General Biology II: Circulation

Flatworms, cnidarians, nematodes

Can you list some animals without a circulatory system?

Circulatory fluid, interconnected vessel network, heart (muscular pump)

What are the 3 components for the circulatory system?

Open Circulatory System

These contain hemolymphs that act as your circulatory fluid → found in Mollusca & arthropods that is in charge of bathing tissues

It is pumped through vessels to reach interconnected sinuses in contractions

When the central heart organ undergoes contractions, what happens to the hemolymph?

Hemolymph sucked back to heart via pores

When the central heart organ undergoes relaxation, what happens to the hemolymph?

Low Pressure

This forces the hemolymph throughout body and spread out (less costly, but more effective)

Closed Circulatory fluid

Fond in annelids, cephlapods and vertebrates that has blood as circulated fluid that moves within vessels (different compared to intestinal fluid) and contains a heart → has an advantage of higher BP which means it is more efficient with bigger, active animals

Hemolymph

Your circulatory fluid in the open circulatory system that is an interstial fluid bathing tissues

Blood

Circulated fluid that moves within vessels that is different than intestinal fluid

Capillaries, veins, arteries

3 Blood vessels found in closed circulatory system

Arteries

Bring blood away from heart to organs of body that soon divide into arterioles that deliver blood to capillaries

Veins

These receive blood from your venules, which is sandwiched between muscles for muscle movement

Capillaries

Microscopic blood vessels that infiltrate organs

Valves

Open/close in order to prevent backflow of blood towards the heart

Capillary Beds

Network of capillaries that will infiltrate tissues (exchange material between blood)

Venules

Capillaries merged with each other

Arteries → Arterioles → Capillaries → Tissues → Venules → Veins

SEQ blood flow

Heart

Acts as your muscular pump that will pump blood into large vessels which branch into smaller vessels that gets to the organs (2 or more muscular chambers)

Atria

Receives blood returning to tissues (1-2 depending on species)

Ventricles

Pumps blood away from heart to arteries (1-2 depending on species)

Pericardium

Enclosing sac for heart that supports muscles

Fish Circulatory Patterns

This organism undergoes single circulation with only 2 chambers (1 atrium and 1 ventricle) → blood flow is a single circuit (low metabolism rate, slow system)

1) Atrium will pump blood into ventricle (heart)

2) Ventricle contracts, pumps blood to arteries (heart)

3) Blood to capillary beds in gills (O₂ poor) (Gills)

4) Net diffusion of O₂ in blood (CO₂) and now O₂ rich (Gills)

5) Capillaries will converge into vessels that carry blood to capillary beds in rest of body (body)

6) Blood will return to atrium (heart)

SEQ the blood flow of a fish

1) Atrium will pump blood into ventricle (heart)

1st step of blood flow of a fish

2) Ventricle contracts, pumps blood to arteries (heart)

2nd step of blood flow of a fish

3) Blood to capillary beds in gills (O₂ poor) (Gills)

3rd step of blood flow in a fish

4) Net diffusion of O₂ in blood (CO₂) and now O₂ rich (Gills)

4th step of blood flow in a fish

5) Capillaries will converge into vessels that carry blood to capillary beds in rest of body (body)

5th step of blood flow in a fish

BP will drop in capillary beds in gills (blood has a hard time traveling) as O₂ rich blood reaches organs slowly, but they can combat that by swimming (heart)

Why isn’t single circulation as effective?

Amphibian Circulatory Pattern

This animal has double circulation and blood flow is double circuit where the heart has 3 chambers (1 ventricle + 2 atria) where the ventricle will pump blood into forked artery in 2 circuits → low metabolic rate/slow system

Systematic

Will transport O₂ rich blood to organs which will return to the heart’s right atrium

Pulmocutaneous

Will transport blood from lung/skin → where blood picks up O₂ to become O₂ rich as the circuit returns to left atrium via veins

Systemic

Will transport O₂ (rich) to body then returns to the right atrium

1) Ridge in ventricles

2) Diverts most of the rich blood to systematic and poor blood to pulmocutaneous circuit

3) Mixes a little and can go to either lungs or skin

SEQ amphibian atria (R/L) pumping into a single ventricle

Human Circulatory Pattern

Double circulation with more vigorous blood flow with a 4 chambered heart (2 atria + 2 ventricles) where the 2 circuits are seperate

Arteries

These bring blood away from heart

Veins

These bring blood to the herat

Cardiac Output

Volume of blood pumped by left ventricle by systematic circulation

Heart Rate x Stroke Volume

How can you calculate cardiac output?

Stroke Volume

Amount of blood pumped in a single contraction

Right Atrioventricular (tricuspid), Left Atrioventricular (mitral), Semilunar valves (Pulmonary Valves and Aortic Valves)

What are the 4 valves found to prevent backflow?

Right Atrioventricular Valve (Tricuspid)

This is the valve where it will allow the blood to enter into the right ventricle

Left Atrioventricular Valve (Mitral)

This is the valve where it will allow the blood to enter into the left ventricle

Semilunar

Ventricles to heart exit

Pulmonary valve

This valve has deoxygenated blood that leads to heart exit

Aortic Valve

This valve has oxygenated blood that leads to heart exit

1) Blood enters the atria

2) Gets through a valve

3) Ventricles will contract it

4) Another valve will close once blood fully flows and exits to prevent backflow

SEQ the human heart pathway

The lungs

Where does the right ventricle send the blood to (deoxygenated)?

