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AP0509 Component 2 Exam > Lymphatic and Endocrine Systems > Flashcards

Lymphatic and Endocrine Systems Flashcards

1
Q

3 main lines of defence of lymphoid/immune system

A
  • protective surface: skin, mucous surfaces, acid secretion
  • non-specific cellular response: phagocytic cells, inflammation, anti-viral agents
  • specific immune response: antigen recognition
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2
Q

2 types of immune response

A
  • humoral response: antibody production (B cells)

- cellular response: T cells

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3
Q

Lymphoid organs

A
  • thymus
  • lymph nodes
  • spleen
  • bone marrow
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4
Q

Mucosa-associated lymphoid tissue (MALT)

A
  • located in walls of gastrointestinal, respiratory and urogenital tracts
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5
Q

Gut-associated lymphoid tissue (GALT)

A
  • palatine, lingual and pharyngeal tonsils
  • mucosal nodules in oesophagus
  • Peyer’s patches in small intestine
  • Lymphoid aggregates in large intestine and appendix
  • lymphocytes and plasma cells in lamina propria small and large intestines
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6
Q

Bronchus-associated lymphoid tissue (BALT)

A
  • lymphoid follicles associated with mucosa of bronchi
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7
Q

Thymus

A
  • major activity in childhood
  • decrease size and activity in puberty
  • infiltrated by lymphocytes during development
  • production of immunocompetent T cells from T lymphocytes
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8
Q

Lymph nodes

A
  • encapsulated, highly organised aggregates of lymphocytes
  • arranged along vessels of lymph vascular system
  • filtration of lymph
  • storage/proliferation of B+T lymphocytes
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9
Q

Spleen

A
  • filter blood as part of immune system
  • recycling old RBCs
  • storage platelets and WBCs
  • helps to fight certain kind of bacteria (pneumonia, meningitis)
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10
Q

Other lymphoid aggregates

A
  • Tonsils
  • Peyer’s patches
  • appendix
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11
Q

Where do T and B cells emigrate to and from?

A
  • from thymus/bone marrow

- to peripheral lymphoid organs as part of adaptive immune system

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12
Q

Thymus gland as “training school for T lymphocytes”

A
  • lymphocytes move into cortex thymus
  • nurse cells surround lymphocytes and from isolated barrier
  • nurse cells test developing T cells by exposing to foreign and self antigens
  • only those that recognise foreign antigens survive and undergo further training
  • possible T cells exposed to many kinds of molecules
  • lymphocytes progressively develop into immunocompetent T cells
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13
Q

Blood, lymphatics and bone marrow

A
  • Little structure or aggregate
  • Cells in transport
  • Stained with H&E, Wright’s, Giemsa or Wright-Giemsa stain (combination of Eosin, Azure Blue, Methylene Blue)
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14
Q

Reticuloendothelial/ mononuclear phagocyte system

A
  • haemopoietic stem cells in bone marrow: tissue specific macrophages
  • Kupffer cells: liver
  • Microglia cells: brain
  • Reticular cells: lymphoid tissues
  • Alveolar macrophages: lungs
  • Histiocytes: subcutaneous tissue
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15
Q

Histology of thymus

A
  • Connective tissue capsule
  • Connective tissue trabeculae (Blood vessels, adipose cells)
  • Lobules with Cortex and Medulla (thymic reticular cells, thymic or Hassal’s corpuscles, adipose cells)
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16
Q

Thymic reticular cells

A
  • Contain secretory granules containing thymic hormones (thymulin, thymopoietin, thymosin, interleukins,
    interferons)
  • involved in the blood-thymus barrier
  • Contact of immature T cells and foreign antigens would cause T cells to die by apoptosis)
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17
Q

Thymic/Hassal’s corpuscles

A
  • function is unclear, involution by puberty
  • found in medulla of human thymus, formed from dysfunctional epithelial reticular cells arranged concentrically
  • keratin positive in stain
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18
Q

Histology of lymph node

A
  • capsule
  • perinodal adipose tissue
  • trabecula
  • subcapsular sinus
  • afferent lymphatic vessels
  • lymphatic nodules
  • hilum (efferent lymphatic vessels, lymphatic artery and vein)
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19
Q

Lymphatic nodules (or lobules)

A
  • outer cortex: inactivated B cells or follicles. May develop into germinal centre when activated
  • inner or paracortex: T cells
  • medulla: large blood vessels, medullary sinus and medullary cords (antibody-secreting plasma cells)
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20
Q

