Circulatory Systems (lecture 23)

Circulatory System

Body’s Internal transportation network. Moves important materials (O2, nutrients, hormones) to cells, waste products (CO2, nitrogenous waste) away from cells.

Circulatory System Benefit

• Speeds up transport across body in bigger animals

Some small animals don’t have circulatory system bc their body cells are close enough so nutrients and O2 can be moved around by simple diffusion.

Basic Components of Circulatory System (3)

1. Fluid

2. Interconnecting Vessels (arteries, veins, capillaries)

3. Pump (heart)

Functions of Fluid in Circulatory System

Carry materials (blood or hemolymph)

Circulatory system types

Open and Closed

Open Circulatory System (who/fluid type/how it works)

• found in invertebrates

• fluid type: hemolymph

• Pumped into open spaces (sinuses) and bathes tissues directly

Closed Circulatory System (who/fluid type/how it works)

• found in vertebrates

• fluid: blood

• Blood stays inside vessels, it never directly touches body tissues, exchange happens through capillaries

Type of vessels in Vetebrates (3)

1. Arteries

2. Capillaries

3. Veins

Arteries

Carry Blood away from heart

Capillaries

Tiny blood vessels where blood exchange w/ tissues happens

Veins

Carry blood towards the heart

Fish (vertebrate) circulation type and steps (3)

single circulation (one big loop)

heart → gills (pick up O2) → body (delivery O2) → heart

Fish Heart (chambers?)

• two chambered heart

• 1 atrium (received blood)

• 1 ventricle (pumps blood)

Fish Metabolism / Blood flow

• slow metabolism

• Slow blood flow

• slow system

Amphibians (vertebrate) circulation type and circuits (2)

• Double circulation (two connected loops)

• Pulmocutaneous circuit

• Systemic Circuit

Pulmocutaneous circuit (amphibians)

blood goes to:

1. lungs

2. heart

and picks up oxygen

Systemic circuit (amphibians)

Blood delivers O2 to rest of the body → returns to right atrium

Amphibians Heart (chambers?)

3 chambered heart: 2 atria and 1 ventricle (w/ a ridge to separate oxygenated and deoxygenated blood)

Mammals (and birds) Type of circulation

Double Circulation (full separated)

Mammals (and birds) circuits

1. Pulmonary circuit

2. Systemic circuit

Pulmonary circuit (Mammals)

heart → lungs → heart

Systemic Circuit (Mammals)

heart → body → heart

Mammals Heart (chambers?)

4 chambered heart with 2 atria and 2 ventricles (complete separation of oxygenated and deoxygeneated blood)

Mammals metabolism

high metabolic rate - endotherms (generate own heat)

Cardiac Output

The amount of blood pumped by the left ventricle per minute

Cardiac Output Equation

heart rate(# of beats per min) times stroke volume (amount of blood pumped by 1 contraction)

60 to 100 bpm

Normal Range of beats per min

Heart Valves (4) and Function

• Semilunar: pulmonary and aortic valves

• Atrioventricular: mitral and tricuspid valves

  Function: Prevent back flow of blood

Sound of Heartbeat

Caused by valves closing

“Lub” sound

AV valves closing, low pitch, deep

“Dub” sound

Semilunar valves closing, high pitch sound

Heart Murmur

Blood leaks backwards into ventricles causing a “lub - shhh - dub” sound

Heartbeat Electrical Control Path (5)

SA node → AV node → Bundle branches → Apex → Purkinje Fibers

Sinoatrial Node (SA) (4)

• the “pacemaker”

• found in right atrium

• initiates electrical impulses that cause atria to contract first

• auto rhythmic cells

auto rhythmic cells

Cells that can self-depolarize

Atrioventricular Node (AV)

delays impulse for 1/10th of a second to give ventricle time to fill up before contracting

Purkinje fibers

Spread signal through ventricles for them to contract and send signal to body and lungs

Baroreceptors

Specialized sensory neurons

Baroreceptors Functions (2)

1. Detect blood pressure

2. Send signals to the medulla in the brain

Cardiac Centers (2 autonomic nerves) what what they act on

• Controlled by medulla

1. Sympathetic nerve: Speeds up heart rate

2. Parasympathetic nerve: Slows down heart rate

Both act on the SA node (natural pacemaker)

Endocrine System Stress Response (3)

• Activates sympathetic nerves

• Adrenal gland releases epinephrine (adrenaline)

• Fever (high temp) can also increase heart rate

Blood Vessels Structure (arteries and veins) (3)

• Endothelium

• Smooth muscle

• Connective Tissue (lots collagen fibers)

Arteries Structure

Very elastic, thick smooth muscle

Blood Vessels Structure (Capillaries) (2)

1. Endothelium

2. Basal lamina

3. Site of gas exchange

Interstitial Fluid

Fluid that surrounds cells in tissues, providing nutrients and removing waste. Since blood is under pressure, some fluid moves into here.

Plasma

Fluid part of blood - always under pressure

Blood pressure

Pressure on capillary wall

Blood pressure > osmotic pressure (At the Arterial End)

Fluid exits into tissues - blood moves out of the capillary

Osmotic pressure > blood pressure (At the Venous End)

Some fluid returns to capillary ~15% stays in the tissue → causes swelling if not removed to the capillary

Osmotic pressure

Opposes blood pressure

Lymphatic System

Helps return the fluid into the capillaries

Lymphatic System Function Functions (3)

1. Collect and return interstitial fluid

2. Absorb lipids (ooh from digestion)

3. Immunity