Lecture 10 - Circulation

Question 1

Components of the Circulatory System

Answer 1

• Heart: muscular pump
• Blood: fluid that can transport things around the body
• Blood vessels: conduits through which the fluid can be pumped around the body

Question 2

Purpose of the Circulatory System

Answer 2

Pump nutriients, respiratory gases, wastes, hormones

Question 3

Atrium

Answer 3

• region of the heart that receives incoming blood

* A = first

Question 4

Ventricle

Answer 4

Region of the heart that pumps outgoing blood

Question 5

Arteries

Answer 5

• Carry blood away from the heart
• branch out into arterioles

A=away

Question 6

Veins

Answer 6

• Carry blood back to the heart
• smaller vessels (venules) join together to form larger vessels

Question 7

Capillaries

Answer 7

• where arteries (arterioles) and veins (veinules) meet
• thiny, thin walled

Question 8

Fish Circulatory System

Answer 8

• 2 chambered heart
• blood is pumped in a single circuit

heart–> gills–> tissue of the body –> heart

Process:

1. Atrium receives blood from the body
2. pumps it into the more muscular ventricle
3. ventricle pumps blood to gills (gas exhange)
4. blood elaving gills colelcts in large artery
5. distributes blood to smaller arteries leading to tissues and organs of the body
6. in tissues blood flows through beds of capilllaries
7. blood collects in veins
8. returns to atrium of heart

Question 9

What is the disadvantage of fish circulation?

Answer 9

• blood loses pressure as it travels through gills
• limits ability to supply tissues with nutrients, oxygen

Question 10

Why do birds/mammals have a different system of circulation?

Answer 10

• high nutrient demands and thus a very high density of vlood vessels
• heart must generate a high blood pressure to perfuse all the vessels
• have developed two separate circuits for blood flow
  1. pulmonary (heart–> lungs –> heart)
  2. systemic (heart –> tissues –> heart)

oxygenated blood can be pumped out of the heart to tissues at hihg pressure

Question 11

Features Separate Pulmonary and Systemic Curcuits

Answer 11

• 4 chambered hearts
• Two Circuits:
  1. Pumlonary
  2. Systemic
• Oxygenated and deoxygenated blood cannot mix
• Systemic receives blood with highest oxygen content
• blood with lowest oxygen content and highest CO2 is sent to lungs
• Can operate at different pressures
• large/higher pressure to pump blood through vessels of systemic
• lower pressure needed for pulmonary circuit in lungs

Question 12

Comaprison of Pressure in Systemic and Pulmonary Circuit

Answer 12

• systemic: large pressure needed for pumping blood thruogh all the vessels (longer distance)
• pulmonary: lower pressure (shorter distance)

Question 13

Features of the Human Heart

Answer 13

• Right atrium: receives deoxygenated blood from systemic circuit
• right ventricle: pumps deoxygenated blood through pumlonary circuit to get deoxygenated
• left atrium: receives oxygenated blood from the pulmonary circuit
• left ventricle: pumps oxygenated blood through the systemic circuit to get delivered to tissues

* one way valves prevent back flow

Question 14

Right Heart vs Left Heart

Answer 14

• right heart receives deoxygenated blood (blue) and pumps it to lungs
• left heart receives oxygenated blood (red) and pumps it to the body

Question 15

Path of Blood flow INTO the heart (right side)

Answer 15

1. right atrium receives deoxygenated blood from superior and inferior vena cava
2. Blood flows through an atrioventricular (av) valve into the right ventricle
3. filling of the ventricle results from passive flow while the heart is relaxed between beats
4. at the end of filling, the right atrium contracts

Question 16

Where does the heart recieve blood from?

Answer 16

• superior and inferior vena cava
• into the av valve

Question 17

How blood is pumped to lungs (2)

Answer 17

1. right atrium contracts, right ventricle contracts
2. AV valve closes
3. Blood is pumped into the pulmonary artery leading to lungs (through pulmonary valve)
4. gas exchange occurs in the lungs
5. oxygenated blood returns to heart via the pulmonary veins

Question 18

How blood flows in heart after beind oxygenated in lungs (3)

Answer 18

1. re-enters heart in left atrium
2. blood enters left ventricle through another AV valve
3. ventricular filling is passive, completed with the atria contract
4. left ventricle (very powerful), contracts
5. pushes open aortic valve
6. blood rushes into aorta to begin circulation throughout the body

Question 19

The Cardiac Cycle

Answer 19

* both sides of the heart contract at the same time

1. relaxation
2. contraction of the two atria
3. contraction of the two ventricles

Two phases:

• diastole:
• ventricles relax
• at very end, atria contract
• systole:
• ventricles contract

Question 20

What are the sounds of the heart beat?

