NS - CVS I

Question 1

What are some advantages and disadvantages of multicellularity?

Answer 1

Advantages
* Defined internal environment (better homeostatic control)
* Efficient

Disadvantages
* Complex
* Coordination required
* Diffusion is slow

Question 2

What are some features of bulk flow? (4)

Answer 2

• Movement of fluid down a pressure gradient
• Rapid
• Energy required to produce pressure gradients
• Important for long distances

Question 3

Why i there a need for 2 circuits and 2 ventricles in birds and mammals? (3)

Answer 3

1. High metabolic rate
2. Lungs reduce hydrostatic pressure
3. Needs high blood pressure in tissues

Question 4

How did the heart develop? (6)

Answer 4

1. Two parallel tubes form
2. Tubes fuse, so does their lumen
3. Gives a common space (2 inflows above and below)
4. Differential growth occurs (Ventricle grows down, atria is pushed up)
5. Atria grows out into the 2 inflow vessels
6. Inflow and outflow forms at the top, atrium is above the ventricle

Question 5

What changes within the heart during its development?

Answer 5

1. Pinching of the central region separates ventricles and atria
2. Two septa grow down (passage left between atria, complete separation of ventricles)
3. A-V and semilunar valves form at pinching points

Question 6

What muscles are striated and voluntary?

Answer 6

Skeletal Muscle - Striated and Voluntary
Cardiac Muscle - Striated and Involuntary
Smooth Muscle - Unstriated and Involuntary

Question 7

What is a difference between a cardiomyocyte and skeletal muscle cells?

Answer 7

Cardiomyocyte consists of automatic contractions
* Skeletal myocyte relies on synaptic signals

Question 8

What are 8 structural features of a cardiac muscle cell?

Answer 8

1. Plasma membrane
2. Nucleus
3. Sarcolemma
4. Myofibrils- contain Myosin and Actin
5. Sarcomere- contractile unit
6. Mitochondria- provide ATP for contraction
7. Intercalated discs- junctions between adjacent cells
8. T-tubules- penetrate the cell from the membrane (transmit electrical signals)