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AP 710 - Microanatomy > Final Exam > Flashcards

Final Exam Flashcards

1
Q

Pituitary

A

Froms from the roof of the oral cavity, grows upward as Ratheke’s pouch, lumen of pouch becomes the residual cleft between the pars distalis and pars nervosa

Hypophysis - pituitary is divided into an anterior pituitary (mostly pars distalis with along with pars tuberalis and pars intermedia) and posterior pituitary (pars nervosa and infundibular stalk)

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2
Q

Pars distalis of Pituitary

A

Cords or clusters of cells associated with sinusoids

Cords or clusters of cells seperated by many capillaries or sinusoids

Cells:

Chromophobes

Chromophils

a. Acidophils (produce growth hormone and prolactin)
b. Basophils (produce TSH, LH, FSH, and ACTH

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3
Q

Neurohypophysis

A

Contains numerus unmyelinated axons

Cell bodies are in the hypothalamus

Secrets oxytoicn and vasopressin

These travel down the hypothalamo-hypophyseal tract to pars nervosa

Swelling called Herring bodies are seen in the pars nervosa

Pituicytes are the cells in the pars nervosa

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4
Q

Thyroid

A

Cells origin from an outgrowth of buccal cavity

Thyroid follicles are hollow spheres filled with colloid

Colloid - Made up of thyroglobulin

Follicular cells - Cubodial epithelium, have microvili on apical edge, held together by tight junction to prevent leakabe of thyroglobulin

  • Have a storage and endocrine phase
  • In endocrine phase, stored thyroglobulin is taken up by follicular cels and broken down into T4 and T3 (active hormone)

Parafollicular cells - Isolated clusters of cells within the basal lamina of follicles. Larger paler cells and produce calcitonin

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5
Q

Parathyroid Gland

A

Located in or around thyroid

Capsule of internal parathyroids is areolar CT of thyroid

Parenchyma: Cords, cluster with numerous capillaries

Chief Cells - Predominant cel type. Light and dark cells. Dark chief cells produce parathyroid hormone (PTH).

Oxyphil Cell - Large cell with acidophilic cytoplasm of unknown fuction

PTH - Raise blood calcium levels, increases the activity of osteoclasts, wich tear down bone to release calcium

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6
Q

Adrenal Gland

A

Located on cranial pole of kidney

Capsule around adrenal sends trabeculae into the parenchyma. There are also fine reticular fibers within the parenchyma.

Cortex - divided into 3 regions

Zona glomerulosa - Produces mineralocorticoids (mainly aldosterone) which act on the kidney to keep more sodium and water in the blood instead of excreting them. Not influenced by ACTH.

Zona fasciculata - Widest zone. Cells have a foamy cytoplasm. Steroid producing cells: glucocorticoids such as cortisol, secreted when the pituitary secretes ACTH.

Has a large amount of SER and numerous lipid inclusions.

Zona reticularis - Closely packed cels in anastomosing cords; this zone produces some weak androgens and some glucocorticoids

Medulla - Made up of chromaffin cells. Pheochrome cells.

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7
Q

Paragnaglia

A

Small bodies containing chromafin cells that are found associated with abdominal aorta

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8
Q

Pineal Gland

A

Photoreceptor in lower vertebrates

Secretions of melatonin and serotonin.

3 lobes:

Pinealocytes - large cells; open nucleus

Astrocytes

Brain sand (corpora arenacea)

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9
Q

Thyroid Follicles

A

NA/I symporter - NA help iodine move in against the concentration gradient

Oxidation of iodine occurs in the follicle colloid

Iodination can then occur of thyroglobulin to break it down int T4 and T3

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10
Q

Thyroid System

A

TRH is released from the hypothalamus and stimulates release of TSH to act on the thyroid gland

The thyroid hormone releases T3 and T4

T3 and T4 work to increase metabolism, growth and development, increase catecholamine effect

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11
Q

Parafollicular Cells

A

Produce calcitonin which lower serum calcum

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12
Q

Cells of the Parathyroid

A

Chief - smaller and bluer

  • Produce PTH
  • PTH -> increase serum CA

(osteoclasts/kidney/gut (vitamin D))

