Histology Flashcards
What is the inner cytosol?
The cytoplasm - half way between a gel and fluid
What is the cytoskeleton?
And what is it made from?
A structure that determines the shape and fluidity of the cell made from thin and intermediate filaments and microtubules
What are inclusions?
Nutrients or pigments within the cell that do not have activity. They may or may not be bound by a membrane.
What is the plasmalemma?
The cell membrane which separates the cytoplasm from outside environment
Structure of the plasmalemma
Bimolecular layer of amphipathic phospholipid molecules
Chemical elements in hydrophilic heads
Choline and phosphate
Chemical molecules in hydrophobic tails
Fatty acid chains and cholesterol
Exocytosis
A form of active transport when the cell transports molecules out of the cell
Endocytosis
A form of active transport when the cell transports molecules into the cell
Molecules that are highly permeable through the cell membrane
Water, oxygen and small hydrophobic molecules
Molecules that are not highly permeable through the cell membrane
Charged ions
Mitochondria function
Energy production
Rough endoplasmic reticulum function
Protein synthesis
Smooth endoplasmic reticulum function
For cholesterol and lipid synthesis/detoxification
Golgi apparatus function
For modification and packaging of secretions
Lysosomes (hydrologic enzymes) function
For intravenously digestion
Nucleus function
Contains genetic code
Inclusions
Components that have been synthesised by the cell itself or taken up from extracellular environment
Microfilaments are composed of?
Fine strands of the protein actin
Diameter of microfilaments
7nm
Intermediate filaments function
Bind intracellular elements together and to the plasmalemma
Diameter of intermediate filaments
10-15nm
Microtubles structure
Hollow tubules composed of two types of tubular subunits, alpha and beta
Where do microtubles originate from?
The centrosome (MTOC)
Microtubles allow … to produce motion
Cilia and flagella
Microtubles function
They serve as a motorway. Dynein and kinesin attach to the microtubles and move along them using ATP
Kinesin
An ATPase that moves towards the cell periphery
Dynein
An ATPase that moves towards the cell centre
What is the nucleus surround in?
A nuclear envelope (an inner and outer membrane)
Perinuclear cystern
Space between the inner and outer nuclear membrane
The nucleus is the region of
RNA synthesis
mRNA and tRNA are transcribed in what?
The nucleolus, a dense area within the nucleus
The nucleus contains two types of DNA, name them
Euchromatin and heterochromatin
Euchromatin is?
Partially unwound DNA undergoing transcription
Heterochromatin is?
Highly condensed DNA not undergoing transcription
Where are the ribosomes formed?
In the nucleolus
Ribosome function
Protein synthesis
What is each ribosome made up of?
A small subunit which binds to RNA and a large subunit which catalyses the formation of peptide bonds
Endoplasmic reticulum
Network of interconnecting membrane bound compartments in the cell
Rough endoplasmic reticulum appearance and role
Studded with ribosomes. Helps to synthesise proteins destined for insertion into membranes or for secretion
Smooth endoplasmic reticulum role
Continues the processing of proteins produced in the RER and has a vital role in the site of synthesis of lipids
What does the Golgi complex do?
Modifies and packaged macromolecules that were synthesised in the endoplasmic reticulum
What modifications can the Golgi apparatus make to macromolecules?
Add sugars and cleave some proteins
The mitochondria structure
It has an inner and outer membrane. The inner membrane is extensively folded to form cristae to increase surface area
Function of Mitochondria
Power generators of the cell which produce ATP and contain their own DNA
Occluding Junctions Function
They link cells to prevent diffusion and are a focal region of close opposition between adjacent cell membranes
Anchoring Junctions Role
Provide mechanical strength
Types of anchoring junctions
Adherent junctions and desmosomes
Adherent junctions
Link submembrane actin bundles of adjacent cells
Desmosomes
Link sub membrane intermediate filaments or adjacent cells (stronger)
Communicating junctions
Allow selective diffusions of molecules between adjacent cells
What do communicating junctions look like
Physical pores
What are the pores of communicating junctions produced by?
Connexion proteins
What are communicating junctions found in?
