Biology 3

Question 1

Nancy arrived at the emergency room in a coma.

You suspect a drug overdose which has depressed her rate and depth of breathing.

As a consequence you expect her PaCO2 level to be:

A increased

B decreased

C normal

Answer 1

A increased

Question 2

Draw a typical ECG, name the parts, and what they represent

Answer 2

_{An ECG recording is the sum of all of the electrical potentials generated by all the cells of the heart at any instance in time.}

_{Each deflection (wave) of the ECG represents either depolarization or repolarization of the specific parts of the heart.}

_{Because depolarization occurs before mechanical contraction, the waves of depolarization can be associated with contraction and relaxation of the atria and the ventricles.}

A typical ECG recording and the waves are shown below (Figure 58).

The P wave corresponds to depolarization of the atria.

The QRS complex corresponds to depolarization of the ventricles.

The T wave corresponds to repolarization of the ventricle.

Question 3

1. In what form is most CO2 in blood?
2. Write the equation

Answer 3

1. Bicarbonate ion
2. Carbonic acid which dissociates into bicarbonate and proton

Question 4

Determine the # of chromosomes in an organisms’ sex cells.

Answer 4

It is half the amount of chromosones.

Question 5

Eye

1. What are the steps of light detection by photoreceptor cells?

Answer 5

_{The retina contains two types of photoreceptor cells, the rods and cones. Because the light-sensing portion of the photoreceptor cells faces the back of the retina, the light must travel through several layers of cells before it is detected.}

Photopigment proteins (G-protein coupled receptors) in the plasma membrane of the photoreceptors contain retinal, a derivative of vitamin A that changes its conformation in response to a photon of light (Figure 31).

The change in conformation of retinal affects the conformation of the photopigment protein which starts a signal transduction cascade.

_{The signal transduction cascade reduces the amount of cGMP which causes a cGMP-gated cation channel to close (Figure 31). This hyperpolarizes the photoreceptor cell and eventually results in signaling to the central nervous system}

Question 6

5. Each of the following changes will result in increased blood flow to a tissue EXCEPT:

B. decreased vessel diameter

A. increased blood volume

D. decreased peripheral resistance

C. increased blood pressure

Answer 6

B. decreased vessel diameter
Well done!

Question 7

19. Parasympathetic stimulation of the sinoatrial (SA) node will:

A. hyperpolarize the pacemaker cells

B. decrease the heart rate

C. increase the rate of depolarization

E. A and C

D. A and B

Answer 7

D. A and B
Well done!

Question 8

How many inputs can there be controlling Ca++ channels into smooth muscle?

Answer 8

MEMBRANE ACTIVATION

Contraction of smooth muscle, like skeletal muscle, is dependent on a rise of cytosolic Ca++ due to changes in the plasma membrane. However, smooth muscle does not have T tubules. Instead Ca++ enters from the ECF by diffusion through calcium channels in the plasma membrane. These Ca++ channels include: voltage-gated channels, ligand-gated channels and mechano-gated channels. The inputs that regulate contraction include:

Autonomic nervous system via voltage gated Ca++ channels.
Hormones via ligand-gated Ca++ channels.
Stretch via mechano-gated Ca++ channels.

At any one time, multiple inputs, some excitatory and others inhibitory, can be activated in a single cell. The net effect is dependent on the relative intensity of these inputs. Note that the intracellular Ca++ of smooth muscle can increase (or decrease) due to changes in the membrane potential from graded depolarization, hyperpolarization, or an action potential

Question 9

Nervous

1. What does the somatic nervous system control?

Answer 9

The efferent portion of the peripheral nervous system consists of the somatic nervous system and the autonomic nervous system.

The autonomic nervous system controls the function of glands, smooth muscle, cardiac muscle, and the neurons of the GI tract.

It is composed of two neurons in series that can either excite or inhibit the target organ.

In contrast, the somatic nervous system contains single neurons that excite skeletal muscles.