  • PTH -> slightly lowered serum PO4

(complicated interaction between gut/kidney/bone)

Oxyphil - bigger and redder

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13
Q

Regulation

A
  • One of the very few endocrine systems not regulated by the pituitary gland
  • Calcium concentratioins in blood provide direct feedback to parathyroid, stimulating or restricting PTH production
  • Calcium sensitity is through the CaSR (calcium sensing receptor) protein
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14
Q

Adrenal Gland

A

Zona glomerulosa

  • Not much influenced by ACTH

Incluenced more by Angiotensin II

Produces mineralocorticoids: aldosterone

Causes increase Na and water retention by kidney

Zona fasciculata

Is stimulated to produce glucocorticoids by ACTH

- Cortisol

Glucocorticoids suppress inflammation and outside liver are catabolic (increase gluconeogenesis)

Zona reticularis

Is stimulated to produce adrogens by ACTH

  • Androstenedione

Medulla

Chromafin (aka pheochrome) cells produce catecholamines

Stimulated by preganglionic fibers of the sympathetic nerous system

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15
Q

Pineal Gland

A

Light Sensitive

  • Acts as a light sensing organ in lower animals

Produces melatonin

  • May regulate/restrict puberty through action on the pituitary
  • May afect seasonal breeding cycles
  • May affect circadian rythm

Cells

Pinealocytes - produce melatonin

Brain sand (corpora arenacea)

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16
Q

Testes

A
  • Male gametes
  • Spermatozoa
  • Testosterone
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17
Q

Dick Ducts

A
  • Ductuli efferents
  • Epididymus
  • Ductus (vas) deferens
  • Ejaculatory duct

Collects, stores spermatozoa from each testis and conducts their maturation

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18
Q

Dick Glands

A
  • Seminal vesicles
  • Prostate gland: Secretes seminal fluid
  • Semen: Consists of seminal fluid and spermatozoa
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19
Q

Penis

A
  • The organ of copulation
  • Bulbourethral glands of Cowper: Secrete a fluid which lubricates the urethra for the passage of semen during ejaculation
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20
Q

Testes

A
  • Exocrine component: Produces spermatoza
  • Endocrine component: Leydig cells produce testoerone and sertoli cells produce estrogen
  • Capsule forms tunica albuginea
  • Stroma: Mediastinum tesis at the anterior pole surround the “rete testis”
  • The tunica albuginea is surrounded by tunica vaginalis
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21
Q

Testis Parenchyma

A

Seminiferous tubules

  • Basal lamina around seminiferous tubules
  • Myoid cells, smooth muscle outside basal lamina
  • Stratified epithelium cells: The various stages of developing germ cells + Sertoli cells inside the tubules
  • Sertoli cells: Supporting or sustentacular cells are nurse cells, tall triangle shaped cells (hard to see cell outlines)
  • Sertoli cells function as physical and nutitional support, phagocytosis, secretion of estrogen, androgen-biding protein, activin, and inhibin
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22
Q

Sertoli Cells

A

Support spermatogenesis nutritonally and hormonally

Sertoli cells create blood-testis barier

Held together by tight junctions

THE ADLUMINAL COMPARTMENT IS THE IMMUNE PRIVILEGED AREA

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23
Q

Spermatogensis

A

3 phases

Mitosis, meiosis, metamorphosis

Spermatocytogenesis (mitotic state) - Spermatogonia divide and eventually give rise to spermatocytes

Meiosis - Spermatocyte become a haploid spermatid

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24
Q

Spermatogonia Cell Division

A
  • A cells: stem cells that have round nucleus with condense chromatis

Primary spermatocytes: largest cells, begining of meiosis, 4N DNA, chromosoam cross-over occurs

Secondary spermatocytes: Smaller with 2N DNA, undergo 2nd meiotic division

Spermatids: Small round cells, nuclei become flattend and heterochromatic and are haploid (1N DNA)

Mature spermatozoa: Formed during the metamorphosis stage. Development of the acrosome, flagellum, and nuclear condensation. Head is covered by acrosomal cap with cointains hyaluronidase.

