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Monday, 2 November 2020
Heart – External Features
Sunday, 1 November 2020
General Anatomy -Cardiovascular System
by physiogyan
General Anatomy -Cardiovascular System
Q. What are the components of the cardiovascular system?
A. Cardiovascular system includes heart and blood vessels i.e. arteries, arterioles, capillaries, venules and veins.
Q. What are the different types of circulation?
A. a. Systemic circulation: It is responsible for transporting oxygenated blood through arteries to the entire body and then returns deoxygenated blood to the heart via veins. The circulation of blood flow is as follows:

b. Pulmonary circulation: It consist of that part of circulatory system which pumps deoxygenated blood to the lungs and returns oxygenated blood to the heart. The circulation of blood flow is as follows:

c. Portal circulation : It is part of systemic circulation. The blood passes through two sets of capillaries,the circulation begins with capillaries and ends with capillaries. The vessel between the two sets of capillaries is known as portal vein. Portal circulation is found at the following sites:
a. Hepatic portal system – between intestines and liver.
b. Renal portal system - in the kidney.
c. Hypothalamo-hypophyseal system – between hypothalamus and hypophysis cerebri.
d. Suprarenal portal system – between the cortex and medulla of adrenal gland.
Q. Enumerat the:
a. types of arteries and write examples of each.
b. avascular tissues or structures.
c. structures/organs supplied by end arteries.
d. types of capillaries with examples of each.
e. sites where sinusoids are found.
f. factors responsible for venous return.
g. sites where arterial pulsation is felt.
A. a. Types of arteries:
• Elastic /conducting arteries. e.g. aorta, pulmonary trunk.
• Muscular/distributing arteries . e.g. radial artery, femoral artery etc.
b. Avascular tissues/structures:
• Epithelium
• Epidermis of skin
• Hair
• Nail
• Cornea
• Cartilage
c. Structures or organs supplied by end arteries:
• Heart
• Kidneys
• Liver
• Brain
• Retina
d. Types of capillaries:
a. Continuous capillaries : e.g. in muscle, brain, connective tissue, skin, lung.
b. Fenestrated capillaries . e.g. in endocrine glands, intestinal villi, renal glomeruli.
e. Sites where sinusoids are found:
• Liver
• Spleen
• Bone marrow
• Anterior pituitary gland
f. Factors responsible for venous return:
• Contraction of muscles
• Presence of valves in the veins
• Negative intrathoracic pressure
• Pulsation of arteries
g. Sites where arterial pulsations can be felt:
• Carotid artery – along the anterior border of sternocleidomastoid muscle at the level of cricoids cartilage.
• Brachial artery – In front of the elbow medial to the tendon of biceps brachii.
• Radial artery – lateral side of front of forearm at wrist
• Femoral artery – below the inguinal ligament at midinguinal point
• Popliteal artery – in the popliteal fossa
• Dorsalis pedis artery – on the dorsum of foot between the tendon of extensor hallucis longus and extensor digitorum longus.
Q. Describe in brief the characteristic features and functions of the arteries,arterioles, capillaries venules and veins.
A .
Q. Enumerate the differences between the arteries and veins.
A. Differences between the arteries and veins
Q. Explain the following terms.
a. End arteries
b. Functional arteries
c. Anastomosis
d. Collateral circulation
A. a. End arteries : End arteries are those arteries that do not anastomose with their neighbouring arteries. In case of blockage of an end artery due to a thrombus, the part supplied by it undergoes ischemia and later avascular necrosis. e.g. in kidneys, brain and retina.
b. Functional end arteries: Functional arteries are those arteries whose terminal branches do anastomose, but the anastomosis is not sufficient to maintain the blood supply to the part they supply in case of any blockage in the artery. e.g. coronary arteries.
c. Anastomosis : Anastomosis is defined as communication between the neighbouring blood vessels. It is of two types:
i. Arterial anastomosis : The branches of an artery are connected to the branches of another neighbouring artery. The anastomosis provise collateral channel for circulation when one of the arteries is blocked. e.g. labial branches of facial arteries, intercostals arteries, uterine and ovarian arteries, arterial arcades in the mesentery of intestine etc.
ii. Arteriovenous anastomosis: The direct connection between the arteries and veins without the intervention of capillaries is termed arteriovenous anastomosis. Their function is to regulate temperature and regional blood flow. They are found in the lip, ear nose, nasal mucosa, kidney , intestine etc.
d. Collateral circulation: Collateral circulation is possible when an area of tissue or an organ has a number of different pathways for blood to reach it. This is as a result of anastomosis formed between adjacent blood vessels. In this process small (normally closed) arteries open up and connect two larger arteries or different parts of the same artery and serve alternate route of blood supply.
By physiogyan| | Tags: anastomosis, avascular sites, collateral circulation, difference between artery and vein, end arteries, important questions on cardiovascular system, types of arteries, types of blood vessels, types of capillaries | Categories: heart

Conducting System and Nerve Supply of Heart
Conducting System and Nerve Supply of Heart
by physiogyan
What are the components of conducting system of the heart?
Conducting system of heart is meant for initiating and maintaining cardiac rhythm and establish proper co-ordination between the atrial and ventricular contactions. It is made up of specialized cardiac muscle fibers having a high degree of sensitivity and autorhythmicity.
Components of conducting system
Sinuatrial node (SA node)
Is also known as pacemaker.
Initiates the cardiac impulse.
Is located in the upper part of crista terminalis by the side of the opening of superior vena cava.
Impulse from SA node to AV node is carried by intermodal fibers.

Atrioventricular node (AV node )
Is situated in the right atrium , in the lower part of interatrial
septum.
It lies in the triangle of Koch, which is bounded by:
Base of septal cusp of tricuspid valve
Orifice of coronary sinus
Tendon of Todaro
Atrioventricular bundle of HIS
From the AV node it descends in the interventricular septum and divides into:
Right ventricular branch
Left ventricular branch
The two branches descend in the interventricular septum and spread out in the walls of the respective ventricles to end as Purkinje fibers.
Describe briefly the nerve supply of heart.
The heart rate and the cardiac output are controlled by autonomic nervous system.
Sympathetic fibers are provided by the cardiac branches of superior, middle and inferior cervical ganglia ( preganglionic fibers reach from T2-T5 spinal segments).
Parasympathetic fibers are provided by the cardiac branches (superior, inferior and recurrent) of the left & right vagus nerves.
The sympathetic and parasympathetic fibers reach heart via the superficial and deep cardiac plexuses.
Superficial cardiac plexus is located below the arch of aorta. it is formed by:
Cardiac branch of superior cervical ganglion of left sympathetic chain.
Inferior cervical cardiac branch of left vagus.
Deep cardiac plexus is located behind the arch of aorta and in front of tracheal bifurcation. It is formed by:
Cardiac branches of middle and inferior cervical ganglion of both the sympathetic chain and from the superior cervical ganglion of right sympathetic chain.
Cardiac branches of T2-T5 ganglion of both the sympathetic chain.
Superior and recurrent branches of both the vagi and inferior cardiac branch of right vagus.
Physiogyan | | Tags: physiogyan