Frumulífeðlisfræði

Question 1

Hver er munurinn á hjartavöðva og rákóttum vöðva varðandi striation?

Answer 1

Rákóttir: Striated

Hjartavöðvi: Striated but arrangement less organised

Question 2

Munurinn á nucleus í hjartavöðva vs. rákóttum vöðva:

Answer 2

Rákóttir: Multiple nuclei located peripherally

Hjartavöðvi: Usually single nucleus (but can be two), located centrally

Question 3

Munurinn á discs í hjartavöðva vs rákóttum vöðva:

Answer 3

Rákóttir: None

Hjartavöðvi: Intercalated discs

Question 4

Munurinn á gap junctions í hjartavöðva vs rákóttum vöðvum:

Answer 4

Rákóttir: No

Hjartavöðvi: Yes

Question 5

Hver er munurinn á hjartavöðva vs rákóttum vöðvum hvað varðar kalk influx?

Answer 5

Cardiac myocytes, like skeletal myocytes, contract via excitation-contraction coupling. Cardiac myocytes, however, use a mechanism that is unique to cardiac muscle called calcium-induced calcium release (CICR). This involves the influx of calcium ions (Ca2+) into the cell, triggering further release of ions into the cytoplasm (a ‘calcium spark’).

Question 6

Summera upp neurological action potential í 6 skrefum:

Answer 6

1. Resting potential: Small subset of potassium channels open, permitting K+ to enter and exit the cell based on electrochemical forces. There is no net movement of K+ ions. (see above)
2. Threshold: As a depolarising stimulus arrives, a few Na+ channels open, allowing Na+ ions to enter the neuron. The increase in positive ions inside the cell depolarises the membrane potential and brings it closer to the threshold at which the action potential is generated (-55mV). Once the threshold of excitation is reached, the neuron will fire an action potential. It is an ‘all or nothing’ phenomenon.
3. Depolarisation phase: After the threshold potential is reached, additional voltage-gated sodium channels open, and Na+ ions rush into the cell. The voltage across the membrane rapidly reverses and reaches its most positive value.
4. Repolarisation phase: At the peak of the action potential, two processes occur simultaneously. Many of the voltage-gated sodium channels begin to close, and more potassium channels open. This allows positive ions to leave the cell and causes the membrane potential to shift back towards the resting membrane potential. As the membrane potential approaches the resting potential, the potassium channels are maximally activated and open.
5. Hyperpolarisation phase: The membrane potential then hyperpolarises beyond the resting membrane voltage as more potassium channels are open at this point than during the membrane’s resting state, allowing more positively charged potassium ions to leave the cell.
6. Recovery: A return to steady-state occurs as the additional potassium channels opened during the action potential close. The membrane potential is now determined by the subset of potassium channels that are normally open during the membrane’s resting state.

Question 7

Hámarks flæði á mín. með bláum 22G æðalegg:

Answer 7

36ml/mín sem gerir 28 mín. fyrir 1L.

Question 8

Hámarks flæði á mín. fyrir grænan 18 GG æðalegg:

Answer 8

90ml/mín sem gerir 11 mín fyrir 1L.

Question 9

Hámarksflæði á mín. í orange 14GG æðalegg:

Answer 9

240mL/klst eða 4mín per 1L.

Question 10

Cardiac action potential í 5 fösum (0-4):

Answer 10

Phase 0 – Rapid depolarization phase
An action potential is triggered once the membrane potential reaches the threshold (approximately -70 mV)
Fast Na+ channels open and there is a rapid influx of Na+ ions
Na+ channels automatically inactivate after a few milliseconds
L-type Ca2+ channels open

Phase 1 – Early repolarisation phase
Commences once Na+ channels inactivate
Some K+ channels open briefly
Efflux of K+ and Cl– ions

Phase 2 – Plateau phase
Slow influx of Ca2+ ions via L-type channels that opened in phase 0
Efflux of K+ ions via delayed rectifier K+ channels
Plateau sustained by balance between movement of Ca2+ and K+ ions

Phase 3 – Rapid repolarisation phase
L-type Ca2+ channels close
K+ channels remain open and there is further efflux of K+ ions