The movements controlled by the somatic nervous system can be voluntary or involuntary (reflexes)

Question 10

ICF & ECF

Compare the ICF and ECF for the following items

1. redox

which has higher concentrations

2. K+
3. Na+
4. Ca++
5. proteins
6. phosphates

Answer 10

1. ICF reducing, ECF oxidising
2. ICF
3. ECF
4. ECF
5. ICF
6. ICF

Question 11

Increasing venous return increases cardiac output by:

decreasing end diastolic volume

increasing the stroke volume

decreasing the ejection fraction

increasing heart rate

Answer 11

increasing the stroke volume

Question 12

Cell membranes - water transport

1. How does water move in and out of cells?

Answer 12

Osmosis is the movement of water across membranes

Aquaporins selectively conduct water molecules in and out of the cell, while preventing the passage of ions and other solutes.

Also known as water channels, aquaporins are integral membrane pore proteins.

Water molecules traverse through the pore of the channel in single file. The presence of water channels increases membrane permeability to water.

_{Some of them, known as aquaglyceroporins, also transport other small uncharged solutes, such as glycerol, CO2, ammonia and urea across the membrane, depending on the size of the pore. For example, the aquaporin 3 channel has a pore width of 8-10 Ångströms and allows the passage of hydrophilic molecules ranging between 150-200 Da. However, the water pores are completely impermeable to charged species, such as protons, a property critical for the conservation of the membrane’s electrochemical potential difference.[8]}

Question 13

Judy was holding a stack of books when Bill added three more. To prevent dropping the books, Judy’s muscles increased their force of contraction through an increase in the:

length of the muscle.
number of motor units activated.
speed of the myosin ATPase.
strength of each cross bridge interaction with myosin

Answer 13

number of motor units activated

Question 14

Smooth muscle

1. TONIC CONTRACTION =
2. PHASIC CONTRACTION =

Answer 14

TONIC CONTRACTION = sustained contracted state over time without fatigue.

PHASIC CONTRACTION = graded force generated by increasing stimulus up to fused tetanus.

Question 15

Two types of muscle sensory receptors

Encapsulated sensory receptors situated in tendons near the junction with the muscle detect changes in muscle tension instead of changes in muscle length.

1. What are they called?

Answer 15

Two types of muscle sensory receptors

_{In order for the body to be able to control muscle contraction properly, there must be feedback about the contractile status of individual muscles.}

_{The muscle spindle is an important muscle sensory receptor that provides information about muscle length and the rate of change of muscle length.}

In addition, Golgi tendon organs are encapsulated sensory receptors situated in tendons near the junction with the muscle (Figure 38). They detect changes in muscle tension instead of changes in muscle length.

_{Both types of sensory receptors send information to the spinal cord and the brain that is usually subconscious.}

Question 16

Muscle

Skeletal muscle fibers are classified by the speed of their myosin ATPase and preferred metabolism

Recruitment is the process of activating different types of muscle fibers within a fascicle in response to need.

1. What is the order of recruitment?

Answer 16

Skeletal muscle fibers are classified into one of three types distinguished by the speed of their myosin ATPase and preferred metabolism:

• *fast, glycolytic fibers** fatigue quickly
• *fast, oxidative, glycolytic fibers** resist fatigue
• *slow, oxidative fibers** resist fatigue

Recruitment is the process of activating different types of muscle fibers within a fascicle in response to need.

Recruitment starts with slow, oxidative fibers that do not provide a lot of force but can provide fine muscle control.

If more tension is needed, fast-oxidative-glycolytic fibers can be recruited.

Finally, fast, glycolytic fibers that fatigue rapidly increase tension the most dramatically are recruited.

Question 17

Neuron

1. Does an action potential have a refractory period?
2. What are the implications?

Answer 17

1. Once the Na+ channels have inactivated, the membrane must repolarize before the channel returns to the closed state and can be opened again.

This means that there is a refractory period that prevents another action potential from occurring before the first one has ended.

