The heart (Latin cor) is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions. The term cardiac means "related to the heart", from the Greek kardia (καρδια) for "heart". Heart - The human heart. Heart - Early development. The human embryonic heart (EHR) begins beating at approximately 21 days after conception, or five weeks after the last normal menstrual period (LMP), which is the date normally used to ...

Including:

Heart - The human heart
Heart - Early development Heart - Structure Heart - The cardiac cycle Heart - Regulation of the cardiac cycle Heart - Other physiological functions
Heart - Diseases and treatments Heart - First aid Heart - The hearts of other animals
Heart - Heartbeat Heart - Food use
Heart - As an icon

Read more here: » Heart: Encyclopedia - Heart

See also:

Heart, Heart - The human heart, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - First aid

The study of diseases of the heart is known as cardiology. Important diseases of the heart include: Coronary heart disease is the lack of oxygen supply to the heart muscle; it can cause severe pain and discomfort known as Angina. A heart attack occurs when heart muscle cells die because blood circulation to a part of the heart is interrupted. Congestive heart failure is the gradual loss of pumping power of the heart. Endocarditis and myocarditis are inflammations of the heart. Cardiac arrhythmia is an irregularity in the heartbeat. It is sometimes treated by implanting an artificial pa ...

See also:

Heart, Heart - The human heart, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - Diseases and treatments

The heart (Latin cor) is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions. The term cardiac means "related to the heart", from the Greek kardia (καρδια) for "heart". Heart - The human heart. Heart - Structure. In the human body, the heart is normally situated slightly to the left of the middle of the thorax, underneath the sternum (breastbone). It is enclosed by a sac known as the pericardium and is ...

Including:

Heart - The human heart
Heart - Structure Heart - The cardiac cycle Heart - Regulation of the cardiac cycle Heart - Other physiological functions
Heart - Diseases and treatments Heart - First aid Heart - The hearts of other animals
Heart - Heartbeat Heart - Food use
Heart - As an icon

Read more here: » Heart: Encyclopedia - Heart

The heart (Latin cor) is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions. The term cardiac means "related to the heart", from the Greek kardia (καρδια) for "heart". Heart - The human heart. Heart - Early development. The human embryonic heart (EHR) begins beating at approximately 21 days after conception, or five weeks after the last normal menstrual period (LMP), which is the date normally used to ...

Including:

Heart - The human heart
Heart - Early development Heart - Structure Heart - The cardiac cycle Heart - Regulation of the cardiac cycle Heart - Other physiological functions
Heart - Diseases and treatments Heart - First aid Heart - The hearts of other animals
Heart - Heartbeat Heart - Food use
Heart - As an icon

Read more here: » Heart: Encyclopedia - Heart

The heart (Latin cor) is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions. The term cardiac means "related to the heart", from the Greek kardia (καρδια) for "heart". Heart - The human heart. In the human body, the heart is normally situated slightly to the left of the middle of the thorax, underneath the sternum (breastbone). It is enclosed by a sac known as the pericardium and is surrounded by the lungs. In normal adul ...

Including:

Heart - The human heart
Heart - The cardiac cycle Heart - Regulation of the cardiac cycle Heart - Other physiological functions
Heart - Diseases and treatments Heart - First aid Heart - The hearts of other animals
Heart - Heartbeat Heart - Food use
Heart - As an icon

Read more here: » Heart: Encyclopedia - Heart

Cardiac cycle is the term used to describe the sequence of events that occur as a heart works to pump blood through the body. Every single 'beat' of the heart involves three major stages: atrial systole, ventricular systole and complete cardiac diastole. The term systole is synonymous with contraction of a muscle. Electrical systole is the electrical activity that stimulates the myocardium of the chambers of the heart to make them contract. This is soon followed by Mechanical systole, which is the mechanical contraction of the heart. The term dia ...