Lymph flow in lymph node

A
  • efferent lymphatics leave lymph node at hilum
  • lymph goes into medullary sinus, contains B cells and plasma cells
  • lymph flows in deep cortex, dominated by T cells
  • flows into outer cortex, contains B cells
  • dendritic cells, initiate immune response
  • afferent lymphatics carry lymph to node from peripheral tissues
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21
Q

Histology of Spleen

A
  • capsule
  • trabeculae
  • white pulp: active immune response
  • red pulp: filtration of RBCs
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22
Q

White pulp in spleen

A
  • lymphoid follicles (rich in B lymphocytes)

- periarteriolar lymphoid sheaths (PALS, rich in T lymphocytes)

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23
Q

Red pulp in spleen

A
  • sinuses (sinusoids)
  • splenic cords
  • marginal zone
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24
Q

Functions of red pulp

A
  • Removal of old red blood cells (iron recycled)
  • Storage of red blood cells and lymphocytes
  • Produces all types of blood cells (only during foetal life)
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25
Q

Endocrine system

A
  • Consists of DUCTLESS GLANDS that secrete HORMONES into blood
    system
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26
Q

Effects of endocrine system

A
  • regulation of ion content and water balance of internal environment
  • immune system regulation
  • regulation of blood glucose and other nutrients & energy balance
  • Help cope with emergency demands (trauma, stress, extremes of temperature)
  • Role in sequential integration of growth & development
  • Contribute to basic processes of reproduction including gamete/sperm production, nourishment of embryo/foetus, and delivery of new-born
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27
Q

Exocrine glands

A
  • Secrete products onto free surface areas or into ducts, then to body cavities, lumen,
    or to body surface.
  • e.g. sweat glands, mucous glands, glands producing digestive enzymes
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28
Q

Endocrine glands

A
  • Secrete hormones directly into the blood rather than through a duct
  • e.g. pituitary glands, ovaries, testes
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29
Q

Principal endocrine glands

A
  • Pituitary (neuroendocrine organ)
  • Thyroid
  • Parathyroid
  • Adrenal
  • Pineal
  • Thymus
30
Q

Other organs with endocrine tissue

A
  • Hypothalamus (neuroendocrine organ)
  • Pancreas
  • Ovaries
  • Testis
  • Kidney
  • Stomach
  • Small intestine
  • Placenta
  • Liver
31
Q

Amines (hormones)

A
  • simplest hormone molecules, produced from an amino acid. Water soluble
  • thyroxine produced in thyroid gland
  • epinephrine produced in adrenal gland (medulla)
32
Q

Proteins and peptides (hormones)

A
  • consist of chains of amino acids, also water soluble
  • Oxytocin in hypothalamus
  • Insulin in pancreas
  • Pituitary hormones (GH, LH etc) in anterior pituitary
  • calcitonin in thyroid
  • parathyroid hormone in parathyroid gland
33
Q

Steroids (hormones)

A
  • Derived from cholesterol, Lipid soluble
  • aldosterone in adrenal cortex
  • testosterone in testis
  • oestrogen/progesterone in ovaries
34
Q

Pituitary

A
  • situated in sella turcica of sphenoid bone, attached by a stalk to the floor of 3rd ventricle of brain
  • adenohypophysis (anterior pituitary): pars distalis, pars intermedia, pars tuberalis
  • neurohypophysis (posterior pituitary): pars nervosa, infundibulum
35
Q

Adenohypophysis

A
  • pars anterior: largest of organ
  • secretory cycle: chromophobes give rise to chromophils, return to chromophobe upon secretion
  • alpha and beta cells produce all hormones of anterior lobe and release them into bloodstream
  • pars tuberalis: vascular, consists of solid cords of non-granular epithelial cells
  • pars intermedia: small, much less vascular than pars anterior, cells usually clear
36
Q

Pars nervosa (neurohypophysis)

A
  • Functional part are groups of axons of neurosecretory cells that are mainly originating from hypothalamus
  • Also present are blood vessels and connective tissue
  • Herring bodies are structures found in the posterior pituitary, represent terminal end of axons from hypothalamus, and hormones are temporarily stored in these locations, they’re neurosecretory terminals
  • Pituicytes are neuroglia type cells - supporting not secretory
37
Q

Infundibulum (neurohypophysis)

A
  • hollow stalk which connects the hypothalamus and the posterior pituitary gland
38
Q

Variation in structure of anterior/posterior lobes

A
  • cleft in young

- isolated cysts in adult

39
Q

Variation in structure of lobes in pregnancy

A
  • Anterior lobe larger (135%) due to oestrogen-stimulated hyperplasia and hypertrophy of prolactin cells (to ensure lactation)
40
Q

