4 - The Eukaryotic Cell; The Nervous System

Question 1

Nucleus=

***DNA cannot leave the______, ______ must take place here; and RNA leaves the nucleus through_______

Nuclear Envelope/Membrane=

Nuclear Pores=

Nucleolus=

Answer 1

Nucleus= major feature distinguishing a prokaryotic cell and a eukaryotic.
***DNA cannot leave the nucleus, transcription must take place here; and RNA leaves the nucleus through nuclear pores.

Nuclear Envelope/Membrane= a double phospholipid bilayer which the nucleus is wrapped.

Nuclear Pores= large holes through the nuclear envelope.

Nucleolus= within the nucleus is this area, where rRNA is transcribed and the subunits of the ribosomes are assembled.

Question 2

Endocytosis=

Phagocytosis=

Pinocytosis=

Exocytosis=

Answer 2

Endocytosis= cells can acquire substances from the extracellular environment through this mechanism.

Phagocytosis= to eat; outreach and grab the thing.

Pinocytosis= to drink; it allows entry but coming in.

Exocytosis= the reverse of endocytosis.

Question 3

Endoplasmic reticulum (ER)=

Cytosol=

ER lumen (cisternal space)=

Answer 3

Endoplasmic reticulum (ER)= a thick maze of membranous walls that separate the cytosol from the ER lumen or cisternal space.

Cytosol= the aqueous solution inside the cell.

ER lumen (cisternal space)= the extracellular fluid side of the ER.

Question 4

Rough ER (granular)=

Smooth ER=

Answer 4

Rough ER (granular)= ER near the nucleus has many ribosomes attached to it on the cytosolic side, giving it a granular appearance.

Smooth ER= lacks ribosomes. Contains G6P. Triglycerides are produced here as well (including steroids). Adipocytes containing predominately fat droplets which are important for energy and body temp regulation. Also detoxifies the cell from drugs, pesticides, toxins, and pollutants.

Question 5

Golgi apparatus=

Secretory Vesicles=

Lysosomes=

Peroxisomes=

Answer 5

Golgi apparatus= the newly synthesized proteins, from the Rough ER, moved thorough the lumen to here. A series of flattened membrane bound sacs. The golgi organizes the proteins, maybe changing their structure slightly, and at the end makes a vesicle full of proteins. Modifies and packages proteins for use in other parts of the cell and outside the cell.

Secretory Vesicles= vesicles transported somewhere else in the cell. May contain enzymes, growth factors, or extracellular matrix components. Exocytosis.

Lysosomes= organelle containing enzymes for digestion. The enzymes here are capable of breaking down every major type of macromolecule within in the cell; especially things taken in by endocytosis.

Peroxisomes= are vesicles in the cytosol. They break down hydrogen peroxide, inactivate toxic substances like alcohol, regulate oxygen concentration, play a role in the synthesis/breakdown of lipids , and in the metabolism of nitrogenous bases and carbs.

Question 6

Cytoskeleton=

Microtubules=

Microfilaments=

Answer 6

Cytoskeleton= a network of filaments that determine the cell’s structure and motility.

Microtubules= one of the major types of filaments in the cytoskeleton; which are larger than microfilaments. They are also involved in the construction of flagella, cilia, and the spindle apparatus. (cilia are only found in the fallopian tubes and the respiratory tract.

Microfilaments= the other major type of cytoskeleton. Smaller than microtubules. They squeeze the membrane together in phagocytosis and cytokinesis. They are also the contractile force in microvilli and muscle. Actin forms the major component of the microfilaments. Microfilaments produce the contracting force in muscle, as well as being active in cytoplasmic streaming (responsible for amoeba-like movement), phagocytosis, and microvilli movement.

Question 7

Axoneme=

Dynein=

Centrosome=

Centrioles=

Answer 7

Axoneme= the major portion of each flagellum and cilium; which contains nine pairs of microtubules forming a circle around the two lone microtubules in an arrangement known as 9 + 2.

Dynein= a protein that connects each of the outer pairs of microtubules to their neighbor.

