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Mammalian Physiology > Lecture 4 > Flashcards

Lecture 4 Flashcards

1
Q

Induced pluripotency.

A

The forced expression of 4 different genes, which causes de-differentiation of cells.

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2
Q

Process of induced pluripotency.

A

Fuse 2 cells of early fertilization phase from the embryo, forcing them to become a tetraploid blastocyst; the cells that give rise to embryonic cells will be diploid.

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3
Q

Urine adjustment.

A

This is done to keep blood osmolarity. process: the stimulus is an increased concentration (of ions (osmolarity) in the blood, which triggers the hypothalamus to release ADH. ADH is released from the pituitary gland, causing re-absorption of water from the urine; we will have a thirst response.

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4
Q

Function of an anti-diuretic.

A

Reduces the amount of urine lost by the body.

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5
Q

Definition: vasopressin.

A

Level of water in our body affects our blood pressure.

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6
Q

Function of ADH during a dehydration response.

A

ADH acts on the distal tubules of the kidney, increasing water permeability by inserting aquaporin channels into the cell membranes; overall effect is increased water re-absorption by the kidney and decrease of water in the urine flow.

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7
Q

Receptors in the endocrine system bind to a ligand and stimulate…

A

An intracellular signalling cascade.

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8
Q

G-protein process.

A

Ligand bind to G protein and activates it. Active G protein then activates adenylyl cyclase, which converts ATP into cAMP. cAMP then activates protein Kinase A (a phosphorylating enzyme; adds a phosphate group). The protein is phosphorylated, which alters its shape and function.

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9
Q

Function of a kinase.

A

it is a phosphorylating enzyme; adds a phosphate group.

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10
Q

Characteristics of integral membrane proteins.

A

They span the entire membrane, used to attach cells in order to form tissues through cell-to-cell connections, gives integrity to the membrane, and binds ECM to give structure to tissues.

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11
Q

Characteristics of integrins.

A

They are structural adhesion proteins, involved in cell-to-cell or cell-to-ECM connections, a heterodimer made of alpha and beta subunits, involved in wound healing, embryo attachment, and cancer invasion; triggers a transduction pathway upon ligand binding.

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12
Q

Which integrin subunit is involved in embryo attachment?

A

Alpha-6 in involved in embryo attachment to the uterus by co-colacilses with osteocontin.

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13
Q

Cytoplasm.

A

Gel-like substance that includes many organelles suspended in a watery intracellular fluid (the cytosol).

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14
Q

2 groups of organelles.

A

Membranous organelles (specialized sacs or canals like the Golgi, ER, plasma membrane, lysosomes, and proteosomes) and non-membranous organelles (made of microscopic filaments like the cytoskeleton, ribosomes, cilia, flagella, nucleolus).

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15
Q

Characteristics of the ER.

A

Made of canals with membranous walls, they pan the cell for protein transport.

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16
Q

Rough endoplasmic reticulum.

A

Ribosomes found on the outer surface of the membranous walls, they synthesize proteins, and they transport proteins to the Golgi.

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17
Q

Smooth endoplasmic reticulum.

A

No ribosomes on the membranous walls, synthesize some lipids and carbohydrates, can renew membrane components, removes and stores Ca2+ from the cell’s interior.

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18
Q

Characteristics of ribosomes.

A

Non-membranous structure, composed of 2 subunits (one large and one small), each subunit contains rRNA; synthesize proteins; they can form groups of polyribosomes.

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19
Q

Proteins synthesized by the RER.

A

Any protein synthesized on the RER is destined for transport or for the cell’s domestic use.

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20
Q

Golgi apparatus.

A

Membranous organelle consisting o f cistern (grooves) near the nucleus, it processes and modifies proteins destined for transport through the use of enzymes; processed proteins leave the final cistern in a vesicle.

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21
Q

Cisternae.

A

Grooves in the Golgi apparatus.

22
Q

Route of protein transfer.

A

The proteins are made on the ER, travel through the ER, then leave the ER in a vesicle. The vesicle fuses with the Golgi, where it is modified. The vesicle them fuses with the plasma membrane for release outside of the cell.

23
Q

Lysosomes.

A

Small sacs that pinch off from the Golgi apparatus. Function: digestive/recycling system through phagocytosis (for export out of the cell).

24
Q

Tay-Sachs.

A

Cannot produce the enzyme that breaks down lipid-gangliosides, autosomal recessive gene is responsible. Lysosomes lack the enzyme hexoaminidase A needed to break down fatty acid derivatives; the cell is no longer functional and reaches toxicity, so it dies. Individual with Tay-Sachs disease do not live past the age of 6.

25
Q

Proteosomes.

A

They destroy defective proteins by tagging them with ubiquitin molecules; unfolds the protein and breaks the peptide bonds.

26
Q

Parkinson’s disease.

