ORGANELLES Flashcards
1
Q
NUCLEUS
A
- largest organelle
- has a nuclear envelope (similar to the plasma membrane but has tiny pores = allowing larger particles to go through
- directs cell’s metabolic activities
- contains body genetic materials
- non-dividing cells (DNA) present in the network of threads = chromatin
- dividing cells divide chromatin from chromosomes
- RNA found in the nucleus
- nucleolus = manufacture of ribisomose
2
Q
MITOCHONDRIA
A
- a powerhouse of the cell
- enzymes that synthesise APT found in the inner membrane
- APT (aerobic respiration) = energy currency of cell & releases energy breaks down in the cell.
- process needs O2 = metabolic active cells
3
Q
RIBOSOMES
A
- synthesis of proteins from amino acid, using RNA
- Ribosome proteins used within the cells
- enzymes needed for cellular metabolism
- Ribosomes found on the outer surface of the nuclear envelope & endoplasmic reticulum = manufacture of proteins for export from the cell, e.g. hormones
4
Q
ENDOPLASMIC RETICULUM (ER)
A
- extensive series of interconnecting membranous in the cytoplasm
- 2 types: smooth & rough
- SMOOTH: synthesis of lipids (some lipids replace & repair plasma membranes) & steroid hormones, detoxifies some drugs = converting glycogen into glucose when cells need energy
- ROUGH: studded with ribosomes = site of protein synthesis “exported from the cell.”
5
Q
GOLGI APPARATUS (GA)
A
- stacks of closely folded flattened membranous sacs
- present in all cells, but larger ones synthesise & export proteins
- proteins move from the ER to the Golgi apparatus
- vesicles are stored
- move into the plasma membrane = fuse it, expelling the content of the cell = EXOCYTOSIS
6
Q
LYSOSOMES
A
- small membranous pinched from GA
- contain enzymes involved in breaking down organelles and large molecules (e.g. RNA &DNA)
- inside the cell, smaller parts are recycled/exported from other waste material e.g. lymphocytes
7
Q
CYTOSKELETON
A
- an extensive network of tiny protein fibres
- cytoskeleton = internal support systems for organelles
- guiding the movement of materials around the interior
8
Q
MICROTUBULES
A
- tiny fibres made of actin
- found inside the cell membrane
- cell support and gives shape
- actin involved contractile process in muscle cells
9
Q
MICROTUBULES
A
- fibres = large
- rigid protein
- give mechanic support
- provide a pathway for the internal movement of:
> organelles
> Chromosomes during cell division
10
Q
CENTROSOME
A
- organisation of microtubules within the cell
- consist of a small cluster of microtubules
- plays an important role in cell division
11
Q
CELL EXTRACTION
A
- plasma membrane
- their main component are microtubules
> Microvilli - tiny projections that expose the surface of certain types of cells, e.g., line of the small intestine absorb nutrients in the small intestine
> Cilia hair-like contain microtubules lie across the border of some cells to move the substance across the surface
trapped particles are moved = ciliary action away from the lung towards the mouth to be swallowed
> Flagella - long-whip like - contain microtubules from a tail of spermatozoa propelled through the female reproductive system
12
Q
CELL CYCLE
A
- can be replaced by cell division
- maintain functions & tissue integrity
- cell division happens with different types of tissues carefully regulated to allow maintenance & repair to happen
- natural lifespan & ageing cells programmed to “self-destruct”
- PHYOCYTOSIS removes breakdown products = apoptosis
- cells with nuclei = 46 chromosomes DIVIDED BY MITOSIS
- result in 2 new genetically identical daughter cells
- the only exception is formations of gametes = sex cells = happens through meiosis
- the period between cell division 2 stages: light microscopy (M stage) & interphase
13
Q
INTERPHASE
A
> FIRST GAP PHASE (G1): grows in size and volumes
- usually, the longest phase
- most variable in length
