Sys Path Exam 3

Year 2 Semester 1

what does it mean to be a tropic hormone

grow in response to stimuli

3 results of endocrine pathology

1. increase function

2. decrease function

3. no change in function

continum of disorders of growth of endocrine system

hyperplasia → adenoma → carcinoma

Types of endocrine hyperplasia 4

1. diffuse hyperplasia (tropic hormones)

2. nodular/adenomatous hyperplasia (small nodules)

3. adenoma (solitary, encapsulated, compressed)

4. carcinoma (larger, solitary, aggressive)

what cells make up the pituitary gland

• acidophils (distalis)

• basophils

• chromophobes (not stain)

what is the most common pituitary pathology in a horse

equine pituitary pars intermedia dysfunction

what is the name of the structure connecting the two lobes of the thyroid gland

isthmus

3 cells that make up the thyroid gland

1. follicular cells

2. C cells → calcitonin → inhibit PTH

3. Colloid (store T hormone and I-)

what is the most common endocrine adenoma in horses

pituitary adenoma

second most is thyroid adenoma

compnents of parathyroid gland in dogs and cats

4 pieces

Internal and external

what makes up the parathyroid gland cellularly

chords of chief cells (make PTH) and blood sinuosids

what 2 electrolytes does the parathryroid gland respond to

Ca and P

unique about placement of ruminant parathyroid gland

external by bifurcation of common carotid

what is unique about the locations of the horse parathyroid glands

Upper: dorsal to thyroid gland

lower: thoracic inlet

what is the impact of low calcium on carnivores vs ruminants

carnivores: tentany

ruminants: paresis

Ca functions -7

• mm contraction

• blood coagulation

• enzyme activity

• neural excitability

• hormone release

• skeletal integrity

• membrane permiability

why are there often no consequences of urinary pathology

high reserve capacity of the kidney

when would you see isothenuria and azotemia and renal failure in the level of renal function

normal: 66%

isothenuria: lose 70%

azotemia: 70-75%

renal failure: >75%

role of proximal convoluted tubule

• protein resportion

• high metabolism

role of loop of henle

resorption especially of water

role of distal convoluted tubule

• resorb water in response to ADH

• resorb Na and excrete K in response to ALD

shape of adrenal glands in ruminants and horses

ruminants: LN looking

horses: elongated and flattened

what is the concern with surgery of the adrenal gland

near vena cava and sympathetic ganglia

what is the abnormal cortex medulla ration

1:4 or 4:1

what is a common non pathological finding in the adrenocortical tissue of adrenal gland

pericapsular nodules

cellular origins of adrenal cortex and medulla

cortex: mesodermal

medulla: neural crest

what are the 3 layers of the adrenal gland

1. zona glomerulosa

2. zona fasciculata

3. zona reticularis

what is in the bubbly appearance of the adrenal cortex cells

cholesterol - raw material to make steroid hormones

what regulated the zona glomerulosa of the adrenal gland

Renin/angiotensin

what does the zona glomerulosa secrete

aldosterone (mineralocorticoids)

what is the impact of aldosterone

save sodium pass potassium

what does the zona fasciulata of the adrenal gland

glucocorticoid hormones: cortisol and corticosterone → impact metabolism

what does the zona reticularis of adrenal gland secrete

sex steroids and corticosteroids (maybe estrogen)

what regulates the layers of the adrenal cortex

ACTH (trophic hormone) regulates fasciculata and reticularis

renin. angiostenin regulate glomerulosa

what is different about rodent adrenal glands

• they do not have zona reticularis

• have x zone that regresses with age - puberty for males and pregnancy for females

what secretes ACTH

pars intermedia and pars distalis of pituitary gland

when is the renin angiostenson system activated(3)

1. hypovolemia

2. severe dehydration

3. sodium depletion

what does aldosterone act on and what does it do

• renal nephoron and sweat glands

• save sodium pass potassium

adrenal medulla

1. secretory cells

2. what do they make

1. chromaffin cells

2. epinephrine/norepinephrine (tyrosine derived)

what is the name of bilateral severe hemorrhage assocaited with necorsis of adrenal corticies

Waterhouse -Friederchsen syndrome

what is the most common naturally occuring cause of cushings in a dog

functional pituitary tumor (adenoma)

what is the main reason a client would bring a hypercortisolism patient into the vet

PUPD

what are chromaffin adrenal medullary cells

postganglionic neurons

most important things produced by adrenal gland

cortisol and aldosterone

what is the cellular composition of the pancreas

clusters of cells: islets of langerhans, glomeruloid endocrine organs

cell types of the pancreas and functions

Beta (most)- secrete insulin and insulin antagonist (islet amylod polypepride)

alpha - secrete glycagon

delta - secrete somatostatin→ inhibitory control of alpha and beta

PP(F)- produce pancreatic polypeptide

epsilon - produce ghrelin= appetite stimulant

function os insulin

• respond to hyperglycemia

• major anabolic hormone

• increase rate of transfer of glucose into target cells to form intracellular glycogen

• lipogenesis

• protein synthesis

how does insulin reduce extracellular glucose

1. facilitating glucose entry into cells

2. converting glucose into glycogen (glycogenesis)

what controls the hypoglycemia effects of insulin

glucagon released from pancreatic alpha cells

what is the job of glucagon and how does it do it

elevate extracellular glucose

• glucogenesis

• break up polymer glycogen into glucose = glycogenolysis

function of islet amylod polypeptide (IAPP/ amylin)

