Essential anatomy & physiology

Question 1

Define epithelium

Answer 1

Cellular mono- or multilayer which forms the skin epidermis and lines the inner surface of hollow organs

Question 2

Function of epithelium

Answer 2

PROTECTION
Sensation
Secretion
Absorption

Question 3

Origin of epithelium

Answer 3

Ectoderm (epidermis)
Endoderm (GI tract lining)
Mesoderm (peritoneum)

Question 4

Define endothelium

Answer 4

Cellular monolayer which lines the inner surface of blood and lymphatic vessels and heart

Question 5

Function of endothelium

Answer 5

TRANSPORT
filtration
secretion
coagulation
haemodynamics

permeability barrier
synthesis collagen & proteoglycans for basement membrane maintenance
synth & secrete molecules promoting thrombus formation
secrete vasoactive factors
produce molecules which mediate the acute inflammatory reaction
Produce some growth factors

Question 6

Origin of Endothelium

Answer 6

Mesoderm

Question 7

Similarities between epithelium & endothelium

Answer 7

Both form and interface between an underlying layer and an outer environment

Question 8

classifications of epithelium: simple

Answer 8

Simple squamous
Simple cuboidal
Simple columnar
Pseudostratified columnar

Question 9

classifications of epithelium: Stratified

Answer 9

Stratified squamous
Stratified cuboidal
Stratified columnar
Transitional epithelium - allows expansion & stretching for urinary organs

Question 10

Red blood cells

Answer 10

40-45% of blood
biconcave disc = large SA
disk diameter 6.2-8.2um
no nucleus = flexible, change shape
contains haemoglobin containing iron - binds oxygen
life span of 120 days

Question 11

White blood cells

Answer 11

1% of blood
granulocytes + agranulocytes
made from multipotent HSCs

Question 12

Neutrophil

Answer 12

Multi lobed nucleus
fine cytoplasmic granules
life span 6h-few days
kill bacteria by phagocytosis

Question 13

Eosinophils

Answer 13

Bi-lobed nucleus
Large granules which contain chemokine, cytokines, toxic proteins & enzymes
lifespan 8-12 days
important in allergy for the release of histamines, granules & their toxins

Question 14

Basophils

Answer 14

Pale nucleus - hidden by granules
Bi-lobed/tri-lobed
life span few hours-days
activated by IgE - functions in allergic reactions
release histamine - dilates vessels to recruit immune cells to area of injury
secrete heparin, promoting mobility by preventing clotting

Question 15

Lymphocytes

Answer 15

one nucleus
life span: naïve - weeks, memory - years
T cells = cell-mediated immunity
B lymphocytes = humoral immunity/antibody production
activation via antigen recognition via TCR/BCR
T cells and B cells activate each other

Question 16

Monocytes

Answer 16

kidney shaped nucleus
life span few hours-few days
enter tissue & differentiate into macrophages (maybe dendritic & NK)
phagocytose old, damaged + dead cells
present antigens to T cells
secrete cytokines - promote adaptive immune response

Question 17

Systemic circulation

Answer 17

oxygen and nutrients delivered to the lower limbs
deoxygenated blood delivered back to right side of the heart

Question 18

Pulmonary circulation

Answer 18

deoxygenated blood reaches lungs to re-oxygenate

Question 19

Portal circulation

Answer 19

75% of hepatic blood supply
Goes via the digestive tract and then goes to the liver partially oxygenated - delivers antigens and nutrients to be processed
Important filtration barrier
Removed harmful things from the blood before it goes round the rest of the body

Question 20

Microcirculation?

Answer 20

The circulation of blood within organs
includes lymphatic capillaries & collecting ducts
delivery of oxygen and nutrients
removal of CO2
regulation of blood flow = blood pressure
relation of tissue perfusion = inflammation

Question 21

Structure of microcirculation

Answer 21

Ateriole - carry blood to capillaries
Capillary - site of exchange between blood & tissues
Venule - Drains blood from capillaries into larger veins

Question 22

the 3 mechanisms of capillary exchange

Answer 22

diffusion (conc. gradient)
bulk flow (pressure gradient)
transcytosis (vesicular transport)

Question 23

Lymphatic system - function

Answer 23

Removal of excess interstitial fluid from tissues
absorption of fatty acids & fats (chyle)
Transportation of WBCs to and from lymph nodes
Transportation of APCs to lymph nodes for AP & stimulation of an adaptive immune response

Question 24

Primary lymphoid organs

Answer 24

Thymus
Bone marrow

Question 25

Secondary lymphoid organs

Answer 25

Spleen
Lymph noces
Tonsils
MALT
Peyer’s patches
adenoids

Question 26

Lymph formation

Answer 26

decrease in hydrostatic pressure & an increase in osmotic pressure form the arterial to the venous ends of blood capillaries

fluid leaves capillary through arterial end and repenetrates the blood at the venous end - some fluid drained by lymphatic capillaries

Question 27

2 main systems of lymph vessels

Answer 27

Superficial vessels - arise in subcutaneous tissue, accompany venous flow
Deep vessels - drain the deeper structures

Question 28

Lymphatic vessel drainage

Answer 28

Right lymphatic duct drains lymph from the upper right quadrant of the body

thoracic duct is larger & drains lymph from the rest of the body

2 ducts empty into the venous circulation at the subclavian veins via the right and left venous angles

Question 29

Thymus

Answer 29

irregular
bilobed
lower neck behind sternum
cortex & medulla
only active until puberty & then regresses

Site of maturation of T cells
Mature T cells enter lymphatic circulation

Question 30

Lymph node drainage

Answer 30

multiple channels draining into the lymph node, only one channel draining out
bottleneck slows down flow, allowing Ag presentation to occur
Through node to hilum

Question 31

Sinuses for lymph node drainage

Answer 31

Subcapsular
Intermediate
Trabecular
Medullary

Question 32

lymph node blood supply

Answer 32

In at hilum as nodal artery
Blood supply is countercurrent to lymphatic vessels
penetrates parenchyma to cortex, capillaries form around follicles
High endothelium venues (HEV) in paracortex
Microcirculation in outer cortex
out at hilum as nodal vein

Question 33

B cells and the lymph node

Answer 33

Germinal centre - activated B cells migrate from the follicle to the medulla

Medulla - activated B cells develop into plasma cells in the medullary cords. Release antibody into the efferent lymph

Question 34

Spleen

Answer 34

consumes red blood cells
can survive without spleen but very predisposed to encapsulated bacteria infection as would have lost biggest lymph node in the body

White pulp - B cells & T cells, produces active lymphocytes in response to blood-borne Ag

Red pulp - venous sinuses, blood-filled cavities. Splenic cords: connective tissue containing RBCs & macrophages

Question 35

MALT?

Answer 35

mucosal associated lymphoid tissue
physical barrier, killing of microbes via locally produced antibiotics
killing of microbes & infected cells by intraepithelial lymphocytes