Smooth muscle, cardiac muscle and epithelial tissue
Exocytosis
A form of active transport when the cell transports molecules out of the cell and is often receptor mediated
Phagocytosis process
Bacteria or larger particle binds to the cell surface receptors triggering extensions of the cell to engulf it forming a phagosome. The phagosome binds to lysosomes carrying digestive enzymes producing a phagolysome
two types of stains common stains used to bind to certain types of molecules
eosin and haematoxylin
haematoxylin is a —– dye with an affinity for ——- and stains them —-
basic, acidic molecules, purplish blue
nucleus dna and ribosomes
eosin is a —— dye with an affinity for —– and stains them
acidic, basic, pink or red
epithelia can form —– —— and –
solid organs (liver) and glands
what is always found between epithelial cells and what purpose does this serve?
adhesions allows strong sheets to be formed
what is found at the basal surface of epithelial cells?
basal lamina
what is basal lamina?
layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits
are epithelia cells vascular or non-vascular?
non-vascular
how do nutrients from capillaries reach the basal lamina?
they must diffuse across the basal lamina
squamous cell shape
flattened
cuboidal cell shape
like a cube
columnar cell shape
like a column, tall and thin
simple. how many layers?
1
stratified. how many layers?
two or more layers
pseudostratified. how many layers?
1, looks like multiple layers but all cells are in contact with the basal lamina
what do glandular epithelia produce?
secretory products such as milk sweat oil hormones etc
where are secretory products secreted from?
endocrine glands and exocrine glands
endocrine glands. where are products secreted? ducts or ductless
products are secreted towards the basal end of the cell and are then distributed throughout the body. ductless.
exocrine glands. where are products secreted? ducts or ductless?
products are secreted towards the apical end of the cell either into the lumen of an internal space, into a duct, or onto the body surface. They are ducted glands
three categories of connective tissue
soft connective tissue, hard connective tissue and blood and lymph
soft connective tissue examples
tendons, ligaments, storm of organs, dermis of skin
hard connective tissue examples
bone and cartilage
what two components makes up connective tissue?
extracellular matrix and cells. the type of connective tissue is determined by the types and relatives amounts of these two components
what does the extracellular matrix consist of?
fibres (collagen, reticular and elastic fibres|) tissue fluid and ground substance
soft connective tissue: loose
loosely packed fibres separated by abundant ground substance. cells are relatively plentiful
soft connective tissue: dense
densely packed bundles of collagen fibres. can be dense regular or dense irregular
what causes the semi-rigid nature of the matrix
the highly hydrated nature of ground substance
how does cartilage receive nutrients
it receives it from adjacent tissues by diffusion through its matrix
three types of cartilage
hyaline, elastic and fibrocartilage
what defines the type of cartilage
the extracellular matrix
two types of hard connective tissue
cartilage and bone
type of bone that is the outer shell of dense cortical bone that makes up the shaft
diaphysis
type of bone that looks like a thin mesh and is at either end of the bone
cancellous or trabecular
the name of canals that penetrate bone
Haversian canals
role of Haversian canals
to allow nerves and blood vessels to run through bones
cells found living in bones are called
osteocytes
how is forced produced my muscle
the movement of actin fibres over myosin fibres with the aid of accessory proteins allows force to be produced
two other names for smooth muscle
involuntary or visceral
why is smooth muscle called smooth muscle
it has no visible ridges
why can smooth muscle be called visceral
because it is mostly found in organs
general shape of muscle fibres
elongated cells with a great range in length
what is found at the centre of each muscle fibre?
a cigar shaped nucleus
other names for skeletal muscle
voluntary or striated (ridged)
what do muscles of the body respond to?
conscious control
shape of skeletal muscle cells
Giant multinucleate cylindrical cells
nuclei within skeletal muscle fibres description
each fibre has many nuclei that are elongated and located at the periphery of the cell, just internal to the cell membrane
difference in cardiac muscle compared with striated muscle
the striations in cardiac muscle are less prominent and the fibres are much shorter
where is the nucleus located in cardiac muscle?
one singular nucleus located near the centre of the fibre
sites of end-to-end attachment in cardiac muscle between adjacent cells
intercalated discs
what does nervous tissue consist of?
neurons and support cells (glial cells)
are there more neurons or glial cells?