• stored with insulin in beta cells and co secreted

• blocks the effects of glucagon

• anatagonize insulin effects

what is the ANS control of insulin secretion

Stimulated by PNS

inhibited by SNS

function of somatostatin

antagonize effects of insulin and glucagon

what is an increase and a deccrease of pancreatic endocrine funciton associated with

increase: islet tumors

decrease: (involve only insulin) - diabetes mellits

what is the general rule for the location of paired organs

right is more rostral

dog and cat parathyroid gland amounts

4 total, internal and external

what does the parathyroid gland listen to

Ca and P

what is the cellular composition of parathyroid glands

chief cells and blood sinusoids

horse parathyroid locations

Upper and lower (thorasic inlet)

what is the impact on calcium:

1. Vitamin D

2. PTH

3. calcitonin

4. FGF23

1. high

2. low

3. low p

how is vitamin D activated

activate cholecalciferol in liver and kidney (regulated by PTH)

what is the impact of

1. too low vitamin D

2. too high vitamin D

1. metabolic bone disease

2. increased calcium = mineralization

what does calcitonin do

decrease Ca and increase P

FGF23

1. what produces it

2. what is the impact

3. what is its purpose

1. osteocytes and osteoblasts

2. increase P excretion and decreased vitamin D activation

3. guard from hyperphosphatemia

significance of parathyroid cyst

incidental

what is the appropriate compensatory response to increased calcium

C cell hyperplasia - produce calcitonin which decreases Ca

how to differentiate between thyroid c cell carcinoma and C cell hyperplasia

IHC, look for calcitonin secretion

what cells are involved in bone remodeling

osteoblasts: resportion

osteoclasts: ossification

— work together

what is bone modeling

osteoblasts and osteoclasts work independently to shape skeletal anatomy

what is a green stick fracture

1 cortex intact, 1 cortex fractured

what is woldd’s law

bone deposited where it is needed, removed from where it is not needed

2 types of mechanical bone injuries

1. acute: abrupt, physical force

2. chronic: repetative, lower level forces on bones

what are the 3 components of bone

1. minerals

2. collagen

3. cells (osteoblasts, osteocytes, osteroclasts)

bone fracture classification

1. open/compounded

2. closed

3. simple

4. transverse

5. obliwue

6. spiral

7. comminuted

8. greenstick

9. avulsion

10. infarctions

11. stress

12. physeal

1. bone penetrates skin

2. bone not penetrate skin

3. clean break of bone into 2 parts

4. break perpendicular along bone

5. break at 45 degree (shear forces)

6. break wraps around bone along axis (torsion)

7. bone fragments into many pieces

8. minimal seperation between fracture ends, intact periosteum (young)

9. bone fragment where tendon ligament attachments are torn away (tension)

10. multiple microfractures with adjacent trabeculae and no gross displacement

11. repeated, low level trauma, exercise causing cortical microfractures

12. young, involve growth plate

describe primary fracture healing

• direct

• stabilized fragments - fixation

• restore bone shape (anatomic reduction)

• sterile fracture

• no fracture gap

• minimal callus

• from surgical intervention

describe secondary fracture

• indirect

• minimal movement at fracture

• poor anatomic reduction

• non perfect healing conditions

• natural

forces acting on bone

1. bending

2. torsion (twist)

3. shearing

4. tension (collagen 1)

5. compression (minerals)

stages of secondary bone healing

1. hematoma: trauma, vessels, stabilize fractures

2. inflammation: neutrophils, macs

3. callus (fibrous tissue → cartilage → bone)

4. remodeling

describe the development of a bone callus

• inital fibrous: fibrocytes and fibroblasts with low O2

• stabilize blood vessels to bring mroe O2

force on growth plate

tension

what are the main diabetogenic hormones

all counter insulin

• glucagon

• glucocorticoids

• thyroxine

• epinephrine

• growth hormone

• progesterone (pregnancy diabetes)

3 main pathologies of endocrine pancreas

1. decreased function (beta cells)

2. inflammation

3. disorders of growth (hyperplasia, islet tumors)

common clinical signs of diabetes mellitus

1. hyperglycemia/glucosuria (overwhelm reabsorption of glucose by tubular cells)

2. weight loss

3. increased appetite

4. catabolism of protein

5. decreased ability to metabolize carbohydrates

6. decreased pilogenesis

7. increased ketone bodies

what is the significance of diabetic ketoacidosis

medical emergency

what is the #1 cause of diabetes mellitus in dogs

vacular degeneration of beta cells : become filled with vacules for unknown reason

what species does not usualy get bone tumors

horses

what does a woven bone callus indicate

progressive, cyclic trauma

what species most likely does not get chondrosis

cats

what is AEC

articular - epysial complex

main factor of metabolic bone disease

distubrance on Ca homeostasis causing failure of bone production, mineralization and maybe maintance

in what animals is metabolic bone disease more severe

young

4 metabolic bone disease overarching causes

1. endocrine

2. genetic

3. toxic

4. nutritional

what do growth arrest lines in the bone generally mean

metabolic bone disease

what regulates extracellular Ca

PTH, Vitamin D, Calcitonin

what is the homeostatic priority of Ca regulation

maintain serum Ca at the expense of bone

what is significant about vitamin D in dogs and cats

they need it in their diet

function of calcitonin

inhibit PTH: decrease Ca and P

function of Fibroblast growth factor 23

bing renal tubular cells, decrease P and decrease activation of vitamin D

name for loss of bone mass

osteopenia

species most common to get ostitis

foals, calves, small ruminants, pigs