Unit 7

Question 1

Living organisms keep their internal environments within a certain range (they maintain a stable internal condition), despite fluctuations in their external environment

Answer 1

Homeostasis

Question 2

Physiological mechanisms of an organism maintain variables in a homeostatic ___

Answer 2

range of tolerance

Question 3

The maintenance of homeostasis in the body typically occurs through the use of negative ___ that control the body’s internal conditions

Answer 3

feedback loops

Question 4

In this type of feedback, a response to a homeostatic variable being out of the optimal range counteracts the effect of the original stimulus, returning the homeostatic variable to the set point within the optimal range

Answer 4

Negative feedback

Question 5

Examples of homeostatic variables in humans that are regulated by negative feedback control mechanisms (6)

Answer 5

1. heart rate
2. ventilation rate
3. blood glucose
4. body temperature
5. blood osmolality
6. blood pH

Question 6

Negative vs. positive feedback loop

Answer 6

Negative feedback aims to counteract the change, bringing the system back to a stable state, while positive feedback amplifies the change, pushing the system further away from its original state

Question 7

Examples of homeostatic variables in humans that are regulated by positive feedback control mechanisms (4)

Answer 7

1. blood clotting triggers more blood clotting
2. uterus contractions trigger more uterus contractions during childbirth
3. a fruit ripening will trigger more fruits around it to ripen
4. a cancer cell will cause there to be more cancer cells

Question 8

a change in a physiological variable that triggers the feedback system

Answer 8

Stimulus

Question 9

a specialized cell or group of cells that detect the change in the stimulus and sends information to the control center. In humans, sensory neurons convey messages from receptor cells to the central nervous system

Answer 9

Receptor

Question 10

Counteraction to the original physiological stimulus that triggered the feedback system

Answer 10

Response

Question 11

the part of the system that processes the information from the sensor and determines the appropriate response. In humans, the brain is the central information integration organ and the hypothalamus is the part of the brain that controls homeostasis

Answer 11

Control system

Question 12

the cell, tissue, or organ that carries out the response. In humans, motor neurons output from the brain to communicate to effector muscles and glands

Answer 12

Effector

Question 13

a monosaccharide sugar that is readily broken down by cells to produce ATP quickly and efficiently through cellular respiration

Answer 13

Glucose

Question 14

In which organ is glucose absorbed into the bloodstream via facilitated diffusion and indirect active transport

Answer 14

Small intestine

Question 15

Is glucose polar or nonpolar

Answer 15

Polar

Question 16

Symptoms of hypoglycemia (10)

Answer 16

1. Sweating
2. Shakiness
3. Extreme hunger
4. Nausea
5. Dizziness
6. Confusion
7. Fast heart rate
8. Behavior changes
9. Seizures
10. Coma

Question 17

Symptoms of hyperglycemia (12)

Answer 17

1. Increased thirst
2. Increased urination
3. Fatigue
4. Lightheadedness
   5 Dry mouth
5. Headache
6. Blurry vision
7. Shortness of breath
8. Heart disease
9. Stroke
10. Eye damage
11. Kidney damage

Question 18

Receptor: these are the primary cells that sense blood glucose levels. Specialized neurons in the brain, such as those in the hypothalamus, also act as glucose sensors.

Answer 18

Beta-cells in the pancreas

Question 19

Control center: these cells in the pancreas secrete the hormones insulin and glucagon

Answer 19

Endocrine cells

Question 20

Effectors: these cells take up glucose from the blood and store it as glycogen in response to high blood glucose (insulin)

Answer 20

Liver cells

Question 21

Effectors: these cells take up glucose from the blood for energy and store it as glycogen in response to high blood glucose (insulin)

Answer 21

Muscle cells

Question 22

Effectors: these cells take up glucose from the blood and convert it into fat in response to high blood glucose (insulin)

Answer 22

Adipose cells

Question 23

Effectors: these cells release stored glucose into the blood by breaking down glycogen in response to low blood glucose (glucagon)

Answer 23

Liver cells

Question 24

clusters of cells within the pancreas where the hormones insulin and glucagon are produced and secreted

Answer 24

Islets of langerhans

Question 25

What kind of islet cells release insulin

Answer 25

Beta cells

Question 26

What kind of islet cells release glucagon

Answer 26

Alpha cells

Question 27

This organ plays a critical role in maintaining glucose homeostasis by storing excess glucose when blood glucose is high and then releasing glucose back into the bloodstream when blood glucose levels drop

Answer 27

Liver

Question 28

Insulin signals the liver to link glucose molecules together to form ___, which is a multi-branched ___ of glucose used as an ___ ___ molecule

