Chapter 42: Circulation and Gas Exchange Flashcards by Kristen Mazowiecki

Animals with gastrovascular cavities do not require

an organ system for transporting nutrients and gases within the body because each cell is in close contact with a source of nutrients and oxygen

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Small molecules can move between cells andtheir surroundings by

Diffusion

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Diffusion is only efficient…

over small distances because the time it takes to diffuse is proportional to the square of the distance

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Open circulatory system

circulatory fluid is not contained in vessels during its entire trip through the body, but instead drains into the body cavity; circulatory fluid directly bathes the cells and and the blood is not kept in blood vessels

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Closed circulatory system

circulatory fluid is contained within vessels during its entire trip (a circuit) through the body and never leaves the network of blood vessels; interstitial fluid bathes cells

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Single circulation

blood travels from the heart to the gas exchange structures, and then directly to the rest of the body without being pumped a second time by the heart

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Double circulation

blood travels from the heart to the gas exchange structures, but then returns to the heart to be pumped a second time before traveling to the rest of the body (4 chambered heart)

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Pulmonary circuit

the arteries and veins that circulate blood through the gas exchange organs (heart and lungs)

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Systemic circuit

the arteries and veins that circulate blood through all parts of the body other than the gas exchange structures

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2 atria and 1 ventricle, no septum found in….

Amphibians

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2 atria and 1 ventricle partially divided by an incomplete septum found in….

Reptiles excluding birds

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2 atria and 2 ventricles with complete septum found in…

Mammals and birds

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pulmonary circuit pathway

right ventricle to respiratory surface (oxygen gained, CO2 lost) and back to left atrium
(RV > lungs > LA)

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systemic circuit pathway

takes oxygenated blood from the left ventricle of the heart to the tissues, removes carbon dioxide from the tissues, then returns deoxygenated blood to the right atrium
(LV > organ tissues > RA)

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What week of fetal development does heart start beating?

Third

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The vertebrate cardiovascular system works in tandem with the….

Respiratory system

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Blood

the tissue that transports oxygen, carbon dioxide, hormones, wastes, and nutrients to the body

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Atrium

a chamber of the heart that receives blood arriving from the rest of the body

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Ventricle

a chamber of the heart that pumps blood out of the heart; receive blood from large veins and direct it into the ventricles

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Artery

large blood vessels that carry blood away from the heart toward capillaries

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Capillaries

small blood vessels with very thin walls where exchange between blood and interstitial fluid occurs

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Veins

blood vessels that return blood from the capillaries back to the heart

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Left ventricle

Pushes blood throughout body

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Right ventricle

Pushes blood to nearby lung (less muscular)

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septum

thick wall dividing two sides of the heart

As the ventricles contract...

the atria relax

Left side of heart

receives oxygenated blood from lungs; pumps blood to the rest of body (far distance).

Right side of heart

receives deoxygenated blood from body; pumps blood to lungs (short distance).

diastole

relaxation (filling phase)

systole

contraction (pumping phase)

Cardiac cycle (3 steps)

1. Entire heart in diastole 2. Atria systole & ventricle diastole 3. Ventricle systole & atria diastole

atrioventricular valves

separate the atria from the ventricles (atrial blood enters ventricles through here)

aorta

blood pumped throughout body via this

Valves within the heart prevent

backflow of blood

chordae tendinae

heart strings; hold valves in place

sound caused by blood pressure against the atrioventricular valves

lub

semilunar valves closing makes this sound

dub

semilunar valves

The valves between the ventricles and the major arteries leaving the heart

The 2 AV valves

tricuspid and mitral

The 2 SL valves

pulmonary and aortic

If the two ventricles are slightly out of sequence, so that one closes first, the second sound may “stutter” or “split”. A constant “split” may indicate:

hypertrophy (enlargement) of one ventricle

pulse

heartbeats per minute

Blood pressure

the pressure that blood exerts in all directions, including against the walls of blood vessels (systolic pressure over the diastolic pressure)