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25
Q

Testicular Stroma and Ducts

A
  • Leyding cells: acidophilic foamy cytoplasm and produce testosterone (lightly eosinophilic large cytoplasm). Endocrine cells - produce testosterone (controlled by LH).
  • Straight tubules: simple squamous or cuboidal epitheium, connect seminiferous tubules to rete testis
  • Rete testis: anastomonic tubules located in mediastinum
  • Ductuli efferets - Connect rete testes to epididymis; epithelium is ciliated, simple columnar
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26
Q

Rete Testis & Ductuli Efferents

A

Move non-motile spermatozoa to epididymis

Lined by a single layer of cuboidal epithelial cels with microvilli and single cilicum at rete tests or cilia at ductuli efferents

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27
Q

Genital Ducts

A

Ductus Epididymis - Coiled tube that stores sperm while it matures

  • Divided into head, body, and base
  • Epithelium is pesudostratified columnar with sterocilia
  • Connects to ductus deferens
  • Takes about 10 - 15 days

Ductus Deferens - Epithelium becomes pseudostratified columnar, gradually loses sterocilia

  • Lumen contains spermatozoa in the mature male animal
  • Tunica muscularis is very thick
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28
Q

Epididymis

A

Maturation of spermatozoa

Stay in epididymis for 2 weeks

Pseudostratified columnar epithelial cells with seterocilia lined with a sing smooth muscle laery

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29
Q

Ductus deferens

A

Three layers of smooth muscle. Peristatic contration is controlled by sympathetic nervous system during ejaculation

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30
Q

Seminal vescile

A

Associated with ductus deferens and secrete seminal fluid

Seminal fluid is alkaline and helps neutralize the acidity of the vaginal tract

Contains proteins, fructose, mucus, vitamin C, flavins, phosphorylcholine, and prostaglandins

Vesicular glands are absent in carnivores

Simple columnar epithelium have lipofuscin granules in cytoplasm

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31
Q

Accessory Organs

A
  • Ampulla: Terminal part of vas deferns
  • Prostate: Body surround urethra. Concentrically laminated concentrations of secretory product
  • Have ejaculatory ducts, a sort part of the vas deferns joins with the duct of the seminal vesicles
  • Produces half of the seminal fluid which cointains fibrinolysin and ciric acid. Helps liquify coagulated semen. Tall columanr secretory epithelial cells with round nuclei.
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32
Q

Urethra

A

Transition epithelium

Pelvic part has colliculus seminalis, an area where deferens ducts, seminal vesicles, and prostatic ducts empty into the urethra

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33
Q

Penis

A

Has a capsule of tunica albuginea

Ereticle tissue: Vascular sinuses in the CT

  • Corpus cavernosum penis
  • Corpus cavernosum urehra

Glans: Extension of corpus spongiosum and covered with stratified squamous eithelium of prepuce

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34
Q

Ovary

A

Has a cortex and a medulla and a tunica albuginea

Has both endocrine (hormones) and exocrine (oocytes) fuction

The hormones are produced by the developing follices

Follicles are transformed after ovulation to corpora lutea

Ovary responds to pituitary hormones, including FSH and LH

Cortex is where follices developed and is peripherally located

Tissue between follices is the stoma (fibroblast-like with lipid droplets)

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35
Q

Tunica Albuginea and Serosa

A

Tunica albuginea is the CT around the outer edge of the cortex

Tunica serosa covering the ovary has simple cuboidal epithelium (outer most layer)

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36
Q

Ovarian Medulla

A

Contains the blood vessels for the ovary

Contains a system of channels lined by cuboidal epithelium called the rete ovarii

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37
Q

Oogenesis

A

Oogonia divide mitotically until birth and give rise to primary oocytes which become arrested in meiotic prophase I

When simulated to divide the primary oocyte complete meiosis I dividing to form the secondary oocyte and 1st polar body

The secondary oocyte is formed just prior to ovulation

The secondary oocyte undergoes the 2nd meiotic division right after fertilization

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38
Q

Ovarian Follicles

A

The oocytes are inside follicles, surrounded by a capsule-like structure called the zona pellucida and a layer of epithelial cells called granulosa cells

The zona pellucida is a thick glycoprotein layer secreted by both the oocyte and the granulosa cells

There is a basement membrane around the follicular epithelial cells and a theca around the follicle outside the basement membrane

Stages of development are described based on their apperance

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39
Q

Primordial Follicle

A

Oocyte is surrounded by a single layer of squamous cells.