Answer 28

Glycogen, polymer, energy storage

Question 29

a cell that processes and transmits information through electrical and chemical signals in the nervous system. They are the basic structural and functional unit of the nervous system

Answer 29

Neuron

Question 30

neurons located entirely within the CNS that connect other neurons. They receive information from the sensory neurons and process the information to coordinate a response

Answer 30

Interneurons

Question 31

Finger-like projections that act as the primary site for receiving sensory information from the environment

Answer 31

Dendrites

Question 32

glial cells that wrap around the axon and form the myelin sheath

Answer 32

Scwann cells

Question 33

A long, slender extension that carries the electrical signal. Most sensory neurons have a single one that branches into two parts, one extending to the periphery and the other to the spinal cord

Answer 33

Axon

Question 34

the part of the neuron that releases neurotransmitters into the synapse to transmit signals to other neurons or cells

Answer 34

Axon terminal

Question 34

layers of lipid that acts as an insulator, allowing for faster signal transmission along the axon through a process called saltatory conduction

Answer 34

Myelin sheath

Question 35

The point of contact between a motor neuron and a muscle fiber, where the nerve transmits an electrical impulse to the muscle to cause it to contract

Answer 35

Neuromuscular junction

Question 36

A membrane that has a positive electrical charge on one side and a negative charge on the other side. Almost all cells exhibit some degree of this. Required for a neuron to send an impulse

Answer 36

polarized membrane

Question 37

The difference in charge between the inside and outside of the cell membrane

Answer 37

Membrane potential

Question 38

The inside of cells generally have a ___ charge, so the membrane potential is expressed as a ___ value

Answer 38

Negative

Question 39

The resting membrane potential of a neuron

Answer 39

~-70mV

Question 40

Three factors that contribute to the negative charge of the resting potential

Answer 40

1. The sodium-potassium pump actively transports three sodium ions out of the cell for every two potassium ions it brings in 2. K+ ions can leak out through the cell membrane, leaving the cell and further increasing the charge imbalance. 3. Negatively charged proteins within the neuron also contribute to the charge imbalance

Question 41

The electrical signal that a neuron generates to transmit information along its cell membrane from the dendrite to the synaptic terminal. The basic unit of neuron function

Answer 41

Action potential

Question 42

the region at the end of an axon where the electrical signal from the action potential is converted into a chemical signal that is sent to a neighboring cell

Answer 42

Synaptic terminal

Question 43

These are factors in the speed of a neutral impulse as it is propagated along and axon (3)

Answer 43

1. The body size of the animal 2.The axon diameter size 3. Whether or not the axon is myelinated

Question 44

Generally, an animal's body size __ significantly affect the speed of its neuron impulses, meaning that nerve conduction velocity remains relatively ___ across different sized animals.

Answer 44

Does not, constant

Question 45

Larger diameter axons have a ___ conduction velocity because a larger axon experiences ___ resistance to ion flow

Answer 45

Faster, less

Question 46

Myelination ___ the speed of neuron impulses

Answer 46

Increases

Question 47

These cells grow around the neuron axon creating layers of myelin

Answer 47

Schwann cells

Question 48

Gaps between the Schwann cells

Answer 48

Nodes of ranvier

Question 49

In myelinated neuron axons, the impulse can jump from one Node of Ranvier to the next, speeding the transmission to as quick as __ meters per second

Answer 49

100

Question 50

used to understand the strength and direction of a linear relationship between two variables

Answer 50

Correlation coefficient

Question 51

Sulaxane and Bhavasar found that there was a significant ___ correlation between height and the nerve velocity

Answer 51

Negative

Question 52

used to communicate how close the data are to the line of best fit

Answer 52

Coefficient of determination

Question 53

the space between the axon terminal of the presynaptic neuron and the postsynaptic cell

Answer 53

Synaptic gap

Question 54

Other name for the synaptic gap

Answer 54

Synaptic cleft

Question 55

Main types of synapses (3)

Answer 55

1. Synapse between a sensory cell (such as a photoreceptor in the eye or a hair cell in the ear) and a sensory neuron 2. Synapse between neurons, where one neuron transmits a signal to another neuron 3. Synapse between a motor neuron and a muscle or gland, where the neuron triggers contraction (neuromuscular junction)

Question 56

Chemical messengers that carry information between cells at the synapse. They move by diffusion between the adjacent cells and have very localized effects

Answer 56

Neurotransmitters

Question 57

Types of neurotransmitters (5)

Answer 57

1. Amino Acids 2. Amines 3. Peptides 4. Esters 5. Gasses

Question 58

The main inhibitory and excitatory messengers in the nervous system

Answer 58

Amino acid neurotransmitters

Question 59

small molecules synthesized by modification of amino acids. They have a wide variety of neurotransmitter functions