Centrosome= the major microtubule-organizing center (MTOC) of the cell.

Centrioles= function in the production of flagella and cilia, but are not necessary for microtubule production.

Question 8

Tight Junctions=

Desmosomes=

Gap Junctions=

Answer 8

Tight Junctions= are water tight seals from cell to cell that can block water, ions, and other molecules from moving around and past cells.

Desmosomes= join two cells at a single point. They attach directly to the cytoskeleton of each cell.

Gap Junctions= are small tunnels connecting cells. They allow small molecules and ions to move between cells. Gap junction in cardiac muscle provide for the spread of the action potential from cell to cell.

Question 9

Mitochondria=

Extracellular matrix=

Answer 9

Mitochondria= the powerhouses of the eukaryotic cell. According to the endosymbiont theory mitochondria may have evolved from a symbiotic relationship between ancient prokaryotes and eukaryotes. Mitochondria have their own separate DNA, which is transcribed and translated to RNA and proteins. Meaning they have their own ribosomes as well (55-60s). However, most proteins used by the mitochondria is coded for by nuclear DNA. Mitochondria is surrounded by two phospholipid bilayers. Inner membrane invaginates to form cristae. Between the inner and outer membrane is the intermembrane space.

Extracellular matrix= the stuff that surrounds the cell and that it is formed by the cell itself.

Question 10

Neuronal Communication=

Hormonal Communication=

Interstitial fluid=

***Local mediators are released by a variety of cells into the ________ (fluid between cells) and act on neighboring______a few millimeters away. They can be proteins, other amino acid derivatives, or even fatty acids.

Answer 10

Neuronal Communication= tends to rapid, direct, and specific.

Hormonal Communication= tends to be slower, spread through the body, and affects many cells and tissues in many different ways.

Interstitial fluid= the fluid between cells.
***Local mediators are released by a variety of cells into the interstitial fluid (fluid between cells) and act on neighboring cells a few millimeters away. They can be proteins, other amino acid derivatives, or even fatty acids.

Question 11

Neuron=

Dendrites=

Axon Hillock=

Axon=

***Unipolar for _______ only, Bipolar for__________ area of the brain, and Multipolar (most _______ of the brain.)

***The signal travels from the ______ to the_______, where an action potential is generated and moves down the axon to the synapse. Neurons do not depend upon_______ to obtain glucose.

Answer 11

Neuron= the functional unit of the nervous system. A neuron is a highly specialized cell capable of transmitting an electrical signal from one cell to another via electrical or chemical means. It is high specialized and has lost its ability to divide. Depends on glucose for energy, and doesn’t rely on insulin.

Dendrites= receive a signal to be transmitted.

Axon Hillock= the disturbance in the electric field is transferred here immediately from the cytosol of the cell body which is highly conductive and any electrical stimulus.

Axon= if the stimulus is great enough, the axon hillock generates an action potential in all directions including to this part.

***Unipolar for sensory only, Bipolar for retina, inner ear, olfactory area of the brain, and Multipolar (most neurons of the brain.)
***The signal travels from the dendrites to the axon hillock, where an action potential is generated and moves down the axon to the synapse. Neurons do not depend upon insulin to obtain glucose.

Question 12

Action Potential=

Resting potential=

***Na+/K+ move three positively charged sodium ions ______ of the cell while moving ________ two positively charged potassium ions.

Answer 12

Action Potential= is a disturbance in the electric field across the membrane of a neuron. An all or nothing fashion. In order to create an action potential the stimulus must be greater than the threshold stimulus.

Resting potential= is established mainly by an equilibrium between passive diffusion of ions across the membrane and the Na+/K+ pump.

***Na+/K+ move three positively charged sodium ions out of the cell while moving in two positively charged potassium ions.

Question 13

Voltage gated sodium channels=

Depolarization=

Repolarization=

Hyperpolarization=

Voltage gated potassium channels=

Answer 13

Voltage gated sodium channels= integral membrane proteins of a neuron’s membrane.

