Cardiac muscle 1

physiology

Smooth muscle

Involuntary and localized to tubes or holllow organs

What are smooth muscle arranged in

sheets

what is smooth muscle stimulated by

Calcium

smooth muscle: multi-unit

contraction is performed smaller units independently (still stimulateed by nerves )

Smooth muscle: single unit

contract performed as a single coordinated unit (Functional Synctium)

• Cells are connected by gap junctions

• Self-stimulated

• No membrane potential maintenance/ Pacemaker potentials

Cardiac muscle

Lines the heart in a branched/interconnected arrangement of cells

Skeletal muscle traits in cardiac muscle

• Striated with myosin/actin (thick/thin) filaments

• Sliding filament contract method and calcium

smooth muscle traits in cardiac muscle

• Involuntary

• Self-stimulated and ANS regulation

• Single-unit contractions

• Has pacemaker potentials/contraction

What are the components of the circulatory system

Heart, blood vessels, blood

Circulatory system: heart

• Exerts pressure on blood allowing it to be pushed to where it needs to go

• Requires a level of pressure and pressure gradient for controlling blood flow

Circulatory system: blood vessels

• Tubes that act as passageways for blood to travel in (From heart to tissue/organs and back)

• Artery, Vein, Capillary, Venule, Arteriole etc. are types of blood vessels

• Vasodilation and Vasoconstriction

• Vaso → blood vessels

Circulatory system: blood

• Transport medium for materials or nutrients

• Nutrients, hormones, white blood cells, oxygen, waste, carbon dioxide

two circuit loops in circulatory system

Pulmonary Circuit and Systemic Circuit

pulmonary circuit location

• Between the heart and the lungs

• Pulmonary/Pulmonology refers to respiratory or lung specialties

what is the purpose of the pulmonary circuit

to extract oxygen from the lungs

systemic circuit location

• Between the heart and body tissues

• Branches into parallel pathways that reach all organs

systemic circuit purpose

Delivers Oxygen (O2) in exchange for CO2 waste

Artery / Arteries / Arterioles

• Blood vessels that carry oxygenated blood away from the heart

• Outgoing oxygen for delivery to other organs/tissues

Veins / Venules

• Blood vessels that carry deoxygenated blood toward the heart

• After organs/tissues have utilized oxygen. (Usually carries waste products like CO2)

What are the exceptions in the pulmonary circuit

the oxygen traits are reversed

• Pulmonary Arteries take blood away from the heart, but are deoxygenated

• Pulmonary Veins bring blood back to the heart, but are oxygenated

how many functions does the systemic circuit have

multiple while the Pulmonary Circuit is predominantly for lungs and obtaining oxygen

Systemic circuit: transportation

• Respiratory system → delivers oxygen

• Digestive system → delivers nutrients

• Excretion → waste removal

Systemic circuit: regulation (hormonal)

• Hormonal → transfer hormone molecules to target cells i.e.

Antidiuretic hormone

Systemic circuit: regulation (temp)

• Temperature → vasodilation = release heat, vasoconstriction = retain heat

Systemic circuit: protection ( clotting factors)

stops blood loss i.e. scabs

Systemic circuit: protection ( immune system)

delivers white blood cells to fight infections

Structure of the Heart

• The heart is one organ comprised of separately functioning pumps

• Two halves and four chambers

upper chambers

atria/ atrium

atria/ atrium

• Receives blood that is returning back to the heart

left atrium

oxygenated blood from the lungs

right atrium

deoxygenated blood from other organs/tissues

lower chambers

ventricles

ventricles

Receives blood from the atria / atrium

• Blood from the atria are then pumped out away from the heart

Right Ventricle

pumps deoxygenated toward the lungs

Left Ventricle

pumps oxygenated blood to the body

septum

A separator that dividess the left side from the right side of the heart

septum left side

oxygen rich

septum right side

oxygen poor

How does blood circulate?

