the differences in histoarchitectural structure in vertebrates is presented in this slide.

1. A Presentation by
GROUP-B4
BLOOD VESSELS

2. BLOOD VESSEL:
The blood vessels are
the part of the
circulatory system,
and microcirculation,
that transports blood
throughout the
whole body.

3. TYPES OF BLOOD VESSELS:
There are three major types of blood
vessels. They are as follows:
(1)Arteries: The arteries carry the blood
away from the heart. They are thick
walled.
(2)Capillaries: Capillaries are narrow-
diameter tubes that can fit red blood
cells in single-file lines and are the
sites for the exchange of nutrients,
waste, and oxygen with tissues at the
cellular level.
(3)Veins: The veins carry blood from the
capillaries back toward the heart.
They are thin walled and have valve to
prevent the backflow of blood.

4. STRUCTURE:
• The arteries and veins have three layers. The middle layer is
thicker in the arteries than in the veins.
• The inner layer, Tunica intima is the thinnest layer. It is a layer
of simple squamous epithelium glued by a polysaccharide
intercellular matrix and surrounded by a thin layer of
subendothelial connective tissue.
• The middle layer Tunica media is the thickest layer in arteries. It
consists of elastic fiber, connective tissue, polysaccharide and
elastic lamina. Veins only have internal elastic lamina.
• The outer layer is Tunica adventitia and is the thickest layer in
veins.
• Capillaries consists of little more than a layer of endothelium
and occasional connective tissue.

6. FUNCTION:
A blood vessel’s main function is to transport blood around the
body. Blood vessels also play a role in controlling blood
pressure. Blood vessels are found throughout the body.

7. COMPERATIVE STUDY OF BLOOD VESSELS
Pieces
Arterial System:-
 Carry oxygenated Blood.
 Have thick and more elastic
made up of Tunica intima,
Tunica Media, Tunica
externa
Efferent Branchial Arteries:-
Collects The blood from
Capillaries of gill lamellae.
Afferent Branchial Arteries
Supply arterial branches to the
anterior and posterior gill
lamellae.
Amphibians
Arteries:-
 Carry oxygenated Blood.
 Have thick and more elastic
walls
 Made up of three concentric
layers ie Tunica intima, Tunica
Media, Tunica externa.
 Arterial System can be divided
in to:-
 Carotid arch:- Lower jaw and
tongue , Orbit and brain
 Systemic arch:- Oesophageal,
occipitovertebral,
subclavian(Forelimbs)
 Pulmo-cutaneous arch:- to
lung and skin and buccal cavity

9. Pieces and Amphibia Cont..
Capillaries
 Their walls are very thin.
 Only tunica intima is present.
 Exchange of foods, gases, waste
takes place between blood and
tissue
Veins
 Carry deoxygenated blood
 Have thin, fibrous and less elastic
walls, than arteries provided with
valves.
Venous system can be divided into
 Anterior Cardinal system
 Posterior Cardinal System
 Hepatic Portal System
 Cutaneous System.
Capillaries
 Found abundantly in excessive
metabolism sites.
 Their walls are very thin.
 Only tunica intima is present.
 Exchange of foods, gases, waste
takes place between blood and
tissue
Veins
 Carry deoxygenated blood
 Have thin, fibrous and less elastic
walls, than arteries provided with
valves.
Venous System can be divided into
 Pulmonary Veins
 Caval veins
 Renal portal vein
 Hepatic portal

10. Comparative Study of Blood Vessels of
Reptiles and Aves
Arterial system
 Three aortic arches (1
pulmonary 2 systemic)
1. One Pulmonary arch
 Lies ventrally arises from the
right ventral side of the
ventricle .
 Right PA goes to right lung
and left PA goes to left lung.
1. Two Systemic arch
 Both the systemic arches
arise directly from the cavum
dorsale of the ventricle
carrying oxygenated blood.
 Right and left communicates
each other by Foramen of
Panizzae.
Arterial system
 Pulmonary aorta and
systemic arch
1. Pulmonary aorta
 Arise from a single
pulmonary aorta which
passes ventral to aortic arch
bifurcates.
 Each of these enters into
lung
2. Aortic arch (systemic):-
 Arises from left ventricle.
 Left aortic arch is absent in
birds
 Coronary arteries arise from
right aortic arch

11. Reptile
Some Extensions
 Common carotid arteries
 Common subclavian artery
 Anterior esophageal artery
 Dorsal Aorta is formed by
union of right and left
systemic arches , extends
backwards mid dorsal line
beneath the vertebral
column it give rise to: Post
esophageal, Gastric, Coeliac,
hepatic, rectal iliac, caudal
arteries etc
Aves
Simply the arterial
system in Aves is
similar that of reptiles.

12. Reptiles Birds

13. Reptiles VS Birds
Venous System in Reptiles
1. Pulmonary:- brings oxygenated blood
from lungs to arteries
2. Precaval :- Drains blood from Head,
Neck, Shoulders, Forearm, and Thoracic
wall
Histologically each precaval is formed by
four veins Jugular, Subclavian, Intercostal,
laryngo-tracheal.
3. Postcaval :- collects blood from
posterior body parts i.e. Kidneys Gonads
and Liver
4.Hepatic Portal :- collects blood from
alimentary canals, formed by hepatic
portal vein and Porto- abdominal vein
5. Renal Portal:- Cloacal and rectal veins
meet afferent renal veins
Blood from hindlimb is collected bi
internal and external iliac.
Venous System in Birds
1. Pulmonary veins:- brings
oxygenated blood from lungs to
arteries
2. Precaval veins:- similar in lizard
3. Postcaval veins:-Coccygeo-
Mesentric vein is the
characteristic of Bird. Receive
blood from cloaca and rectum.
4. Hepatic portal:- collects blood
from Rectum, ileum, duodenum
and gizzard.
Coccygeo-Mesentric vein connects the
two portal systems
5. Renal Portal: it is greatly reduced in
the pigeon. Includes two Hypogastric
or renal portal veins.

14. Mammals
• Heart is four chambered. Blood circulation is double, closed
and complete.
• Histologically there are three distinct layers or tunics in
the blood vessels of mammals:-, that form the walls of
blood vessels.

15. Contd.
• Tunica media is composed of smooth muscle,
• Tunica externa is connective tissue (collagen and elastic
fibers).
• The elastic, connective tissue stretches and supports
the blood vessels, while the smooth muscle layer helps
regulate blood flow by altering vascular resistance
through vasoconstriction and vasodilation.
• Unlike veins and arteries, capillaries have only one
tunic; this single layer of cells is the location of
diffusion of oxygen and carbon dioxide between the
endothelial cells and red blood cells, as well as the
exchange site via endocytosis and exocytosis.

16. Veins ans Arteries in Mammals