Including:

Cardiac cycle - Atrial systole
Cardiac cycle - Detection of atrial systole
Cardiac cycle - Ventricular systole
Cardiac cycle - Detection of ventricular systole
Cardiac cycle - Complete cardiac diastole Cardiac cycle - Regulation of the cardiac cycle Cardiac cycle - Physiological mechanism of systole

Read more here: » Cardiac cycle: Encyclopedia - Cardiac cycle

Cardiac muscle is myogenic, which means that it is self-exciting. This is in contrast with skeletal muscle, which requires either conscious or reflex nervous stimuli. The heart's rhythmic contractions occur spontaneously, although the frequency or heart rate can be changed by nervous or hormonal influences such as exercise or the perception of danger. For example, the phrenic nerve accelerates heart rate and the vagus nerve decelerates heart rate. The rhythmic sequence of contractions is coordinated by the sinoatrial and ...

See also:

Cardiac cycle, Cardiac cycle - Atrial systole, Cardiac cycle - Detection of atrial systole, Cardiac cycle - Ventricular systole, Cardiac cycle - Detection of ventricular systole, Cardiac cycle - Complete cardiac diastole, Cardiac cycle - Regulation of the cardiac cycle, Cardiac cycle - Physiological mechanism of systole

Read more here: » Cardiac cycle: Encyclopedia II - Cardiac cycle - Regulation of the cardiac cycle

Systole, or contraction, of the heart is induced as the sarcolemma, or thin sheath, of the myocardial cells, or heart muscle cells, of the sinoatrial node, or the cluster of cells in the heart that initiate a heart beat, slowly depolarises beyond the threshold. At this point, the voltage-gated calcium channels open and allow calcium ions to pass through, into the sarcoplasm, or interior, of the muscle cell. Some calcium ions bind to the receptors on the sarcoplasmic reticulum, or network, causing the ...

See also:

Cardiac cycle, Cardiac cycle - Atrial systole, Cardiac cycle - Detection of atrial systole, Cardiac cycle - Ventricular systole, Cardiac cycle - Detection of ventricular systole, Cardiac cycle - Complete cardiac diastole, Cardiac cycle - Regulation of the cardiac cycle, Cardiac cycle - Physiological mechanism of systole

Read more here: » Cardiac cycle: Encyclopedia II - Cardiac cycle - Physiological mechanism of systole

Atrial systole is the contraction of the heart muscle (myocardia) of the left and right atria. Both atria contract at the same time. As the atria contract, the blood pressure in each atrium increases forcing additional blood into the ventricles. The additional flow of blood is called atrial kick. Atrial kick is absent if there is loss of normal electrical conduction in the heart, such as during atrial fibrillation, atrial flutter, and complete heart block. Cardiac cycle - Detection of atrial systole. Electrical systole of the atria ...

See also:

Cardiac cycle, Cardiac cycle - Atrial systole, Cardiac cycle - Detection of atrial systole, Cardiac cycle - Ventricular systole, Cardiac cycle - Detection of ventricular systole, Cardiac cycle - Complete cardiac diastole, Cardiac cycle - Regulation of the cardiac cycle, Cardiac cycle - Physiological mechanism of systole

Read more here: » Cardiac cycle: Encyclopedia II - Cardiac cycle - Atrial systole

Cardiac Diastole is the period of time when the heart relaxes after contraction in preparation for refilling with circulating blood. Ventricular diastole is when the ventricles are relaxing, while atrial diastole is when the atria are relaxing. Together they are known as complete cardiac diastole. During ventricular diastole, the pressure in the (left and right) ventricles drops from the peak that it reaches in systole. When the pressure in the left ventricle drops to below the pressure in the left atrium, ...

See also:

Cardiac cycle, Cardiac cycle - Atrial systole, Cardiac cycle - Detection of atrial systole, Cardiac cycle - Ventricular systole, Cardiac cycle - Detection of ventricular systole, Cardiac cycle - Complete cardiac diastole, Cardiac cycle - Regulation of the cardiac cycle, Cardiac cycle - Physiological mechanism of systole

Read more here: » Cardiac cycle: Encyclopedia II - Cardiac cycle - Complete cardiac diastole

Heart - Structure. In the human body, the heart is normally situated slightly to the left of the middle of the thorax, underneath the sternum (breastbone). It is enclosed by a sac known as the pericardium and is surrounded by the lungs. In normal adults, its mass is 250-350 g, but extremely diseased hearts can be up to 1000 g in mass. It consists of four chambers, the two upper atria (singular: atrium< ...