2. However, because of the refractory period, the action potential travels in one direction along the axon and not in two directions.

In addition, each action potential that is produced down the axon will be identical and will not diminish over time or distance

Question 18

In a post-synaptic neuron, which of the following changes would increase the likelihood of an action potential firing?

A increasing the number of excitatory synapses
B increasing the firing rate of an excitatory synapse
C moving an inhibitory synapse closer to the initial segment
both A and B
A, B, and C

Answer 18

both A and B

Question 19

Hearing

1. Draw the anatomy of the ear

Answer 19

Question 20

1. What is cardiac output?
2. And how is it adjusted?

Answer 20

CARDIAC OUTPUT (CO) is the volume of blood ejected by one ventricle in a period of time. Cardiac output is one measure of the effectiveness of the heart as a pump.

It dynamically adjusts by changing either the heart rate or stroke volume or both.

Cardiac output = stroke volume x heart rate

CO= SV x HR

For an average resting heart rate of 70 beats per min (bpm) and a stroke volume of 70 mL per beat, the CO = ~ 5L/min.

The average total volume of blood circulating in the body is ~ 5L. Therefore, each ventricle pumps all of the blood of the body through it in only one minute.

Question 21

Senses

1. In other systems such as vision, taste, and hearing, a ...?……?…..cell produces graded potentials that can trigger an action potential in an afferent neuron

Answer 21

In other systems such as vision, taste, and hearing, a specialized receptor cell produces graded potentials that can trigger an action potential in an afferent neuron

Question 22

Muscle

1. In the Anaerobic metabolism ATP pathway - how long do the stores last?
2. What sort of activity?

Answer 22

Skeletal Muscle Metabolism

Muscle fibers depend on ATP to produce force.

There are three pathways a muscle fiber uses to make ATP.

1. Creatine phosphate converts ADP to ATP in a single, fast reaction. As a result, 4 moles of ATP are produced per minute from creatine phosphate. However, the stores of creatine phosphate are limited so they are used up in the first 10 seconds of intense exercise. Creatine phosphate is the primary source of ATP during a short, high intensity activity such as the 100 meter dash.
2. Anaerobic metabolism burns glucose as well as the large stores of muscle glycogen (a glucose polymer) to produce lactic acid and ATP in the absence of oxygen. Since only glycolysis is used, 2.5 moles of ATP can be produced per minute. Anaerobic metabolism is used during the first 1.5 minutes of high intensity activity and is the primary source of ATP for the 400 meter dash.
3. Aerobic metabolism uses glycogen, blood glucose, or fatty acids to produce ATP, CO2, and water in the presence of oxygen. Only 1 mole of ATP is made per minute but the available fuel sources are limited only in extreme circumstances. Aerobic metabolism is the primary source of ATP during endurance activities such as a marathon.

Question 23

1. What does an ECG represent in general?
2. What does each deflection represent?

Answer 23

An ECG recording is the sum of all of the electrical potentials generated by all the cells of the heart at any instance in time.

Each deflection (wave) of the ECG represents either depolarization or repolarization of the specific parts of the heart.

Because depolarization occurs before mechanical contraction, the waves of depolarization can be associated with contraction and relaxation of the atria and the ventricles.

A typical ECG recording and the waves are shown below (Figure 58). The P wave corresponds to depolarization of the atria. The QRS complex corresponds to depolarization of the ventricles. The T wave corresponds to repolarization of the ventricle.

Question 24

3. The driving force of blood flow is a(n) __________ gradient.

B. volume

A. osmotic

D. gravity

C. pressure

Answer 24

C. pressure
Well done!

Question 25

Neuron

1. Where does an action potential start?
2. What determines if an action potential is formed?

Answer 25

1. In either case, the graded potentials can start in the dendrites or cell body and if it is strong enough travel to the axon initial segment, where the neuron has the highest concentration of voltage-gated ion channels and the lowest threshold, to start an action potential.