These follicles are quiescent.

Thre is a basement membrane between the follicle and the ovarian stroma.

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40
Q

Primary Follicle

A

Oocyte is surrounded by cuboidal granulosa cells

Zona pellucida forms around oocyte

Theca may be forming

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41
Q

Secondary Follicle

A

Small pockets of follicular fluid appear between granulosa cells

The pockets have not yet coalesced into 1 large fluid cavity

The theca become obvious

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42
Q

Tertiary Follicle

A

Has 1 large fluid-filled cavity with a layer of cranulosa cells around the stratum granulosum

The oocyte is surrounded by granulosa cells called the cumulus oophorus

The corona radiata is the layer of granulosa cells immediately in concat with the zona pellucida

The cumulius oophorus is attached to the wall of the follicle by a mass of granulosa cells called the hilus

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43
Q

Granulosa Cells

A

Follicles are divided into special areas including:

Cumulus oophorus

Corona radiata

Stratum granulosum

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44
Q

Atretic Follicle

A

Follicular atresia - follicles degenerate and become atretic

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45
Q

Ovarian Cycle - Luteal Phase

A

The corpus luteum (CL) is a transiet endocrine gland derived from an ovulated follicle that produces progesterione which helps maintain pregnancy

Eventually regressing and ability to produce progesterone and involutes to become a CT scar

PGF2alpha lyses

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46
Q

Ovarian Cycle - Follicular Phase

A

The CL is regressing

The follicle is maturing

Estrogen is being produced by granulosa cells in response to FSH

Rising estrogen in the late follicular phase initiate the LH surge which triggers ovulation

Endometrium is proliferating

Theca cells have LH receptors which cause produce androgens that diffuse into the follice

Granulosa cells have FSH recepors and produce estrogen and will later develop LH receptors

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47
Q

Pre-Ovulatory LH Surge

A

Rising estrogen levels during the follicular phase stimulate the release of LH from the pituitary and the high estrogen at the end of the follicular phase causes an LH surge which:

  • Stimulates primary oocyte to complete meiosis I
  • Starts process of ovulation
  • Indues formation of the CL in the ovulated follicle
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48
Q

Events at Ovulation

A

The LH surge causes release of collagenase and other enzymes to digest tissues at the ovulation site

The stroma overlying the follice becomes avascular and degenerates

Tecal layers thin

The oocyte and the cumulus oophorus break free from antral wall

The follicle protrudes from wall of ovary at the “stigma”

The oocyte is released from the follicle

After ovulation, a CH forms as blood fills in the follicle lumen. The wall of follicle collapses and creats folds.

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49
Q

Luteal Phase

A

The CL forms from the granulosa and the theca cells after ovulation:

  • Granulosa cells proliferate, enlarge and become granulosa lutein cells.
  • Theca interna cells convert to theca lutein cells.
  • Progesterone is produced by the CL.
  • The uterine glands are secreting.
  • LH secretion maintains function of the CL.
  • Progesterone stimulates the development of uterine endometrium.
  • Progesterone (and estrogen) produced by the CL inhibit FSH and LH release.
50
Q

CL Regression

A

The fate of the CL depends on wheter copulation and/or fertilization occurs.

