1. Functions of a

transport/circulatory c. Reptiles

d. Birdssystem

2. Invertebrate circulation

a. Diffusion

b. Aided by gastrovascular cavity

c. Water vascular system

d. Open circulatory system

e. Closed circulatory system

d. Birds

e. Mammals1) Pathway of blood

2) Cardiac cycle

3) Maintenance of heartbeat

4) Principles governing blood

circulatione. Closed circulatory system

3. Vertebrate circulation

a. Fishes

b. Amphibians

circulation

5) Lymphatic system

6) Blood composition and

function

7) Cardiovascular disease

� Transports materials

� Nutrients from digested food

� Respiratory gases: CO2 and O2

� Waste materials: toxins and nitrogenous wastes

� Antibodies

� Hormones

� Enzymes

� Immune functions

� Maintains homeostasis

� Blood pH

� Heat transport

Gastrovascular cavity in simple invertebrates

� Cnidarians (e.g. Hydra) � Cnidarians (e.g. Hydra) and flatworms (e.g. planarians)

� No system required� Single opening: exchange

of materials with the environment

� Central cavity for digestion and digestion and distribution of substances throughout the body

� Body walls two cell layers thick ���� materials undergo diffusion

Water vascular system in

echinoderms

� multi-purpose:

locomotion, food and

waste transport,

respiration

� movement of muscles

pump water into canals

� closed system of canals � closed system of canals

connecting tube feet

� madreporite ���� ring

canal ���� radial and

lateral canal ���� tube feet

���� ampullae

Open circulatory system

� Phylum Arthropoda, � Phylum Arthropoda, Phylum Mollusca (with one exception)

� hemolymph� heart(s) →→→→ sinuses →→→→

ostia →→→→ heart(s)� diffusion from sinuses to

organs� often serve a support

purpose� often serve a support

purpose� disadvantage: loss of

pressure in sinuses� insects: well-developed

respiratory systems, O2not transported through the blood

Closed circulatory system or cardiovascular system

� cephalopods, annelids, vertebrates

� presence of blood vessels

� advantages

1. rapid flow

2. may direct blood to 2. may direct blood to specific tissues

3. blood cells and large molecules remain within vessels

4. can support higher levels of metabolic activity

� Heart

Atrium� Atrium

� Ventricle

� Blood vessels

� Arteries

� Arterioles

� Capillaries and � Capillaries and

capillary beds

� Venules

� Veins

� Blood

FISHES

� Single-circulation

� Fish heart� Fish heart

� 2-chambered� atrium and ventricle

� African lungfish heart

� 3-chambered� 2 atria� 2 atria

� LA: O2-rich blood

� RA: O2-poor blood

� spiral fold

� partially divided ventricle

Amphibians

� True double circulation� True double circulation� Pulmocutaneous and

systemic circulation are partly separated

� Amphibian heart� 1 ventricle� 2 atria:

� LA: O2-rich blood� LA: O2-rich blood� RA: O2-poor blood

� advantage: oxygen-rich blood reaches the body’s organs faster

� disadvantage: some mixing of O2-rich and poor blood occurs

Reptiles

� Reptilian heart

� 3-chambers

(crocodilians have 4)

� 2 atria

� 1 ventricle (2 in

crocodiles and

alligators)alligators)

� partially divided,

decreases mixing

Birds and Mammals

� 4 chambered heart:� 2 atria

� 2 ventricles

� full separation of

pulmonary and systemic pulmonary and systemic

circuits

� Advantages1. no mixing of oxygenated and

deoxygenated blood

2. gas exchange is maximized

3. pulmonary and systemic circuits

operate at different pressuresoperate at different pressures

� Importance

1. Endothermic ���� high nutrient and

O2 demands in tissues

2. Numerous vessels ���� great deal of

resistance, so requires high

pressure

� R side of heart:

� pulmonary circuit� pulmonary circuit

� L side of heart:

� systemic circuit

� one way valves:

� atrioventricular

valves

semilunar valves� semilunar valves

1. right atrium receives O2-

poor blood from superior

and inferior venae cavae

2. from right atrium into the

right ventricle through the

tricuspid valvetricuspid valve

3. pumped into the

pulmonary artery through

the pulmonary semilunar

valve to lungs

4. O2-rich blood from lungs is

returned to the left atrium

via the pulmonary veinsvia the pulmonary veins

5. enters the left ventricle via

the mitral or bicuspid valve

6. exits the left ventricle into

the aorta via the aortic

semilunar valve

7. circulated to body tissues