Circ Systems Pt 2

Open

What type of CS do Polychaetes have?

Closed

What type of CS do Oligochaetes have?

Molluscs

What Annelid class have mainly open CS, but some of them have closed CSs?

Open

What type of CS do Arthropods have?

Ostia

Found in Crustaceans; Small holes in the heart or vessels that can be open or closed to regulate blood flow.

Sinus

An open space adjacent to open ended blood vessels.

In decapods, these can be shut down through muscles to control blood flow.

Open

What type of CS do insects have?

Hemolymph

Transports nutrients and waste through system. Found in Insects.

Arteries

Tubes in which blood flows away from the heart

Aterioles

Branches of smaller arteries, found within tissue, blood flows into capillaries

Capillaries

Site of diffusion of molecules between blood and interstitial fluid.

Receives blood from arterioles.

Lack the tunica media and externa

Venules 

Formed when capillaries group together

Veins

Carry blood back to the heart

Grouped together venules

Tunica media

Component of the wall surrounding the central lumen

internal lining

made of smooth, epithelial cells (vascular endothelium)

Central Lumen

The cavity within veins

Tunica media

Component of the wall surrounding the central lumen

Middle Layer

Smooth muscle and elastic connective tissue

Tunica Externa

Component of the wall surrounding the central lumen

Outermost Layer

Made up of collagen

Continuous Capillary

Type of Capallary

Cells are held together by tight junctions

present in skin and muscle

Fenestrated Capillary

Type of Capallary

Cells contain pores, specialized for exchange

Found in the kidneys, endocrine organs, and intestines

Sinusoidal Capillary

Type of Capallary

Few tight junctions; Porous for exchange of larger proteins 

Found in the liver and bone

Leaky Capillaries

Capillaries that are the sites of greater exchange

What type of CS do all vertebrates have?

Closed

One

How many circuits for respiration do water-breathing fish have?

Two

How many circuits for respiration do air-breathing fish have?

Pulmonary Circuit

Right side of the heart

Systemic Circuit

Left side of the heart

Four

How many heart chambers do birds and mammals have?

2,2

Within the 4 chambered heart, there are __ atria, and __ ventricle(s)

High Pressure

What amount of pressure is within the systemic circuit?

Low Pressure

What amount of pressure is within the pulmonary circuit?

Three

How many heart chambers do amphibians and reptiles have?

2, 1

Within the reptile/amphibian heart, there are __ atria and __ ventricle(s)?

Systole

Phase of the cardiac cycle

The contraction, when the blood is forced out into circulation

Diastole

Phase of the cardiac cycle

Relaxation, when the blood enters the heart

Neurogenic

Is the arthropod heart neurogenic or myogenic?

What series are the fish heart chambers arranged in?

Sinus Venosus, Atrium, Ventricle, Bulbus arteriosus

Trabeculae

Within Amphibian Hearts, in the ventricle

Helps prevent mixing of oxygenated and deoxygenated blood in the ventricle

Spiral Fold

Within Amphibian Hearts, in the cornus arteriosus

Helps direct deoxygenated blood to the pulmocutaneous circuit

Directs oxygenated blood to the systemic circuit

2,3

Reptiles have __ atria, and __ interconnected ventricular components

Cavum Venosum

Within the reptile heart

An interconnected ventricular component

Leads to the systemic aortas

Cavum pulmonale

Within the reptile heart

An interconnected ventricular component

Leads to pulmonary artery

Cavum arteriosum

Within the reptile heart

An interconnected ventricular component

separates the oxygenated and deoxygenated blood

AV Valves

Between the atria and the ventricles.

Tricuspid on the right, Bicuspid on the left

Semilunar Valves

Between ventricles and the arteries

Aortic between left ventricle and aorta

Pulmonary between right ventricle and pulmonary artery

Ventricular Diastole

Phase of the Mammalian Cardiac Cycle

Pressure in the atria exceeds ventricular pressure.

AV valves open and the ventricle fills

Atrial Systole

Phase of the Mammalian Cardiac Cycle

Atrial contraction forces additional blood into ventricles

Ventricular Systole

Phase of the Mammalian Cardiac Cycle

Ventricular contraction pushes the AV valves closed

increases pressure inside the ventricle 

Ventricular Systole

Phase of the Mammalian Cardiac Cycle

Increased ventricular pressure forces the semilunar valves open.

Blood is ejected

Ventricular Diastole

Phase of the Mammalian Cardiac Cycle

When the ventricles relax

Artery pressure exceeds ventricular pressure

Closes the semilunar valves

Myogenic

Are vertebrate hearts neurogenic or myogenic?

Cardiomyocytes

Produce spontaneous rhythmic depolarization

Do not require nerve signals 

Electrically coupled via gap junctions to ensure coordinated contractions

Pacemaker Cells

Cells with intrinsic rhythm. Derived from cardiomyocytes.