  • CL of pregnancy

Corpus albicans: The CL is gradually replaed by a CT scar

51
Q

Oviduct Divisions

A
  • Infundibulum - funnels shaped, with fimbriae
  • Ampulla - extends caudally from infundibulum
  • Isthmus - a narrow, muscular segment joining the uterus
52
Q

Oviduct Layers

A
  • Mucosa - the epithelium and the underingly CT tissue
  • Tunica muscularis - irregularly arranged smooth muscle
  • Tunica serosa
53
Q

Oviduct Mucosa

A
  • Mucosa is folded
  • Epithelium is simple columnar ciliated
  • Non-ciliated secretory cells
54
Q

Uterus

A

Layers:

  • Endometrium: Equivalent to the tunica mucosa and submucosa and contains uterine glands
  • Myometrium: Equivalent to the tunica mscularis, it is the inner circular layer, outer longitudinal layer
  • Perimetrium: Tunica serosa, a thin layer of fibroelastic CT covered by a mesothelium
55
Q

Cervix

A

Epithelium is columnar mucous cells

Tunica muscularis has inner circular and outer longitudinal layers

56
Q

Vagina and Vestibule

A

Vagina

Stratifed squamous non-keratinized epithelium

No muscularis mucosa, therefore the lamina propria is joined to the submucosa

Tunica muscularis: inner circular, outer longitudinal

Vestibule

Contains major and minor vestibular glands

57
Q

Proestrus

A

Beginning of endometrial growth

CL from previous cycle is regressing

New follices are growing: theca cells and granulosa cells

58
Q

Estrus and Metestrus

A

Estrus

  • Ovulation occurs during this phase in most species
  • CL develops during this phase in the dog

Metestrus

  • Defined as the period of CL development
  • Progesterone levels climbing
  • No metestrus in dog since CL develops in estrus
59
Q

Diestrus

A

Phase of active CL

Uterus reaches maximal endometiral gland development and activity

CL regresses toward end if no implantation

Anestrus - prolonged period of sexual inactivity

60
Q

Vaginal Smear

A

Anestrus - Mainly non-keratinized cells, few PMNs

Proestrus - PMNs early, numerous RBCs, keratinized cells increasing

Estrus - Some RBCs, mainly keratinized cells

Metestrus - Diestrus: PMNs reappear, RBCs variable

61
Q

Mammary Gland

A

Compound gland with large ducts in the interlobular CT (modified sweat gland - apocrine and merocrine)

Both the alveoli and the intralobular ducts are secretory, with simple cuboidal to columnar epithelium

Corpora amylacea are concentrations of secretory materal found scattered in alveoli

Alveoli regress when the gland is inactive

Myoepithelial Cells - Contractile cells that surround alveoli and respond to oxytocin to cause milk “letdown”. Found between basal lamina and alveolar cells.

Non-secretory portion: Interlobular ducts, lobar ducts, and lactiferous sinus

62
Q

Mammary Glands Ducts & Stroma

A

Ducts

Epithelium: bein as simple cuboidal, lobar ducts have bistratified columnar epithelium. Smooth muscle and elastic fibers surround large ducts.

Stroma: the loose collagenous and adipose tissue stroma is a major component of non-lactating glands. Stroma become very scant during lactation.

63
Q

Mammary Gland Sinus System

A

Lactiferous sinus = Teat sinus + Gland sinus

Bistratified columnar epithelium

Streak canal (lactiferous duct): Transition from bistratified columnar epithelium to the skin of the teat

64
Q

Unilobar Kidney

A

Found in dog, cat, horses, and small ruminants

Broad papilla forms renal crest

Collecting ducts feed into renal pelvis

65
Q

Multilobar Kidney

A

Found in cow, pig, and primate

66
Q

Renal Lobe

A

Outer Cortex:

  1. Pars convoluta
  2. Pars radiata

Inner Medulla:

  1. Loops of Henle
  2. Collecting ducts - Open through tiny openings in papilla called area cribosa
67
Q

Area Cribosa

A

Collecting ducts open through tiny opening in papilla called area cribosa

68
Q

Uriniferous Tubules

A

Uriniferous Tubule - The functional unit of each kidney is the microscopic uriniferous tubule

Includes:

A. Nephron - produces urine

B. Collecting duct - collects, concentrates, and transports urine

69
Q

Nephron

A

Includes:

A. Renal corpuscle

a. Glomerulus
b. Glomerular capsule

B. Renal tubule

a. Proximal and distal convoluted tubules
b. Loops of Henle
c. Connecting tubule

70
Q

Renal Corpuscle

A

Glomerulus - Tuft of capillaries

Glomerular (Bowman’s) Capsule - Houses the glomerulus

The glomerulus connects the afferent arteriole to the efferent arteriole

Capsule consists on an internal (visceral) and an external (parietal) lined by epithelial cels

