circulatory system (tesses version)

Question 1

what is the function of the circulatory system

Answer 1

to transport -nutrients , cells, respiratory gasses and cell to cell communications

Question 2

not all organisms have circulatory systems, explain how a organism with out one can exchange materials with the external environment

Answer 2

via diffusion EG. sponges

Question 3

what are some differences between circulatory systems in water and on land

Answer 3

in water they need to fight fluid resistance rather than on land needing to fight gravity so blood needs to be pumped at a higher pressure

Question 4

of endothermy and ectothermy which has a higher metabolic cost

Answer 4

endothermy

Question 5

what features do endotherms have in their circulatory system

Answer 5

-4 chambers
-higher blood pressure
-complete separation of oxygenated and deoxygenated blood
-active heat distribution

Question 6

in ectotherms what are the key features in their circulatory system

Answer 6

-2 or 3 chambered
-mixing of oxygenated and deoxygenated blood
-lower blood pressure
-passive heat distribution

Question 7

what are the key features of a open circulatory system

Answer 7

-hemolymph not blood
- flow through body cavity
-surrounds organ directly

Question 8

describe hemoglobin

Answer 8

-iron based
-bound to red blood cells
-high affinity to oxygen
-readily releases oxygen
-sensitive to changes in pH and temperature

Question 9

describe hemocyanin

Answer 9

copper based
free floating
lower affinity to oxygen
lower release rate
less sensitive to pH and temperature

Question 10

describe the locations of the myocardium epicardium, endocardium and pericardium

Answer 10

epicardium -outer most layer
endocardium- innermost layer
myocardium -thickest layer
pericardium outer membrane

Question 11

what does the term stroke volume refer to

Answer 11

the volume of blood that is ejected out of a ventricle

Question 12

what is the cardiac cycle

Answer 12

the period of time from the contraction of the atria to the ventricle relaxation

Question 13

what does the term systole refer to

Answer 13

the period of contraction when the heart i emptying

Question 14

what does the term diastole refer
to

Answer 14

the period of relaxation as the chambers fill with blood

Question 15

what are the two types of cardiac mussel

Answer 15

contractable and noncontractible (pacemaker cells)

Question 16

in a diagram explain gap junctions t-tubeless and desmosomes

Answer 16

gap junctions look like = tubules look like gastric pits and desmosome look like little cells

Question 17

What are the two main phases of the cardiac cycle?

Answer 17

A1: Systole (contraction) and diastole (relaxation).

Question 18

What does it mean that the heart is myogenic?

Answer 18

It means the heart generates its own electrical impulses without external neural input.

Question 19

Which part of the heart initiates electrical excitation?

Answer 19

The sinoatrial (SA) node, also known as the heart’s pacemaker.

Question 20

What causes the rapid depolarization of atrial and ventricular muscle cells?

Answer 20

Increased membrane permeability to sodium (Na⁺) and calcium (Ca²⁺).

Question 21

Why can’t cardiac muscle undergo summation of contractions?

Answer 21

Because it has a long effective refractory period, preventing another contraction too soon.

Question 22

How is heart rate increased?

Answer 22

By sympathetic nerve stimulation and epinephrine (adrenaline).

Question 23

How is heart rate decreased?

Answer 23

By parasympathetic nerve stimulation (mainly via the vagus nerve).

Question 24

What is stroke volume?

Answer 24

The amount of blood ejected by a ventricle per heartbeat.

Question 25

What mechanisms increase stroke volume?

Answer 25

Frank-Starling mechanism (increased end-diastolic volume). Increased contractility due to sympathetic stimulation or epinephrine

Question 26

1. What prevents action potentials from travelling through the connective tissue of the heart? A. The connective tissue is electrically excitable B. Connective tissue contains voltage-gated ion channels C. The connective tissue is non-conductive and acts as an electrical insulator D. The connective tissue delays the signal for ventricular filling

Answer 26

c

Question 27

2. Why is it necessary to direct the electrical signals through the AV node instead of just letting it spread downward from the atria? A. To allow the atria and ventricles to contract simultaneously B. To delay the signal so the ventricles contract after the atria have emptied C. To prevent signal loss in the bundle branches D. To reduce the strength of the contraction in the ventricles

Answer 27

b

Question 28

3. What would happen to heart rate if the SA node stopped working? A. The heart would stop completely B. The atria would continue to contract but the ventricles would stop C. A slower rhythm would be established by other pacemaker cells like the AV node D. Heart rate would increase due to unregulated signals

Answer 28

c

Question 29

4. How does the autonomic nervous system control cardiac output? A. It only increases heart rate through the sympathetic nerves B. It modulates both heart rate and stroke volume via sympathetic and parasympathetic pathways C. It causes direct muscle contraction through somatic nerves D. It inhibits hormone release to slow cardiac output

Answer 29

b

Question 30

. A new cardiac drug, ivabradine, selectively blocks If channels in the heart. What effect would it have, and for what condition might it be used? A. It increases heart rate and is used for bradycardia B. It reduces contractility and is used for heart block C. It slows heart rate by reducing pacemaker activity and is used for tachycardia or angina D. It strengthens atrial contraction and is used for atrial fibrillation

Answer 30

c