Answer 20

• as ventricles begin to contract, AV valves close
• “lub”
• transition from diastole to systole
• as ventricule begin to relax, aortic and pulmonary valves close
• “dup”
• transition from systole to diastole

Question 21

What is a heart murmer

Answer 21

• when valves do not close completely, there is a backwards flow of blood
• “whoosh”

Question 22

What is your pulse?

Answer 22

• pressure wave created by the contraction of the left ventricle in systole

Question 23

Properties of Cardiac Muscle Cells

Answer 23

• has electrical signaling properties (like a neuron)
• can fire action potentials
• cardiac muscle cells are directly connected to each other via gap junctions
• cytoplasms are connected so direct and rapid spread of electrical signal
• coordinated contraction

Question 24

How do cardiac cells communicate?

Answer 24

• gap junctions
• dont use neurotransmitters

Question 25

Pacemaker cells

Answer 25

- cardiac muscle cells that can initiate action potentials without stimulation from the nervous system - fire action potentials and stimulate neighboring cells to contract - **Sinoatrial (SA) node** is the primary pacemake of the heart

Question 26

Sinoatrial Node

Answer 26

Primary pacemake of the heart in right atria

Question 27

Properties of the pacemaker

Answer 27

1. slower to rise 2. broader 3. slower to return to resting potentia

Question 28

Process of Pacemaker

Answer 28

1. **RESTING** * specialized Na+ channels are open * open at hyperpolarized voltage * resting potential is less negative 2. **RISING** * voltage gated Ca++ channels open --\> ca++ influx * open and close more slowly than voltage gated Na+ channels = broader shape 3. **FALLING:** same as usual \*hyperpolarization then causes the Na+ channels to open and AP start again * voltage gated K+ chanels open

Question 29

Nervous System and Heart Beat

Answer 29

- rate of heart beat can be controlled by nervous system - regulates rate at which the resting potential dirfts upwards toward threshold - some neurotransmitters can **stimulate depolarization** * resting potential reached more quickly * interval between pacemaker AP is decresed * heart beats faster - some neurotransmitters **stimulate hyperpolarization** * membrane potential rises even more slowly * interval between pacemaker action potentials lengthen * heart slows down

Question 30

Process of pacemaker and atrial contraction

Answer 30

1. heart beat begins with AP in sinoatrial node 2. action potential spreads rapidly through electrically coupled cells of the atria 3. there ar no gap junctions between the cells of the atria and the cells of the ventricles \* ventricles do not contrac tin unison with the atria

Question 31

atrioventricular (AV) node

Answer 31

- at junction of atria and ventricles - specialized cardiac cells - stimulated by depolarization of the atria

Question 32

Ventricular Contraction

Answer 32

1. AV node generatea AP 2. conducted to ventricles via "bundle of his"

Question 33

Bundle of His

Answer 33

- modified muscle fibers that conduct signal but do not contract - branches out across ventricles as Purkinje fibers - ensure that cardiac action potential spreads rapidly and evenly - muscle cells of the ventricles experience AP and contract

Question 34

Unique Properties of Cardiac Muscle Cells

Answer 34

1. very long depolarization phase * allows for prolonged muscle contraction 2. **rising phase** * is due to Na+ channels like a normal AP 3. **Falling** * Voltage gated Ca++ channels open * allows for extended plateau of depolarization * Ca++ allows muscle cells to contract * falling phase is due to K+ channels like normal AP

Question 35

Summary of Contraction Patterns

Answer 35

- right and left atria contract at the same time * coordinated by gap junctions - the right ventricle and the elft ventricle contract at essentially the same time * coordinated by bundle of his, purkinjie fibers, gap junctions - Atria and ventricles contract at different times * signal originates in sinoatrial node (atria) and spreads to AV node (ventricles)

Question 36

What coordinates the atria to contract?

Answer 36

gap junctions

Question 37

What coordinates the right and left ventricles to contract?

Answer 37

- bundle of his, purkinjie fibers, gap junctions

Question 38

ECG/EKG

Answer 38

Electrocardiogram Electrical events int he cardiac muscle can be recorded by electrodes on the surface of the body

Question 39

Features of EKG

Answer 39

P=depolarization of the atrial muscle * atrial contraction * end of diastole Q-S= depolarization fo ventricles * ventricle contraction * blood pumped out * systole * start AV valves close * lub) T= relaxation and repolarizatoin of ventricles * start of diastole * aortic and pulmonary valves close * "dub"