- sometimes doesn’t continue around the cell cycle, entering the resistance phase (G0)
- The resistance phase is still highly active, carrying out specific functions
- cells may stay in G0 permanently
Synthesis of DNA (S phase) chromosomes replicate, forming 2 identical copies of DNA
- DNA cells = 92 chromosomes, e.g. enough for 2 cells (divided by mitosis)
Second gap phase (G2) further growth & preparation for cell division
- normally tightly controlled with checkpoints between stages to find errors
- disruption in the process might lead to tumour development
14
Q
MITOSIS
A
- continuous process
- involving four stages
- visible by light microscopy
15
Q
PROPHASE
A
- replicated chromatin tightly coiled and easier to see under the microscope
- each of the 46 chromosomes
- paired with its copy in double chromosomes unit
- 2 chromatids join together by mitotic spindle formed from microtubules
- nuclear envelope disappears
16
Q
METAPHASE
A
-chromatids align, centre of the spindle
- attached by centromeres
17
Q
ANAPHASE
A
- centrometres are seprate
- each end of the spindle as microtubules from the mitotic spindle shorten
18
Q
TELOPHASE
A
- mitotic spindle disappears
- chromosomes uncoil
- nuclear envelope reforms
- telophase cytokinesis occurs
- cytosol = intercellular organelles - plasma membrane splits = 2 identical daughter cells
19
Q
TISSUES
A
- a large number of the same types of cells
- classified as the size, shape and functions of cells
- types of cells:
> Epithelial tissues or epithelium
> connective tissues
> muscle tissue
> nervous tissues
20
Q
EPITHELIAL TISSUE (ET)
A
- covers the body
- lines cavity
- hollow organs and tubes
- found in glands
> Protection of underlying structures
> secretion
> absorption - cells are tightly packed
- interceulluar structure
- Interconnective tissue made by ET
- 2 types:
> Simple: single layer of cells
> Stratified: several layers
21
Q
SIMPLE EPITHELIUM
A
- a single layer of identical cells
- 3 types of cells
- found on absorptive or secretory surface
SQUAMOUS (PAVEMENT)
> single layer, flattened cells
> Fit closely together (pavement stones) = thin small membrane = easy diffusion
> form linings of:
. the heart
. blood vessels
. lymph vessels
CUBOIDAL: - cub-shaped cells
- fit closely together
- lies on the basement of the membrane
- forms wall of kidney
- found in some glands
- involved in absorption, secretion/secretion
COLUMNAR EPITHELIUM - a single layer of tall, thin cells
- lines organs (the stomach)
- lining of small intestine lined with microvilli (good for absorption)
- contains goblet cells = secrete mucus = inhaled particles stick to mucus
- moved towards the throat by the cilia in respiratory tracts
22
Q
STRATIFIED EPITHELIUM
A
- consists of several layers
- cell division in the lower layer pushes cells nearer and near to the surface
- main function: protect underlying structures from mechanical wear and tear
- 2 types: stratified squamous & transitional
STRATIFIED SQUAMOUS - several layers of cells
- deepest layers of the cells are mainly columnar
- grow towards the surface become flattered and they are shed
23
Q
KERATINSED STRATIFIED EPITHLUM
A
- found in dry surfaces
- can wear and tear
- dead cells lost their nuclei and packed with protein keratin
- tough, waterproof protective layer
- prevents drying live cells underneath
- surface layer = rubbed off and replaced from below
24
Q
NON-KERATINSED STRATIFIED EPITHLUM
A
- protect moist surfaces
- can wear & tear
- prevents drying out
- lining in mouth & vigina
25
TRANSITIONAL EPITHELIUM
- composed of several layers of pear-shaped cells
- lines unitary tract = bladder
- allows for stretching
26
CONNECTIVE TISSUE
- intercellular substances (matrix) present in larger amounts
- fibres present in the matrix
- supporting networks = the cells attach
- connective tissue = good blood supply
main functions:
> Binding and structural support
> protection
> transport
> insulation
27
FIBROBLASTS