Depolarization= the process of making the cell positive on the inside and negative on the outside.

Repolarization= the process of making the inside of the cell more negative.

Hyperpolarization= the inside of the membrane becomes in more negative than at the resting potential.

Voltage gated potassium channels= but they are less sensitive and take longer to open.

Question 14

Synapse=

Electrical synapses=

Chemical synapses=

Synaptic Cleft=

Brownian motion=

***It is the slowest step in the transfer of a nervous signal, why?

Answer 14

Synapse= the transmission of neural impulses from one cell to another chemically or electrically.

Electrical synapses= are uncommon, composed of gap junctions between cells. But they are much faster than chemical synapses. (Cardiac muscle, visceral smooth muscle, and very few neurons in the CNS contain electrical synapses.)

Chemical synapses= is unidirectional. (called a motor plate when connecting a neuron to a muscle) Small vesicles filled with neurotransmitter rest just inside the presynaptic membrane.

Synaptic Cleft= the sudden influx of Ca2+ ions causes some of the neurotransmitter vesicles to be released through an exocytotic process.

Brownian motion= random motion of the molecules.

***It is the slowest step in the transfer of a nervous signal, and that it can only transfer a signal in one direction!

Question 15

Neurotransmitter=

Second messenger system=

Answer 15

Neurotransmitter= attaches to its receptor for only a fraction of a second, if may allow the cell to be stimulated over and over again.

Second messenger system= activating another molecule inside the cell to make changes.

Question 16

Myelin=

***Myelinated axons appear______, while neuronal cell bodies appear_______!!!***

Nodes of Ranvier=

Saltatory conduction=

Answer 16

Myelin= sheaths that electrically insulate the axons of the CNS. In the peripheral nervous system, myelin is produced by Schwann cells. Increasing the rate at which the axon can transmit signals.

***Myelinated axons appear WHITE, while neuronal cell bodies appear GRAY!!!***

Nodes of Ranvier= tiny gaps between myelin.

Saltatory conduction= as the action potential moves down from one node of ranvier to the next the jump is called Saltatory conduction.

Question 17

Sensory (afferent) Neurons=

Interneurons=

Motor (efferent) Neurons=

Nerves=

Answer 17

Sensory (afferent) Neurons= receive signals from a receptor cell that interacts with its environment. The sensory neuron then transfers the signal to other neurons. 99% of sensory input is discarded by the brain. Sensory neurons are located dorsally (toward the back) from the spinal cord.

Interneurons= transfer signals from neuron to neuron. 90% of neurons in the human body are interneurons.

Motor (efferent) Neurons= carry signals to a muscle or gland called the effector. Motor neurons are located ventrally (toward the front of abdomen).

Nerves= neuron processes (axon and dendrites) are typically bundled together to form nerves.

Question 18

Central nervous system (CNS)= .

Peripheral nervous system (PNS)=

–>The PNS is broken down into the ?

Answer 18

Central nervous system (CNS)= consists of the interneurons and support tissue within the brain and the spinal cord. The function of the CNS is to integrate nervous signals between sensory and motor neurons.

Peripheral nervous system (PNS)= handles the sensory and motor functions of the nervous system, basically everything else besides the brain and spinal cord.

–>The PNS is broken down into the Somatic Nervous system and Autonomic nervous system.

Question 19

Somatic Nervous System=

Autonomic nervous system (ANS)=

Answer 19

Somatic Nervous System= designed primarily to respond to the external environment, it contains sensory and motor functions. Skeletal muscle motor neurons only. Cell bodies of somatic motor neurons are located in the ventral horns of the spinal cord. The neurons synapse directly on their effectors and use acetylcholine for their neurotransmitter, and are considered voluntary.

Autonomic nervous system (ANS)= the motor portion of the ANS then conducts these signals to smooth muscle, cardiac muscle, and glands. Involuntary; controlled by hypothalamus. Motor portion broken down into: Sympathetic and parasympathetic.