Podocytes - Epithelial cells that line the visceral layer

  • Have cytoplasmic processes called foot processes or pedicles
  • Pedicles interdigitate to form filtration slits

Vascular pole - Afferent and eferent arterioles enter/leave

Urinary pole - Where proximal tubule originates

71
Q

Mesangial Cells

A

Phagocytic cell found between capilarries of glomerulus

Cytoplasmic processes extend between endothelial cells

Function is to clean the GBM (glomeular basement membrane) of the particulate matter

72
Q

Renal Function

A
  1. Filtration
  2. Tubular reabsorption
  3. Tubular secretion
73
Q

Glomerular Basement Membrane

A

Lamina rara externa - adjacent to podocyte processes - heparan sulfate - filters by charge

Lamina densa - central zone - type IV collagmen - fliters by size

Lamina rara interna - adjacent to endothelial cells - heparan sulface - filters by charge

74
Q

Glomerular Filtration

A

~ 20% - 25 of cardiac output

Glomeular Filtration Rate (GFR)

75
Q

Tubular Reabsorption

A
  • Substances are reabsorved selectively in different parts of the uriniferous tubules
  • Active Transport: Glucose, amino acids, Na+
  • Glucose passes freely through the filtration barrier (PCT)
  • Na+ (PCT and Loope of Henle)
  • Passive Diffusion: Water and urea
  • Urea passes frely across the filtration barier by diffusion and passively absorbed in PCT
  • The extent of water reabsorptioin influence the amount of urea in the urea
  • Hormones like parathyroidhormone (PTH), aldosterone, antidiuretic hormone (ADH) also influence the rabsorption process
76
Q

Tubular Secretion

A

1. Endogenous compounds

  • Creatinine, histamine, metabolic products of hormones

2. Exogenous compounds

  • Antibiotics, asprin, other drugs
    3. Water, cations, and anions pass into tubular lumen by passive or active mechanisms
77
Q

General Features of Tubular Epithelium

A

Function of epithelium is determine by:

  1. The asymmetric distribution of channels and transporters in the apical and basolateral membranes
  2. The permeability of the zona occludens (paracellular transport)
78
Q

Proximal Convoluted Tubule (PCT)

A

Simple cuboidal epithelium with brush border

79
Q

Loop of Henle

A
  • U shaped structure with a thin descending limb and a thick ascening, both composed of simple squamous epithelia
  • Function: Passive reabsorption of Na+ and Cl-
  • The thin ascending limb of the loop become the thick ascending limb which is composed of simple cuboidal epitheium
  • Function: Active reabsorption of varous electrolytes
80
Q

Distal Convoluted Tubue (DCT)

A

- Zone of transition

- More empty lumens

81
Q

Collecting Duct

A

Has 2 types of cells:

  1. Principal cells
  2. Intercalated cells
82
Q

JG Apparatus

A

Consists of 3 types of cells:

  1. Macula densa of the DCT
    a. Taller epithelium with more apparent nuclei
    b. Chemoreceptors for Na+ and Cl-
  2. Juxtaglomerular cells
    a. Located in the wall of afferent arteriole
    b. Have cigar shaped nuclei
    c. Secrete renin
  3. Extraglomerular mesangial cells
    a. Lacris or Polkissn cells
    b. Located outside glomerulus
83
Q

Urothelium

A

Called transitional epithelium

Found only in the urinary tract

84
Q

Fluid Transport in the Urinary System

A

Upon delivery at a minor calyx, filtrate is no longer modified by rabsorption or secretion and is called urine

It flows passively into the renal pelvis but moves by peristalsis along the ureters for temporary storage in the bladder, which is emptied through the urethra

85
Q

Review

A

Gray Matter

  • Made up of nerve cell bodies
  • Fibers (mostly unmyelinated)
  • Glial cells
  • Neuropil is the background of gray matter, composed of glial processes and unmyelinated nerve processes
86
Q