Phase 4 – Resting phase
Resting potential restored by Na+/K+ ATPase and Na+/ Ca2+ exchanger
Resting potential is approximately -90 mV
Na+ and Ca2+ channels are closed in the resting phase

Question 11

Bygging frumukjarnans (nucleus):

Answer 11

The nucleus is the largest organelle in the cell and contains most of the cell’s genetic material. The nucleus is enclosed by two lipid membranes, called the nuclear envelope, that separate the nucleus and its contents from the cytoplasm. There are tiny holes called nuclear pores situated within the nuclear envelope that assist in the regulation of the exchange of materials such as proteins and RNA, between the nucleus and the cytoplasm.

Question 12

Nucleolus: hvar er hann og hvað gerir hann?

Answer 12

The nucleus also contains the nucleolus, a smaller structure that lacks a surrounding membrane and occupies approximately 25% of the volume of the nucleus.

The primary function of the nucleolus is to transcribe ribosomal RNA (rRNA) and combine it with proteins to form incomplete ribosomes. rRNA is important for the construction of ribosomes, which are the site of protein translation.

Question 13

Hvar fer protein translation fram?

Answer 13

Ribosomes

Question 14

Mitochondria: bygging og hvað þær gera:

Answer 14

Mitochondria are membrane-bound organelles that are responsible for the production of the cell’s supply of chemical energy. This is achieved by using molecular oxygen to utilise sugar and small fatty acid molecules to generate adenosine triphosphate (ATP). This process is known as oxidative phosphorylation and requires an enzyme called ATP synthase. ATP acts as an energy-carrying molecule and releases the energy in situations when it is required to fuel cellular processes.

Question 15

Dæmi um 3 hlutverk kjarnans í frumunni:

Answer 15

• The control gene expression and facilitate the replication of DNA during the cell cycle.
• The production of messenger RNA (mRNA) which encodes for enzymes and, therefore, assists with the control of the metabolic functions of cells.
• The control of the structure of the cell via the transcription of DNA which encodes for structural proteins.

Question 16

Hvað er sarcolemma, endomysium, epimysium og fascicle?

Answer 16

• Utan um hvern og einn myofibers er endomysium
• Nokkrir slíkir saman mynda fascicle
• Utan um allan vöðvann er epimysium.
• Alveg innst, fyrir innan endomysium er sarcolemma. Hún er í raun frumuhimnan fyrir myofiberinn.

Question 17

Hvað er idiopathic systemic capillary leak syndrome (ISCLS)?

Answer 17

ISCLS is a rare disorder characterised by episodes of severe hypotension, hypoalbuminemia, and haemoconcentration.

Question 18

Continous capillaries: hvar eru þær og 3 eiginleikar þeirra:

Answer 18

• found in skeletal muscle, myocardium, skin, lungs and connective tissue
• least permeable
• continuous layer of endothelium and basement membrane
• intercellular clefts transmit water and small lipid-insoluble solutes

Question 19

Fenestrated capillaries: hvar eru þær og hverjir eru 3 eiginleikar þeirra?

Answer 19

• found in kidneys, exocrine glands, intestine and endocrine glands
• specialised for rapid fluid filtration
• endothelium has “windows” or fenestrae bridged by a thin porous membrane through which water, nutrients and hormones can pass
• basement membrane is intact

Question 20

Discontinual eða sinusoidal capillaries: hvar eru þær og hverjir eru 2 eiginleikar þeirra:

Answer 20

• found in spleen, liver and bone marrow
• allow movement of blood cells
• endothelium has gaps > 100nm and an incomplete basement membrane

Question 21

Hvar eru tight capillaries og hverjir eru eiginleikar þeirra?

Answer 21

• found in central nervous system
• continuous capillaries with adjacent endothelial cells joined by tight junctions forming an impermeable barrier that prevents the passage of lipid-insoluble solutes and maintains a constant environment for the brain.

Question 22

Hvað eru pericytes og hvað gera þeir?

Answer 22

Pericytes are accessory cells associated with continuous capillaries that wrap around the capillary to envelop part of the wall.

They are thought to regulate vessel structure and diameter and may be a source of fibroblasts.

