Biological tissues Flashcards
week 14 (115 cards)
1
Q
define tissue
A
an assemblage of similarly specialised cells united in performing a specialised function
2
Q
what are the 2 functions of epithelia? examples
A
covering/ lining for body surfaces
skin, gut, respiratory tract, blood vessels, body cavities, ducts
the functional units of secretory glands and solid organs
salivary tissue, liver
3
Q
what are the 4 cell-cell connections?
A
desmosomes
hemidesmosomes
tight junctions
adherens junctions
4
Q
what is the function of desmosomes?
A
connect the intermediate filament networks of adjacent cells
5
Q
what is the function of hemidesmosomes?
A
attach epithelial cells to the underlying basement membrane
6
Q
what is the function of tight junctions?
A
form a seal between cells that is so strong that even ions cannot pass through
7
Q
what is the function of adherens junctions?
A
join the actin filaments of neighbouring cells, mechanically connecting them
8
Q
how are epithelia classified?
A
cell shape
how they are stacked together
special features
9
Q
define squamous
A
slightly irregular shape
can be stratified into layers
10
Q
where is the nucleus located in a squamous cell?
A
centrally
11
Q
what is the function of cuboidal cells?
A
secretory
12
Q
what is the function of columnar cells?
A
absorptive
13
Q
define stratified
A
more than 1 layer of cells
14
Q
what are the 3 types of stratified cells?
A
keratinised
transitional
nothing
15
Q
define psuedostratified
A
1 layer of cells but looks like more
16
Q
3 examples of finger-like projections
A
cilia
microvilli
stereocilia
17
Q
what are cilia for?
A
motile - movement of substances
18
Q
what are microvilli for?
A
absorption
19
Q
what are stereocilia for?
A
sensory (non-motile)
20
Q
3 examples of secretory cells
A
mucus producing
enzyme producing
hormone producing
21
Q
3 examples of glands
A
tubular
coiled
compound
22
Q
where are tubular glands found?
A
intestine, uterine glands
23
Q
where are coiled glands found?
A
sweat glands
24
Q
where are compound glands found?
A
pylorus
25
what is the function of exocrine glands?
release their contents onto an epithelial surface directly or via a duct
26
what is the function of endocrine glands?
release their secretions into the bloodstream to act on distant tissues
no duct system
27
define merocrine secretion
vesicles fuse with the cell membrane to secrete the product of the gland
28
define apocrine secretion
part of the cell with vesicle is pinched off to release the product
29
define holocrine secretion
a mature cell dies completely to secrete the product
30
connective tissue =
support cells + extracellular matrix
31
what are the 2 types of cells that form connective tissue?
parenchymal cells
support cells
32
what is the function of parenchymal cells?
examples (3)
provide the main function of a tissue
brain tissue, nervous tissue, muscle
33
what is the function of support cells?
provide the structural scaffolding of a tissue
34
what are the 2 types of connective tissue?
connective tissue proper
specialised connective tissue
35
what are the 2 types of connective tissue proper?
loose irregular connective tissue
dense irregular connective tissue
36
what are the 6 types of specialised connective tissue?
dense regular (found in tendons)
cartilage
adipose tissue
haemopoietic tissue
blood
bone
37
what are the 5 main cells responsible for forming connective tissue?
fibroblasts
chondrocytes
osteoblasts
myofibroblasts
adipocytes
38
what is the function of fibroblasts?
secrete the extracellular matrix components in most tissues
39
what is the function of chondrocytes?
secrete the extracellular matrix components of cartilage
40
what is the function of osteoblasts?
secrete the extracellular matrix components of bone
41
how does osteoid form bone?
becomes mineralised when it picks up calcium
42
what is the function of osteocytes?
mechanic sensing of bone
stimulate more bone to be made on the surface and produce more matrix
43
what is the function of osteoclasts?
secrete acid to dissolve old bone
44
what is the function of myofibroblasts?
secrete extracellular matrix components and have a contractile function
45
what are myofibroblasts important for?
tissue responses to injury
46
what are the functions of adipocytes? (4)
lipid-storing support cells
act as an energy store
have an endocrine function
act as physical padding in some anatomic regions
47
define extracellular matrix
bioscaffold of tissues
48
what is extracellular matrix composed of?
fibrillar proteins and ground substance
49
what is the function of ground substance?
fills the spaces between fibres and cells
contains lots of GAGs and glycoproteins
50
what are the 4 qualities of muscle tissue?
excitability
contractibility
extensibility
elasticity
51
how is the movement in muscle tissue generated?
by the interaction of the proteins actin and myosin
52
what are the 3 components of muscle cells?
