Ch 14 Circulatory system

blood 

c.t that can be divided into a cellular and extracellular components 

Cellular component of blood =

Formed Elements

3 classes of formed elements

1. erythrocytes

2. leucocytes

   1. granular & agranular

3. thrombocytes

Erythrocytes

red blood cells

• most numerous blood cell

• have hemoglobin to carry oxygen

Leucocytes

white blood cells. serve to protect from infections

• Granular Leucocytes - neutrophils, eosinophils, and basophils

• Agranular Leucocytes - lymphocytes and monocytes

thrombocytes

platelets;  clotting response 

The formed elements are produced by the process

hemopoiesis 

extracellular component of blood = 

plasma 

plasma proteins include:

1. albumen: serves for blood viscosity 

2. globulins: includes immunoglobulins 

3. fibrinogen: inactive form of fibrin; protein required for clotting 

three tunics of blood vessels

1) tunica interna/intima

2) tunica media 

3) tunica externa/adventitia 

Tunica Intima/interna

inner most tunic in contact with blood

• typically has lining of endothelium

tunica media

composed of smooth muscle

tunica externa/adventitia

composed primarily of loose c.t

• has numerous small blood vessels that service larger arteries and veins = Vasa Vasorum

Arteries

carry blood from heart to body

• have thickest walls because they carry blood in highest pressure 

• tunica media is thickest tunic

3 classes:

1. Arterioles

2. muscular 

3. elastic 

Arterioles

smallest arteries that carry blood into capillary beds

• precapillary sphincter guards entrance of capillary beds 

  • blood bypasses bed when sphincter is closed by way of arteriovenous shunt 

Capillaries

microscopic blood vessels where materials are exchanges b/w tissues and blood

• walls are very thin to maximize diffusion

• no tunics. just endothelium wall 

3 classes:

1. continuous 

2. fenestered/discountinuous 

3. sinusoids 

continuous capillaries

most numerous and widely distributed type of capillary

• appear as uninterrupted ring in cytoplasm cross section

fenestered/discountinuous capillaries

numerous pores in endothelium walls => less barrier for diffusion

Sinusoids

are only found in specific parts of body (liver) and may or may not be true capillaries

• have a wider lumen

• have macrophages guarding pores 

Veins

serve to carry blood from body → heart

Their walls are proportionately thinner than are those of similar sized arteries since they carry blood at a lower pressure.

• As blood travels through the true veins towards the heart,
  blood pressure will gradually increase

in larger veins, the tunica externa is the thickest tunic and it is rich in collagen, not muscle

Venules

smallest subclass of veins

the first vessels to receive blood from capillary beds

• this is when blood is at its lowest pressure.

valves

prevent the backflow of blood

The heart

located in pericardial cavity & covered in serous membrane called Pericardium

3 tunics:

1. Endocardium: inner, endothelial lining

2. myocardium: middle, thickest layer. cardiac muscle 

3. epicardium: outer layer composed of c.t and pericardium 

Heart wall receives its own blood supply from _____

coronary blood vessels

Single Circuit Heart

found in fish

blood flow:  heart → gills → body → heart 

double circuit heart

found in amniotes

1. pulmonary circuit: carries deoxygenated blood from heart into lungs to pick up O₂. Oxygenated blood flows back into heart.

2. systematic circuit: oxygenated blood is carried from heart → body. deoxygenated blood is carried back into heart

Fish hearts

4 portion sequence: sinus venous, atrium, ventricle, & conus Arteriosus 

have a 2 chambered heart: 1 atrium & 1 ventricle 

Sinus venous - Fish hearts

receives deoxygenated blood from tissues

travels through the Sinoatrial Aperture, into the
atrium

• Aperture guarded by unidirectional valves 

Atrium- Fish Heart

receives blood from the sinus venosus and pushes it into

the ventricle through the Atrioventicular Aperture

• is a thin walled muscular sack

• Aperture guarded by unidirectional valves 

Ventricle - Fish Heart

a muscular, thick walled chamber that serves as the main pumping chamber of the heart.

• pumps blood into the conus arteriosus

Conus Arteriosus - Fish Heart 

receives blood from the ventricle and conducts it to the gills.

• wall of the conus arteriosus is primarily composed of cardiac muscle and elastic c.t.

Cartilaginous fishes have a larger conus arteriosus.
Bony fishes, have a shorter conus arteriosus.

