Human Body Systems: Blood, Heart, Muscles, and Joints Explained

Blood Components and Functions

• Which of the following is not a function of blood? (Blood produces plasma hormones.)
• A normal hematocrit is _________ of the total blood volume. (37% to 52%)
• Antibodies belong to a class of plasma proteins called _________. (gamma globulins)
• Serum is blood plasma with _________ removed. (fibrinogen)
• An increase in the albumin concentration of the blood tends to affect blood pressure. (true)
• The plasma protein that contributes to viscosity and colloid osmotic pressure of the blood, and is also the most abundant of the plasma proteins, is _________. (albumin)
• Which of the following statements is true regarding erythrocytes? (Erythrocytes contain glycolipids that determine blood type.)
• Most oxygen being transported in the blood is bound to _________. (heme groups in hemoglobin)
• Oxygen binds to the _________ of a hemoglobin molecule. (iron-containing heme)

• The structure of hemoglobin consists of 4 protein chains.

  Two of the chains are alpha and two are beta proteins.

  Each of the protein chains are conjugated to a nonprotein heme group.

  This group contains an iron ion in the center.

  This center portion will reversibly bind oxygen.

• The main reason for erythrocyte death at the end of their life span is the deterioration of _________. (membrane proteins)
• Which of the following is not a function of red blood cells? (Synthesizing its own membrane proteins)
• Which of the following is most likely to cause anemia? (renal insufficiency)
• From infancy onward, red blood cells are produced by the _________. (red bone marrow)
• _________ have a finely granular cytoplasm and a nucleus typically divided into 3 to 5 lobes. (Neutrophils)
• Which of these is a granulocyte? (An eosinophil)
• Which of the following is the least abundant of the formed elements? (Basophils)
• Heparin and histamine are secreted by _________. (basophils)
• Allergies stimulate a rise in _________ count. (eosinophil)
• Which of the following is not a function of lymphocytes? (Phagocytizing large parasites)
• Platelets release _________, a chemical vasoconstrictor that contributes to vascular spasm. (serotonin)
• Which of the following is not a function of platelets? (Transporting oxygen)
• Thrombopoiesis is the synthesis of _________. (platelets)
• The structural framework of a blood clot is formed by _________. (A fibrin polymer)

Blood Vessels

• A blood vessel adapted to withstand great fluctuations in blood pressure would be expected to have _________. (an elastic tunica media)
• The smooth muscle of the tunica media of a large vessel is nourished mainly by the diffusion of nutrients from blood in the vessel lumen. (false)

• Capillary beds have precapillary sphincters at the junction of capillaries and the metarteriole.

  Constriction of these sphincters reduces the blood flow through their respective capillaries.

  When this occurs, blood is diverted to tissue or organs elsewhere.

  When the sphincters are open, blood will fill the capillary bed.

• The layer of the blood vessel wall that strengthens the vessel and allows changes in vessel diameter is the tunica _________. (media)
• Plasma solutes enter the tissue fluid most easily from _________. (fenestrated capillaries)
• The skeletal muscle pump propels blood in the veins toward the heart, and the _________ prevent(s) backward flow of blood toward the extremities. (valves)
• Blood sometimes flows into a capillary bed from a(n) _________. (metarterioles)
• From the time blood leaves the heart to the time it returns, it always passes through only 1 capillary bed. (False)

• The aorta is the first vessel blood enters upon exiting the heart.

  The large (elastic) arteries expand and recoil with every heartbeat due to a histologically dominant network of elastic tissue in the tunica media.

  Just prior to entering capillary beds, arterioles have become extremely thin and present only a few layers of smooth muscle.

  The site of gaseous exchange, or capillaries, are characterized by extremely thin walls with only endothelium and basal lamina, which better suits diffusional requirements.

  After exiting the capillary, venules contain no muscle and are the first vessel that blood enters on its way back to the heart.

  The medium veins contain abundant but irregularly spaced smooth muscle with frequent valves present in the tunica interna.

  The superior vena cava is an example of a large vein that includes smooth muscle circularly and longitudinally arranged in the tunica media and externa, respectively.

