Chapter 42: Circulation and Gas Exchange Flashcards
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
Small molecules can move between cells andtheir surroundings by
Diffusion
Diffusion is only efficient…
over small distances because the time it takes to diffuse is proportional to the square of the distance
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
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
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
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)
Pulmonary circuit
the arteries and veins that circulate blood through the gas exchange organs (heart and lungs)
Systemic circuit
the arteries and veins that circulate blood through all parts of the body other than the gas exchange structures
2 atria and 1 ventricle, no septum found in….
Amphibians
2 atria and 1 ventricle partially divided by an incomplete septum found in….
Reptiles excluding birds
2 atria and 2 ventricles with complete septum found in…
Mammals and birds
pulmonary circuit pathway
right ventricle to respiratory surface (oxygen gained, CO2 lost) and back to left atrium
(RV > lungs > LA)
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)
What week of fetal development does heart start beating?
Third
The vertebrate cardiovascular system works in tandem with the….
Respiratory system
Blood
the tissue that transports oxygen, carbon dioxide, hormones, wastes, and nutrients to the body
Atrium
a chamber of the heart that receives blood arriving from the rest of the body
Ventricle
a chamber of the heart that pumps blood out of the heart; receive blood from large veins and direct it into the ventricles
Artery
large blood vessels that carry blood away from the heart toward capillaries
Capillaries
small blood vessels with very thin walls where exchange between blood and interstitial fluid occurs
Veins
blood vessels that return blood from the capillaries back to the heart
Left ventricle
Pushes blood throughout body
Right ventricle
Pushes blood to nearby lung (less muscular)
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)
- Entire heart in diastole
- Atria systole & ventricle diastole
- 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
- Diffusion
- Endo/exocytosis
- 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)
- It regulates the internal environment of the body by diffusing ions (electrolytes) into the fluid around tissues
- Blood clots
- transports heat between the body core and the skin
- transports hormones and nutrients
- 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
Hematopoieticstem 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
more
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