The initial segment is the beginning of the axon that connects to the neuronal cell body at the axon hillock.

2. Because a neuron can have many dendrites and have many other neurons contacting the dendrites or cell body, the axon hillock and initial segment can integrate those signals by requiring that signals reach a threshold before an action potential is formed.

The strength, frequency and location of a stimulus received by a neuron will determine if threshold is reached because graded potentials are formed, not action potentials.

Question 26

Spinal cord

1. How many muscle fibres does a motor neuron control?.

Answer 26

The axons of motor neurons are myelinated and have large diameters for fast conduction of action potentials.

As the axon approaches a skeletal muscle fiber (muscle cell) it usually branches to form synapses with anywhere from three to one thousand muscle fibers.

_{However, each muscle fiber is usually innervated by only a single neuron.}

_{A motor unit consists of a neuron and all of the muscle fibers it innervates.}

_{A single neuron innervates fibers from only one muscle and the innervated muscle fibers are usually spread throughout the muscle}

Question 27

Neurons

1. How do synapses in the mammalian nervous system transmit between the presynaptic and postsynaptic neurons?

Answer 27

Most synapses in the mammalian nervous system transmit between the presynaptic and postsynaptic neurons using chemicals called neurotransmitters.

As the action potential from the presynaptic neuron travels to the end of the axon, calcium is released from voltage-gated calcium channels and causes vesicles full of neurotransmitters to fuse with the plasma membrane and dump their contents into the space between the two neurons called the synaptic cleft.

The neurotransmitters diffuse across the synaptic cleft and either directly or indirectly activate ion channels on the postsynaptic neuron to cause a graded potential.

In an excitatory synapse, ion channels are opened that let positive ions into the cell causing a graded potential that depolarizes the membrane and may or may not be sufficient to reach threshold (excitatory postsynaptic potential).

In an inhibitory synapse, chloride enters the cell or potassium leaves the cell causing a graded potential that hyperpolarizes the membrane and moves the membrane potential farther from threshold (inhibitory postsynaptic potential).

Question 28

Nervous system

1. Where are the ganglia for the sympathetic system usually located?
2. Where are the ganglia for the parasympathetic system usually located?

Answer 28

1. The ganglia for the sympathetic system are for the most part

next to the spinal cord

2. The ganglia for the parasympathetic system are usually

very close to or within the target organs.

Question 29

1. Which parts of the nervous system modulate heart rate?
2. How is heart rate slowed?
3. How is heart rate sped up?

Answer 29

HEART RATE (HR) can be modulated by autonomic nervous stimulation.

Increased parasympathetic stimulation of muscarinic receptors on the heart slows the firing of the SA node. Parasympathetic stimulation does so by delaying the closing of K+ channels (efflux). The increased K+ efflux further hyperpolarizes the cells and slows the opening of the If channels.

In contrast, sympathetic stimulation speeds heart rate by shortening the time to threshold. Sympathetic stimulation increases Na influx via the If channels and closes the K channels

Question 30

The region of the heart that normally has the highest rate of spontaneous action potentials is the:

Purkinje fibers

Atrioventricular (AV) node

Bundle of HIS

Sinoatrial (SA) node

Answer 30

Sinoatrial (SA) node

Question 31

In the last half mile of a marathon run, you would expect which of the following?

A PaCO2 to increase

B PaCO2 to decrease

C PaCO2 to remain 40 mmHg

Answer 31

B PaCO2 to decrease

Question 32

Which of the following is the typical order of motor unit recruitment?