Diastolic pressure

the force your blood exerts on the walls of your closed circulatory system during relaxation

Systolic pressure

the force of left ventricle contraction, which pushes blood through the circulatory system

hypertension

High BP (reading higher than 130/80)

mycardium

heart muscle; undergoes rhythmic contractions without receiving nerve impulses

Heart beat is controlled by

intrinsic (inside the heart) and extrinsic (outside the heart) factors

artificial pacemaker

a medical device that uses electrical impulses (delivered by electrodes that contact the heart muscles) to regulate the beating of the heart

arrhythmia

abnormal heart beat

tachycardia

fast heart beat

The heart beat is initiated in the

sinoatrial node

blood vessels

transport blood through the body

Arteries are _____ walled and _____ pressured

thick; high

Veins are _____ walled and _____ pressured

thin; low

Arterioles

small vessels that branch from larger arteries and are structurally similar to arteries

Blood leaving capillaries collects in larger vessels called

Venules

Veins have (2 things)

Valves to prevent backflow | Skeletal muscle to pump

Capillary walls are composed of

a single layer of epithelial cells surrounded by a layer of connective tissue

Precapillary sphincters

regulate blood flow

Mechanisms of exchange between the blood and interstitial fluid in capillary beds include

1. Diffusion 2. Endo/exocytosis 3. Bulk flow

Large blood proteins are responsible for

Blood's osmotic pressure

Lymphatic system

A system of vessels and lymph nodes that return fluid, small proteins and solutes to the blood

Lymph

Fluid lost by capillaries

How is blood critical to homeostasis? (5 things)

1. It regulates the internal environment of the body by diffusing ions (electrolytes) into the fluid around tissues 2. Blood clots 3. transports heat between the body core and the skin 4. transports hormones and nutrients 5. Cellular elements in the blood transport oxygen and destroy pathogens in the body

Liquid portion of the blood

Plasma

Solid portion of the blood

Cellular elements erythrocytes (red blood cells), leukocytes (white blood cells), and platelets

Electrolytes in the blood

Phosphorus and potassium

_____ help maintain blood’s osmotic pressure, so water will remain inside the vessels instead of diffusing into tissues

Proteins

hormones, nutrients, and gases are dissolved in the

plasma

Cellular elements of the blood originate in the

bone marrow

______ in the bone marrow give rise to different types of blood cells

Hematopoietic stem cells

White blood cells (leukocytes)

defensive cells and are critical to the immune system

Neutrophils

destroy bacteria

Eosinophils

liberate histamines and serotonins in allergic reactions

Lymphocytes

produce the immune response in your body

B cells

produce antibodies

T cells

help in pathogen attacks

Monocytes

for phagocytosis of foreign bodies

Red blood cells (RBC; erythrocytes)

carry oxygen bound to hemoglobin

Hemoglobin

four-subunit protein with each protein capable of carrying four oxygen molecules (and having four heme groups) to the tissues

In mammals RBCs do not have:

A nucleus

C02 is also transported as bicarbonate ions in the plasma where it serves as a

Buffer

Normal blood pH

7.3-7.4

thrombin

an enzyme that converts fibrinogen to fibrin in blood clotting

_____ and _____ depend on the integrated functioning of the cardiovascular and respiratory systems

Mammals and birds

Single circulation is _____ efficient than double circulation

We use only about ____ percent of the oxygen that we breathe in

4 to 5

Air pathway to the alveoli

Pharynx > larynx > trachea > bronchi > bronchioles > alveoli

Inhalation and exhalation are governed by muscular movements of the

Thoracic cavity

Your ____ drops when you inhale

Diaphragm

Inhalation is a _____ process

Active

Exhalation is a _____ process

Passive

Respiratory rate is governed by

the medulla oblongata and the pons in the brain stem.

The body can sense the levels of carbon dioxide and oxygen in the blood through

chemoreceptors in the carotid artery and aorta

High carbon dioxide levels immediately trigger

an increase in the depth and rate of respiration