Cardiovascular and Nervous System

Decrease in heart beat is called bradycardia.

A short conus arteriosus with a spiral valve directs blood as it leaves the ventricle. 

Heart murmurs are abnormal sounds caused by turbulent blood flow, most commonly due to defective heart valves (stenosis or regurgitation). The turbulence occurs as blood flows through abnormal valve openings. Poor oxygenation would cause cyanosis, not murmurs.

The normal resting pulse rate for healthy adults is 60-100 beats per minute, with 72 being the average. The option '70-80 per minute' falls within this normal range. 97 per minute is on the higher end of normal, while 80-90 and 120 are elevated rates that could indicate stress, exercise, or other conditions.

All birds (aves) have a four-chambered heart with complete separation of oxygenated and deoxygenated blood. This is an adaptation supporting their high metabolic rate and endothermy (warm-bloodedness), enabling the sustained energy demands of flight. The four chambers are two atria and two ventricles.

Fish (Pisces) have a two-chambered heart consisting of one atrium and one ventricle. This single circulation system is less efficient than the three or four-chambered hearts of other vertebrates, but sufficient for their aquatic lifestyle where buoyancy reduces the circulatory demands of overcoming gravity. Blood passes through the heart once in each complete circuit.

Cardiopulmonary reflexes are diverse cardiovascular reflexes originating in the heart and lungs that exert a tonic depression of heart rate and vascular tone.

The QRS complex is one of the components of a typical electrocardiogram (ECG) tracing of a complete cardiac cycle, normally occuring after the P wave. A wide and misshapen QRS may reflect bundle branch block or ventricular origin of the heart beat.

Cardiac magnetic resonance imaging is a non-invasive imaging modality providing accurate assessment of global and ventricular function, myocardial perfusion and myocardial scar.

The anterior coronary plexus is composed partly from the superficial and partly from the deep parts of the cardiac plexus. It accomodates the right coronary artery, and provides branches to the right atrium and ventricle.

Yes, it is correct. While pumping the blood, different chambers of the heart contract and relax in turns. The contraction and relaxation of different chambers produces a thumping sound. One heart beat indicates one cycle of pumping action by all the four chambers.

Yes, it is correct. Lubb happens when  upper chamber of the heart contracts and blood flows downward.

The vagus nerve (parasympathetic) releases acetylcholine that slows heart rate by decreasing SA node activity. This is opposite to sympathetic stimulation which increases heart rate. Vagal stimulation can reduce heart rate to 40-60 beats/minute.

Frog hearts have myogenic properties, meaning they can generate their own electrical impulses without external nerve stimulation. When kept moist, the cardiac muscles continue to contract rhythmically for extended periods even after removal from the body. Option A correctly states this phenomenon. Option B is incorrect because dry conditions cause tissue damage. Option C is false as the heart will beat autonomously. This is a classic demonstration of cardiac muscle automaticity.

A dermatologist is a specialist in skin ailments; a neurologist in ailments of brain and nervous system; a psychiatrist in behavioural ailments.