glial cells outnumber neurons
the surrounding connective tissue on nerves for the CNS
Meninges
the surrounding connective tissue on nerves for the PNS
Epineurium
multipolar neurons
they are the most commo, have many dendrites and only one axon
bipolar neurons
they have one dendrite and one axon
pseudounipolar
the axon is split into two branches, one branch runs to the spinal cord and the other runs to the periphery
three types of principle glial cells of CNS
astrocytes, microglia and oligondenrocyes
astrocytes
principle glial cell of CNS: support, ion transport, induce blood brain barrier
microglia
principle glial cell of CNS: provide immune surveillance
oligodendrocytes
principle glial cell of CNS: produce myelin in the brain and spinal cord
Schwann cells
principle glia of PNS; produce myelin and support axons
what are the four basic tissue types?
epithelium, connective tissue, muscle, nervous tissue
where is most fluid absorbed in the digestive tract?
in the small intestine
how much fluid reaches the colon?
about 1.5 litres
name the three main salivary glands
parotid, submandibular and sublingual glands
why does the pancreas not digest itself?
the enzymes are produced in an inactive form
what type of cartridge are tracheal rings?
hyaline cartilage
what is the difference between bronchi and bronchioles
bronchi are surrounded in cartilage and bronchioles are surrounded by smooth muscle
what are alveoli lined with?
simple squamous epithelium to provide the thinnest distance between blood and air
4 major layers of the digestive tract - lumen and going outwards
- muscosa
- submucosa
- muscularis externa
- serosa or adventitia
3 parts of the mucosa
a) epithelium: sits on a basal lamina
b) lamina propria: loose connective tissue
c) muscularis mucosae: thin layer of smooth muscle
what is submucosa, the 2nd inner layer of the digestive tract?
loose connective tissue
what is muscularis externa? the 3rd layer of the digestive tract
two thick layers of smooth muscle, an inner circular layer and an outer longitudinal layer
what is the serosa or adventitia? 4th layer of the digestive tract
an outer layer of connective tissue that either suspends the digestive tract or attaches to other organs
the name for the digestive tracts nervous system
the enteric nervous system
where does the enteric nervous system receive input from?
from the autonomic nervous system
what are ganglia?
groups of neurons between the two muscle layers that make up the muscularis externa (3rd layer of the digestive tract
four sections of the trachea from airway outwards
airway, respiratory epithelium, lamina propria, hyaline carolinge of tracheal ring
bronchi and bronchioles: which has the smaller airway?
bronchioles
bronchi and bronchioles: which has hyaline cartilage in their walls?
bronci
bronchi and bronchioles: which one has smooth muscle predominating their walls?
bronchioles
columnar cells of the epithelium get shorter the…
further down the respiratory tract you go
does gas exchange happen over the epithelia?
no
general arrangement of lobules
hexagonal arrangement
where are lobules found?
in the liver
what is found at each corner of the lobule?
a branch of the hepatic portal vein and hepatic artery
what do the hepatic portal vein and hepatic artery do?
deliver blood to the lobule
what is at the centre of a lobule?
central vein
where does the central vein drain to?
the hepatic vein
blood travelling from a corner of a lobule to the centre does so via what?
hepatic sinusoids
what are the sheets of liver called?
hepatocytes
what are the spaces for blood flow in the liver called?
sinusoids
combination of hepatic portal vein, bile duct and hepatic arteriole in the corner of a lobule is collectively called the…?
portal triad
why is the pancreases unusual?
it is both an exocrine gland and an endocrine gland
what does the exocrine pancreas produce?
about a litre each day of digestive juices which help to breakdown proteins, lipids, DNA/RNA etc
the endocrine pancreas consists of small, scattered islands of tissue called…
islets of langerhans, which produce a number of hormones including insulin
layers, inwards to outwards inc elastic membrane
Tunica intima, internal elastic membrane, tunica media, external elastic membrane, tunica adventitia
which leukocyte is the most common and multi lobbed?
neutrophil
which leukocyte has granules which stain red?
eosinophils
which leukocyte is the rarest and is bi-lobed?
basophil
what colour is a basophil
intensely stained blue-purple
which leukocyte is a precursor of macrophages?
monocytes