Amphibian Hearts

displays modifications that allow oxygenated blood returning from the lungs or swim bladder to be separated in the heart from deoxygenated blood returning from the other organs

• Interarterial Septum

• Interventricular Septum 

• Spiral Valve 

• Near disappearance of ventral aorta 

Interatrial Septum - Amphibian hearts

establishes either the complete or partial separation of a right and left atrium.

• left atrium is oxygenated 

• right atrium is deoxygenated 

Interventricular Septum - Amphibian Heart 

serve to separate oxygenated and deoxygenated blood

Spiral valve -amphibian hearts

it forces oxygenated blood into the aortic arches that go to the tissues.
It also forces deoxygenated blood into the aortic arches that go to the lungs or gills

Amniote Hearts 

have 2 atria and 2 ventricles 

• Birds and adult mammals lack a sinus venosus

• right and left atria are separated completely by an interatrial septum

During embryonic development the interatrial septum is
perforated by an opening called the

Foramen Ovule 

• seals up prior to birth/hatching 

• Fossa Ovalis marks where ovale once was 

Right Atrium - Amniote Heart

receives deoxygenated blood from superior and inferior vena cava (mammals and birds)

Left atrium - amniote hearts

receives oxygenated blood from the lungs by way
of the Pulmonary Veins

Superior and Inferior vena cava in mammals and birds are homologous to what vessels in reptiles and fish?

Sinus venosus 

cavum venosus

third ventricle in some reptiles that helps to shunt oxygenated from deoxygenated
blood.

flap of fibrous c.t on each valve

cusps

prevent the backflow of blood from the ventricles into the atria

Atrioventricular valves 

In mammals, AV valves are anchored by c.t strands called _________ to bundles of smooth muscle called ________

Cordae tendineae

Papillary muscle

prevent the backflow of blood from the arteries
(aorta and pulmonary trunk) into the ventricles.

Semilunar valves

Specialized cardiac muscle tissue with the ability to beat
without nervous stimulation and to coordinate that beat through ion exchange

Nodal Tissue

• ANS nerves stimulate nodal tissue to vary heart rate due to physiological needs 

Birds and mammals lose the sinus venosus during development only as a mass of nodal tissue in the right atrium remains called

Sinoatrial Node

• point that receives ANS innervation

Fibrous strands nodal tissue will run through the ventricles to improve the efficiency of conduction.

Purkinje fibers

Conduction system

SA nodes fires, sending a wave of depolarization to
both atria causing them to contract.

The SA node will also stimulate (simultaneously) another cluster
of nodal tissue called the Atrioventricular Node.

• This causes the AV node to send a wave of depolarization to both ventricles causing them to contract

Specialized arterial structures where an incurrent
artery gives rise to numerous branching and anastomizing vessels that will be drained by a second (excurrent) artery

Rete Mirabilia 

• Some help to store oxygen for deep diving marine mammals.

• Some help to maintain internal temperatures

Cardinal Streams - what pair drains the head?

Anterior cardinal veins

• empty into common cardinal veins 

Cardinal Streams - drain many renal vessels from the kidneys along their length and the caudal vein and drain into common cardinal veins

Posterior Cardinal Veins

• run lateral to kidneys 

Which veins run from the pelvic girdle to the pectoral girdle and then will drain into the common cardinal veins. receive a vein from each limb girdle

Lateral Abdominal Veins 

Which portal system drains nutrient rich blood from the digestive tract to the liver for screening and processing prior to its distribution throughout the body

Hepatic Portal System

which veins are first embryonic vessels to appear and run from yolk sac to the heart?

Vitelline Veins 

• eventually degenerate and become the liver sinusoids 

Mammals will show a remnant of the posterior cardinals called _____

Azygous

• drains intercostals

• drains into Precave

In mammals, the left posterior cardinal will become the _______

Hemiazygous

• drains intercostals 

• drain into Azygous 

Common Cardinals in amniotes are also known as the _____

Precavae

The anterior cardinal Veins in amniotes have become the ______

Internal Jugular Veins 

In reptiles, The two lateral abdominal veins will briefly connect to the two ______

Allantoic veins 

• allantoic vein of mammals are termed the Umbilical Veins

The renal portal system in amphibians and reptiles uses the________ to carry blood from the hindlimbs to the______

External Iliac Vein

Renal Portal Vein