Directionality of blood flow

Starts with blood entering the

right atrium

right atrium has

• Deoxygenated blood and high CO2

• systemic circuit veins

where does the blood come from in the right atrium

the superior and inferior vena cava

from the right atrium where does the blood get pumped to

the right ventricle

the right ventricle

pumps blood to lungs for replenish oxygen

The Systemic Circuit funnels blood

into the right side of the heart

the right side funnels

blood into the pulmonary circuit

After leaving the right ventricle, blood is sent to the lungs via the

pulmonary artery

for the lungs arteries and veins are

reversed

within the lungs the blood becomes

oxygenated

Oxygenated blood leaves the lungs and re-enters the

left atrium of the heart ( it enters via the pulmonary vein

Blood is pumped from left atrium to the

left ventricle

the blood leaves the left ventricle through the

aorta

where is blood pumped back into from the aorta

systemic circuit

the left side of the heart

receives oxygenated blood from the lungs

The left and right sides pump

equal amounts of blood

what would uneven flow lead to

excess heart strain

pump strength

pressure and resistance

pressure

force exerted on vessel walls

resistance

friction between the walls and blood

Pressure and Resistance: Pulmonary

lower pressure and resistance

Pressure and Resistance: Systemic

higher pressure and resistance

which side of the heart works harder

Left side works harder than the Right side

where does the right side pump blood to

the lungs

where does the left side pump blood to

the entire body

how many directions can blood move

in one direction

blood order

Veins → Heart Atria → Heart Ventricles → Arteries → Tissues

valves

prevents improper blood flow (Opens and closes passively with blood flow)

where are valves found

in blood vessels and heart

Heart: Atrioventricular Valves

Located in between the atria and the ventricles of the heart

Atrioventricular Valves names

Tricuspid Valves and Bicuspid (Mitral) Valves

Tricuspid

right

bicuspid

left

Heart: Semilunar Valves

• Located in between the ventricles and the arteries

• Normally closed when the ventricles are being filled

semilunar valves names

Pulmonary Valve and Aortic Valves

heart sounds: Lub

closing of the Atrioventricular

• systole

heart sound: dub

closing of the Semilunar

• diastole

How does the heart pump? How does it keep going and maintain heart rate?

Heart specific action potentials called pacemaker potential

• Pacemaker potentials are spontaneously generated

Heart contains

pacemaker nodes (Atrioventricular/Sinoatrial)

peacemaker nodes

These generate action potentials or pacemaker pontetials

what do peacemaker nodes result in

rhythmic contraction of the heart

Autorhythmic

initiates and conducts action potentials

what does Autorhythmic contain

slow voltage-gated Sodium channels

when do slow voltage-gated Sodium channels open

during hyperpolarization

Sodium will slowly/gradually increases membrane potential until it triggers

voltage-gated Calcium channels

Calcium influx causes

a rapid depolarization

what are slow voltage-gated Sodium channels followed by

conventional Repolarization/Hyperpolarization with Potassium

Contractile

performs the mechanical work necessary for pumping

Autorhythmic cells stimulate

contractile cells

contractile cells are similar to neuron action potentials but what is the catch

Contractile cells have a rapid Sodium depolarization

what is rapid Sodium depolarization followed by

a slow influx of Calcium called the Plateau Phase

why do we have the plateau phase

• The slow influx of Calcium helps control the length of the refractory period

• This allows time for the heart to both fill with blood and pump it out before receiving the next contraction signal

The Atria and Ventricle form a

functional syncytium

syncytium

grouping of cells

the functional syncytium has

Synchronous contraction of both chambers (spreading Action potential throughout the heart)

What blocked direct cinduction

the septum

what does the septum regulate

in-flow, out-flow of blood between left and right sides

Sinoatrial Node (SA)

• Initiates action potential signaling

what does the SA node set peacemaker potentials around

70-75 beats per min

Where do the SA nodes send the signals

to the atrioventricular node

Atrioventricular Node (AV)

Receives the signal and pacemaker potentials from the SA Node