- large & possess irregular processes
- manufacture collagen & elastic fibres
- extracellular materials
- inelastic college fibres = main structural protein
-supporting fibrous networks in. highly active tissue (the liver)
- Fibroblast = active tissues repair tissue (wound healing)
- bind together the cut surface of wounds
28
FAT CELLS
- adipocytes = fat cells
- vary in size
- shape = amount of fat they store
29
MACROPHAGES
- large irregularly shaped cells
- a body defence mechanism against foreign bodies
30
LEUKOCYCTES
- white blood cells
- neutrophils migrate in significant numbers during infection = tissue defence
- plasma cells = develop from B-lymphocytes
31
MAST CELLS
- found in loose connective tissue/areas exposed to external invaders
- cytoplasm packed with granulates: heparin, histamine released during tissue damage
- released granular contents = degranulation
- histamine: local and general inflammatory reactions (allergies)
- Heprine: prevents congratulations of the blood, maintains blood flow supplying with O2
32
LOOSE CONNECTIVE TISSUE
- matrix = fibrous & fat cells
- mast cells & macrophages separated elastic & collagen fibres = provides elasticity
> under the skin
> between the muscles
> around the blood vessels and nerves
> glands
33
ADIPOSE TISSUE
- consists of fat cells
- large fat globules
- 2 types: white and brown
WHITE ADIPOSE TISSUE:
> 20%-25% body weight in adults with normal BMI
> Storage for chemical energy
> secret hormone = leptin
> supports kidneys and keeps eyes in their sockets
BROWN ADIPOSE TISSUE:
> mitochondria & more extensive capillary network
> keeps infants warm
> metabolically active
34
LYMPHOID TISSUE
- defence from the body invaders
- forms the framework of lymph nodes
- branches fibres = white blood cells (monocytes & lymphocytes)
35
DENSE CONNECTIVE TISSUE
FIBROUS TISSUE:
- closely packed bundles of collagen fibres
- fibrocytes (old and inactive fibroblast)
where can they be found:
> forming ligaments = bind bones together
> protective covering
> forms muscles sheats = muscle fascia
36
ELASTIC TISSUE
- considered extension and recoil
- masses of elastic fibres secreted by fibroblast
37
CARTILAGE
- firmer than other connective tissue
- embedded
- reinforced by collagen and elastic fibre
3 types: hyaline cartilage, fibrocartalige and elastic fibrocartalige
38
HYALINE CARTALIGE
- a small group within the cell nest
- solid and smooth
- provide flexibility, and support smooth surfaces for movement at the joint
found:
> articular cartilage end of long bone = synovial joints
> Costal cartilage attaches ribs to the sternum
> forming rings around the larynx, trachea and bronchi
39
FIBROCARTILIAGES
- dense masses of white collagen fibres
- cells widely dispersed
- tough, slightly flexible
tissue found:
> Intervertebral discs between the bodies of the vertebrae
> Bones of the knee joint = semilunar cartilage
> Deepening the cavities without restricting movement
40
ELASTIC FIBROCARTILAGE
- flexible tissue
- yellow elastic fibres
- provides support and maintains the shape
41
BONE
- strengthened by calcium and phosphate salts
- bones have considerable capacity for growth in the first 2 decades of life
- regeneration throughout life
2 types of bones:
- compact: solid/dense appearance
- spongy/cancellous bone 'spongy' or fine honeycomb appearance
42
MUSCLE TISSUE
- contract & relax
- provide movement
- contraction requires a blood supply providing good O2, calcium & nutrient & remove waste products
specialised muscle cells:
> skeletal muscles
> smooth muscles
> cardiac muscles
43
SKELETAL MUSCLES
- microscopic
- voluntary under conscious control
- forms diaphragm, allowing a degree of voluntary control in breathing
- fibres contain multiple nuclei & can be up to 35 cm long
- skeleton muscle contraction is stimulated by motor nerve impulses originating in the brain or spinal cord ending in neuromuscular junction
44
SMOOTH MUSCLES
- involuntary, not under conscious control
