and prime lower chamber. 3. lower chamber contracts, the AV valve closes (1st sounds) blood ejects through the semi-lunar valve which then closes (2nd sou
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What system controls heart beat
Autonomic nervous system combined with an internal pace maker
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Pathway of Conduction
1.Stimulus initiated in SAN 2.atrial muscle fibres contract 3.conduction via AVNode 4.spreads down AV bundle to right and left branch bundle eventually forming purkinje fibres 5.fibres conduct impulses to muscle fibres of both ventricles 6.contractio
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Two types of muscle in heart
Pacemaking and contractile
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Excitation-contraction coupling definition
physiological process of converting an electrical stimulus to a mechanical response
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Excitation
Cardiac muscle is excited by spread of depolarizing current through gap junctions. triggers the opening of ca2+ channels. ca2+ binds to troponin enabling crossbridge cycle to occur. to terminate ca2+ is pumped out cytosol
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What controls heart function
Heart muscle itself and the AutonomicNS
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Cardiac output (equation)
Heart rate x stroke volume
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How much blood pumped in a minute
5-25L
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Starlings law of the heart
Stroke volume of the heart increases with increase in volume of blood filling the heart. -ventricular wall stretches causing cardiac muscle 2 contract more forcefully. increase in load experienced by each muscle fiber = greaterheart contraction &beat
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Heart beat at rest
SAN at 70bpm
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Neuronal activity during exercise
Parasympathetic activity falls, sympathetic activity increases - increase heart beat and contractile force
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Neurotransmitter parasympathetic NS
Acetylcholine
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Neurotransmitter for Sympathetic NS
Norepinephrine (post ganglionic) Acetylcholine (pre ganglionic)
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Other cards in this set

Card 2

Front

Open system

Back

Heart pumps blood into open ended vessels

Card 3

Front

Hemolymph

Back

Preview of the front of card 3

Card 4

Front

Closed System

Back

Preview of the front of card 4

Card 5

Front

Purpose of closed system

Back

Preview of the front of card 5
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