BIOL 273 - Unit 4.1 + 4.2

Question 1

What are the materials transported between the environment to tissues

Answer 1

nutrients/ water/ gases (O2)

Question 2

What are the materials transported between tissues of body

Answer 2

wastes/nutrients/ hormones

Question 3

What are the materials transported from tissues to external environment

Answer 3

metabolic wastes, gases (CO2), heat

Question 4

What is the pericardium

Answer 4

a tough membranous sac surrounding the heart
- made of two layers with a small amount of fluid between them that acts as lubricant

Question 5

What are coronary arteries

Answer 5

• Nourish the heart muscle
• Heart ha a high oxygen demand - depends on adequate blood flow
• lack of blood supply to heart - leads to a heart attack

Question 6

Left atrium

Answer 6

receives blood from the pulmonary vein - sends to the left ventricle

Question 7

Left venctricle

Answer 7

receives blood from left atrium - sends to body via aorta

Question 8

Right atrium

Answer 8

receives blood from venae cavae - sends to the right ventricle

Question 9

Right ventricle

Answer 9

receives blood from right atrium - sends to lungs

Question 10

Valves

Answer 10

ensure flow is unidirectional
(doesn’t exist at entrance to the atria’s since atrial contraction is already weak relative to ventricular contraction)

Question 11

Atrioventricular valves ; what are its other names and where is it found

Answer 11

tricuspid and bicuspid (mitral)
- attached on ventricular side to collagenous cords

Question 12

What prevents valves from being pushed back into atrium

Answer 12

chordae tendineae

Question 13

Semilunar valves

Answer 13

aortic and pulmonary
- inside aorta and pulmonary arteries - prevents backflow into ventricles
- do not need cords to brace them because of their shape

Question 14

What are the two divisions of blood flow

Answer 14

1. pulmonary circuit
2. systemic circuit

Question 15

Describe the main idea of the pulmonary circuit

Answer 15

blood vessels in the lungs and those that connect the lungs to the heart

Question 16

Describe the path of the pulmonary circuit

Answer 16

• blood flows from right atrium to right ventricle - pumped to pulmonary arteries to the lungs
• lungs have many capillaries to increase O2 transfer
• Oxygenated blood has low pressure - need to return to heart via pulmonary veins to left atrium

Question 17

Describe the main idea of systemic circuit

Answer 17

encompasses the rest of the blood vessels in the body

Question 18

Describe the path of the systemic circuit

Answer 18

• blood flows from left atrium to left ventricle (pumped to aorta that branches into smaller arteries and then to capillary networks throughout the body)
• oxygen diffuses from the blood into the tissues in the capillary beds - then flow to small venules and then larger veins
• oxygen poor blood has low pressure - need to return to hear via superior/inferior vena cava to the right atrium

Question 19

How is the heart muscle different from other muscles

Answer 19

• heart does not need input from the nervous system

Question 20

What are the specialized heart cells called and what is its function and location

Answer 20

cells called autorhythmic cells that excite heart without nervous system
- forms a conducting system in heart that spontaneously generates AP’s

• found in SINOATRIAL NODE (right atrium near superior vena cava)

Question 21

Describe the membrane of pacemaker cells

Answer 21

unstable membrane potential
- slow drift (from -60 mV) of depolarization until it reaches threshold (pacemaker potential) to rapidly depolarize+repolarize

Question 22

What are the special channels of pacemaker cell membranes and what is it permeable to

Answer 22

“funny” channels
- permeable to K+ and Na+

Question 23

What is the cause of slow depolarization of the membrane of pacemaker cells

Answer 23

sodium influx greater than potassium efflux
(net influx of positive charge)

Question 24

What is the cause of the membrane continued depolarization in pacemaker cells

Answer 24

funny channels close; caclium channels open
- leads to threshold reached
- leads to rapid influx of calcium from calcium channels (steep polarization)

Question 25

What is the cause of the end of depolarization in pacemaker cells

Answer 25

calcium channels close and potassium channels open slowly ; efflux of potassium causes repolarization

Question 26

What is a major difference between action potentials and pacemaker potentials in the pacemaker cells

Answer 26

• sodium and calcium ions influx for pacemaker potential
• only calcium influx for action potential

Question 27

How does heart rate go up

Answer 27

Norepinephrine released via post ganglionic sympathetic neuron onto the cells of the SA node
- epinephrine for reinforcement
- bind to beta adrenergic receptor

Question 28

What happens when norepinephrine and epinephrine are bindind to beta adrenergic receptor

Answer 28

involved use of G proteins - release of cAMP
- membrane depolrizes due to second messenger passway
- makes it easier for cell to hit threshold (heart rate goes up)

Question 29

How is heart race reduced

Answer 29

Acetylcholine released from parasympathetic neurons
- target cells have muscarinic receptors
- more potassium released,
- pacemaker starts at a more negative value therefore it takes longer to reach threshold potential

Question 30

Describe the events of conduction in heart muscle contraction

Answer 30

1. AP fired from SA node - spreads to adjacent cells
2. Rapid spread through cells of internodal pathway
3. signal passed through AV node ONLY at AV junction (connective tissue acts as insulator prevents electrical signals from atrium to ventricle)
   - therefore AV node ONLY pathway for action potential
4. Signal is carried to bottom of heart through bundle of His
5. His divides into left and right branches (Purkinje fibres)