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Cell Physiology Flashcards

1
Q

Key function of cells (5)

A
  • protection and support (e.g. bones)
  • Movement (e.g. muscle cells)
  • Communication (e.g. neurons)
  • Metabolism (e.g. nucleated cells, take in nutrients from food and convert them into energy)
  • Transport (e.g. neurons carrying NT or RBC carrying oxygen)
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2
Q

How are cells studied? (3)

A
  • cytological / histological analysis (cells stained and looked at under a microscope)
  • Biochemical analysis (cells separated by individual cellular components)
  • Cytogenetic analysis (analysis of chromosomes and genes / DNA)
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3
Q

Cell structure

A

Cells are surrounded by a plasma, or cell, membrane. The membrane has various ‘gates’ to permit cellular traffic in to, and out from, the cell.
The plasma membrane is an outer, protective boundary.
Inside of the cell, there is a fluid referred to as the cytoplasm or intracellular fluid [ICF]. NB. Cytosol = cytoplasm minus the organelles.
Outside of the cell, the surrounding fluid is called interstitial fluid [ISF] or intercellular fluid.

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4
Q

Organelles in eukaryotic cell (7)

A

Nucleus
Nucleolus
Mitochondria
Lysosomes
Endoplasmic reticulum (smooth and rough)
Ribosomes
Golgi apparatus (and vesicles)

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5
Q

Nucleus

A

The ‘control centre’ of the cell due to storing genetic material.
This is stored within DNA [deoxyribonucleic acid] along with a variety of proteins, to form chromosomes. DNA regulates protein synthesis within the cell; therefore regulating the chemical reactions of the cell.
Chromosomes are a structure of DNA and protein: Somatic cells are diploid: their nucleus contains 23 pairs of chromosomes [One of each pair from mother, and the other from father]. This makes 46 in total; and is referred to as the human diploid number. Gametes [ova and sperm] are haploid: their nucleus contains 23 unpaired chromosomes [23 is the human haploid number]

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6
Q

Nucleolus

A

A round body located
inside the nucleus of a eukaryotic cell. It is not surrounded by a membrane, but sits in the nucleus.
The nucleolus makes ribosomal subunits from proteins and ribosomal rRNA. Undertakes a critical role in the synthesis of proteins in the cell.

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7
Q

Mitochondria

A

Mitochondria are responsible for metabolism and energy production. The metabolism of nutrients is located with the cristae of the mitochondria. The organelle is enclosed [and therefore protected] by a double membrane.
A dominant role for the mitochondria is the production of ATP [adenosine triphosphate] re: aerobic respiration. ATP is the cell’s major source of energy.
Mitochondria is heavily implicated within the process of apoptosis.
Mitochondria has its own DNA, known as mtDNA; this is inherited from the maternal lineage.

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8
Q

Lysosomes

A

A membrane-bound cell organelle containing degrading enzymes to destroy unnecessary materials within the cell. Critical for cell homeostasis and survival of the cell/life. They assist within the destruction of invading viruses and bacteria. If damaged [and unable to initiate repair]- lysosomes can elect to die via apoptotic mechanism.
Lysosomal storage diseases are inherited metabolic disorders that are pathognomonically characterised by an abnormal accumulation of toxins; these can be fatal and often seen in childhood

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9
Q

Smooth endoplasmic reticulum (SER)

A

Ribbon like membranes.
These are single membrane cell organelles.
No attached ribosome.
Considered as one of the components of cytoskeleton along with microtubules and microfilaments.
Manufactures lipids and carbohydrates, detoxifies harmful chemicals and stores calcium.
Responsible for the synthesis of phospholipids.

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10
Q

Rough endoplasmic reticulum (RER)

A

Critical for protein and lipid synthesis.
Transports synthesised proteins to Golgi apparatus.
Usually has a ribosome attached; hence appearing ‘rough’ or ‘studded’ [cf. smooth].
The ribosomes are held in position by cell surface receptors known as ribophorins

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11
Q

Ribosome

A

Free moving organelles located within the cytoplasm.
Important for the synthesise of new proteins from amino acids.
Sometimes referred to a the ‘protein factories’ of the cell.
Often bound to the Rough ER.
Can also be distributed throughout the cell

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12
Q

Golgi apparatus

A

A complex set of intracellular vesicles [transporting proteins].
Important for secretion and intracellular transport [vesicular mediated transport].
Modifies, and distributes, proteins and lipids for secretion or for use within the cell.
Flattened membrane sacs stacked on top of each other.
Eponymously named after Camillo Golgi- a pioneering neuroanatomist.