Variation in structure of lobes in puberty

A
  • growth spurt is associated with increase in pars anterior due to great increase of alpha cells producing growth hormone
41
Q

Hypopituitarism

A
  • decreased (hypo) secretion of one or more of the eight hormones normally produced by pituitary gland
    (e. g. pituitary dwarfism - decreased production of GH)
42
Q

Hyperpituitarism

A
  • increased (hyper) secretion of one or more of the 8 hormones normally produced by pituitary gland (e.g. pituitary adenoma
    producing growth hormone)
  • Induces gigantism if the condition develops before union of epiphyses of
    long bones (in childhood).
  • Induces acromegaly if the condition develops after union, when bony overgrowth causing somatic enlargement specifically in the extremities and face (in adult)
43
Q

Acidophils

A
  • somatotropes (growth hormone)

- Lactrotropes (prolactin)

44
Q

Basophils

A
  • Thyrotropes (thyroid stimulating hormone)
  • Gonadotropes (luteinizing hormone or follicle-stimulating hormone)
  • Corticotropes (adenocorticotrophic hormone)
45
Q

Thyroid gland

A
  • located below larynx, in front of Trachea
  • 2 lobes connected by mass of tissue - Isthmus
  • Very rich blood supply, can deliver high levels of hormone quickly
  • Gland filled with microscopical sacs - Follicles
  • produces 3 hormones: T3, T4 and Calcitonin.
  • Consists of Follicular cells and Parafollicular cells (or C cells)
46
Q

Follicular cells

A
  • Thyroxine (T4)
  • Tri-iodothyrine (T3)
  • Hormones that regulate base metabolic rate and influence growth/maturation of nervous tissue
47
Q

Parafollicular cells

A
  • Calcitonin
  • Regulates blood calcium levels in conjunction with Parathyroid hormone
  • Recognised by extensive unstained cytoplasm
48
Q

Thyroid follicles

A
  • lined by simple cuboidal epithelium (= follicular cells) filled with glycoprotein complex called Thyroglobulin or Thyroid Colloid (=precursors to thyroid
    hormones T3 and T4)
49
Q

Certinism (thyroid gland disorder)

A
  • Lack of thyroxine from birth or before birth
  • Could be from lack of thyroid gland or lack of iodine in mother
  • Irreparable mental defects
  • Stunted growth
  • Reduced growth and function of many organs
50
Q

Myxedema (thyroid gland disorder)

A
  • Occurs because of severe hypothyroidism that is not diagnosed or is not treated successfully.
  • a person may experience symptoms such as drowsiness, confusion and hypothermia as well as changes to the skin
51
Q

Goitre (thyroid gland disorder)

A
  • a swelling of the neck resulting from enlargement of the thyroid gland
  • due to lack of iodine in diet, over- or underproduction of
    thyroid hormones or nodules in gland itself
  • In most cases, the swelling is small and does not cause any
    symptoms
52
Q

Parathyroid

A
  • Small oval shaped gland, closely associated with thyroid gland
  • Principle role is regulation of serum calcium and phosphate levels via parathyroid hormone
53
Q

Chief (principal) cells in parathyroid

A
  • Most abundant, secrete parathyroid hormone.

- Prominent nucleus, little cytoplasm, varies staining intensities depending on degree of secretory activity

54
Q

Oxyphil cells in parathyroid

A
  • produce additional autocrine and paracrine factors, function and secretions not fully known
  • Larger, less numerous than chief cells, small densely stained nuclei, strongly eosinophilic cytoplasm
55
Q

Tetany (parathyroid gland disorder)

A
  • calcium deficiency due to hypoparathyroidism
  • Causes neurones to depolarise without usual stimulus, leading to increased nervous impulses causing twitches, spasms and convulsions.
56
Q

Osteitis fibrosa cystica (parathyroid gland disorder)

A
  • blood phosphate lowered, blood calcium increased, produces pathological deposits of calcium in several
    organs (kidneys/arteries)
  • Condition arises from
    hyperparathyroidism
  • Characterised by increased activity and number of osteoclasts, multiple bone cavities. Bones less resistant, and prone to fractures
57
Q

Adrenal

A
  • Small flattened glands closely linked to upper pole of each kidney
  • 2 distinct areas: adrenal cortex and adrenal medulla
58
Q