• A circulatory pathway in which the blood flows through two capillary beds in series before it returns to the heart is called a/an _________. (portal system)
• Intestinal blood flows into the liver by way of the _________. (hepatic portal vein)
• The lungs receive a systemic blood supply by way of the _________. (bronchial arteries)

The Heart

• The coronary blood vessels are part of the _________ circuit of the circulatory system. (systemic)
• The left and right regions of the heart pump at the same time. The right side of the heart pumps to the _________ and the left side of the heart pumps to the _________. (lungs; body's)
• The outermost layer of the heart wall is known as the _________. (epicardium)
• The epicardium contains adipose tissue, but the endocardium does not. (true)
• • Covers the valve surfaces and is continuous with the endothelium of the blood vessels (Endocardium)
  • Thickest layer; made of muscle and performs the work of the heart (Myocardium)
  • Outermost layer; contains adipose tissue (Epicardium)
• The thickest myocardium is normally found in the left ventricle. (true)
• The ear-like extension that covers the left atrium is called the left _________. (auricle)
• To get from the right atrium to the right ventricle, blood flows through the right AV valve, which is also known as the _________ valve. (tricuspid)
• _________ prevent the AV valves from bulging into the atria during ventricular systole. (Tendinous cords)
• Conical muscles seen in the ventricles that tug on the tendinous cords are called _________. (papillary muscles)
• Which valve is found between the right atrium and right ventricle? (tricuspid)
• Blood enters the heart from the venae cavae to the time blood leaves the heart by way of the aorta: (Right Atrium, Tricuspid valve, Right Ventricle, Pulmonary valve, Left Atrium, Mitral valve, Left Ventricle)
• Blood in the superior and inferior venae cavae flows through the semilunar valves as it enters the right atrium. (False)

• When atrial pressure is greater than ventricular pressure, the AV valves open.

  When ventricular pressure rises above atrial pressure, the blood in the ventricle pushes the AV valves closed.

  In the semilunar valves, when the pressure in the ventricles is greater than the pressure in the arteries, the semilunar valves are forced open.

  When ventricular pressure is lower than arterial pressure, arterial blood holds the semilunar valves closed.

• • Atrial pressure is greater than ventricular pressure (AV valves open)
  • Ventricular pressure rises above atrial pressure (AV valves closed)
  • Pressure in the ventricles is greater than the pressure in the great arteries (Semilunar valves open)
  • Ventricular pressure is lower than arterial pressure (Semilunar valves closed)
• Opening and closing of the heart valves is caused by _________. (pressure change)
• What would be the long-term result if the aortic valve was narrowed and it took more effort to pump blood through it? (Left ventricular hypertrophy)
• The myocardium receives oxygen and nutrients from _________. (the coronary circulation)
• Which of the following is not included in the cardiac conduction system? (The tendinous cords)

Cardiac Conduction System

• Normally, the only way electrical signals can get from the atria to the ventricles is to pass through the AV node and AV bundle. (True)

• The contraction of the heart begins with autorhythmic depolarization of the sinoatrial node located in the superior portion of the posterior atrial wall.

  From the pacemaker, the wave of depolarization disperses through the myocardium of the atria.

  Depolarization then arrives at the atrioventricular node located in the inferior interatrial septum.

  The AV node fires, causing the signal to travel into the AV bundle branches as it passes through the interventricular septum.

  Making a U-turn at the apex of the heart, the signals are then carried by the subendocardial branches through the exterior walls of the ventricles.

• • The pacemaker that determines the heart rate (sinoatrial (SA) node)
  • The electrical gateway to the ventricles (atrioventricular (AV) node)
  • Signals leave the AV node and descend along this structure toward the apex (AV Bundle)
  • Distribute the electrical excitation to the ventricles (subendocardial branches / Purkinje fibers)
• If it takes an electrical impulse longer to get through the AV node, what will the ECG look like? (There will be an extended distance between P and Q)
• Ventricular systole begins during the recording of the _________ of the ECG. (QRS complex)
• Ventricular systole begins during the recording of the QRS complex of the ECG. (true)
• A distinctive feature of intercalated discs is the presence of electrical junctions called _________. (gap junctions)
• What is the name of the opening between the two developing atria in a fetal heart? (Foramen ovale)
• The fetal structure of the ductus arteriosus becomes constricted and forms the _________ two to four days after birth. (ligamentum arteriosum)
• Beginning 10 to 15 hours after birth, the ductus arteriosus begins to close and becomes the _________. (ligamentum arteriosum)
• Which of the following is not true for the ventricular systole? (The ventricles relax)
• The semilunar valves close during _________. (ventricular diastole)
• For the atrioventricular valves to be open, the atria _________ and the ventricles _________. (may be in systole or diastole; must be in diastole)
• Atrial contraction accounts for most of the ventricular filling. (False)
• The ventricles begin to fill during ventricular diastole. (true)
• The _________ is/are the pacemaker(s) of the heart. (sinoatrial node)
• Which of the following is the correct sequence of travel by an electrical signal through the heart? (Sinoatrial node – Atrioventricular node – Atrioventricular bundle – Bundle branches – Subendocardial branches)
• Which of the following is true concerning the heart conduction system? (Electrical signals pass slowly through the atrioventricular node.)
• In the ventricles, the electrical signals travel along the interventricular septum to the apex of the heart, where it then spreads superiorly along the ventricle walls. (false)
• Electrical signals are carried by the subendocardial branches from the bundle branches to the ventricular walls. (True)