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13
Q

Vesicles

A

Employed in multiple cellular functions- including:
i). Movement of molecules ii). Digestion of particles iii). Secretion of materials
Many vesicles are made in the Golgi apparatus.
These are small, spherical organelles which are separated from the cytosol by at least one lipid bilayer.

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14
Q

2 Main forms of cell division

A

Mitosis and meiosis

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15
Q

Mitosis

A

Cell division that produces a genetically identical daughter cell. These cells are continuously dividing to create a new population. The number of chromosomes remains the same within the replicated daughter cell.

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16
Q

Mitosis Stages (6)

A

Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis

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17
Q

Interphase

A

Before mitosis
Nucleolus and nuclear envelope are distinct and the chromosomes are in the form of threadlike chromatin

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18
Q

Prophase

A

The chromosomes appear condensed and nuclear envelope starts to break down

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19
Q

Metaphase

A

Thick coiled chromosomes, each with two chromatids are lined up on the metaphase plate (middle of the cell)

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20
Q

Anaphase

A

The chromatids of each chromosomes have separated and are moving towards the pole of the cell

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21
Q

Telophase

A

The chromosomes are at the poles and are becoming more diffuse. The nuclear envelope is reforming. Cytoplasms are dividing

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22
Q

Cytokinesis

A

Division is completed and two daughter cells are formed

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23
Q

Meiosis

A

Cell division that produces a genetically non-identical daughter cells. This only occurs in the gonads [ovaries- oogenesis; and testes- spermatogenesis] and produces ova and sperm. Meiosis is essential to produce egg [ova] and sperm cells for sexual reproduction. The number of chromosomes is halved within the replicated daughter cell.

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24
Q

Meiosis stages

A

prophase I. the chromosomes condense, and the nuclear envelope breaks down.
Metaphase I. pairs of homologous chromosomes move to the equator of the cell.
Anaphase I.
Telophase I and Cytokinesis.
Prophase II.
Metaphase II.
Anaphase II.
Telophase II and Cytokinesis.

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25
Q

Meiosis crossing over

A

Crossing over occurs when chromosomal homologs exchange information during metaphase of Meiosis I. During this stage, homologous chromosomes line up on the metaphase plate and exchange genetic information.

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26
Q

Meiosis random assortment

A

When cells divide during meiosis, homologous chromosomes are randomly distributed during anaphase I, separating and segregating independently of each other. This is called independent assortment. It results in gametes that have unique combinations of chromosomes.

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27
Q

Aerobic respiration

A

When energy is created from oxygen and glucose
Produces 38 ATP

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28
Q

Anaerobic respiration

A

Takes place in the cytoskeleton
Produces 2 ATP
GLUCOSE -> ENERGY + PYRUVIC ACID
Pyruvic acid is converted to lactic acid (which causes muscle cramps and fatigue)

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29
Q

Phosphorylation

A

P + AMP ↔ ADP + P ↔ ATP
Mitochondria is key for synthesis of energy [in the form of ATP [adenosine triphosphate] and also for storage of ATP, for use when required.

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30
Q

Apoptosis

A

Programmed cell death triggered by Specialised enzymes within the mitochondria - very important for survival. These are referred to as caspases.

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31
Q

Plasma membrane

A

This phospholipid [phosphate and lipids [fats and oils]] bilayer encompasses the cell, offering structure, integrity and shape. This membrane houses various channels to selectively permit molecular traffic.
Critical when considering in the context of pharmacokinetics; particularly within the context of treating neurological and psychiatric conditions.
The membrane is constructed of structural phospholipids [fats containing a phosphate group].
The membrane is a bilayer [as two layers of membrane working together]. The membrane is hydrophobic [‘water hating’], therefore protects the inside of the cell from substances in the interstitial fluid. Substances which permit the transfer for fluids are referred to as hydrophilic.

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32
Q

Why is transport across the membrane so important?

A

To ensure the survival of the cell, and of the organism [permits the entry of nutrition into the cell, and excreting waste from the cell].

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33
Q

Three main mechanisms of transmembrane [‘across the membrane’] transport

A

1) Passive mechanism (no energy required)
2) Active carrier-mediated mechanism (energy required)
3) Active vesicle-mediated mechanisms (energy required)

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34
Q

Passive mechanisms [no energy required]

A

Include osmosis and simple diffusion, which are non-carrier mediated, and facilitated diffusion, which is carrier-mediated. All require a concentration gradient, with substances moving to populate a less concentrated area.

