BL105 CH 19 & 20: Cardiovascular

What is myocardium?

Muscular tissue of the heart

What are the 4 chambers?

R & L Atrium: receiving chambers; R & L Ventricle: dispensing chambers

What is the function of valves in the heart?

prevent backflow

Why is the left side of the heart bigger than the right side?

Left side of the heart requires higher pressure to carry oxygenated blood to the rest of the body

Which circuit receives deoxygenated blood?

Pulmonary circuit

Which circuit receives oxygenated blood?

Systematic circuit

Draw out the pathway of blood flow through the heart and the 2 circuits

RA → RV → Lungs (pick up O2) → LA → LV → rest of body (to capillaries to drop of O2) → return to RA

What is the purpose of coronary arteries?

Supply O2 and nutrients to the myocardium

What happens when the coronary arteries become blocked?

Muscles can’t receive O2 and nutrient -> atherosclerosis (Heart Attack)

Why do the cardiac muscle cells have lots of mitochondria?

Require a lot of ATP to support heart beat and pump blood

What is the cardiac stimulation system? What does it do?

Specialized cells generate and transmit an electrical impulse to stimulate contraction of heart muscle. cardiac stimulation originates in the heart but can be influenced by Autonomic Nervous System.

Cardiac cycle (what happens during each event?)

o   Atrial Systole: both atria contract; valves open, blood → ventricles

o   Ventricular Systole: both ventricle contract; blood → pulmonary & systemic circuits

o   Diastole: Both atria and ventricles relax

What is the relationship between electrical stimulation and muscle contraction?

electrical stimulation occurs first; muscle contraction occurs second

What are the blood vessels?

o   Arteries: carry blood away from heart

o   Capillaries: exchange solutes & h2o w/ cells of body

o   Veins: return blood to heart

How does the blood vessel structures relate to their function?

Arteries: Smaller lumen, thicker layers withstand higher pressure

Capillaries: Single thin layer of cells -> can extend to all tissues, and exchange materials easily

Veins: Larger lumen, thinner layers -> less pressure

Describe what happens during capillary exchange

o   O2 and nutrients dropped off -> Tissue

o   Tissue -> CO2 & waste to blood

3 ways blood is returned to the heart through veins:

o   Contraction of skeletal muscle (legs)

o   One way valves in veins

o   Pressure changes from breathing

negative feedback mechanism— regulation of systemic blood pressure

• stimulus: BP increases 

• sensor: sensory neurons + baroreceptors 

• control center: brain (medulla oblongata)  

• effector: blood vessel + heart 

• response: BP returns to normal, decreased HR 

What are baroreceptors?

Sensors that detect blood pressure

What part of the brain receives / sends signals regarding changes in blood pressure?

Medulla oblongata (brainstem)

How do the heart and vessels respond to brain signals in order to change BP?

Heart rate INCREASES, Vessels CONSTRICT

Why is high blood pressure (hypertension) damaging to the body?

• Too much pressure can cause aneurysm (ballooning out of blood vessel)

• High pressure damages capillaries

CV disease: hypertension

Elevated BP

blood vessels become stiff and resistant to blood blow

heart has to work harder

damages capillaries

Heart attack

sudden death of an area of myocardium due to blocked coronary artery

Stroke

Interruption in blood supply to brain

Aneurysm

Defect in arterial wall that causes ballooning

Atherosclerosis

Thickening and hardening of vessel wall, damage to inner layer of vessel because fat deposits in wall eventually form plaque