Question 20

Sympathetic=

Parasympathetic=

Reflex arcs=

Answer 20

Sympathetic= “fight or flight”–> increases heart rate, stroke volume, and constricts blood flow to “digestive” organs to open up the volume of flow to skeletal muscles. Neurons cell bodies found in the spinal cord. Sympathetic nervous systems uses either epinephrine or norepinephrine (adrenaline & noradrenaline)

Parasympathetic= “rest and digest”–> slows the heart rate and increases digestive and excretory activity. Neurons cell bodies can be found in both the brain and spinal cord. Parasympathetic uses acetylcholine for the postganglionic neurons.

Reflex arcs= often involve inhibition as well as excitation of muscle groups.

Question 21

Lower brain consists of:–>

1)
2)
3)

4)

Answer 21

Lower brain consists of:–> integrates subconscious activities such as respiratory system, arterial pressure, salivation, emotions, and reaction to pain and pleasure.

1) medulla
2) hypothalamus
3) thalamus

4) cerebellum

Question 22

Higher brain consists of:

1)

Answer 22

Higher brain consists of:

1) Cerebrum (cerebral cortex)–> the cerebral cortex is incapable of functioning without the lower brain. It acts to store memories and process thoughts.

Question 23

Nervous System Breadown:

***Sensory receptors transduce __________ to neural signals.***

Answer 23

***Sensory receptors transduce physical stimulus to neural signals.***

Question 24

Cornea=

Lens=

Ciliary muscle=

Retina=

Answer 24

Cornea= the part of the eye where light first strikes which mean the light reflects off an object in the external environment then hits the cornea. It is nonvascular and made of collagen; refractive index=1.4 which means most bending of light actually occurs at the interface of the air and the cornea and not at the lens.

Lens= from the anterior cavity the light enters here. Stiff suspensory ligaments tug on the lens to flatten it.

Ciliary muscle= the muscle to which the stiff suspensory ligaments which tug on the lens are connected to. Ciliary muscle circles the lens, when it contracts the opening of the circle decreases allowing the lens to become more like a sphere and brining its focal point closer to the lens; when it relaxes the lens flattens increasing the focal distance making it less powerful.

Retina= covers the inside of the back (distal portion) of the eye. It contains light sensitive cells called Rods and cones.

Question 25

Rods=

Cones=

***_______ is a precursor to all the pigments in rods and cones.

Iris=

***Since the eye is a _______ lens, and the object is outside the ________, the image on the retina is __________ and _______________

Answer 25

Rods= sense all photons with wavelengths in the visible spectrum (390-700nm) They cannot distinguish colors.

Cones= Three types of cones, each with a different pigment that is stimulated by a slightly different spectrum of wavelengths. Thus cones distinguish colors. ***Vitamin A is a precursor to all the pigments in rods and cones.

Iris= the iris is the colored portion of the eye. It is made from circular and radial muscles. In a dark environment the sympathetic nervous system contracts the iris dilating the pupil allowing more light to enter. In a bright environment, the parasympathetic nervous system contracts the circular muscles of the iris constricting the pupil and screening out light.

***Since the eye is a converging lens, and the object is outside the focal distance, the image on the retina is real and inverted.

Question 26

The ear is divided into three parts:

1)
2)
3)

Answer 26

The ear is divided into three parts:

1) outer ear
2) middle ear–> three small bones: Malleus, incus, and Stapes.(act as a lever system translating the sound waves.
3) inner ear–>Cochlea and Semicircular canals.

Question 27

Tympanic membrane=

Cochlea=

Semicircular canals=

Answer 27

Tympanic membrane= the eardrum, which starts in the middle ear. External auditory canal carries the waves to this part of the ear.

Cochlea= the spinal part of the inner ear; detects sound. The alternating increase or decrease in pressure are detected by hair cells(actually microvilli) of the organ of Corti and transduced into neural signals, which are sent to the brain.

Semicircular canals= responsible for balance and detecting orientation and movement of the head. Each canal contains fluid and hair cells; when the body moves the momentum of fluid is changed impacting on the hair cells, and the body senses motion.