Circulation & Function
What is the main function of the cardiovascular system in animals?
To transport oxygen, nutrients, hormones, and waste products throughout the body and help regulate temperature and pH.
How many chambers are in a typical mammalian heart and what are they called?
Four chambers: two atria (left & right) and two ventricles (left & right).
Which livestock species have four‑chambered hearts? (List at least three.)
Cattle (cows), horses, pigs, sheep, goats, and most other mammals have four‑chambered hearts.
What is a common noninvasive test used to listen to heart sounds in livestock?
Auscultation with a stethoscope.
What is the primary cellular component of blood that carries oxygen?
Red blood cells (erythrocytes).
Name two ways the cardiovascular system helps maintain homeostasis in an animal body.
Transporting hormones; redistributing blood flow to active muscles; maintaining body temperature; removing CO2 and wastes.
How many chambers are in a typical mammalian heart and what are they called?
The mitral (bicuspid) valve (between left atrium and left ventricle).
Compare the relative size of the heart to body weight in a cow versus a pig (which generally has a larger heart proportionally?)
Typically pigs have a heart proportionally similar to other monogastric mammals; ruminants like cows often have relatively large hearts but proportionally pigs may have slightly larger heart-to-body ratios in some comparisons — answer may vary by source; accept a short comparative justification.
Name one sign a livestock animal might show if it has heart failure or circulatory problems.
Exercise intolerance, coughing, swelling in limbs or brisket, pale or blue-tinged mucous membranes, rapid or irregular pulse.
Define systole and diastole in one sentence each.
Systole: ventricular contraction that ejects blood; Diastole: ventricular relaxation when chambers fill with blood.
Explain how oxygen and carbon dioxide are exchanged between blood and tissues (use simple steps).
Oxygenated blood reaches capillaries; oxygen diffuses from capillary blood into tissues while CO2 diffuses into the blood; deoxygenated blood returns via veins to the heart and lungs.
Describe the structural difference between arteries and veins and explain why that difference matters.
Arteries have thicker, more muscular walls to handle high pressure; veins have thinner walls and valves to assist low-pressure return — this allows arteries to maintain pressure and veins to act as capacitors for blood return.
Describe one anatomical or physiological adaptation of the equine (horse) heart that supports high aerobic activity.
Horses have large stroke volumes and well-developed myocardium with high capillary density in cardiac muscle to support sustained high cardiac output during exercise.
What is an electrocardiogram (ECG/EKG) and what basic information does it give about the heart?
An ECG records the electrical activity of the heart and provides information on heart rate, rhythm, and conduction abnormalities.
Explain how capillaries support nutrient and gas exchange (mention structure that makes this possible).
Capillaries are one cell layer thick (endothelium) with thin walls and narrow lumen allowing diffusion of gases and small molecules between blood and tissues.
Describe the pathway of blood flow starting from the body tissues back to the body tissues
Body tissues → veins → right atrium → tricuspid valve → right ventricle → pulmonary artery → lungs → pulmonary veins → left atrium → mitral (bicuspid) valve → left ventricle → aorta → arteries → arterioles → capillaries → back to veins.
Name the valve between the right atrium and right ventricle and explain what could happen if it fails to close properly.
The tricuspid valve; failure can cause regurgitation (backflow), reduced forward output, fluid accumulation, and signs of congestion.
How does the heart rate of a newborn calf typically compare to that of an adult cow? (state which is faster and why)
Newborn calves have faster heart rates than adult cows because of higher metabolic rate and smaller stroke volume; therefore heart rate is higher to maintain cardiac output.
Explain why anemia can affect cardiovascular function in livestock.
Anemia reduces oxygen‑carrying capacity; the heart must increase cardiac output (higher heart rate and stroke volume) to deliver sufficient oxygen, increasing workload and potentially causing tachycardia or heart failure if severe.
Describe how peripheral vasoconstriction helps an animal conserve heat in cold weather.
Vasoconstriction narrows arterioles in the skin and extremities, reducing blood flow to the surface and extremities to minimize heat loss and maintain core temperature.
Explain how the cardiovascular system interacts with the endocrine system to respond to a sudden stress
Stress triggers sympathetic nervous system and adrenal release of adrenaline (epinephrine) which increases heart rate, stroke volume, and redirects blood to muscles; cardiovascular system raises cardiac output to supply oxygen and fuel.
Explain the role of the cardiac conduction system and identify the primary pacemaker of the heart.
The conduction system electrically coordinates contraction; the sinoatrial (SA) node is the primary pacemaker initiating impulses.
For a ruminant (e.g., cow) and a monogastric (e.g., pig), describe one way their circulatory demands differ based on digestive physiology and activity patterns.
Ruminants require extensive blood flow to support fermentation and rumen motility, affecting resting distribution; monogastrics direct more blood to intestinal absorptive processes and have different demands during feeding and exercise.
Describe one congenital heart defect that can occur in livestock and one likely consequence for the animal’s health or performance.
Examples: ventricular septal defect (VSD) — consequence: mixing of oxygenated and deoxygenated blood, reduced exercise tolerance, possible failure or murmurs.
Explain how dehydration affects blood volume and how the cardiovascular system compensates acutely.
Dehydration reduces plasma volume decreasing stroke volume and blood pressure; compensations include increased heart rate (tachycardia) and peripheral vasoconstriction to maintain perfusion.