BIOL 224 Lab Exam 1

Question 1

Define Homeostasis

Answer 1

a steady internal condition maintained by responses that compensate for changes in external environment

Question 2

Define Negative Feedback

Answer 2

process that returns a variable to the set point

Question 3

Define Set Point

Answer 3

desired or target value for an essential variable

Question 4

Define Vasoconstriction

Answer 4

is a process that narrows blood vessels.

It occurs when a fall in core temperature goes below the set point. The hypothalamus sends signals through the autonomic system and causes an immediate response to constrict blood flow. This reduced blood flow cuts down the amount of heat delivered to the skin and lessens the amount of heat lost from the body surface.

Question 5

Define Vasodilation

Answer 5

Is a process that widens blood vessels.

It occurs when core temperature rises above the setpoint. The hypothalamus sends signals through the autonomic system that trigger a response to lower body temperature. These signals smooth muscles of arterioles in the skin to increase blood flow.

Question 6

Define Local Blood Flow

Answer 6

the amount of blood travelling through vessels that supplies blood to tissues.

It can be increased or decreased by altering the diameter of the vessels through Vasoconstriction and vasodilation. (volume)

Question 7

Define Blood Pressure

Answer 7

the measurement of hydrostatic pressure exerted against the walls of the vessels. It is determined by the force and amount of blood pumped by the heart and the size and stiffness of the arteries.

Question 8

Define Hypotension

Answer 8

also known as low blood pressure, is a medical condition in which blood pressure drops below a normal range; less than 90/60 mmHg.

Question 9

Define Hypertension

Answer 9

also known as high blood pressure, is a medical condition in which blood pressure is chronically elevated above normal values.

Question 10

Define Plethysmograph

Answer 10

a machine that measures changes in volume in different areas of your body. It measures these changes with blood pressure cuffs or other sensors.

Question 11

Define Thermoreceptor

Answer 11

Sensory receptor that detects the flow of heat energy.

Receptors of this type are located in the skin where they detect changes in the temperature of the body surface.

Question 12

Explain how central blood pressure relates to peripheral blood flow and vice versa

Answer 12

They have an inverse relationship, as blood pressure increases, blood flow decreases and vice versa.

Question 13

Relate changes in pulse amplitude based on the physiological regulation of blood flow

Answer 13

○Pulse amplitude does not equal pulse rate
○Pulse amplitude is related to volume of blood pressure

○Vasoconstriction reduces blood flow = lower pulse amplitude = more blood volume = less blood flow

○Vasodilation increases blood flow = higher pulse amplitude = less blood volume = more blood flow

Question 14

Compare the effects of vasoconstriction and vasodilation on peripheral blood flow

Answer 14

Vasoconstriction kills blood flow (narrow)

Vasodilation encourages blood flow (widen)

Question 15

Define CNS

Answer 15

consists of the brain and spinal cord.

Is responsible for collecting sensory (afferent) information from sensory neurons and receptors, comparing that to learned or innate information stored within the interneurons of the CNS, and then sending appropriate motor (efferent) signals to peripheral cells, tissues and organs.

Question 16

Define Afferent Neuron

Answer 16

sensory neurons that carry nerve impulses from sensory stimuli towards the central nervous system and brain

Question 17

Define Sensory Neuron

Answer 17

activated by sensory input from the environment, collect sensory information

Question 18

Define Efferent Neuron

Answer 18

motor neurons that carry neural impulses away from the central nervous system and towards muscles to cause movement.

Question 19

Define Motor Neuron

Answer 19

These neurons transmit impulses from the spinal cord to skeletal muscles and smooth muscles . They directly control all of our muscle movements.

Question 20

Define Interneuron

Answer 20

a neuron which transmits impulses between other neurons.

Question 21

Define Visuomotor Learning

Answer 21

when vision and movement work together to produce actions

Question 22

Define Sensorimotor Adaptation

Answer 22

ability to gradually modify our motor commands in order to compensate for changes in our body and in the environment.

Question 23

Define Prismatic Adaptation

Answer 23

Sensory-motor adaptation that occurs after the visual field has been artificially shifted laterally or vertically

Question 24

Explain the differences between auditory and visual reaction times

Answer 24

auditory is MUCH faster - shorter pathway to brain - less complex

Visual is slower - longer pathway to brain - more complex

Question 25

Explain the underlying neurophysiology of prismatic adaptation and its significance in terms of nervous system function

Answer 25

The neurophysiology of the brain is filled with neuroplasticity and can adapt itself when the outside environment changes in order to survive.

