Circulatory Systems

Question 1

Homeostasis

Answer 1

Maintenance of an approximately constant internal environment

• refers to pattern not process
• often occurs regardless of external environment

Question 2

Feedback control systems

Answer 2

Provides the process/mechanism whereby homeostasis is achieved
Regulate many physiological variables

Question 3

Physiological variables

Answer 3

Temperature
pH
Solute concentration
O2 and CO2 in blood

Question 4

Conformation

Answer 4

Internal environment tracks external environment

Question 5

Regulation

Answer 5

Internal environment regulated independently of external environment (within limits)

Question 6

Circulatory system

Answer 6

Propulsive organ (heart)
Arterial system (blood distribution and pressure reservoir)
Capillaries
Venous system (blood volume reservoir and return system)

Question 7

Capillaries

Answer 7

Micro circulation for the transfer of materials between the blood and tissues. They are distributed in parallel in such a way that no cell is more than a cell or two away from a capillary

Question 8

Movement through the circulatory system

Answer 8

Rhythmic contraction of the heart
Elastic recoil from arteries which stretch as they fill by cardiac pumping
Squeezing of blood vessels during movement
Peristaltic movement of smooth muscle surrounding vessels

Question 9

Open circulatory system

Answer 9

Heart pumps into an open space (hemocoel), which lies between the endoderm and ectoderm.
Hemolymph is not moved through capillaries, but directly bathes the tissues
Hemocoel = 20-40% of body volume
Hemolymph = 30%
Pressures low (4-10 mmHg)

Question 10

Closed circulatory system

Answer 10

The fluid within closed systems is blood and the system is composed of a set of vessels. Blood differs in composition from other extracellular fluid
There is also lymphatic system for returning filtered materials back to the circulation. 
Blood = 5-10% of total body volume
Pressures high (systolic= 120; diastolic = 80 mmHg)

Question 11

Systolic

Answer 11

Pressure caused by contraction of heart

Question 12

Diastolic

Answer 12

Pressure between heart beats

Question 13

4 heart types

Answer 13

Extrinsic muscle pump (expands and compresses vessel; unidirectional)
Caudal heart (oscillates cartilaginous rod propelling blood through valved veins)
Pulsatile heart (peristaltic contractions)
Chambered heart (coordinated contractions of muscle wall)

Question 14

Heart

Answer 14

A series of muscular chambers connected in such a way to allow blood flow in only one direction
Chambers guarded by valves or septa that minimize back flow through the system

Question 15

Mammalian heart

Answer 15

4 chambers
2 atria
2 ventricles
Multiple chambers allow for stepwise increase in blood pressure

Question 16

Sequence of heart beats

Answer 16

Mid diastole
Atrial contraction
Isometric ventricular contraction
Ventricular ejection
Isometric ventricular relaxation

Question 17

Cardiac output

Answer 17

= stroke volume x heart rate

SV = before contraction volume - post contraction

Question 18

How does the heart contract

Answer 18

Specialized muscle cells (contain less actin/myosin, are thin and pale)
Sinoatrial node (65bpm)
Internodal pathways
Atrioventricular node (55bpm)
Network of conduction fibres

Question 19

Network of conduction fibres

Answer 19

Bundle of His
Left and right bundle branches
Purkinje fibres