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35
Q

Active carrier-mediated mechanisms [energy required]

A

Include Primary and Secondary Active Transport mechanisms. These requires direct ATP for primary and secondary active transport. For both it is possible to go ‘against’ the concentration gradient.

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36
Q

Active vesicle-mediated mechanisms [energy required]

A

Examples include endocytosis and exocytosis [essentially the ‘bringing in’ and ‘sending out’ of the cell]. An example would be secretion of hormones.

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37
Q

Two main forms of endocytosis

A

pinocytosis or cell drinking [internalisation of fluid matter] and phagocytosis or cell eating [internalisation of particulate matter].

38
Q

Concentration gradient

A

A concentration gradient can be defined as the process of particles moving through a solution [or gas] from an area with a higher number of particles to an area with a lower number of particles.

39
Q

2 cell death mechanisms

A

i) . Apoptosis- programmed cell death [single cell death], well controlled, predictable, manageable. Maintains organ sizes in the body.
ii) . Necrosis- multiple cell death as a result of pathology [illness], poorly controlled, unpredictable, and poorly managed. Associated with the inflammatory response.

40
Q

Apoptosis vs Necrosis

A

Apoptosis
Affects single cells
No inflammatory response
Cell shrinkage evident
Membrane integrity maintained
Cells digested by neighbouring cells
Programmed, well controlled cell death

Necrosis
Affects multiple (or groups) of cells
Significant inflammatory response
Cell swelling evident
Membrane integrity impaired
Random DNA degradation
Associated with pathology

41
Q

Homeostasis

A

Homeostatic mechanisms seek to return the body back to a ‘normal range’. This is crucial for the maintenance of cell survival [and therefore tissue, organ, organ system, and organism survival].
Examples of homeostatic variables:
Core Body Temperature
Blood Pressure [BP]
Blood Sugar Level [BSL]
Blood volume
Blood pH

42
Q

What is homeostasis regulated by

A

Feedback loops

43
Q

Negative feedback

A

Negative indicates that any deviation from the normal range, or set point, is reduced [i.e. if the temperature is too high, negative feedback loops return temperature to a standardised range].

44
Q

Positive feedback

A

Positive indicates that any deviation from the normal range, or set point, is amplified [i.e.
lactation; the suckling of a neonate enhances prolactin release and amplifies production of colostrum/milk].

45
Q

3 elements of feedback loops

A

Receptor/Sensors detects and monitors any change
Control Centre [receives information from the receptor, establishes the normal range,
and controls the effector]
Effector/Communication System [produces response to correct abnormality [e.g.
sweating to reduce temperature or shivering to increase temperature]].

46
Q

Organs that control homeostasis

A

There is no specific organ which controls homeostasis.
The integumentary, renal, cardiovascular, respiratory, endocrine, and nervous systems all play a part in maintaining the internal environment within narrow specified limits. The hypothalamus is involved to a degree in each of these regulations.

47
Q

Thermoregulation

A

Body’s way of maintaining the optimum bodily temperature
Regulated by a negative feedback loop . i). The receptors/sensor consist of thermoreceptors [central and peripheral]. ii). The control centre is the hypothalamus.
iii). The effectors consist of many physiological responses secondary to temperature dysregulation.

48
Q

Thermoregulation receptors/sensors

A

Thermoreceptors are nerve endings that respond to temperature changes. There are two types of thermoreceptors:

i) . Central thermoreceptors – located in central nervous system [CNS]
ii) . Peripheral thermoreceptors – located in the integumentary system.

49
Q

Hypothalamus

A

The hypothalamus is relatively small, but crucial structure located within the limbic system, just ventral the thalamus. The hypothalamus is approximately the size of an almond and weigh c.4 grams. The hypothalamus is the control centre for temperature control; consider the hypothalamus as an internal thermostat. The hypothalamus receives incoming [or afferent] information from the thermoreceptors, and organises appropriate effectors [efferent responses].
The hypothalamus is also contributory to pituitary endocrine control, circadian biorhythms, controlling appetite [satiety], and regulating emotional responses.

