Cardiovascular system 1

visceral pericardium

info

• on surface

• simple squamous

parietal pericardium

location and contents

• pericardial sac around heart

• simple squamous

• loose CT

pericardial space

location and function

• contains pericardial fluid

• lubrication and protection

layers of heart

• epicardium

• myocardium

• endocardium

epicardium

• outermost layer

• consistent with visceral pericardium

myocardium

• wall of heart

• cardiac muscle with CT

endocardium

• lines the chamber

• inner lining

• simple squamous

right and left atria

• thin walled

• irregular shape

• carnival and dorsal

• interatrial septum divides them

• right and left ventricles

• thick walled

• angled

• caudal and ventral

• interventricular septum divides them

valves

description, types

• flaps of CT, cusps

• Atrioventricular (AV) valves

• Semilunar valves

Atrioventricular (AV) valves

• Right – tricuspid 

• Left - mitral

• Separating each atrium from each ventricle

• Chordae tendineae

  • “heart strings”

• Papillary muscles 

  • attach to chordae tendineae

Semilunar valves

• Aortic

  •  between left ventricle and aorta

• Pulmonary 

  • between right ventricle and pulmonary artery

Pulmonary circuit

• right side of heart

• Heart to lungs (deoxygenated blood) and back (with oxygenated blood)

• Pick up oxygen, give off carbon dioxide

Systemic circuit

• left side of heart

• Heart to body with (with oxygenated blood) and back (with deoxygenated blood)

• Pick up carbon dioxide, gives off oxygen to tissues (cells)

pulmonary circuit expanded

• Deoxygenated blood from body enters right atrium

• Through right AV valve (tricuspid) into right ventricle

• Through pulmonary semilunar valve into pulmonary artery

• Pulmonary artery branches to smaller arteries

• to smaller arterioles 

• to capillaries of alveoli of lungs

• Venules to veins

• to larger veins 

• to pulmonary vein into left atrium of heart

systemic circuit expanded

• Oxygenated blood from pulmonary vein 

• to left atrium of heart

• Through left AV valve (mitral valve) to left ventricle

• Through aortic semilunar valve to aorta 

• Branches to large arteries to smaller arteries 

• to arterioles to capillaries in tissues all over body

• Venules to veins to larger veins 

• to cranial and caudal vena cavae to right atrium

cardiac action potential

• Fluctuating resting membrane potential (RMP)

  • Leaky Na+ channels

  • Slowly increases RMP to threshold

• 2.  Voltage gated Na+ channels open

  • Na+ rushes into cell for rapid voltage increase  depolarization 

• 3.  Plateau phase as Ca++ enters cell

• 4.  Repolarization as K+ leaves cell

myocardium

microscopic anatomy

• Mostly cardiac muscle  

  • striated

• Purkinje fibers  

  • Specialized cells for initiation and carrying of A.P.

• Intercalated disks  

  • Specialized cell junctions for flow of A.P.  contract as one unit

characteristics of cardiac muscle

intrinsic

• No nerve impulse needed

• Initiates its own action potential within the heart itself within the right atrium via sinoatrial (SA) node

characteristics of cardiac muscle

involuntary

• Not under conscious control

• A.N.S. (Parasympathetic/Sympathetic) controls rate and force

conduction network

• spreads AP through heart

• Pacemaker: Sinoatrial (SA) node in right atrium

  • Sets rate of firing

  • Spreads across both atria

• AP -> Atrioventricular (AV) node

  • Pause as atria contract

• AP -> AV bundle

• Right and left bundle branches -> Down ventricular septum

• Purkinje fibers through walls of ventricles

  • Carry AP impulse very quickly

ECG - electrocardiogram

• Measures electrical movement across heart—moves across body

• Tells us heart rate, regularity of beats

sinus rhythm

normal

arrhythmia

abnormallity

leads

points of electrode attachment

Parts

• P wave   

  • depolarization of atria

• PR interval  

  • conduction through AV valve

• QRS complex  

  • depolarization of ventricles (strongest and fastest)

• T wave  

  • repolarization of ventricles

cardiac muscle

• physical and mechanical events of heart filling, contraction

• can be interposed on electrical events

systole

• contraction

• created high pressure

diastole

• relaxation and filling

• lower pressure

events in the heart pt 1

• AV valves 

  • open when atrial pressure is greater than ventricular pressure

• SL valves open 

  • when ventricular pressure is greater than arterial pressure

• AV valves close 

  • when ventricular pressure is greater than atrial (as ventricles contract)

• First heart sound  

  • ”lub” or S1 sound

events in the heart pt 2

• Turbulent blood against closed valves  

  • produced when the ventricles contract and AV valve close

• SL valves close 

  • at end of ventricular systole when arterial pressure is greater than ventricular pressure

• Second heart sound

  • ”dub” or S2 sound

• Turbulent blood against closed valves

• Occasional third heart sound

  • rapid ventricular filling

  • Especially in large, slow hearts

Heart murmurs

• valves don’t close completely or blood flow is extra turbulent

mammalian fetal circulation

• 2 special vessels through umbilical cord

• Umbilical vein

  • One vessel

  • From placenta to fetus

  • Relatively oxygen and nutrient rich blood

• Umbilical arteries

  • Two vessels

  • From fetus to placenta

  • Relatively oxygen and nutrient poor blood

• 3 shunts (bypasses)

3 shunts

• Ductus venosus

  • Bypasses liver

  • Umbilical vein connects to caudal vena cava

• Foramen ovale

  • Right to left atrium

  • Bypasses lungs

  • Will close with first breath

• Ductus arteriosus

  • Pulmonary artery to aorta

  • Bypasses lungs

portal systems

• blood system from one organ to another

• bypassing general circulation

  • Hepatic

  • Renal

Hepatic

• Hepatic portal vein collects blood from gastrointestinal tract to liver

• Liver processes nutrients

• “Filters” blood: wastes, drugs

• Blood enters the caudal vena cava (unoxygenated)

Renal

• Hind limbs to renal portal system to kidneys

• maintain consistent blood supply to kidney when filtration is reduced

• Filters toxins before sending back to general circulation

• Lower vertebrates (birds, reptiles, amphibians, fish)

single circuit systems

• fish

  • 2 chambers in heart (atrium and ventricle)

• amphibians

  • 3 chambered heart  

    • 2 atria and 1 ventricle

• reptiles

  • Most have 3 chambered heart  

    • 2 atria and 1 ventricle