respirtory and circulatory system

Small, simple animals can rely on ____ diffusion of gases because they are only a few cell layers thick.

passive

Larger animals cannot rely on diffusion alone and require____ to carry oxygen throughout their body.

oxygen carriers

____is the primary oxygen carrier used by vertebrates.

Hemoglobin

Hemoglobin is composed of____ subunits, each capable of binding an oxygen molecule.

four

Oxygen binds to the____ ring in hemoglobin, which contains an iron atom.

heme

When oxygen binds to hemoglobin, it changes____ the of the heme ring and the entire subunit.

conformation

Carbon dioxide binds to the ____terminal of the hemoglobin subunits rather than the heme ring.

carboxy

The binding of oxygen to hemoglobin is non-covalent, reversible, and____ affinity.

high

Hemoglobin binds____ monoxide 200–300 times more readily than oxygen, preventing proper gas exchange.

carbon

The red color of blood comes from the presence of ____in the heme group of hemoglobin.

Fe²⁺ (iron)

Even deoxygenated blood appears red because of____ the content in hemoglobin.

iron

As oxygen concentration increases, the percentage of hemoglobin saturated with oxygen increases in an____ -shaped curve.

S

Hemoglobin is nearly ____% saturated with oxygen under normal atmospheric conditions.

100

The binding of one oxygen molecule to hemoglobin makes it____ for other subunits to bind oxygen.

easier

High concentrations of ____shift the hemoglobin saturation curve, requiring more oxygen to achieve the same saturation.

CO₂

The presence of ____, CO₂, and pH changes can influence how hemoglobin binds to oxygen.

temperature

Hemocyanin is an oxygen carrier that uses the metal ion ____instead of iron.

copper

Hemocyanin is found in animals like ____and ____.

molluscs; arthropods

Unlike hemoglobin, hemocyanin is an____protein not found inside blood cells.

extracellular

Hemocyanin does not contain a ____ring, unlike hemoglobin.

heme

Hemocyanin gives the hemolymph of certain invertebrates a____ tint.

bluish

The function of circulation is to move fluids to carry ____ and ____.

nutrients; waste products; oxygen; carbon dioxide

Circulation also helps regulate____ by distributing heat throughout the body.

body temperature

As body size increases, diffusion alone becomes insufficient, so a is____ needed to move fluid.

pump

The pump responsible for circulation in vertebrates is the____ .

heart

The heart is made entirely of ____muscle.

cardiac

Cardiac muscle is involuntary, ____(has stripes), branched, and has only ____nucleus per cell.

striated; one

Cardiac cells communicate using ____junctions located in structures called ____discs.

gap; intercalated

These gap junctions allow ions to pass freely between cells, enabling synchronized ____ signaling.

electrical

The average human has about____ liters of blood.

5

Only about____ % of blood volume can be safely lost at a time.

20

____make up about 45% of blood volume and are packed with hemoglobin for oxygen transport.

red blood cells (erythrocytes)

Mammalian red blood cells lack a____ and most other organelles.

nucleus

About 50% of blood is____ , a fluid containing salts, ions, and other biomolecules.

plasma

____are white blood cells that retain a nucleus and are part of the immune system.

leukocytes

White blood cells are outnumbered by red blood cells by about____ to one.

1000

____are cell fragments that monitor blood vessels for leaks and initiate clotting.

platelets (thrombocytes)

Platelets help initiate clotting by releasing ____, which is cleaved into active ____.

fibrinogen; fibrin

Fibrin forms a ____that acts as a patch for damaged vessels.

mesh

This clotting mesh captures____ and dead cells to plug leaks in blood vessels.

collagen

Hemoglobin binds oxygen at the ____ ring and changes its conformation.

heme

In a ________ circulatory system, blood stays within vessels for the entire journey from the heart and back. closed

closed

In a____ circulatory system, blood leaves vessels and bathes tissues directly for part of its journey.

open

Vertebrates, cephalopods, annelids, and some invertebrate chordates have a ____circulatory system.

closed

Insects and arthropods typically have a(n) ____ circulatory system.

open

Open systems are ____efficient than closed systems.

less

Closed systems require more ____to function properly.

energy

Ancestral vertebrates like fish have a ____ circulatory system with a 2-chambered heart.

single

In fish, blood is pumped from the ____ to the gills for gas exchange.

ventricle

After gas exchange in fish, oxygenated blood travels through the body and returns to the ____ .

heart

Gills ____are to rupture, requiring low pressure for blood flow.

sensitive

Lungfish have a modified circulation route that allows blood to go from gills to the body or to ____ .

lungs

Amphibians have a partially separated heart with ____circuits.

two

Amphibian hearts have heavily ____ trabeculated to help direct blood flow.

ventricles

In amphibians, the two atria are ____ but share a single ventricle.

separate

The protruding walls in the amphibian ventricle are called ____ .

trabeculae

In reptiles, the wall between the left and right sides of the heart is more ____ .

pronounced

____ arteries carry deoxygenated blood from the heart to the lungs.

pulmonary

____ veins return oxygenated blood from the lungs to the heart.

pulmonary

Systemic arteries carry ____ blood from the heart to the body.

oxygenated

Systemic veins carry ____ blood back to the heart.

deoxygenated

In mammals, there is full separation of atria and ____ .

ventricles

Mammals are the only vertebrates with a true ____-chambered heart.

four

In systemic circulation,____ carry blood away from the heart.

arteries

In systemic circulation, ____ return blood to the heart.

veins

Pulmonary arteries carry ____ blood.

deoxygenated

Pulmonary veins carry ____ blood.

oxygenated

Arteries = blood ____ from the heart.

away

Veins = blood ____ to the heart.

back

In insects with open circulation, body ____ helps push hemolymph back toward the heart.

contracting

Trabeculae help direct oxygenated and deoxygenated blood within the same ____ in amphibians.

ventricle