Question 23

Magn Na, K, Ca++, Cl, bíkarbónats, prótína og albúms í intracellular vökva:

Answer 23

Na+ 10
K+ 140
Ca2+ <0.01
Cl- 3-30
HCO3- 9
Protein (-ve) 50
Albumin (-ve) 61-88

Question 24

Magn Na, K, Ca++, Cl, bíkarbónats, prótína og albúms í interstitial vökva:

Answer 24

Na+ 143
K+ 4
Ca2+ 3
Cl- 129
HCO3- 29
Protein (-ve) 1
Albumin (-ve) 0

Question 25

Magn Na, K, Ca++, Cl, bíkarbónats, prótína og albúms í plasma:

Answer 25

Na+ 143
K+ 4
Ca2+ 3
Cl- 108
HCO3- 29
Protein (-ve) 10
Albumin (-ve) 3

Question 26

Hver er munurinn á interstitial vökva, intravascular vökva og transcellular vökva?

Answer 26

• Interstitial fluid (ISF): This is the tissue fluid found in the spaces between the cells and accounts for approximately 65% of the ECF (10 L of fluid).
• Intravascular fluid: This is the plasma, which is the liquid component of the blood and accounts for approximately 25% of the ECF (3.5 L of fluid).
• Transcellular fluid: This is the final 1.5 L of fluid and comprises intraocular fluid, cerebrospinal fluid, urine in the bladder, and fluid within the lumen of the bowel.

Question 27

Hver er munurinn á kalíum jónum í innanfrumu vs utanfrumuvökva?

Answer 27

The potassium ion (K+) concentration is much higher in the ICF than in the ECF

Question 28

Hver er munurinn á Na jónum í innanfrumu vs utanfrumuvökva?

Answer 28

the sodium ion (Na+) concentration is much higher in the ECF than in the ICF

Question 29

Hver er munurinn á ca++ og cl- jónum í innan- vs. utanfrumuvökva?

Answer 29

Calcium ion (Ca2+) and chloride ion (Cl-) concentrations are also higher in the ECF

Question 30

Hvað er Poiseuille´s law?

Answer 30

The flow of fluids through an intravenous cannula can be described by Poiseuille’s Law. It states that the flow (Q) of fluid is related to a number of factors: the viscosity (n) of the fluid, the pressure gradient across the tubing (P), and the length (L) and radius (r) of the tubing:

Q = πPr4/8nL

Question 31

Hver er munurinn á súrefnis- og orkuþörf coronary vs rákóttra vöðva?

Answer 31

Coronary muscle has a high basal metabolic rate with oxygen demands 20 times that of skeletal muscle at rest.
A number of adaptations help meet this demand.

Coronary muscle has a greater number of capillaries per mm2 than skeletal muscle (approximately 400 vs 3000 respectively).

Oxygen extraction rates are higher in coronary muscle than in skeletal muscle (approximately 70% vs 25% respectively at rest).

Coronary muscle uses fatty acids as the primary energy whereas skeletal muscle uses glucose.

Question 32

Er einhver munur á beta 2 viðtökum í hjartavöðva vs. rákóttum vöðvum? Hvað gera þeir?

Answer 32

Arterioles in the skeletal muscle and cardiac muscle circulation contain β2 receptors. Sympathetic stimulation of these receptors causes vasodilation. In both tissues, metabolic hyperaemia is the primary mechanism of increasing blood flow to meet increased demand.

Question 33

Úr hvaða segmentum taugakerfisins er parasympatiska kerfið?

Answer 33

Craniosacral.

Question 34

Hvað gerir autonomiska taugakerfið og í hvaða tvo hluta skiptist það?

Answer 34

The autonomic nervous system (ANS) is a division of the peripheral nervous system that supplies smooth muscle and glands. It acts to regulate numerous body processes, such as blood pressure and respiratory rate, acting as the effector component of homeostasis.

The autonomic nervous system has two sub-divisions:
The sympathetic nervous system
The parasympathetic nervous system

Question 35

Mismunandi hlutverk sympatiska vs. parasympatiska taugakerfisins:

Answer 35

• The sympathetic nervous system (SNS) functions to regulate the body’s ‘fight or flight’ responses. The SNS originates from the thoracolumbar segments of the spinal cord and uses short preganglionic neurons and long post ganglionic neurons.
• The parasympathetic nervous system (PNS) responsible for the body’s ‘rest and digest’ and ‘feed and breed’ activities that occur when the body is at rest. The PNS originates from the craniosacral segments of the spinal cord.