Adrenal cortex

A
  • secretes a variety of steroid hormones linked to cholesterol
  • Mineralocorticoids: electrolyte/fluid haemostasis
  • Glucocorticoids: carbohydrate, protein, lipid metabolism
  • Sex hormones: to supplement gonadal production
59
Q

Adrenal medulla

A
  • highly specialised adjunct to sympathetic nervous system

- Secretes the Catecholamines Adrenalin (Epinephrine) and Noradrenalin (Norepinephrine)

60
Q

3 zones of adrenal cortex

A
  • zona glomerulosa: cells arranged in irregular ovoid clumps. Round, strongly stained nuclei, sparse cytoplasm, abundant smooth ER and mitochondria with triglyceride droplets. Secretes mineralocorticoid hormones
  • zona fasciculata: intermediate but broadest zone. Large secretory cells, abundant cytoplasm, secretes glucocorticoid hormones
  • zona reticularis: thin innermost layer, may be responsible for secretion of small amounts of sex hormone
61
Q

What does adrenal medulla contain?

A
  • small closely packed clumps of secretory cells with large granular nuclei, strongly basophilic cytoplasm
  • chromaffin cells secretes catecholamine hormones adrenalin and noradrenalin.
62
Q

Adrenal gland disorders

A
  • Aldosteronism: due to over secretion of aldosterone
  • Hypertension: largely due to increased sodium and decreased potassium
  • Addison’s disease: due to increased potassium and decreased sodium, leading
    to low blood pressure
  • Cushing’s syndrome: an increase in the production of glucocorticoids such as Cortisol
63
Q

Pineal gland

A
  • Small organ connected by short stalk to brain, containing nerve fibres that communicate
    with the hypothalamus
  • Plays role in biological cycles (circadian rhythms, i.e. sleep and wake cycles)
  • Produces melatonin from the precursor serotonin. Melatonin secretion is inhibited by light and triggered by darkness.
  • largest at infancy and early childhood, involutes rapidly at puberty
  • Melatonin suppresses production of Gonadotrophin Releasing Hormone by the
    hypothalamus, suppressing pituitary gonadotrophin secretion/activation of gonadal
    growth and hormone secretion.
  • controls the onset of puberty
64
Q

Cells of pineal gland

A
  • Pineal Chief cells (Pinealocytes): modified neurones

- Neuroglial cells: similar to astrocytes

65
Q

Ageing in pineal gland

A
  • Appearance of basophylic extracellular bodies called Corpora Arenacea. Also referred to as Pineal Sand or Brain Sand
  • calcified structures in the pineal gland.
  • can be seen on X rays of skull and are useful guide for location of pathological conditions.
66
Q

Pancreas

A
  • Major exocrine and endocrine gland
  • Clumps of endocrine tissue form Islets of Langerhans
  • Clumps of secretory cells supported by fine reticular network containing numerous fenestrated capillaries
  • Small cells with poorly stained cytoplasm, surrounded by strongly stained pancreatic tissue (greater amounts of RER in exocrine cells which secrete protein)
67
Q

3 principal cell types in pancreas

A
  • Alpha cells which secrete Glucagon
  • Beta cells which secrete Insulin
  • Delta cells which secrete Somatostatin
  • All indistinguishable with H&E, require specialised tinctorial stains or immunohistochemistry
    to identify individually
68
Q

Insulin-dependent type 1 diabetes (pancreas gland disorder)

A
  • partial or total destruction of Beta cells due to autoimmune disease (individual susceptibility controlled by several genes)
69
Q

Insulin-dependent type 2 diabetes (pancreas gland disorder)

A
  • occurs later in life, frequently associated with obesity
70
Q

Islet cell tumours (pancreas gland disorder)

A
  • may produce insulin, glucagon, somatostatin, and pancreatic polypeptide
  • Some produce 2 or more of these hormones simultaneously, giving complex clinical symptoms
71
Q

Enteroendocrine cells

A
  • Intestines/Digestive Tract:
  • Found in gastric glands throughout GIT
  • Variety of hormones produced (gastrin, secretin, gastric inhibitory polypeptide, glucagon-like polypeptide, cholecystokinin, somatostatin, motilin, serotonin substance P, vasoactive intestinal polypeptide)
72
Q

Carcinoids or carcinoid tumour (enteroendocrine cell disorder)

A
  • slow-growing neuroendocrine tumour
  • produce several vasoactive substances, mainly serotonin
  • Overproduction of serotonin increase gut motility, but high levels are related to mucosal vasoconstriction and damage

AP0509 Component 2 Exam (21 decks)

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