Answer 59

Amine neurotransmitters

Question 60

Chemical messengers made up of small chains of amino acids that are synthesized and released by neurons

Answer 60

Neuropeptides (peptide neurotransmitters)

Question 61

The general name for a chemical formed when an alcohol bonds to an acid

Answer 61

Ester

Question 62

Three molecules with known inhibitory neurotransmitter function. These are toxic at high concentrations but serve important functions at very low doses

Answer 62

Gasses

Question 63

An excitatory amino acid neurotransmitter that will activate postsynaptic cells

Answer 63

Glutamic acid

Question 64

An inhibitory amino acid neurotransmitter that will depress the activity of postsynaptic cells

Answer 64

GABA

Question 65

An amine that coordinates body movements, pleasure sensations, learning, and memory. It can be both excitatory or inhibitory, depending on the type of receptor it binds to

Answer 65

Dopamine

Question 66

an inhibitory amine neurotransmitter which regulates mood, sleep and wakefulness

Answer 66

Serotonin

Question 67

Inhibitory peptide neurotransmitters which alleviate pain, lower stress, improve mood, and enhance sense of well-being

Answer 67

Endorphins

Question 68

An excitatory ester neurotransmitter with many functions, including triggering muscle contraction at neuromuscular junctions. Forms when acetic acid binds with choline

Answer 68

Acetylcholine

Question 69

The neurotransmitter will diffuse across the synaptic gap and bind to ___ ___ on the postsynaptic cell membrane

Answer 69

transmembrane receptors

Question 70

Steps of neurotransmitter movement between neurons (6)

Answer 70

1. A nerve impulse arrives at the axon terminal of the presynaptic cell 2. Depolarization of the presynaptic cell membrane causes voltage gated calcium (Ca2+) channels in the axon terminal to open 3. As a result, calcium moves into the cell through facilitated diffusion 4. The increase in calcium concentration causes vesicles containing neurotransmitters to… 5. …move towards the end of the axon terminal and fuse with the presynaptic cell membrane to … 6. …release the neurotransmitter into the synaptic gap via exocytosis

Question 71

Each neurotransmitter has a specific transmembrane receptor to which it can ___

Answer 71

bind

Question 72

Often the neurotransmitter receptor is a ___-___ channel. Binding of the neurotransmitter to the receptor leads to the opening of an ___ ___ within the postsynaptic cell membrane. Opening of this allows ___ to move through ___ ___ into the postsynaptic cell, causing the ___ ___ to change

Answer 72

Ligand-gated, ion channel, ions, facilitated diffusion, membrane potential

Question 73

Neurotransmitter effect in which an influx of positive ions (such as Na+) will depolarize the cell, triggering an action potential in the postsynaptic cell membrane

Answer 73

excitatory effect

Question 74

Neurotransmitter effect in which an influx of negative ions (such as Cl-) will hyperpolarize the cell, preventing an action potential

Answer 74

inhibitory effect

Question 75

one of the most common neurotransmitters in both invertebrates and vertebrates. It forms in the presynaptic neuron when acetic acid binds with choline. An enzyme (choline acetyltransferase) combines choline (from the diet) with an acetyl group (produced in aerobic respiration)

Answer 75

Acetylcholine

Question 76

Pathway of acetylcholine (8)

Answer 76

1. Acetylcholine (ACh) is synthesized in the axon terminals by an enzyme that combines choline (from the diet) with an acetyl group (produced in aerobic respiration) 2. Acetylcholine is loaded into vesicles and released from the presynaptic cell via exocytosis 3. Acetylcholine diffuses across the synaptic gap 4. Acetylcholine binds to the acetylcholine receptor in the postsynaptic cell membrane 5. The acetylcholine receptor is a ligand-gated channel, so when the neurotransmitter binds, the Na+ channel opens and Na+ moves into the cell through facilitated diffusion 6. If the threshold potential is reached with the influx of Na+, an action potential will be triggered and propagated as an impulse in the postsynaptic cell 7. An enzyme in the synaptic gap (acetylcholinesterase) rapidly breaks down the acetylcholine into choline and acetate 8. The choline is recycled back to the presynaptic cell and the acetate is excreted as waste

Question 77

Why must neurotransmitter acetylcholine be removed from the synaptic gap after triggering a response in the postsynaptic cell

Answer 77

If it is not removed, the neurotransmitter will continue to bind to receptors on the postsynaptic membrane, resulting in multiple action potentials and continuous response

Question 78

How do neurons prevent acetylcholine from triggering multiple action potentials

Answer 78

In the synaptic gap the enzyme acetylcholinesterase breaks down acetylcholine into substances that cannot activate ACh receptors; choline and acetate