Comparative Anatomy

Circulation

Putting all cells in contact with the surrounding environment!

Circulation Organisms of small number of cells

DO NOT need circulation structures ALL cells are in contact with environment

for food, gases, and waste removal

Organisms of Large Number of Cells need circulation structures due to not all

cells being in contact with the environment Substances made/collected in one part of

the organism are needed in another part. Transportation Structures are needed.

Protozoa No Circulation

Structures Only one cell All cells in contact

with the environment

Hydra No circulatory

structures 2-cells thick All cells in contact

with the Environment

Planaria No circulation

structures Yes, multi-celled,

but the organism is flat.

All cells are in contact with environment

Earthworm Closed Circulatory

System 5 pairs of “hearts” Dorsal blood vessel

(along back) - to head Ventral blood vessel

(along belly) - to tail Branches off at each

segment and connects both top/bottom vessels.

Grasshopper Open Circulation

System “Heart” Dorsal Blood Vessel trickles through the

spaces between cells (no blood vessels)

Returns back to heart.

Human Closed Circulation 4-chambered Heart Right - to Lungs Left - to Body Pathway:

Body, Rt. Atrium, Rt. Ventricle, Lungs, Lt. Atrium, Lt. Ventricle, Aorta, Body

Arteries AWAY from heart carry oxygen-rich

blood thick, elastic walls

to handle pressure allow to expand

under pressure

Capillaries smallest of blood

vessels allow one blood cell

through at a time material exchange

occurs here. Unites arteries with

veins. BP drops

Veins TOWARDS Heart collect blood after pass

through capillaries. Thin walled, less elastic one-way valves near Skeletal Muscles

help pump blood back to heart.

Exercise is important

Blood Pressure Body sensors

too low - surrounding smooth muscles contract too high - surrounding smooth muscles relax

Kidneys too high - remove water too low - re-absorb more water

Blood 4-6 liters of blood 45% of Blood

Red Blood Cells (RBC) White Blood Cells

(WBC) Platelets

55% Plasms

Red Blood Cells Hemoglobin

Iron containing protein that increases the blood’s ability to carry oxygen

Produced in Bone Marrow

No Nucleus Life span 120 days Replace 1% each day

White Blood Cells Do not contain

hemoglobin Made in bone marrow Have nuclei (long life -

many months / years) Immunity Function

destroy foreign invaders (bacteria, virus, parasites, etc.)

Platelets Blood Clotting proteins reach cut, become

“sticky” and clump together - clot forms