Question 26

Define Mechanoreceptor

Answer 26

a sensory receptor that detects mechanical energy, such as changes in pressure, body position, or acceleration. The auditory receptors in the ears are examples of mechanoreceptors

Question 27

Define Proprioceptor

Answer 27

a sensory receptor which receives stimuli from within the body, especially one that responds to position and movement.
Detects motion and position of body

Question 28

Define Chordotonal Organ

Answer 28

an organ used to detect the position of the leg joints as the cockroach moves
Chordotonal sensory neurons → chordotonal sensory neurons synapse with interneurons in the cockroach’s central nervous system (CNS) and forms part of a complex neural reflex pathway that helps to coordinate cockroach movement

are stretch receptor organs found only in insects and crustaceans. They are located at most joints and are made up of clusters of scolopidia that either directly or indirectly connect two joints and sense their movements relative to one another

Question 29

Define Stretch Receptor

Answer 29

a mechanoreceptor that responds and sends signals when stretching occurs ○More stretch increases rate that APs are generated

Question 30

Define Nerve

Answer 30

a bundle of axons

Question 31

Define Afferent Neuron

Answer 31

a neuron that transmits stimuli collected by a sensory receptor to an interneuron (goes into brain

Question 32

Define Sensory adaptation

Answer 32

a condition in which the effect of a stimulus is reduced if it continues at a constant level

Question 33

Describe the anatomy of a cockroaches chordotonal organ

Answer 33

chordotonal organs are ciliated stretch receptors that innervate the joints of the insect body. They are formed by repeats of a characteristic multicellular unit called the scolopidium

Contains mechanically gated ion channels that open more in response to a greater stretch

Question 34

Define Tendon

Answer 34

connective tissue that attaches muscle to bone

Question 35

Define Muscle Bundle

Answer 35

group of muscle fibers

Question 36

Define Muscle Fibre

Answer 36

single muscle cell

Question 37

Define Neuromuscular Junction

Answer 37

synaptic connection between the terminal end of a motor nerve and a muscle

Question 38

Define Motor Unit

Answer 38

The combination of an individual motor neuron and all of the muscle fibers that it attaches to

Question 39

Define Twitch

Answer 39

period of contraction and relaxation of a muscle after a single stimulation

Question 40

Define Tetanus

Answer 40

Summation of all available motor units twitching at a high enough frequency produces a tetanus, maximal output. Summation of many twitches

Question 41

Define Motor Unit Recruitment

Answer 41

the successive activation of the same and additional motor units with increasing strength of voluntary muscle contraction

Question 42

Define Spinal Reflex Arc

Answer 42

system of INVOLUNTARY stretch reflexes
loop consisting of receptors, sensory neurons, interneurons, motor neurons and muscles.

proprioreceptors

Question 43

Define Antagonistic Muscle Pair

Answer 43

as one muscle contracts, the other muscle relaxes or lengthens

Question 44

Define Extensor Muscles

Answer 44

any of the muscles that increase the angle between members of a limb

Question 45

Define Flexor Muscles

Answer 45

any of the muscles that decrease the angle between bones on two sides of a joint

Question 46

Explain how nerves send electrical signals to muscles to cause a response, and the physiological basis for motor unit recruitment

Answer 46

stimulus makes motor neurons release acetylcholine at NMJ, which will create a muscle AP (electric signal) and cause the contraction of the muscle cell

Question 47

What is the functional significance of conduction velocity

Answer 47

high speeds are needed to relay important information to brain or motor neurons to elicit a response, being too slow is dangerous

Question 48

Compare the cellular physiology of a muscle twitch with tetanus

Answer 48

Tetanus is prolonged contraction without relaxation and results from repeating stimulation before the muscle has a chance to relax at all. whereas single twitch can relax and repolarize

Question 49

Describe the sliding filament model of muscle contraction

Answer 49

The sliding filament theory describes the mechanism that allows muscles to contract. According to this theory, myosin (a motor protein) binds to actin.
The myosin then alters its configuration, resulting in a “stroke” that pulls on the actin filament and causes it to slide across the myosin filament. The overall process shortens the sarcomere structure, but does not change the actual length of either filament.

Question 50

Compare spatial and temporal summation and explain the role in muscle contraction

Answer 50

spatial summation is when more than one one afferent neuron cause post synaptic potentials

temporal summation is when the same neuron causes quick post synaptic potentials in succession

the affect is additive for both, generating action potentials if cell is depolarized enough

twitch has not relaxed completely

important for varying strength of muscle contraction

Question 51

Describe the descending motor pathway

Answer 51

descending Motor Pathway:
■Option #1: Rubrospinal aka Spinothalamic
●Cortex - Midbrain (red nucleus in thalamus) - Pons - Rostral medulla - caudal medulla - Spinal cord - dorsal root ganglia - motor neurons

Question 52

What is a Phasic response

Answer 52

If the firing frequency ceases or is greatly reduced when movement of the receptor stops, even though a new position is maintained, such a response is considered to
be phasic.

rapid decline to zero

Question 53

What is a Tonic response

Answer 53

If action potentials continue for as long as the stimulus is maintained and slowly decline overtime, the response is termed tonic.
Tonic, or slowly adapting, responses are typically associated with a prolonged stimulus.

doesn’t go up that high, low response around 0

Question 54

What is a Phasitonic response

Answer 54

middleground, sharp spike then reduction, but flattens out and does not reduce to zero

Question 55

Explain how reflexes are different from reactions

Answer 55

Reflexes are involuntary whereas reactions are voluntary

Reflexes are much quicker because of the monosynaptic pathway, with a sensory neuron sometimes synapting with a motor neuron, important for escape responses / saftey