See also:

Heart, Heart - The human heart, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - The human heart

Heart - Early development. The human embryonic heart (EHR) begins beating at approximately 21 days after conception, or five weeks after the last normal menstrual period (LMP), which is the date normally used to date pregnancy. The human heart begins beating at a rate near the mother’s, about 75-80 beats per minute (bpm). It then accelerates linearly for the first month of beating, peaking at 165-185 bpm during the early 7th week, (early 9th week after the LMP). This acceleration is approximately 3.3 bpm per day, or about 10 bpm every three days, an in ...

See also:

Heart, Heart - The human heart, Heart - Early development, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - The human heart

Heart - Early development. The human embryonic heart (EHR) begins beating at approximately 21 days after conception, or five weeks after the last normal menstrual period (LMP), which is the date normally used to date pregnancy. The human heart begins beating at a rate near the mother’s, about 75-80 beats per minute (bpm). It then accelerates linearly for the first month of beating, peaking at 165-185 bpm during the early 7th week, (early 9th week after the LMP). This is an acceleration is approximately 3.3 bpm per day, or about 10 bpm every three days, a ...

See also:

Heart, Heart - The human heart, Heart - Early development, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - The human heart

The heart of fish have only two chambers: one atrium and one ventricle. In fish, the system has only one circuit. The blood pumps through the gills and on to the the body tissues without returning to the heart. Amphibians and reptiles have a three-chambered heart: two atria and one ventricle. Blood from both the body and the lungs is pumped into the single ventricle, where unoxygenated and oxyge ...

See also:

Heart, Heart - The human heart, Heart - Early development, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - The hearts of other animals

Heart - Heartbeat. Smaller animals have faster heartbeats. This is evident within a species as well, as the young beat their hearts faster than the adults. The Gray Whale's heart beats 9 times per minute, Harbour Seal 10 when diving, 140 when on land, elephant 25, human 70, sparrow 500, shrew 600, and hummingbird 1,200 when hovering. The earthworm has a series of multiple primitive hearts. Heart - Food use. The hearts of cattle, sheep, pigs and certain fowl are consumed ...

See also:

Heart, Heart - The human heart, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - The hearts of other animals

The study of diseases of the heart is known as cardiology. Important diseases of the heart include: Coronary heart disease is the lack of oxygen supply to the heart muscle; it can cause severe pain and discomfort known as Angina. A heart attack occurs when heart muscle cells die because blood circulation to a part of the heart is interrupted. Congestive heart failure is the gradual loss of pumping power of the heart. Endocarditis and myocarditis are inflammations of the heart. Cardiac arrhythmia is an irregularity in the heartbeat. It is sometimes treated by implanting an artificial pa ...

See also:

Heart, Heart - The human heart, Heart - Early development, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - Diseases and treatments

See cardiac arrest for emergencies involving the heart If a person is encountered in cardiac arrest (no heartbeat), cardiopulmonary resuscitation (CPR) should be started, and help called. If an automated external defibrillator is available, this device may automatically administer defibrillation if this is indicated. ...

See also:

Heart, Heart - The human heart, Heart - Early development, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - First aid

Heart - Heartbeat. Smaller animals have faster heartbeats. This is evident within a species as well, as the young beat their hearts faster than the adults. See "Early development" above for information about the early human heart rates. The Gray Whale's heart beats 9 times per minute, Harbour Seal 10 when diving, 140 when on land, elephant 25, human 70, sparrow 500, shrew 600, and hummingbird 1,200 when hovering. The earthworm has a series of multiple primitive h ...

See also:

Heart, Heart - The human heart, Heart - Early development, Heart - Structure, Heart - The cardiac cycle, Heart - Regulation of the cardiac cycle, Heart - Other physiological functions, Heart - Diseases and treatments, Heart - First aid, Heart - The hearts of other animals, Heart - Heartbeat, Heart - Food use, Heart - As an icon

Read more here: » Heart: Encyclopedia II - Heart - The hearts of other animals