A

A neurodegenerative disorder: the proteosome system does not work properly and kills nerve cells in the brain that regulate muscle tension. Dopamine is an inhibitory transmitter that inhibits movements; the affected individual shales because small movements are no longer being inhibited by proper dopamine secretion.

27
Q

Mitochondria.

A

Composed of a linear and outer membrane separated by fluid; powerhouse of the cell; mitochondrial enzymes catalyze oxidation reactions that provide the cell with its energy; contains a single circular DNA molecule, which allows it to produce its own enzymes; it was perhaps a free living bacteria at one time. Mitochondria is only inherited from the mother, involved in Parkinson’s, Alzheimer, and diabetes inheritance. Muscle cells have lots of mitochondria: energy-requiring.

28
Q

Nucleus.

A

Houses the genetic material. Double membrane: nuclear envelope surrounds the nucleoplasm, has the same molecular structure as the plasma membrane, pores allow mRNA to exit. Cells normally only have one nucleus; multi-nucleated cells tend to be cancerous.

29
Q

DNA.

A

Heterochromatin (tightly compacted; genes are silenced) and euchromatic (open, active gene transcription). Gene transcription determines the phenotype.

30
Q

Chromatin.

A

Composed of histone proteins (packaging) and DNA wrapped around the histones.

31
Q

Nucleosome.

A

8 histone proteins with DNA wrapped around it.

32
Q

Cytoskeleton.

A

Supporting framework made up of rigid, rod-like pieces. Provides support, allows movement of proteins and organelles within the cell, serves critical functions in chromatin movement during mitosis and meiosis (responsible for lining the cells and pulling them apart). Made up of microfilaments, microtubules, and intermediate filaments.

33
Q

Microfilaments.

A

Smallest cell fibres made of thin twisted protein molecules; they can slide past each other, causing cell-muscle contraction.

34
Q

Mechanism of contraction.

A

Myosin head binds to actin filaments, releases and attaches again, thereby causing a pulling motion; this is the Sliding Filament Model.

35
Q

Intermediate filaments of the cytoskeleton.

A

Twisted protein strands thicker then microfilaments. form the supporting network of cells.

36
Q

Microtubules.

A

Tiny, hollow tubes that are thick; made of protein subunits arranged in a spiral. Function: to move things around in the cell.

37
Q

Centrosome.

A

Area of the cytoplasm near the nucleus that coordinates building and braking of microtubules in the cell.

38
Q

Cytoskeleton projections.

A

Microvilli (formed from microfilaments, specialized for absorption), cilia and flagella (formed by microtubules, specialized for motion).

39
Q

Microvilli.

A

Found in epithelial cells and intestines; areas where absorption is important, They help increase the surface area.

40
Q

Cilia and flagella.

A

Cell processes with cylinders made of microtubules at their core. Cilia re shorter and more numerous than flagella. Flagella in humans are only found in sperm cells.

41
Q

3 types of cell connections.

A

Gap junctions, tight junctions, and anchoring junctions.

42
Q

Gap junctions.

A

Create communication bridges; l connexins.

43
Q

Tight junctions:

A

prevent movement of materials between cells; helps regulate what enters and its the cells.

44
Q

Anchoring junctions.

A

Cells attach to each other or to the ECM; examples are belt desmosomes or spot desmosomes.

45
Q

Desmosomes.

A

Example: hold skin cells together. Fibres on the outer surface of the desmosome interlock with each other. Spot desmosomes:: connects adjacent membranes, they do not span the whole membrane, only certain points. Belt desmosomes encircle the entire cell like collar.

46
Q

Functions of gap junctions.

A

They use the membrane channels of adjacent plasma membranes to adhere to each other, forming tunnels. Example: the heart uses gap junctions to allow neurones to pass through; allows for unison on contraction.

47
Q

Intercalated discs.

A

Can be found in contractile muscles, like the heart. 2 types of connections: desmosomes (act like VELCRO to connect them physically), and gap junctions (plasma connection).

48
Q

Gap junctions in contractile cells.

A

In the heart: allows electrical impulse to spread from one area of the heart to the whole heart. Functional syncytium: cardiac cells are joined by gap junctions, which allows it to do things in unison.

49
Q

Tight junctions as cell connections.

A

Fuse together and prevent molecules form passing through; can be found in the lining of intestinal epithelium so that enzymes cannot reach the underlying stroma layer and prevent things from slipping into the blood.

50
Q

Function of microvilli in the intestine.

A

Anything passing through into the blood must be selectively absorbed by microvilli.

51
Q

Which type of cell requires lipid synthesis?

A

Liver cell: responsible for endogenous lipid biosynthesis; makes cholesterol which is used for plasma membrane and steroid synthesis.

52
Q

Which type of endoplasmic reticulum is required for cholesterol synthesis?

A

Smooth endoplasmic reticulum (SER).

Mammalian Physiology (10 decks)

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