The Muscles

• The ability to carry an electrical charge along the cell is called (conductivity).
• Also known as responsiveness, (excitability) is a characteristic of all cells, but more highly developed in muscle and nerve cells.
• Muscles can pull bones closer to one another and increase the motility of some organs. This is due to the property of (contractility).
• Skeletal muscles can stretch up to three times their contracted length; this is called (extensibility).
• Muscles can stretch, and when released, return to their original, shorter length. This property is referred to as (elasticity).
• Muscles function in (movement) of the head, neck, and limbs, as well as propulsion of the contents through the digestive tract.
• Muscles also function in (stability) by preventing unwanted movement, as in maintaining posture.
• Using (sphincters), or valves, muscles control the passage of contents from one body cavity or lumen to another.
• Since muscle contraction requires energy to do work, muscles help maintain our body (heat).
• By absorbing a large share of one's (glucose), muscles play an important role in blood sugar control.
• Exercising muscles secrete (hormones) and other signaling chemicals that act on the liver, visceral fat, and the muscle itself to mobilize glucose and fat as fuel.
• Which of the following is not a characteristic of a muscle cell? (Plasticity)
• Which of the following is not a property that all muscle cells must have to carry out their function? (Autorhythmicity)
• Muscle cells respond to stimuli because they are _________. (excitable)
• Each G actin has a region to which a myosin head can bind. This region is called the _________. (active site)
• Each G actin has a region to which a myosin head can bind. This region is called the active site. (True)
• Blood capillaries branch through the endomysium to reach the individual _________. (muscle fibers)
• Acetylcholine (ACh) receptors are found in the (postsynaptic membrane folds).
• The neurons that innervate skeletal muscle fibers are also known as _________. (somatic motor)
• The enzyme that breaks down acetylcholine is called _________. (acetylcholinesterase)
• One motor neuron can supply only one muscle fiber. (false)
• In a relaxed muscle fiber, the active sites of actin are blocked by _________. (tropomyosin)
• To initiate skeletal muscle contraction, calcium ions must bind to the myosin heads. (false)
• Although the sarcomere shortens in contraction, the myofilaments _________. (slide over one another but do not shorten)
• Which of the following is not a characteristic of slow oxidative muscle fibers? (A relatively short twitch, or contraction)
• Slow oxidative fibers are more fatigue-resistant than fast glycolytic fibers. (true)
• Loss of muscle mass from lack of activity is termed _________. (atrophy)
• Which muscle(s) can contract without the need for nervous stimulation? (Smooth and cardiac muscle)

Muscle Contraction and Relaxation

• Unitary smooth muscle cells can stimulate each other because they have _________. (gap junctions)
• Most skeletal muscle tissue arises from embryonic _________. (mesoderm)
• Dystrophin is the protein that is defective in muscular dystrophy. Where is it normally found? (Between the thin myofilaments and the sarcolemma of a muscle fiber)
• During contraction of a muscle, calcium ions bind to the _________. (troponin molecule)
• Which of the following statements correctly identifies when the bond between the actin and myosin head is broken? (When an ATP molecule binds to the myosin head)
• Which statement correctly identifies when energy is released during muscle contraction? (When ATP is broken down into ADP and phosphate)
• The sequence of cross-bridge formation and myofilament movement will be repeated as long as calcium ions are present. (true)
• The sarcomere contracts when cross-bridges form and the actin myofilament slides along the myosin myofilament. (True)
• Muscle contractions are initiated by binding of _________. (calcium ions to troponin)
• During muscle contractions, cross-bridges form between _________. (myosin heads and actin filaments)
• Which of the following is the site of ATP binding and hydrolysis? (Myosin)
• The binding of ATP allows the muscle filaments to slide past one another. (true)
• After cross-bridges form, phosphate is released and then ADP follows. (true)

• Excitation is the process in which action potentials in the nerve fiber lead to action potentials in the muscle fiber.

  First, the motor nerve fiber releases acetylcholine into the synaptic cleft.

  This excites the muscle fiber, and a wave of electrical excitation spreads along the fiber and down into the T tubules.

• The step in which the muscle fiber develops tension and may shorten is called contraction. It begins after the active site on actin is exposed.

  The energized myosin head extends toward the exposed active site on the thin filament.

  A cross-bridge is formed by the attachment of the myosin head to the thin filament.

  The myosin head pulls, moving the thin filament toward the M line. This is called the power stroke.

  Once an ATP binds, myosin will release from the actin and break down the ATP. This is called the recovery stroke.

• Relaxation begins when nerve signals stop stimulating the synaptic knob, and acetylcholine release ceases.

  Acetylcholine is broken down enzymatically, so it can no longer remain bound to its receptor.