Question 36

Hvaða neurotransmitterar eru notaðir í sympatiska taugakerfinu?

Answer 36

The preganglionic neurons use acetylcholine as a neurotransmitter, and the postganglionic neurons use noradrenaline as a neurotransmitter.

An exception to this general pattern of innervation is that of the postganglionic neurons supplying the sweat glands and chromaffin cells of the adrenal medulla, which both use acetylcholine as a neurotransmitter.

Question 37

Hvaða neurotransmitter er notaður í parasympatiska taugakerfinu?

Answer 37

This PNS consists of long preganglionic neurons and short post ganglionic neurons. The preganglionic and postganglionic neurons both use acetylcholine as a neurotransmitter.

Question 38

Úr hvaða hlutum eru sympatiska vs parasympatiska kerfið?

Answer 38

Sympatiska: Thoracolumbar segments Parasympatiska: Craniosacral segments

Question 39

Mismunur á lengd preganglionic neurons í sympatiska vs. parasympatiska kerfinu:

Answer 39

Sympatiska: Short
Parasympatiska: Long

Question 40

Mismunur á lengd postganglionic neurons í sympatiska vs. parasympatiska kerfinu:

Answer 40

Sympatiska: Long
Parasympatiska: Short

Question 41

HVer er týpískur plasma oncotiskur þrýstingur?

Answer 41

Plasma oncotic pressure (πp) is typically 25-30 mmHg. For comparison, interstitial oncotic pressure is typically 5 mmHg.

Question 42

Hvað stýrir plasma oncotiskum þrýstingi að mestu og um hvað snýst Gibbs-Donnan effect?

Answer 42

πp is mainly determined by plasma proteins, with 70% of the oncotic pressure being generated by albumin. The osmotic power of albumin is enhanced by its 17 negative charges which hold Na+ ions in the plasma and increase the plasma osmotic pressure. This is an example of the Gibbs-Donnan effect.

Question 43

Hvaða áhrif hefur það á plasma oncotiskan þrýsting ef háræðar eru mjög lekar?

Answer 43

If a capillary is highly permeable, protein leak from the plasma to the interstitium will negate the oncotic pressure of plasma proteins. In this case the influence of πp on fluid movement at the capillary is negligible. Another way of saying a vessel is highly permeable is the reflection co-efficient is close to 0.

Question 44

Hámarksflæði á mín gegnum bleikan (20GG) æðalegg?

Answer 44

60ml/mín sem gerir 17 mín. fyrir 1L

Question 45

Hvernig er frumuhimnan uppbyggð?

Answer 45

The cell membrane is composed of a double layer of phospholipids, which is referred to as a lipid bilayer. The phospholipids have a ‘water-loving’ (hydrophilic) head and a ‘water-fearing’ (hydrophobic) tail. The hydrophilic head is polar (charged) and can, therefore, dissolve in water. Conversely, the hydrophobic tail is non-polar (non-charged) and cannot dissolve in water.

In an aqueous environment, the polar heads attempt to form hydrogen bonds with the water, whereas the non-polar tails try to avoid the water. This results in the hydrophilic heads pointing away from the water and the hydrophobic tails point towards each another to ‘protect’ themselves from the water. The lipid bilayer, therefore, forms spontaneously due to the properties of the phospholipid molecules. Lipid molecules can diffuse freely within each layer, and the membrane is a fluid structure, with the lipid molecules continuously moving each other from side to side.

Question 46

Hvaða mólekúl komast gegnum frumuhimnuna frítt og hver ekki? Hvers vegna?

Answer 46

The structure of the lipid bilayer allows small, uncharged substances such as water, oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, by simple passive diffusion. Large polar molecules, however, such as glucose and amino acids, cannot cross through the membrane without the assistance of membrane proteins. Charged ions, such as hydrogen, sodium and potassium ions, are also unable to cross the cell membrane because of their charge.

