tissues

Question 1

2 Epithelia types

Answer 1

Covering and lining

Glandular

Question 2

Characteristics of epithelial tissue

Answer 2

apical-basal polarity - apex for transport mechanisms etc
base basement membrane - hemi-desmosomes secure cells to basement membrane. Provides additional barrier. basal lamina,(2 layers) lamina reticularis (collagen fibres
High regenerative
ability limited by contact inhibition
When junctions are removed by damage, cells proliferate via mitosis. Gives high risk of malignancy as uncontrolled proliferation breaking through basement membrane - metastasise through connective tissue. Some are prone to over granulation

Question 3

Types of epithelial junctions

Answer 3

Tight junctions prevent passage of proteins and maintain apical-basal polarity
Adherens junctions maintain cell to cell contact
Desmosomes resist shearing forces and stress can unzip for motility and growth
Hemi desmosomes as before
Gap junctions channels between cells to allow solutes to pass to flow between cells

Question 4

Epithelial tissue is avascular and innervated. What does that mean?

Answer 4

It is supplied by nerves but does not have blood vessels

Solutes diffuse from blood vessels within the underlying connective tissue

Question 5

Classification epithelial tissue by shape

Answer 5

Squamous - flat slabs -
Cuboidal - rounded nuclei
Columnar - tall with oval nuclei often have cilia

Question 6

simple epithelia layers

Answer 6

single cell layer on basement membrane, endothelium lining blood and lymph vessels

Question 7

stratified epithelia layers

Answer 7

layers of cells are stacked on top of basement
membrane (forms border of dermis)
epidermis becomes cornified (keratinised) for protection

Question 8

Vascular endothelium

Answer 8

Endothelium differentiates vascular and lymphatic lining epithelium
tunica intima - simple squamous
Endothelial cells are in contact with blood supply
Permeability via spaces between the squamous endothelial cells can be regluated by cell contraction ad relaxation

Question 9

Functions of epithelia

Answer 9

Protection eg skin, mucosa
Absorption eg lining of digestive tract
Filtration and excretion eg kidneys
Secretion glandular

Question 10

what are pores in endothelial cells called?

Answer 10

Fenestrations

Question 11

what is sinusoidal endothelium? what does it allow?

Answer 11

It is an incomplete basement membrane and allows Transcytosis ( endo and exocytosis

Question 12

what are enterocytes and what do they line and form?

Answer 12

Simple columnar epithelium
lines the ileum and colon
along with basement membrane it forms the villi (absorption) in the ileum and crypts (secretory) ileum and colon

Question 13

enterocytes are joined together by what junctions?

Answer 13

selectively permeable tight junctions to allow passage of Na+ and water into the crypts

Question 14

what do villious enterocytes absorb?

Answer 14

water and electrolytes
carbs as monosaccharides
proteins as small peptides and amino acids
fat as monoglyceride and free flatty acids these are transported from the basal side into hepatic portal veins or lymph in the case of fat for processing or storage in liver

Question 15

what are 80% of the liver cells called?

Answer 15

hepatocytes - highly regenerative

Question 16

what do hepatocytes do?

Answer 16

many metabolic, endocrine and secretory functions which include the metabolism and regulation of carbs, lipids and proteins

Question 17

through what vein do hepatocytes receive blood and where does it enter?

Answer 17

recieves blood from the GI tract via the hepatic portal vein and this enters sinusoids within the liver lobules which then enters the central veins to retuns to the heart via inferior vena cava

Question 18

2 types of connective tissue

Answer 18

Proper (cartilage and membrane that bind, dermis, adipose specialised - bone, cartilage, blood

Question 19

which cells form the extracellular matrix?

Answer 19

Fibroblasts (healing) secrete collagen
Chondroblasts secrete cartilage
Osteoblasts secrete bone

Question 20

..blasts are?

Answer 20

immature cells or cells that produce tissue components

Question 21

…cytes are?

Answer 21

mature cells

Question 22

Blood components

Answer 22

Fluid matrix Plasma (90% water) and 10% proteins, electrolytes, hormones, O2, glucose
Formed elements Erythrocytes rbc 48/54 billion
leukocytes wbc 7.5 million/ml neutrophils, monocytes, lymphocytes, mast cells eosinophils, basophils
platelets (thrombocytes)

Question 23

2 types of nervous tissue and what do they form?

Answer 23

neurons
support cells form
the CNS - spinal cord and brain
peripheral nervous system (PNS) the spinal nerves and branches

Question 24

afferent neurons do what?

Answer 24

conduct action potentials towards the CNS eg sensory neurons

Question 25

what do efferent neurons do?/

Answer 25

conduct action potential away (exit from CNS)form the CNS eg motor neurons

Question 26

myelinated slow or fast?

Answer 26

fast action potential conduction

Question 27

unmyelinated slow or fast?

Answer 27

slower action potential conduction

Question 28

within the CNS neurons form?

Answer 28

grey matter - somata (cell bodies) and synapses

white matter - myelinated axons following tracts

Question 29

all afferent and efferent neurons are bundled into nerves where?

Answer 29

the PNS

Question 30

what do nervous tissue support cells do? name 2 types

Answer 30

they are non-conductive and support insulate and protect the neurons

Question 31

what do schwann cells do?

Answer 31

Schwann cells secrete myelin sheath around myelinated PNS neurons

Question 32

name 2 types of Glial cells and what do they do?

Answer 32

Microglia are macrophages in the brain and spinal cord

Astrocytes help to create the blood-brain barrier and have many other functions

Question 33

the passage of solutes in and out of the blood brain barrier is regulated by?

Answer 33

tight junctions between endothelial cells
Pericytes that can expand and contract to regulate permeability
a basement membrane that surrounds the endothelial cells and pericytes
astrocytes ‘feet’

Question 34

3 types of muscle tissue

Answer 34

skeletal - VOLUNTARY striated myocytes with sarcomeres efferent neurons carry action potentials away from CNS allows movement of body and respiratory muscles

smooth in walls of hollow organs non striated myocytes in sheets with gap junctions blood vessels bronchi involuntary autonomic nervous system and other ligands (histamine, angiotension2 etc)
cardiac forms myocardium faintly striated myocytes with sarcomeres and gap junctions
Involuntary stimulated by autorhythmic cells in the Sinoatrial node and regulated by ANS

Question 35

what do you know about smooth muscle

Answer 35

long, tapered myocytes arranged in sheets
found in walls of hollow organs bronchi and vessel
not striated because actin and myosin filaments are not arranged in sarcomeres. They are anchored by dense bodies which cause contraction in a twisting manner
contraction is syncytial (sync all at same time)due to flow of cation though gap junctions. Na+ and Ca+ pass from myocyte to myocyte and contraction is slow

Question 36

what do you know about cardiac muscle?

Answer 36

joined by intercalated discs. Cardiomyocytes have gap junctions and contract syncytially. have saracomeres like skeletal but not lined up because of the branching of cardio myocytes from myocardium so striation appears faint