- smooth muscles = automatically make their own contractions
- stopped by the automatic nervous system
- regulate hormone and contractions
- smooth muscles = mitochondria = fuel to sustain energy
- organised in sheets in the wall of hollow organs
- contraction and relaxation determine the pressure of the organ
45
CARDIAC MUSCLE
- found in the heart wall
- not under consciousness control
- characteristics of skeleton muscle
- fibres have one nucleus
- the ends of cells & branches are in close contact with the end & adjacent cells
- appears in lines that are thicker and darker than ordinary cross-stripes
- cardiac muscles = of sheet muscle compared to a large number of individual fibres
- heart contracts = intrinsic pacemaker system
- beats in a coordinated manner without external nerve simulation
- rate at the beats influenced by the autonomic nervous system (hormone, metabolites)
46
NERVOUS TISSUE
2 types of tissue:
- excitable tissue: neurones initiate, receive, conduct & transmit information
- non-excitable tissue: glial cells, they support the neurons
47
TISSUE REGENERATION
- rapid turnover regenerate = most effective
- 3 categories:
> Liable cells: replication continuous process regenerates quickly
> Stable cells: retain the ability to replicate infrequently under normal conditions (when stimulated, they are capable of normal cell division)
> Permanente cells unable to replicate include nerve cells; damaged tissue cannot be replaced
- extensive damage replaced by fibrous tissue
- a function of tissue is impaired during this time
48
MEMBRANE:
EPITHELIAL MEMBRANES
- sheets of epithelial tissue
- supportive connective tissue
- cover/line many internal structures or cavities
MUCOUS MEMBRANE:
- moist lining (GI tract, respiratory)
- membrane surface = epithelial cells
- produce secretion = mucus
- as the cells fill with mucus, they develop goblet/flask = goblet cells
- mucus = protect the membranous lining from drying, mechanical injury, chemical injury
- respiratory tract mucus traps inhaled particles, stopping them from going into the lungs
49
SEROUS MEMBRANE
- watery fluid
- a double layer of loose
- connective tissue lined by simple squamous epithelium
- parental layer lines the cavity
- visceral layer surrounds the tissue
- separated by the serous membrane
3 sites:
> Pleura lining the thoracic cavity
> Pericardium lining the abdominal cavity & surrounds the heart
> peritoneum lining the abdominal cavity and surrounding abdominal organs
- enables organs to glid between cavities without damage due to friction
50
SYNOVIAL MEMBRANE
- membrane lines the cavities of synovial joints
- synovial membrane secretes synovial fluid, lubricates & nourishes the joints
51
GLANDS
- a group of epithelium cells
- produce specialised secretions
- those that discharge their secretion onto the epithelium surface of hollow organs directly / throughout a duct = exocrine glands
- range in size and shape
- other glands discharge their secretions into blood and lymph = endocrine gland = secret hormones
52
CHANGES IN CELL SIZE AND NUMBER
- cells within the tissue may enlarge = hypertrophy
- decrease in size or the number of cells = atrophy
- impaired nutrient O2 supply can = atrophy
- Hyperplastia = cells divide more quickly, increasing cell numbers
- Abrnoaml hyperplastia = development of tumours
- mitosis isn't controlled, and daughter cells may show abnormal internal characteristics
53
CELL DEATH:
APOPTOSIS
- ageing cells at the end of their life cycle disintegrate
- The remaining fragments are rapidly phagocytes & macrophages = with no inflammatory reactions
- fewer cells lost by apoptosis are replaced
54
NECROSIS
- the result of lack of O2 = ischaemia
- tissue injury or pathological process
- plasma membrane ruptures = releasing intercellular contents = inflammatory response
- tissue repair is needed to clear the area debris before healing and tissue repair can progress