Question 47

Hvernig tengist stærð axons á taugafrumu hraða taugaboðanna?

Answer 47

The velocity of the action potential increases proportionally with the square root of axonal diameter; the axons with the largest diameter having the fasting conduction velocities. The velocity of the action potential also increases if the neuron is myelinated.

Question 48

Hvert er hlutverk nodes of ranvier?

Answer 48

There are periodic gaps along a myelinate axon, called Nodes of Ranvier, where there is no myelin, and the axonal membrane is exposed. The section of the axon covered in the myelin sheath does not have any gated ion channels, but there is a high density of ion channels in the Nodes of Ranvier. Because of this, action potentials can only occur at the nodes.

Question 49

Hvernig eykur myelin hraða taugaboða?

Answer 49

Certain neuronal axons are covered by an insulating layer called the myelin sheath. The myelin sheath improves conduction by increasing the membrane resistance and decreasing the membrane capacitance. This allows more rapid conduction of electrical signals through a neuron, making them more energy-efficient than non-myelinated neuronal axons.

Question 50

Hvað er saltatory conduction?

Answer 50

The electrical signals are rapidly conducted from one node to the next, where they cause depolarisation of the membrane above the threshold and initiate another action potential, which is, in turn, conducted to the next node. In this manner, an action potential is rapidly conducted down a neuron. This is known as saltatory conduction.

Question 51

Hvaða frumulíffæri býr til lysosomes og í hvernig frumum er sérlega mikið af þeim?
Hvað gerist svo þegar fruman deyr?

Answer 51

Lysosomes are formed by the Golgi apparatus or the endoplasmic reticulum and contain powerful enzymes that can digest cell structures and food molecules such as carbohydrates and proteins. Lysosomes are abundant in animal cells that ingest food through food vacuoles. When a cell dies, the lysosome releases its enzymes and digests the cell.

Question 52

Hvað gerir mitochondrian og hvernig gerir hún það? Hvaða ensím kemur við sögu?

Answer 52

Mitochondria are membrane-bound organelles that are responsible for the production of the cell’s supply of chemical energy. This is achieved by using molecular oxygen to utilise sugar and small fatty acid molecules to generate adenosine triphosphate (ATP). This process is known as oxidative phosphorylation and requires an enzyme called ATP synthase. ATP acts as an energy-carrying molecule and releases the energy in situations when it is required to fuel cellular processes.

Question 53

Hvernig er mítochondrian uppbyggð?

Answer 53

Mitochondria have two phospholipid bilayers, an outer membrane, and an inner membrane. The inner membrane is intricately folded inwards to form numerous layers called cristae. The cristae contain specialised membrane proteins that enable the mitochondria to synthesise ATP. Between the two membranes lies the intermembrane space, which stores large proteins that are required for cellular respiration. Within the inner membrane is the perimitochondrial space, which contains a jelly-like matrix. This matric contains a large quantity of ATP synthase.

Question 54

Hvernig útskýrist refractory periodan?

Answer 54

Every action potential is followed by a refractory period. This period can be further divided into the absolute refractory period and the relative refractory period. This period occurs as once the sodium channels close after an AP, they enter an inactive state during which they cannot be reopened regardless of the membrane potential.

This is followed by the relative refractory period, during which the sodium channels slowly come out of inactivation. During this period, the neuron can be excited by a stronger stimuli than the one usually needed to initiate an action potential. Early on in the relative refractory period, the strength of the stimulus required is very high, and gradually it becomes smaller throughout the relative refractory period as more sodium channels recover from inactivation.

Question 55

Í hvaða 3 hluta skiptist extracellular vökvinn?

Answer 55

• Interstitial fluid (ISF): This is the tissue fluid found in the spaces between the cells and accounts for approximately 65% of the ECF (10 L of fluid).
• Intravascular fluid: This is the plasma, which is the liquid component of the blood and accounts for approximately 25% of the ECF (3.5 L of fluid).
• Transcellular fluid: This is the final 1.5 L of fluid and comprises intraocular fluid, cerebrospinal fluid, urine in the bladder, and fluid within the lumen of the bowel.

Question 56

Magn prótína í interstitial vökva:

Answer 56

1 mEq/L