50
Q

Examples of body response to heat changes

A

Effectors:
Vasoconstriction or vasodilation of cutaneous blood vessels.
Arrectorpili muscles contraction.
Increased metabolism [heat as a by-product of metabolism].
How muscles contribute to heat production:
– Normal muscle tone and involuntary tensing of muscles which happens, even at rest – During exercise. – Respiratory muscle activity [muscle activity during breathing].
Muscular activity [i.e. Shivering]:
– Muscular response to cold. – Oscillating rhythmic muscle tremors 10 –20 times/sec – During shivering, messages sent from brain to muscles to increase heat production
[more about this later]. – Shivering is an effective way of increasing temperature quickly

51
Q

Example of positive feedback

A

childbirth, with excessive production of oxytocin to assist with parturition [vaginal delivery]

52
Q

molecules

A

a group of atoms bound together to perform a function

53
Q

cells

A

a body containing different organelles which work together to perform a specific function

54
Q

tissues

A

a group of cells that work together to perform a specific function

55
Q

organs

A

collection of tissues that structurally form a functional unit specialized to perform a particular function

56
Q

organ system

A

group of organs that work together to perform bodily functions

57
Q

Diagram to show the cavities of the body

A
58
Q

epithelial tissue (epithelium)

A

a type of body tissue that forms the covering on all internal and external surfaces of your body, lines body cavities and hollow organs and is the major tissue in glands

59
Q

simple epithelium

A

consists of a single layer of identical cells and is divided into three main types. usually found on absorptive or secretory surfaces and surfaces subjected to stress where the single layer enhances these processes.

functions are protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.

the three simple epithelium are squamous, cuboidal and columnar

60
Q

squamous epithelium

A

flattened, epithelial cells, very thin and irregular in outline which faccilitate diffusion of gases and other simple molecules.

found in:

heart (known as endocardium)

blood vessels and lymph vessels (known as endothelium)

alveoli

collecting ducts of the neprons in the kidneys

61
Q

simple cuboidal epithelium

A

a single layer thick and made of cube-shaped cells. (in simple)

Function: absorption and filtration processes

Location: secretory ducts of small glands, kidney tubules Function: allows secretion and absorbtion

62
Q

simple columnar epitheliumq

A

elongated and column-shaped and have a height of at least four times their width. Their nuclei are elongated and are usually located near the base of the cells.

Columnar epithelium forms the lining of the stomach and intestines.

63
Q

stratified epithelium

A

consists of several layers of cells of various shapes. continual cell division in the lower layers pushes cells abover nearer and nearer to the surface where they are shed.

main function is to protect underlying structures from mechanical wear and tear.

there are two main types: stratified squamous and transitional

64
Q

stratified squamous epithelium

A

composed of several layers of cells. in the deepest layers cells are mostly columnar and as they grow towards the surface they become flattened and shed.

65
Q

keratinised stratified epithelium

A

found on dry surfaces subject to wear and tear

e.g skin, hair and nails

surface layer consists of dead epithelail cells that have lost their nuclei and contain the protein keratin, which forms a tough, relatively waterproof protective layer that prevents drying of the live cells below.

the surface layer is rubbed off and is replaced from below.

66
Q

non-keratinised stratified epithelium

A

protects moist surfaces subject to wear and tear and prevents them fro drying out

e.g the conjunctiva of the eye, the lining of the mouth, the pharynx, the oesophagus and the vagina

67
Q

transitional epithelium

A

is composed of several layers of pear-shaped cells. it lines several parts of the urinal tract, including the bladder, and allows for stretching as the bladder fills.

68
Q

connective tissue

A

most abundant tissue in the body. most types have a good blood supply.

major functions:

binding and structural support

protection

transport

insulation

69
Q

5 cell types involved in connective tissue

A

fibroblast

fat cells

macrophages

leukocytes

mast cells

70
Q

fibroblasts

A

large cells with irregular processes. they produce collagen and elastic fibres and a matrix of extracellular material.

particularly active in tissue repair when they bind together the cut surfaces of wounds or form granulation tissue following tissue destruction.

71
Q

fat cells (adipocytes)

A

these cells occur singly or in groups in many types of connective tissue and are ubundant in adipose tissue.

they vary in shape and size according to the amount of fat they contain.

72
Q

loose (areolar) connective tissue

A

most generalised type of connective tissue. the matrix is semisolid with many fibroblasts and some adipocytes, mast cells and macrophages, widely separated by elastic and collagen fibres.

it’s found in almost every part of the body, providing elasticity and tensile strength. it connects and supports other tissue.

e.g

under the skin

between muscles

supporting blood vessels and nerves

in the alimentary canal

in the glands supporting secretory cells

73
Q

adipose tissue

A

two type white and brown

consists of adipocytes containing large fat globules in a matrix of areolar tissue

74
Q

white adipose tissue

A

more present in obese people and less present in people underweight.

secretes the hormone leptin (helps to regulate body weight).

supports the kidney and eyeballs.

found between muscle fibres and under the skin, where it acts as a thermal insulator and energy store.