sarcolemma
sarcoplasm
sarcoplasmic reticulum
53
define sarcolemma
muscle plasmalemma
54
define sarcoplasm
muscle cytoplasm
55
define sarcoplasmic reticulum
muscle endoplasmic reticulum
56
describe skeletal muscle cell appearance
large and elongated
57
location of skeletal muscle cells
skeletal/ voluntary muscle
58
does skeletal muscle have striations?
yes
59
how many nuclei do skeletal muscles contain? where?
many peripheral
60
what type of cell-cell junctions do skeletal muscles have?
none
they are so long and individual
61
what type of innervation does skeletal muscle undergo?
somatic (under our control)
62
what is the type of contraction of skeletal muscle cells?
all or nothing
63
do skeletal cells undergo mitosis?
no
64
can skeletal cells undergo regeneration?
yes but limited
65
describe cardiac muscle appearance
short and narrow
66
location of cardiac muscle (2)
heart
adjacent large veins
67
is cardiac muscle striated?
yes
68
how many nuclei do cardiac muscles have? where?
single central
69
what type of cell-cell junctions do cardiac muscle have?
intercalated discs
all contract at the same time
70
what type of innervation does cardiac muscle undergo?
autonomic
71
what is the type of contraction of cardiac muscle?
all or nothing
72
can cardiac muscle undergo mitosis?
no
73
can cardiac muscle undergo regeneration?
no
74
describe smooth muscle appearance
short and spindle shaped
75
location of smooth muscle cells (6)
vessels, organs, viscera (blood vessels), GI tract, uterus, urinary bladder
76
is smooth muscle striated?
no
77
how many nuclei does smooth muscle have? where?
single central
78
what type of cell-cell junctions does smooth muscle have?
gap junctions
79
what type of innervation does smooth muscle undergo?
autonomic
80
what is the type of contraction of smooth muscle?
slow, partial
81
can smooth muscle undergo mitosis?
yes
82
can smooth muscle undergo regeneration?
yes
83
what is smooth muscle specialised for?
continuous contractions of relatively low force
uses very little ATP
84
what are the thin actin filaments of smooth muscle associated with?
tropomyosin
85
what do the thick myosin filaments of smooth muscle bind to?
only bind to actin if 1 chain is phosphorylated
86
what does Ca2+ cause?
contraction
87
where is Ca2+ found?
in the cytosol of smooth muscle
88
where is Ca2+ found in relaxed smooth muscle?
sarcoplasmic reticulum
89
explain membrane excitation
free Ca2+ released into cytoplasm
binds to calmodulin protein
forms a calcium-calmodulin complex
90
what are the functions of the calcium-calmodulin complex? (2)
activates the enzyme myosin light-chain kinase
phosphorylates myosin and permits it to bind to actin
91
what is smooth muscle contraction modulated by?
surface receptors activating internal second messenger systems
92
how are cardiac muscles joined?
end to end and are branched
93
what do cardiomyocytes contain?
the same contractile filaments as in smooth muscle therefore striated
94
what is skeletal muscle responsible for?
movement of the skeleton
95
define sarcomere
functional contractile region of a striated muscle
96
what are sarcomeres composed of?
myofilaments of myosin and actin
97
how do sarcomeres contract? (2)
use sliding-filament model and cross-bridge cycle
98
define neuromuscular junction
branch near the muscle and end on individual muscle fibres
99
define neuron
specialised cell that conduct electrical impulses
100
what are dendrites?
the point at which nerve impulses are received by the cell
101
where are cell bodies found?
mostly in the CNS or arranged in the ganglia of PNS
102
define axon
single nerve fibre which transmits impulses to the distal ends
103
define ganglia
group of nerve cell bodies
104
what are the 3 types of neuron?
multipolar
bipolar
pseudo-unipolar
105
what are the supporting cells of the PNS? (2)
schwann cells
satellite cells
106
what is the supporting cell of the CNS?
glial cells
107
what are the 4 types of glial cells?
astrocytes
oligodendroglia
microglia
ependymal
108
what are the functions of astrocytes?
examples (3)
perform metabolic, structural, homeostatic, and neuroprotective tasks
clearing excess neurotransmitters, stabilizing and regulating the blood-brain barrier, and promoting synapse formation
109
what is the function of oligodendroglia?
produce the myelin that surrounds the axons of myelinated neurons of the CNS
110
how many neurons can an oligodendroglia provide myelin for?
40
111
what are microglia a part of?
the mononuclear phagocyte system of fixed macrophages in tissues
112
what is the function of ependymal cells?
line the cerebral ventricles containing cerebral spinal fluid
113
what is the function of schwann cells?
provide the myelin that covers neurons in the PNS
larger neurones covered in myelin sheath
114
what is the function of satellite cells?
myogenic stem cells responsible for muscle regeneration
115
myelinated axons conduct nerve impulses ...
faster
