intro to cardiac system

Question 1

what is heart disease

Answer 1

• a disease that usually involves valve degeneration, and the valve becoming incompetent or diseases of the heart muscle, resulting in the heart not contracting well OR not filling well
• does not always result in heart failure
• common in small animal and equine practice

Question 2

what is heart failure

Answer 2

a syndrome in which the heart fails to deliver blood effectively to meet requirements of metabolising tissues

Question 3

label

Answer 3

Question 4

in this image, the distended abdomin indicates what

Answer 4

right sided heart failure = ascites

Question 5

what are the functions of the cardio-respiratory system

Answer 5

transport - to and from metabolising tissue
- oxygen and carbon dioxide
- nutrients
- waste
- heat
- hormones

homeostasis
- pH, osmolarity, electrolytes, etc.
- infection

other
- generate pressure (renal filtration and reproduction)

Question 6

describe common themes of all mammalian hearts

Answer 6

dual chambered
- usually forward in thorax: protected by muscle mass of the forelimb

left heart
- pumps oxygenated blood

right heart
- pumps deoxygenated blood

prevents admixture of oxygenated and deoxygenated blood

Question 7

describe the cardiac cycle

Answer 7

systole= contraction
diastole= relaxation
ventricular systole= contraction of ventricles
- results in cardiac output
- atrioventricular valves close
- the source of the first heart sound: LUB

ventricular diastole= relaxation of ventricles
- results in ventricular filling
- semi-lunar valves close
- the source of the second heart sound: DUB

Question 8

how is cardiac function regulated

Answer 8

• electrical activity (electrophysiology) (assessed by ECG)
• contractile function control
• the important role of the autonomic nervouse system
• hormonal mechanisms (local and systemic)

Question 9

how is vasculature regulated

Answer 9

• autoregulation: local blood flow regulation, intrinsic abillity of an organ to maintain a constant blood flow despite changes in perfusion pressure
• the important role of the autonomic nervous system
• hormonal mechanisms (loca and systemic)

Question 10

what is cardiac output

Answer 10

volume delivered into the circulation per minute

Question 11

what is stroke volume

Answer 11

volume delivered by the ventricle per beat

Question 12

what must be considered about cardiac function for the distribution of blood within the heart and vasculature

Answer 12

• vascular constriction and dilation (arteries and veins)
• the maintenance of unidirectional flow in vital organs
• cardiac valves
• vascular valves

Question 13

which organs get the highest percentage of cardiac output compared to weight of the organ? which get the least

Answer 13

Question 14

explain venous return

Answer 14

• deoxygenated blood is returned to the heart
• diastolic cardiac volume is important for cardiac output

important controlling factors
- sympathetic nervous system
- blood volume
- muscle (respiratory) pump

Question 15

what are veins, arteries, portal veins and capillaries

Answer 15

Veins: return to the heart
arteries: from the heart
portal veins: between 2 capillary beds
capillaries: site of diffusion

Question 16

what goes on in the capillary beds

Answer 16

• capillary diffusion
• tissue fluid production
• extracellular vs intracellular fluid

Question 17

cardiac output and systemic vascular resistance are controlled by what

Answer 17

• Heart rate: Increased heart rate increases CO, while decreased heart rate decreases CO.
• Contractility: Increased contractility of the heart muscle increases CO, while decreased contractility decreases CO.
• Preload: Increased preload (the volume of blood in the ventricles at the end of diastole) increases CO, while decreased preload decreases CO.
• Afterload: Increased afterload (the resistance to blood flow in the pulmon