75
Q

brown apidose tissue

A

more mitochondria and a more extensive capillary network than white and is more metabolically active. when broken down it produces more heat than white and is important in keeping newborns warm.

in adults it’s found in small amounts in the upper chest and neck areas.

76
Q

reticular tissue

A

has a semisolid matrix with fine branching reticulin fibres. contains reticular cells and WBC (monocytes and lymphocytes).

found in lymph nodes and lymphatic organs

77
Q

dense connective tissue

A

contains more fibres and fewer cells than loose connective tissue

78
Q

fibrous tissue

A

made up of mainly closely bundles of collagen fibreswith very little matrix. fibrocytes (old and inactive fivroblasts) are few in number are lie in rows between the bundles of fibres.

fibrous tissue is found:

forming ligaments wich bind bones together

functioning as an outer protective covering for bones (periosteum)

functioning as outer protective covering of some organs (eg. the kidneys, lymph nodes and the brain)

forming muscle sheaths called muscle fascia, which extend beyond the muscle to become the tendon that attaches the muscle to bone

79
Q

elastic tissue

A

is capable of consinderable extension and recoil. there are few cells and the matrix consists mainly in masses of elastic fibres secreted by fibroblasts.

found in organs where stretching and alteration of shape is required

eg.

in large blood vessel walls

the trachea and bronchi

lungs

80
Q

cartilage

A

firmer than other connective tissue the cells (chondrocytes)are sparse and lie embedded in the matrix, reinforced by collagen and elastic fibres.

there are three types:

hyaline cartilage, fibrocartilage, and elastic fibrocartilage

81
Q

hyaline cartilage

A

the chondrocytes are arranged in small groups within cell nests and the blueish-white matrix is smooth and solid.

provides flexibility, support and smooth surfaces for movements at joints

it’s found:

on the end of lone bones that form joints

forming the costal cartilage, that attach the ribs to the sternum

forming parts of the larynx, trachea and bronchi

82
Q

fibrocartilage

A

consists of dense masses of white collagen fibres in a matrix similar to hyaline cartilage with the cells widely dispersed.

it is a tough and slightly flexible, supportive tissue

it’s found:

as pads inbetween the bodies of the vertabrae - known as intervertabral discs

between the articulating surfaces of the bones of the knee joint - know as semilunar cartilage

on the rim of the boney sockets of the hip and shoilder joints, deepening the cavities without restricting movement

83
Q

elastic fibrocartilage

A

flexible tissue which consists of yellow elastic fibres lying in a solid matrix with chondrocytes lying between the fibres

provides support and maintains shape of:

eg:

the pinna or lobe of the ear

the epiglottis

part of the tunica media of blood vessel walls

84
Q

bone

A

oesteocytes are surrounded by a matrix of collagen fibres strengthened by inorganic salts especially calcium and and phosphate , which makes bones strong and rigid. bones also have capacuity to grow in the first 2 decades of life and to regenerate throughout life.

two types of bone can be identified by the naked eye:

compact bone - solid / dense appearance

spongy / cancellous bone - spongy / fine honeycombe appearance

85
Q

muscle tissue

A

able to contract and relax providing movement within the body and the body itself.

requires a rich blood supply providing sufficient oxygen calcium and nutrients and removing waste products

86
Q

what are the three types of specialised contractile cells (fibres)?

A

skeletal muscle

smooth muscle

cardiac muscle

87
Q

skeletal muscle

A

are attached to bones by tendons, and they produce all the movements of body parts in relation to each other. Unlike smooth muscle and cardiac muscle, skeletal muscle is under voluntary control.

88
Q

smooth muscle

A

consists of thick and thin filaments that are not arranged into sarcomeres giving it a non-striated pattern

s present throughout the body, where it serves a variety of functions. It is in the stomach and intestines, where it helps with digestion and nutrient collection. It exists throughout the urinary system, where it functions to help rid the body of toxins and works in electrolyte balance.

89
Q

cardiac muscle

A

works to keep your heart pumping through involuntary movements. It does this through specialised cells called pacemaker cells, which control the contractions of the heart.

90
Q

what are the two types of nervous tissue?

A

exitable cells

non-exitable cells

91
Q

exitable cells

A

called neurones - they initiate recieve conduct and transmit information

92
Q

non-excitable cells

A

called glial cells

they support the neurones

FCS (8 decks)

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