Explain cardiac muscle or heart muscle, Biology

Assignment Help:

Explain Cardiac Muscle or heart muscle?

Cardiac muscle, or heart muscle, is a striated muscle that occurs only in the vertebrate heart. The heartbeat is controlled by noncontractile cells in the heart called Purkinje fibers. These cells have no contractile proteins and are specialized for electrical conduction. The heartbeat is initiated by electrical activity of the pacemaker or sinoatrial node (S. A.) in the wall of the right atrium. How heart cells keep up their rhythmic contraction is not known, but heart cells in culture continue to beat, and even single heart cells beat rhythmically, independently of other muscle cells or external innervation.

An electrical impulse spreads from the sinoatrial node to all parts of the atrium and then to the atrioventricular node, which is located adjacent to the partition between the two ventricles. From here, the impulse spreads through the ventricles and triggers simultaneous contraction of the ventricles.

As in smooth muscle, cardiac muscle cells are joined by gap junctions, structures that contain tiny pores through which electrical currents and calcium can pass from one cell to another. Although the heart beats regularly without nervous intervention, there is a main nerve to the heart, the tenth cranial nerve, or vagus. The vagus nerve contains branches of both the sympathetic and autonomic nervous systems. The sympathetic activity speeds the heart rate, and the autonomic slows it. Cardiac muscle has many mitochondria, as would be expected from its constant activity.

 


Related Discussions:- Explain cardiac muscle or heart muscle

Define burette - nutritional biochemistry, Define Burette - Nutritional Bio...

Define Burette - Nutritional Biochemistry A burette is a vertical cylindrical piece of laboratory glassware with a volumetric graduation on its full length and a precision tap,

What vector force does particle b then exert on a, A charged particle A exe...

A charged particle A exerts a force of 2.39uN to the right on charged particle B when the particles are 12.3 mm apart. Particle B moves straight away from A to make the distance be

Vaccines, Ask quesWhat type of antigenic agents may constitute vaccines? ti...

Ask quesWhat type of antigenic agents may constitute vaccines? tion #Minimum 100 words accepted#

Cancer lung, Cancer Lung Incidence of cancer lung is more in persons ...

Cancer Lung Incidence of cancer lung is more in persons who smoke. Environmental and industrial pollution is also a risk factor in the increase in incidence. Clinic

What is particularly of the mucous membranes, How would carbon monoxide poi...

How would carbon monoxide poisoning affect a person's coloring, particularly of the mucous membranes? How would it affect the hemoglobin concentration, hematocrit, and percent oxyh

Internal budget - nutrient budgets, Internal budget - Nutrient Budgets ...

Internal budget - Nutrient Budgets This is concerned with the circulation of nutrients through various biotic and abiotic compartments of a given ecosystem. In other words the

Define dietary management during surgery, Define Dietary Management during ...

Define Dietary Management during Surgery? Surgery increases the nutritional demands of the body and can lead to the elicitation of several nutritional deficiencies/imbalance. M

Define water losses by visible perspiration, Define water losses by visible...

Define water losses by visible perspiration? The water losses by visible perspiration are highly variable; the amount could be as high as 4L in hot climate or during strenuous

Define the ionizing radiation for sterilization, Q. Define the Ionizing rad...

Q. Define the Ionizing radiation for sterilization? Ionizing radiation are high energy electromagnetic waves including X-rays, gamma rays, particulate radiation, cosmic rays wh

Mounting boxes for insect collections, Mounting boxes for insect collection...

Mounting boxes for insect collections Wood or cardboard cigar boxes make very useful and suitable housings for insect collections. After the insect has been separate from the s

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd