Circulation in Animals

A circulatory system minimizes the diffusion distance between ______ and _____ in animals with many cell layer

gas exchange surface and cell membrane

Mammals have a ____

closed, double circulatory system

In a _______ blood is confined to vessels and is distinct from the interstitial fluid - moves fluid in a loop

closed circulatory system

Closed systems are more efficient at ______

transporting circulatory fluids to tissues and cells

Oxygen poor and oxygen rich blood are pumped separately from the right and left sides of the heart in ______

Double circulation

Double circulation maintains higher blood pressure in the organs than ______

single circulation

______ have four chambered hearts with two atria and two ventricles

Mammals and birds

The left side of the heart pumps and receives only _______

Oxygenated blood

The right side of the heart pumps and receives _____

Deoxygenated blood

Mammals and birds are endotherms and require more _____ than ectotherms

O2

______ of the heart contraction drives double circulation in mammals

Coordinated cycles

Blood begins its flow with the right ventricle pumping blood to the _____

lungs

In the lungs, the blook loads ___ and unloads _____

O2; CO2

Oxygen rich blook from the lungs enters the heart at the left atrium and is pumped through the aorta to the body tissues by the _____

left ventricle

What are the three basic components of circulatory systems

Circulatory fluid (blood), a set of tubes (blood vessels), and a muscular pump (the heart)

What is a peristaltic pump?

A wave of contraction created by muscles in a tube pushes blood

The muscular heart ____

is single chambered or multichambered

Blood flows through the _______ to enter the right ventricle

Right atrioventricular valve

The strongly muscular left ventricle pumps the oxygenated blood through the _____ into the ______, from which it flows to the entire systemic circuit

aortic valve; systemic aorta

The right ventricle pumps the deoxygenated blood through the ______ into the ______ from which is flows to the lungs in the ______

pulmonary valve; pulmonary trunk; pulmonary circut

Heart valves dictate _______

a one-way flow of blood through the heart

The heart contracts and relaxes in a rhythmic cycle called the _____

Cardiac cycle

The contraction or pumping phase is called _____

systole

The relaxation or filling phase is called _____

diastole

Describe the cardiac cycle

1. Atrial and ventricular diastole

2. Atrial systole and ventricular diastole: a brief period of atrial contraction forces all the remaining in the atria into the ventricles

3. Ventricular systole and atrial diastole: ventricular contractions pump blood into the pulmonary artery and aorta through the semilunar valves

Some cardiac muscle cells are self-excitable meaning they contract without any signal from the nervous system, this is called

intrinsic control

What is phase 1?

Pacemaker potential: opening of vg funny sodium channels

What is phase 2?

The rising phase or depolarization - the opening of long lasting voltage gated calcium channels

What is phase 3?

The falling phase or repolarization - opening of voltage-gated potassium channels

What is the absolute refractory period?

The interval of time during which a second action potential cannot be initiated, no matter how large a stimulus is repeatedly applied. also, the amount of time it takes for an excitable membrane to be ready to respond to a second stimulus once it returns to resting state

During the absolute refractory period, action potentials can no longer be sent because ______

the sodium channels are closed and inactivated

In addition to the absolute refractory period, the variable speed of the electrical potential spreading through the heart causes the atria to ______

Contract before the ventricles

The pacemaker is influenced by _____

nerves, hormones, body temperature, and exercise

The pacemaker is regulated by two portions of the nervous system _____

The sympathetic and parasympathetic divisions

The sympathetic division ______ the pacemaker

speeds up

The parasympathetic division _____ the pacemaker

slows down

What are the three main types of blood vessels?

Arteries, veins, and capillaries (blood flow is one way)

What do artieries to?

They carry blood to capillaries - the sites of chemical exchange between the blood and interstitial fluid

All blood vessels are built of similar tissue and have three similar layers which are

Endothelium, smooth muscle, and connective tissue

Arteries become smaller in diameter and the walls become _____

thinner

There is ______ in the pressure in the arterial system

a very little drop

The smooth muscles in the walls of the arterioles are responsible for _____

vasomotor control of blood distribution

What is vasoconstriction?

It is the contraction of smooth muscle in the arteriole walls, it increases blood pressure

What is vasodilation

It is the relaxation of smooth muscles in the arterioles; it causes blood pressure to fall

_____ is a major inducer of vasodilation

Nitric Oxide

______ is an important inducer of vasoconstriction

The peptide endothelin

The heart pushes blood through the ______

arterial system

What is blood pressure?

the hydrostatic pressure that blood exerts against the wall of a vessel

In rigid vessels blood pressure is maintained, less rigid vessels deform and blood pressure is ____

lost

Blood pressure is primarily produced by the _____

heart

Pressure is the highest in the _____ and drops to almost zero in the venous system

arterial

What is systolic pressure?