A slow-oxidative, fast-glycolytic, fast-oxidative

B slow-oxidative, fast-oxidative, fast-glycolytic

C fast-oxidative, slow-oxidative, fast-glycolytic

D fast-glycolytic, fast-oxidative, slow-oxidative

Answer 32

B slow-oxidative, fast-oxidative, fast-glycolytic

Skeletal muscle fibers are classified into one of three types distinguished by the speed of their myosin ATPase and preferred metabolism:

fast, glycolytic fibers fatigue quickly
fast, oxidative, glycolytic fibers resist fatigue
slow, oxidative fibers resist fatigue

Recruitment is the process of activating different types of muscle fibers within a fascicle in response to need. Recruitment starts with slow, oxidative fibers that do not provide a lot of force but can provide fine muscle control. If more tension is needed, fast-oxidative-glycolytic fibers can be recruited. Finally, fast, glycolytic fibers that fatigue rapidly increase tension the most dramatically are recruited.

Question 33

Smooth muscle cells differ from skeletal muscle cells in that smooth muscle does NOT contain:

troponin–tropomyosin complexes

myosin ATPase activity

dense bodies

thin filaments

Answer 33

troponin–tropomyosin complexes

Question 34

During contraction, when the cardiac muscle is shortening in length, the I band (thin filament) will:

lengthen
shorten
remain unchanged

Answer 34

shorten

Question 35

7. The steep repolarization of phase 3 of the cardiac contractile cell’s action potential is due to which ion(s)?

A. Ca2+

B. K+

C. Na+

E. A and C

D. A and B

Answer 35

B. K+
Well done!

Question 36

Cardiac Performance

Consider the Pressure-Volume (PV) Loop below. The black PV loop (designated by ABCD) depicts the Left Ventricle of a normal heart.

5. Are the ejection fractions of these two hearts equal? A. Yes, each is 50% B. No. Black loop EJ = 60/120 x 100 = 50%; Red loop EJ = 60/150 x 100 = 40%

Answer 36

Answer 5: B. No.

Black loop EJ = 60/120 x 100 = 50%;

Red loop EJ = 60/150 x 100 = 40%

Question 37

In skeletal muscle the speed of contraction is regulated by the:

A. myosin ATPase

B. troponin - tropomyosin complex

C. plasma membrane CaATPase

D. amount of intracellular glycogen

Answer 37

A. myosin ATPase

Skeletal muscle fibers are classified into one of three types distinguished by the speed of their myosin ATPase and preferred metabolism:

fast, glycolytic fibers fatigue quickly
fast, oxidative, glycolytic fibers resist fatigue
slow, oxidative fibers resist fatigue

The main feature of muscle contraction is the interaction of actin, myosin and ATP.

This fundamental process of contraction is regulated by the tropomyosin-troponin-Ca2+ system

Question 38

Draw cardiac muscle tissue structure

Answer 38

image LINK

Question 39

8. Phase 2 (plateau) of the cardiac contractile cell action potential is due to a combination of:

D. Ca++ influx and K+ efflux
A. Na+ efflux and K+ influx

B. Na+ influx and Ca++ influx

C. Ca++ efflux and K+ influx

Answer 39

D. Ca++ influx and K+ efflux
Well done!

Question 40

The hormone and its regulated substance do not change independently. By monitoring both the hormone and its regulated substance, one can readily deduce the nature of the dysfunction.

_{Cortisol pathway is Hypothalamus CRH}

_{Anterior pituitary ACTH}

_{Adrenal cortes cortisol}

1. Draw a table showing primary, secondary, tertiary pathology vs dysfunction site for high cortisol, and high/low CRH and ACTH

_{ie we have high cortisol and test CRH and ACTH to determine the dysfunction site}

Answer 40

Question 41

In an human what chromosomes indicate– Female? Male?

Answer 41

Female=X

Question 42

If a patient is given a drug that inhibits myosin light chain kinase, the effect will be:

B. decreased airway resistance in the lung.

C. decreased heart beat.

D. decreased tone of postural muscles.

A. decreased diameter of the small arteries.

Answer 42

B. decreased airway resistance in the lung.

myosin light chain kinase -> activating smooth muscle

Question 43

Muscle

1. How many pathways are there to produce ATP in a muscle fibre?
2. What are they?

Answer 43

Skeletal Muscle Metabolism

Muscle fibers depend on ATP to produce force.