  The sarcoplasmic reticulum reabsorbs the calcium.

  Without calcium present in the sarcoplasm, tropomyosin moves back into position, blocking active sites, which prevents additional cross-bridge formation.

  If an appropriate force is applied, such as an antagonistic muscle or gravity, the muscle fiber returns to its resting length.

Joints and Articulations

• An articulation is any point at which two bones meet. (true)
• Bones that join together and are held in place with threads of collagen form a joint that is called a/an (synarthrosis).
• Bones joined together with cartilage between the ends of the bones form a joint called a/an (amphiarthrosis).
• Joints containing a joint cavity are called (synovial) joints. They display varying amounts of mobility.
• Fibrous joints are joints at which two bones are united by hyaline cartilage. (false)
• Symphyses are classified as cartilaginous joints. (True)
• Of the following joint types, which is the least movable? (Sutures)
• Of the following joint types, which is the most movable? (Synovial)
• A suture is a fibrous joint between two (skull) bones.
• The pubic (symphysis) is a cartilaginous joint in the anterior pelvis.
• The synovial joint with the highest degree of movement is called a (ball-and-socket) joint.
• Which of the following is a characteristic of synovial joints, but not of other classes of joints? (Bones held together by fibrous capsule and separated by a thin film of fluid)
• The two pubic bones are united by a/an _________. (symphysis)
• Which type of suture interlocks the two bones like pieces of a jigsaw puzzle? (serrate)
• Coronal, sagittal, and lambdoid are examples of _________. (serrate sutures)
• The joint between the first costal cartilage and the sternum is a _________, whereas the other costal cartilages are joined to the sternum by _________ joints. (synchondrosis; synovial)
• The epiphysis and diaphysis of a child's long bone are bound by a _________ joint. (synchondrosis)
• Synovial fluid is rich in albumin and hyaluronic acid, which give it a viscous texture similar to egg white. (True)
• Bursae are structures associated with fibrous, cartilaginous, and synovial joints. (false)
• Articular discs are found only in certain _________. (diarthroses)
• Ligaments attach bones to each other, and some are integrated into joint capsules of synovial joints. (true)

• The opposing surfaces of bones that are connected via synovial joints are covered with a thin layer of articular cartilage.

  Between the articular surfaces, a thin cavity is filled with synovial fluid, which acts to lubricate the joint surface and nourish the tissues of the internal joint surface.

  The joint capsule maintains the boundary of the joint and contains the synovial fluid.

  The outermost layer of the joint capsule is the fibrous capsule, which is continuous with the periosteum, and provides support to the joint.

  The deeper portion of the capsule is the synovial membrane, which contains cells that synthesize the synovial fluid.

  An example of fibrocartilage that provides additional padding and stability to the joint is the meniscus of the knee.

• Which structure cushions muscles and helps tendons slide over joints? (bursa)
• The shoulder is the only multiaxial ball-and-socket joint in the human body. (false)
• The proximal and middle phalanges form _________ joints. (hinge)
• Circumduction is limited to ball-and-socket joints. (False)

Joint Movements

• Hinge joints, such as the tibiofemoral joint, are monaxial. (true)
• Which of the following wrist movements will tip your palms toward you when you hold out your hands with the palms up? (Flexion)
• Normal chewing in humans involves _________ of the mandible. (elevation and depression)
• If one turns their palms upward, as if trying to cup water in one's hands, the motion required of the forearms is called _________. (supination)
• Suppose one wants to draw a large circle on a piece of paper, but the elbow and wrist are locked in their extended position. The rounded motion required at the shoulder to perform this task is _________. (circumduction)
• Your scapulae _________ when you reach your hands out anteriorly to push open a door. (protract)
• Starting from a bent position, straightening the spine requires _________ of the vertebral column. (extension)
• Suppose one raises his arms to the sides, causing his body to form the letter "T." What is the action taking place at the shoulders? (abduction)

• Decreasing the joint angle, as in bending the elbow or knee, is called (flexion).

  Straightening a joint generally returns a body part to zero position—as in straightening the elbow or knee. This is called (extension).

  Movement of a body part in the frontal plane away from the midline of the body is called (abduction).

  Returning a body part to zero position from an abducted position is called (adduction).

  Closing the mouth is (elevation) of the mandible.

  Opening the mouth is (depression) of the mandible.

  Drawing the shoulders anteriorly, or protruding the mandible outward is (protraction) of the scapulae or mandible.

  Pulling the shoulders back, as in sticking out your chest, is (retraction) of the scapulae.

  Making a conical motion with a limb, as in drawing a circle, is called (circumduction).

  The movement of the thumb from a position of opposition back to zero position is called (reposition).

  When one is standing in anatomical position, joints are said to be in what position? (zero)