The pressure in the arteries during ventricular systole and is the highest pressure in the arteries

What is diastolic pressure?

The pressure in the arteries during diastole and is lower than systolic pressure

The heart rate, also called ____, is the number of beats per minute

pulse

The ____ is the amount of blood pumped in a single contraction

stroke volume

The ____ is the volume of blood pumped into the systemic circulation per minute

cardiac output

Networks of capillaries, ______, are the sites of chemical exchange between the blood and interstitial fluid

Capillary beds

Arteries have thicker walls with more smooth muscles and elastic fibers to accommodate the ______

high blood pressure of blood pumped from the heart

Continuous capillary endothelial cells are held together by _____

tight junctions

Continuous capillary may have _____ that contract to regulate blood flow

pericytes

What are fenestrated capillaries?

they have filtrations and are important in kidneys, endocrine glands, small intestines, and choroid plexus of the brain

Sinusoid in the liver has _____

discontinuous capillaries, irregular blood filled spaces, liver, bone marrow, and spleen

Capillary exchange only occurs across capillary walls between _____

blood and surrounding tissues

What are the three routes across endothelial cells ?

Intercellular clefts, fenestrations, through the cytoplasm or transcytosis

What is diffusion?

Most important mechanism of capillary exchange movement of material through the PM

what is transcytosis ?

endothelial cells pick up material on one side of the PM my pinocytosis or receptor mediated endocytosis, transport it through the cell to the other side where it exits by exocytosis

what is filtration?

hydrostatic pressure forces a fluid through a selectively permeable membrane

Blood plasma loses volume in the initial segments of blood capillaries but regains fluid in the _____

final segments

Venous sinuses are

veins with thin walls, large lumens, no smooth muscle

What do veins do?

lower blood pressure with little fluctuation, thinner walls, less muscular and elastic tissue, expand easily, valves aid skeletal muscles in upward blood flow

When the skeletal muscles compress the veins, they force blood ____-

toward the heart

In the thinner-walled veins,

blood flows back to the heart mainly as a result of muscle action and valves

_____ is the study of the flow of matter, primarily in a liquid state

Rheology

The velocity of blood flow varies and is slowest in the _______ as a result of the high resistance and large total cross-sectional area

capillary beds

The velocity of blood flow varies and is fastest in the _______ as a result of the high pressure generated by the pumping ventricles

aorta, arteries, and arterioles

two mechanism regulate the distribution of blood in the capillary beds:

contraction of the smooth muscle layer in the wall of an arteriole constricts the vessel and precapillary sphincters control the flow of blood between arterioles and venules

The exchange of substances between the blood and interstitial fluid takes place across ______

the thin endothelial walls of the capillaries

The lymphatic system does what?

returns fluid to the body that leaks out from the capillary beds

Fluid, lymph, reenters the circulation directly at the ______ and indirectly through the lymphatic system

venous end

The lymphatic system drains into _____

veins in the neck

______ prevent the backflow of fluid

Valves in the lymph vessels

What are lymph nodes?

Are organs that filter lymph and play an important role in the body’s defense

____ is swelling caused by disruptions in the flow of lymph

edema

What is blood?

it is a connective tissue with several kinds of cells suspended in a liquid matrix called plasma

What is plasma?

About 90% water, with many solutes and inorganic salts in the form of dissolved ions, sometimes referred to as electrolytes

Blood plasma is a fluid matrix of

Suspended blood cells and platelets, nutrients, waste, and hormones, ions, and proteins

what cells transport oxygen?

red blood cells

_____ are fragments of cells that are involved in clotting

Platelets

_____ function in defense by phagocytizing bacteria and debris or by producing antibodies

white blood cells

Blood cells arise from _____

stem cells

erythrocytes, leukocytes, and platelets all develop from a common source:

a single population of cells called pluripotent stem cells in the red marrow of bones

What is hemoglobin?

The iron containing protein that transports O2

Each molecule of hemoglobin binds up to _____

4 molecules of O2

In mammals, mature erythrocytes lack ______

Nuclei and mitochondria

The hormone ______ stimulates erythrocyte production when O2 delivery is low

Erythropoietin (EPO)

What are the five major types of white blood cells (leukocytes):

Monocytes, neutrophils, basophils, eosinophils, and lymphocytes

Leukocytes function in defense by ______

phagocytizing bacteria and debris or by producing antibodies

What are the types of granulocytes

Neutrophils, eosinophils, basophils

What are the types of agrandulocytes?

monocytes, b lymphocytes, and t lymphocytes

What are neutrophiles?

The most numerous leukocytes, acts as the immune system’s first line of defense against infectious pathogens. They capture and destroy invading bacteria or microorganisms by ingesting them