There are three pathways a muscle fiber uses to make ATP.

1. Creatine phosphate converts ADP to ATP in a single, fast reaction. As a result, 4 moles of ATP are produced per minute from creatine phosphate. However, the stores of creatine phosphate are limited so they are used up in the first 10 seconds of intense exercise. Creatine phosphate is the primary source of ATP during a short, high intensity activity such as the 100 meter dash.
2. Anaerobic metabolism burns glucose as well as the large stores of muscle glycogen (a glucose polymer) to produce lactic acid and ATP in the absence of oxygen. Since only glycolysis is used, 2.5 moles of ATP can be produced per minute. Anaerobic metabolism is used during the first 1.5 minutes of high intensity activity and is the primary source of ATP for the 400 meter dash.
3. Aerobic metabolism uses glycogen, blood glucose, or fatty acids to produce ATP, CO2, and water in the presence of oxygen. Only 1 mole of ATP is made per minute but the available fuel sources are limited only in extreme circumstances. Aerobic metabolism is the primary source of ATP during endurance activities such as a marathon.

Question 44

A mutation in a muscle that prevents the sarcoplasmic reticulum Ca+2-ATPase pump from functioning would disrupt which of the following steps?

action potentials traveling down the T tubules

cytosolic calcium increasing when the muscle was stimulated

myosin binding to actin

relaxation

Answer 44

relaxation

Question 45

1. Mary rose quickly from her bed to answer the door. This change in body position resulted in:

A. Increased dilation of peripheral blood vessels

B. Decreased firing of the carotid baroreceptors

C. Increased parasympathetic stimulation of the SA node

D. Unchanged venous return

Answer 45

Answer 1: B. Decreased firing of the carotid baroreceptors

Question 46

After a skeletal muscle fiber is treated with a membrane permeable drug that speeds up the action of the SR Ca+2-ATPase, how would the first twitch differ?

the twitch would last longer

the twitch would be shorter

the twitch would last the same amount of time

the twitch would produce more tension

Answer 46

the twitch would be shorter

the SR Ca+2-ATPase pumps Ca++ back into the Sarcoplasmic Reticulum

Question 47

Muscle

1. Where is Ca++ stored in skeletal muscle?

Answer 47

In skeletal muscle, Ca++ is stored within the cell in a membrane bound compartment called the sarcoplasmic reticulum (SR).

The SR wraps around myofibrils. Ca++ is released from the SR into the cytoplasm in response to an electrical signal (action potential).

The action potential opens a voltage gated channel in the T tubule (invagination of the plasma membrane) which is adjacent to the SR (Figure 44).

This voltage gated channel is called the dihydropyridine receptor. Activation of the dihydropyridine receptor in turn opens a Ca++ channel (ryanodine receptor) on the SR and Ca++ enters the cytoplasm (Figure 44). Ca++ is taken back up into the SR from the cytoplasm by the SR CaATPase.

Question 48

Two types of muscle sensory receptors

_{The <strong>muscle spindle</strong> is an important muscle sensory receptor.}

_{In addition, <strong>Golgi tendon organs</strong> are encapsulated sensory receptors situated in tendons near the junction with the muscle}

1. Both types of sensory receptors send information to the spinal cord and the brain that is usually ….??…..

Answer 48

Two types of muscle sensory receptors

_{In order for the body to be able to control muscle contraction properly, there must be feedback about the contractile status of individual muscles.}

_{The muscle spindle is an important muscle sensory receptor that provides information about muscle length and the rate of change of muscle length.}

_{In addition, Golgi tendon organs are encapsulated sensory receptors situated in tendons near the junction with the muscle (Figure 38). They detect changes in muscle tension instead of changes in muscle length.}

Both types of sensory receptors send information to the spinal cord and the brain that is usually subconscious.

Question 49

Senses

1. How does the central nervous system differentiate between different sensations eg touch, temperature?

Answer 49

Each afferent neuron receives signals from a single type of stimulus.