Chapter 3 - Cell Anatomy and Physiology

Question 1

neurons

Answer 1

~86 billion
- process information

Question 2

glial cells

Answer 2

~85 billion
- support neurons
- structural support, nutrients, protection

Question 3

cerebral cortex cell make up

Answer 3

• 82% of the total brain mass
• contains 16 billion neurons (19% of all neurons)

Question 4

cerebellum cell make up

Answer 4

• 10% of the brain mass
• 69 billion neurons (80% of all neurons)

Question 5

neuron structure

Answer 5

• dendrites
• cell body (soma)
• axon

Question 6

dendrites

Answer 6

collect information from other cells
- provides input

Question 7

cell body (soma)

Answer 7

nucleus
- provides integration

Question 8

axon

Answer 8

transmits messages to other neurons
- provides output

Question 9

axon hillock

Answer 9

where the axon begins at the end of the cell body

Question 10

telodendrions

Answer 10

the lower end of the axon can split into several smaller branches

Question 11

end foot

Answer 11

the button at the end of each telodendrion
- is close to another dendrite or another part of a cell but does not touch it

Question 12

synapse

Answer 12

the ‘near-connection’ containing the area from the end of the end foot to an adjacent dendrite
- forms the information carrier between neurons

Question 13

sensory neurons

Answer 13

• input
• afferent
• have long dendrites outside the CNS
• cell body in the dorsal root ganglion
• short axon inside the CNS

Question 14

bipolar neuron

Answer 14

in the eyes, has a short dendrite and a short axon

Question 15

interneuron

Answer 15

• integrate sensory and motor information within the CNS
• short dendrites and short axons
• only located inside the CNS
• e.g. pyramidal cells and purkinje cells

Question 16

motor neurons

Answer 16

• output
• efferent
• short dendrites inside the CNS
• large cell bodies inside the CNS
• long axons outside the CNS

Question 17

ependymal cells

Answer 17

• glial cell
• on the walls of the ventricles
• produce and excrete CSF

Question 18

astrocytes (scaffold cells)

Answer 18

• glial cells
• provide structural support to the CNS
• stimulate the repair of damaged brain tissue (scarring)
• form the blood-brain barrier (enhance brain activity)

Question 19

blood-brain barrier

Answer 19

• protective barrier between blood vessels and the brain
• ensures that nutrients and certain chemicals can move between blood vessels and neurons, while harmful substances are kept out

Question 20

microglia (defence cells)

Answer 20

• originate in the blood from the immune system and migrate throughout the nervous system
• monitor the health of the nervous tissue and take over the role of the immune system

Question 21

oligodendroglia

Answer 21

myelinate neurons in the CNS (multiple neurons at once)
- myelinated neurons, whose axons are covered in an insulating sheath, transmit information much faster than neurons that are not myelinated
- do not encourage neuronal repair

Question 22

schwann cells

Answer 22

myelinate neurons in the PNS (only one at a time)
- help in restoration of cells in the PNS

Question 23

cell membrane

Answer 23

the ‘wall’ of a cell, consisting of 2 layers of phospholipids
- seperates the intracellular and extracellular fluid

Question 24

phospholipids

Answer 24

consists of a hydrophilic head, which is in contact with the fluid inside and outside the cell, and a hydrophobic tail, which constitutes inside of the membrane
- prevents fluid from crossing it

Question 25

nucleus

Answer 25

• ‘executive office’
• contains 23 pairs of chormosomes (long chains of DNA with a double-stranded helix structure)
• each strand contains a sequence of four nucleotide bases

Question 26

the four nucleotide bases

Answer 26

A always with T, C always with G
“All Tigers Can Growl”
- adenine (A)
- thymine (T)
- guanine (G)
- cytosine (C)

Question 27

genes

Answer 27

segments of DNA strands
- genetic blueprints for the cell’s proteins

Question 28

transcription

Answer 28

important in protein synthesis because RNA can leave the nucleus whereas DNA cannot
- a gene segment of the DNA strand uncoils to expose its nucleotide base inside the nucleus
- allows nucleotides to bind to the exposed nucleotide bases, forming a complementary strand of RNA
- in RNA, a nucleotide base called uracil (U) takes the place of thymine (T)
- once formed the single strand of RNA detaches from the DNA

Question 29

mRNA

Answer 29

the transcribed strand of RNA
- called mRNA because it carries the genetic code outside the nucleus into the endoplasmic reticulum
- protein structures in the endoplasmic reticulum called ribosomes read the genetic code contained in MRNA

Question 30

translation

Answer 30

• ribosomes transform the sequences of nucleotide bases into sequences of amino acids
• chains of amino acids are called polypeptide chains, and proteins are folded-up polypeptide chains
• encoded in sequences of 3 nucelotide bases (codons) on mRNA (single-stranded)
• bound together by peptide bonds

Question 31

enzymes

Answer 31

proteins that enhance chemical reactions within the cell

Question 32

cell membrane proteins

Answer 32

proteins can regulate the flow of substances across the cell membrane (e.g. channels, gates, pumps)

Question 33

messenger molecules

Answer 33

proteins can be expelled from the cell through exocytosis and move from one cell to another transporting information

Question 34

summarized process of proteins

Answer 34

nucleotide bases -> amino acids -> peptides -> proteins -> cells -> behavior

Question 35

golgi bodies

Answer 35

where synthesized protein molecules are wrapped in membranes and marked where they should go
- then transported through microtubules towards their destination

Question 36

channels, gates, and pumps

Answer 36

• some ions are able to pass through channels (potassium ions)
• some ions are able to pass through a gate if the gate is open
• some ions are pulled in whereas others are pushed out with a pump

Question 37

chromosomes

Answer 37

• the nucleus contains 23 pairs
• pairs 1 to 22 are autosomes and determine physical characteristics and behavioral functions
• pair 23 are the sex chromosomes (X or Y form)
• females have an XX pair, males have an XY pair
• each chromosome has thousands of genes
• the corresponding genes within a pair are called alleles (gene of the father and genes of the mother)

Question 38

homozygous and heterozygous

Answer 38

• homozygous: when both alleles are the same (they encode the same protein)
• heterozygous: when the alleles are different (three situations may occur: only the allele from the mother or father is expressed, or both at the same time)

Question 39

dominant and recessive alleles

Answer 39

• dominant alleles: alleles that are expressed
• recessive alleles: alleles that are unexpressed
• when paired with a dominant allele, a recessive gene is often not expressed but can still be passed on to offspring

Question 40

mutations

Answer 40

when genes are passed on to offspring and there is an error in overwriting the information
- when its only a single nucleotide base, it’s called a ‘snip’ (SNP = single nucleotide polymorphism)
- can be neutral, beneficial (increased bone density), or harmful (sickle cell disease)

Question 41

Mendel’s law

Answer 41

when parents are both carriers of a particular recessive gene that causes a disease, e.g. Tay-Sachs disease, there are 3 possible outcomes:
- inherit the wild type alleles, preventing the disease from developing
- inherit a normal allele and a Tay-Sachs allele, resulting in a carrier like their parents
- can inherit 2 Tay-Sachs alllels, causing the disease to develop