Located in the sinus venosus in fish, right atrium for other vertebrates.

Pacemaker Cell Characteristics

Small w/ few myofibrils, mitochondria, or other organelles.

Do not contract

Have unstable membrane potential, drifts upwards until it reaches threshold, initiates AP

Pacemaker, increasing heart rate

Norepinephrine is released from sympathetic neurons

Epinephrine is released from the adrenal medulla

Opens Na+ and Ca2+ channels

Increases rate of depolarization, increases frequency of AP

Pacemaker, decreasing heart rate

ACh is released from parasympathetic neurons

Opens more K+ channels and causes pacemaker cells to hyperpolarize

Increases time for depolarization

Decreases frequency of APs

Plateau Phase

A phase of extended depolarization that corresponds to a refractory period

Lasts as long as the contraction

Usually caused by Ca2+ entry by L-type channels 

Tetanus

Sustained contraction

Phases of the Cardiac Cycle in Mammals

Ventricular Diastole, Atrial Systole, VS; Isovolumetric Contraction, VS; Ventricular Ejection, Ventricular Diastole

Ventricular Filling in Birds and Mammals

Ventricles fill passively during diastole.

Atrial contractions add little blood to the ventricles 

Ventricular Filling in Fish and Amphibians

Ventricles are filled by contraction of the atrium.

Elasmobranchs may use ventricular suction to pull blood from veins.

First Step of the CPMH

SA node depolarizes

depolarization spreads via the internodal pathway 

Second Step of the CPMH

AV node delays the signal

Depolarization spreads through atria via gap junctions

Causes atria to contract

Third Step of the Conducting Pathway in Mammalian Hearts

Depolarization spreads through the bundles of His and Purkinje fibers

Fourth Step of the Conducting Pathway in Mammalian Hearts

Depolarization spreads upward through ventricles, causing ventricles to contract

Modified Cardiomyocytes

Spread AP through myocardium.

Have an elongated pale appearance.

Do not contact, just send out signals 

Can undergo rhythmic depolarization

EKG

Composite recording of APs in cardiac muscle

P Wave

Component of an EKG

Atrial depolarization

QRS Complex

Component of an EKG

Ventricular Depolarization

T Wave

Component of an EKG

Ventricular repolarization

Ventricular Fibrillation

Ventricles do not contract in any coordinated fashion

Leads to blood not effectively being pumped to the rest of the system

Atrial Fibrillation

SA node fires irregularly

Generates normal QRS but P waves can be inconsistent 

Cardiac Output

Heart Rate x Stroke Volume

Heart Rate

Modulated by autonomic nerves and adrenal medulla

Bradycardia

Decreased HR

Tachycardia

Increased HR

Stroke Volume

Component of Cardiac Output

Modulated by various neurons, hormonal, and physical factors

Frank-Starling Effect

States that increased end-diastolic volume results in more forceful contractions and increased SV.

Autoregulation

Heart automatically compensates for increases in volume of blood returning to the heart.

Direct response of the arteriole and smooth muscle.

Arterioles

What is responsible for the distribution of blood?

Intrinsic Factor of Blood Flow Regulation

Metabolic state of the tissue

Extrinsic Factor of Blood Floe Regulation

Nervous and endocrine systems

Vasoconstriction

Norepinephrine from sympathetic neurons causes ___

Vasodilation

Decreased sympathetic tones cause ___

Vasopressin

Posterior Pituitary

Causes generalized vasoconstriction

Angiotensin II

Produced in response to decreased blood pressure

Causes generalized vasoconstriction

Arterial Natruretic Peptide

Produced in response to increased blood pressure promoted generalized vasodilation

Arteries

Velocity of blood is highest where?

Capillaries

Velocity of blood is lowest where?

Veins

Velocity of blood is intermediate where?

Skeletal Muscle Pump

Pump assisting in moving blood back into the heart

Contractions of muscle squeezes the vein

Respiratory Pumps

Pump assisting in moving blood back into the heart

Pressure changes in the thoracic cavity during ventilation

Kidneys

What organ adjusts blood volume/pressure by excreting or retaining water?

Lymphatic System

A system that collects excess filtered fluid and returns it to the circulatory system

Lymph Nodes

Filter lymph to remove pathogens

Lymphatic Veins and Ducts

Lympathic System

Contain valves to prevent backflow

Edema

Accumulation of interstitial fluid

Vertebrate Blood

Composed of plasma, erythrocytes, and other blood cells and clotting cells. Also hematocrit 

Hematocrit

A fraction of blood made up of erythrocytes

Hemocytes

Blood Cells

Participate in:

Oxygen/Nutrient Transport/Storage, Phagocytosis, Immune Defense, and Blood Clotting 

Platelets

In mammals

Fragments of cells within blood