CVA Chapter 14- Circulatory System

Circulatory system

Consists of blood, blood vessels, and muscular, pumping heart

Blood

Connective tissue whose extracellular matrix is plasma and contains formed elements

Formed elements

Cellular component of blood

Erythrocytes

RBCs. Most numerous type, carry hemoglobin to transport oxygen

Leucocytes

WBCs. 2 classes: granular and agranular

Granular leucocytes

Neutrophils, basophils and eosinophils

Agranular leucocytes

lymphocytes and monocytes

Thrombocytes

platelets. Involved in clotting response.

Hemopoiesis

AKA hematopoiesis. Process by which formed elements are produced. Only occur in red marrow in adults

Hemocytoblasts

Multipotent cells that will give rise to five stem cells producing all of the formed elements

Plasma

Extracellular component of blood. Mostly water but also includdes plasma proteins, nutrients, gases, wastes and electrolytes

Plasma proteins

Proteins of the blood. Include:

-albumen: serves for blood viscosity

- globulins: include the immunoglobulins

- fibrinogen: inactive form of fibrin (used for clotting)

Blood vessels

Hollow organs that serve to carry blood throughout body.3 classes: arteries, veins and capillaries

Tunica intima

Innermost tunic of blood vessels. Lined by endothelium

Tunica media

Second tunic of blood vessels. Contains smooth muscle

Tunica adventitia

Outermost layer of blood vessel tunics. Primarily loose c.t.

Vasa vasorum

Small blood vessels that service larger arteries and veins

Arteries

Serve to carry blood AWAY from heart to tissue. Carrying blood at highest pressure, thick tunica media

Subclasses of arteries

Elastic (largest)

Muscular

Arterioles (smallest and deliver blood into capillary beds)

Precapillary sphincter

Circular cuff of muscle located on terminal arteriole. Guards entrance into capillary bed.

Arteriovenous shunt

Allows blood to bypass capillary bed when precapillary sphincter is closed

Capillaries

Microscopic blood vessels of tissues used to exchange materials between tissues and bloods. Very thin to facilitate diffusion composed only of endothelium!

Continuous capillaries

Most numerous and widely distributed class of capillaries. Cross sections of cytoplasm of their endothelial cells appear as uninterrupted rings

Fenestrated capillaries

Class of capillaries that contain pores in endothelial walls where cytoplasm is absent

Sinusoids

Microscopic blood vessels found in certain regions of the body (ex. liver) which may or not may be capillaries

Veins

Serve to carry blood back to heart from body's tissues. Contain numerous valves to prevent backflow of blood

Venules

Smallest subclass of vein. First vessels to receive blood from capillary beds

Pericardial Cavity

Cavity where heart is located

Pericardium

Serous membrane covering heart

Endocardium

Inner lining and includes endothelium

Myocardium

Middle and thickest tissue layer. Rich in cardiac muscle tissue to pump blood

Epicardium

Outer layer of heart wall, composed of c.t. and serous membrane

Single Circuit

Circuit system used in fishes! Blood passes from heart to gills, from gills to rest of the body and from the rest of the body back to heart

Double Circuit Hearts

Circuit system used in amniotes! Two circuits: pulmonary and systematic

Pulmonary Circuit

Circuit of double circuit heart that carries deoxygenated blood from heart to lungs to pick up oxygen. Oxygenated blood is then carried from the lungs back to the heart

Systemic Circuit

Circuit of double circuit heart that carries oxygenated blood from heart to all of tissues of the body. Deoxygenated blood is returned to heart.

Hearts of gill breathing fishes

4 portions: sinus venosus, atrium, ventricle, conus arteriosus. Two chambered heart, one atrium and one ventricle!

Sinoatrial aperture

Where blood travels from sinus venosus into atrium

Atrioventicular aperture

Leads from atrium into the ventricle

Bulbus arteriosus

In teleosts that have shorter conus arterious, this muscular swelling at its base to compensate

Hearts in dipnoans and amphibians

Contain 4 modifications: interatrial septum, interventricular septum (dipnoans)/ ventricular trabeculae (amphibians), spiral valve, shortening of ventral aorta

Heart in amniotes

Typically 2 atria and 2 ventricles. (Turtles have a third ventricle).

Birds and adult mammals lack sinus venosus

Foramen Ovale

During embryonic development in amniotes interatrial septum is perforated by this opening

Fossa ovalis

Depression in adult mammal hearts that remain on interatrial septum

Superior and inferior vena cava

These vessels carry deoxygenated blood into right atrium

Pulmonary veins

Left atria in mammals receives oxygenated blood from lungs by way of these vessels

Auricles

Outpocketings in atria of mammals

Four chambered heart

Complete interventricular septum to prevent mixing of oxygenated and deoxygenated blood in ventricles. Present in crocs, birds and mammals

Three chambered heart

Incomplete interventricular septum allows for some mixing of blood. Present in most reptiles!