The body

Where does the left ventricle send the blood to (oxygenated)?

Lub

A low pitched heart beat that is long lasting, which signifies the atrioventricular valves closing

Dup

Your high pitched heartbeat that is shorter lasting, which signifies semilunar valves closing

Lub-smnh

This means a heart murmur has happened and there is backflow in the semilunar valves

Sinoatrial Node

The pacemaker that will initiate the heartbeat

1) Mass of cardiac muscle atrium which autorhymically initiates heartbeat

2) Generates action potentials on their own

3) Triggers Ca²⁺ channels opening (depolarization)

4) Will create an action potential as the impulse will spread rapidly through atrial walls

5) Both atria contracts simultaneously

6) SA node will reach AV node

7) Will be purposefully delayed 1/10 second to prevent 4 chambers from squeezing at once and complete contractions before ventricles contract

8) Ventricles can fill completely

9) Bundle branches conduct signals from AV nodes to heart apex

10) Signal continues to Purkinje Fibers → ventricles contract

SEQ the initiation of a heartbeat

Autorhythmic

This means self contracting where AP is generated by Ca²⁺ channels that causes impulse to spread rapidly where both atria contract stimultaneously

Bundle Branches

This will conduct signal to heart apex (tip)

Purkinje Fibers

Signal spreads throughout ventricle where it contracts from blood to body/lungs

1) Mass of cardiac muscle atrium which autorhymically initiates heartbeat

1st step to initiating heartbeat

2) Generates action potentials on their own

2nd step to initiating heartbeat

3) Triggers Ca²⁺ channels opening (depolarization)

3rd step to initiating heartbeat

4) Will create an action potential as the impulse will spread rapidly through atrial walls

4th step to initiating heartbeat

5) Both atria contracts simultaneously

5th step to initiating heartbeat

6) SA node will reach AV node

6th step to initiating heartbeat

7) Will be purposefully delayed 1/10 second to prevent 4 chambers from squeezing at once and complete contractions before ventricles contract

7th step of initiating heartbeat

8) Ventricles can fill completely

8th step of initiating heartbeat

9) Bundle branches conduct signals from AV nodes to heart apex

9th step of initiating heartbeat

10) Signal continues to Purkinje Fibers → ventricles contracts

10th step of initiating heartbeat

Artificial Pacemakers

What can also be a replacement if the sinoatrial node stops working at some point?

To prevent 4 chambers from squeezing at once and complete contractions before ventricles contract

Why is the impulse delayed 1/10th of a second before ventricle gets signal to move blood away?

Nervous System

One of the main regulators for the heartbeat (controls your systems)

Baroreceptors

In blood vessels + chambers that sense Blood Pressure change and talk to the medulla by sending the messages afferently

Cardiac Centers

Controls 2 sets of autonomic nerves going to the SA node

Sympathetic

This part of the nervous system speeds up your contraction due to the fight and flight nature

Parasympathetic

This part of the nervous system slow down your contraction due to the rest and digest nature

Endocrine System

The adrenal medulla will be stimulated by sympathetic nerves in response to stress, which increases your heartrate

Temperature

This will increase as heartrate increases, decrease as heartrate decreases

Endothelium

Innermost that lines lumen, provides smooth surface, sliding to minimize resistance to blood flow

Smooth Muscle

Thick in arteries, elastic and involuntary (in arteries than veins)

Connective Tissue

Outer coat with elastic and collagen fibers providing support

Capillaries

This contains the endothelium with basal lamina & only location of gas exchange between blood and ISF

Diffusion, gas exchange, waste removal, nutrient arrival

How are substances moved between blood and tissue?

Plasma

Fluid compartment of blood with no cells → will be under high pressure in closed circulatory system where it might eventually be forced out into tissues

Interstitial Fluid

Plasma forced out into tissues that will bathe tissues, no cells but some proteins (25%) and hypotonic to Red Blood Cells

Fluid Movement

This is the back and forth between capillaries and tissues via opposing forces

Blood Pressure

Pressure exerted on capillary wall due to heart pumping, which will push plasma out of capillary

Osmotic Pressure

Antagonistic to Blood Pressure where blood is hypertonic to the interstitial fluid so ISF wants to flow back into blood

Blood pressure > Osmotic pressure where blood wants to move out of capillary

When you are at the arterial end of capillary, what is greater?

Osmotic Pressure > Blood pressure, where we want to go back into the capillary

When you are at the venous end of capillary, what is greater?

15%

How much fluid remains even after some of them return?

Lymphatic System

This will collect and return interstial fluid to maintain fluid balance, absorbs lipids from digestive system, immunity

Lymph

lymphatic system fluid WBCs, bacteria and other filtrates

Lymph vessels

Where throughout the body, almost all tissues extended

Lymph nodes

Connective tissues with lots of WBCs where pathogens filtered out

Edema

Blocked nodes, swelling due to ISFs, poor circulation