Cavum venosus

Third ventricle, in turtles and some squamates, near superior axis of interventricular septum

Trabeculae carnae

Muscular ridges on the luminal surface of the ventricle to reinforce ventricular walls

Cusps

One or more flaps of fibrous c.t. on each valve of amniote heart

Atrioventricular valves

Prevent backflow of blood from the ventricles into the atria. (Include tricupsid and bicuspid)

Cordae tendineae

C.t. strands that anchor AV valves in mammals

Papillary muscle

Bundles of smooth muscle onto to which AV valves are anchored

Semilunar valves

Prevent backflow of blood from the arteries (aorta and pulmonary trunk) into the ventricles (include pulmonary SL and aortic SL)

Innervation of heart

Cardiac muscle cells possess inherent rhthymicity, ability to beat without nervous stimulation and to coordinate that beat through ion exchange

Nodal tissue

Specialized cardiac muscle tissue. ANS nerves stimulate this tissue to vary heart rate

Sinoatrial node

Mass of nodal tissue in right atrium. The point that receives ANS innervation

Atrioventricular node

Another cluster of nodal tissue that is stimulated by SA node. Cause both ventricles to contract

Purkinje Fibers

Fibrous strands of nodal tissue that run through ventricles

Aortic arches in sharks

First aortic arches develop into those of mandibular arch. Other 5 arches develop shortly after:

First pair will disappear

Second-sixth pair will sprout buds

Spiracular arteries

Branches left in shark development when first aortic arch disappears

First pretrematic arteries

Develop from buds of 2nd aortic arch of shark

Postrematic arteries

Develop from buds of 3rd-6th aortic arch of shark

Afferent Branchial Arteries

Arise from segments located ventral to occlusions in shark aortic arch development

Efferent Branchial Arteries

Arise from segments located dorsal to occlusions in shark aortic arch development

Aortic arches in teleosts

Similar to shark aortic arch development. In most teleosts the first and second arches disappear

Aortic arches in Dipnoans

Pulmonary artery develops from right and left sixth aortic arch (same as in tetrapods!)

Aortic arches in tetrapods

First and second aortic pairs lost

Third arch and paired dorsal aorta become internal carotid arteries

Most amniotes lose fifth arch

Sixth arch become pulmonary arteries!

Dorsal aorta

Is paired in embryonic vertebrates!

Retains its paired state on head as internal carotids. Singular in the trunk and gives rise to paired and singular visceral branches (ex. subclavian, lumbar, iliacs, renals, celiac etc.)

Rete mirabilia

"wonderful maze" specialized arterial structures where an incurrent artery gives rise to numerous branching and anastomizing vessels that will be drained by a second (excurrent) artery (ex. glomeruli, temperature in sharks)

Common cardinal veins

Blood enters the sinus venous by way of these paired vessels in sharks

Anterior cardinal veins

Head is drained with these vessels. Located dorsal to gills in sharks

Posterior cardinal veins

Run lateral to kidneys. Drain many renal vessels from kidneys along length and the caudal vein. Drain into common cardinals In sharks

Posterior cardinal sinuses

Posterior cardinal veins expand into this structure in sharks

Renal portal system

Blood will travel from tail along remnant of old posterior cardinal veins to kidneys, enter the kidneys (pertitubular capillaries) and the exit the kidneys by way of new posterior cardinal and drain into common cardinals

Postcardinals

Located between kidneys. Become the new "posterior cardinal veins" and will drain into common cardinal veins and drain kidneys, gonad and body wall in sharks

Peritubular Capillaries

Capillaries in kidney of sharks that will allow blood to enter kidney after old posterior cardinals are lost

Subintestinal vein

Drains digestive tube in sharks. In development also used to be location where blood from caudal vein entered (but this connection from caudal vein and subintestinal is lost)

Lateral abdominal veins

Run from pelvic girdle to pectoral girdle and then drain into common cardinal veins in sharks.

Hepatic Portal System

Drains nutrient rich blood from the digestive tract to the liver in all vertebrates

Vitelline veins

Among first embryonic blood vessels to appear, run from yolk sac to heart in vertebrates

Hepatic Sinuses

Portion of vitelline veins between liver and sinus venous become this

Inferior vena cava

New vein that replaces lost posterior cardinal veins in amniotes

Azygous

Right posterior cardinal vein becomes this in mammals

Precavae

Common cardinals in amniotes.

Azygous drains into this.

Hemiazygous

Left posterior cardinal vein become this

Superior Vena Cava

Right precava kept in humas

Internal jugular veins

In amniotes the anterior cardinal veisn have become this

Post cava

AKA inferior vena cava or caudal vena cava in mammals. Develops from one of the two subcardinal channels gorwing into peritoneum that the liver is developing into

Ventral abdominal vein

Portion of two lateral abdominal veins will join together during development to from single vessel running from pelvic region to falciform ligament of liver

Allantoic veins

Veins lost in later development when allantois is lost

Umbilical veins

Allantoic vein of mammals termed this. Will drain into the liver from the placenta

Renal portal system of amphibians and reptiles

Use external iliac veins to carry blood from hindlimbs to renal portal vein