Review

A

White Matter

  • Made up of myelinated fibers and glia
  • Divided into dorsal, lateral, and ventral funiculi
  • Funiculi contain ascending and descending tract
87
Q

Meninges

A

3 meningeal layers:

  • Dura mater
    a. Fused to the periosteum of the cranial cavity
    b. Seperated from the periosteum in the vertebral cana by the epidural space
  • Arachnoid
    a. Membrane + trabeculae
    b. Space below is subarachnoid space
  • Pia mater
    a. Closely associated with nervous tissue

Pia + Arachnoid = Leptomeninges

88
Q

CNS Vasculature

A

Pericytes in the perivascular space are responsible for formation and maintenance of vessel basement membrane as well as phagocytosis after injury

Astrocytes processes from a sheath around CNS vessels

The most important vascular adaptation is the tight junctions between vascular endothelial cells. This forms the blood-brain barrier.

89
Q

Ventricular System

A

Ventricles are large cavities inside the brain, lined by ependymal cells, and filled with CSF.

90
Q

Choroid Plexus

A

Found in roof and wall of all ventricles of brain.

Covered in ependymal cells

Secrete CSF

Tight junctions between these ependymal cells form the blood-CSF barrier.

Capillaries here ARE fenestrated.

91
Q

Cerebrospinal Fluid

A

Produced by choroid plexuses in lateral, third, and fourth ventricles

Circulates through central canal

Exits via the lateral foramina to the subarachnoid space

Reabsorbed to the vascular system via the arachnoid villi

92
Q

Brainstem

A

Gray matter in the brain is distributed in the form of nuclei instead of columns

Nuclei: collection of cell bodies within the brain stem, and deep within the cerebrum and cerebellum

Many nuclei are sensory or motor from the cranial nerves

Some are relay areas

93
Q

Cerebellum

A

Coordinates motor activity

Zones:

  • Molecular: Most superficial
  • Purkinje cells: Large flask-like cells. Provide the only efferent route from the cortex to deeper cerebellar nuclei
  • Granular layer
94
Q

Cerebrum

A

Layers of the cortical gray matter:

  1. Molecular layer
  2. Small pyramidal
  3. Large pyramidal
  4. Polymorphic

White Matter

95
Q

ANS

A

Visceral part of the nervous system.

  • Important in homeostasis.
  • Regulates smooth muscle, cardiac muscle, and glands
  • Mainly motor, but also has sensory components
  • Efferent is a 2 neuron system
    1. First ganglion is preganglionic located in the CNS
    2. Second neuron is postganglion located in a peripheral ganglion
96
Q

Sympathetic (thoracolumbar)

A
  • The ganglion are large and near the vertebrae
  • Preganglionic neurotransmitters: ACH
  • Postganglion neurotransmitters: Norepinephrine
97
Q

Parasympathetic (craniosacral)

A
  • Parasympathetic ganglia innervate single organs; the ganglia are microscopic (usually) and are in or near the organ
  • Neurotransmitter of both pre- and postganglionic fibbers is ACH
98
Q

Key Words

A

Anterior Compartment

  • Anterior chamber: between cornea and iris
  • Iris: contains ciliary body
  • Posterior chamber: between iris and lens

Posterior compartment: Filled with vitreous humor

99
Q

Cornea

A
  • Devoid of blood vessels and lymphatics
  • Has remarkable healing power

Epithelium

  • Turnover time of 7 days
  • Germinal cells in the basal layer at limbus-cornea junction

Bowman’s membrane

  • Basal lamina that support epithelium

Substantia propria (stroma)

  • Avascular
  • Keratocytes

Descemet’s Membrane

  • Basement membrane

Corneal Endothelium

  • Mesenchymal epithelium
100
Q

Sclera

A

Sclera proper

  • Dense irregular CT

Limbus

  • Germinal cell center for cornea
101
Q

Vascular Coat or Uvea

A

The vascular rich midle layer of the eye constituting the iris, ciliary body, and choroid

Choroid

  • Vascular rich layer most prominent layer of middle tunic

Tapetum lucidum

  • Found in choroid between vascular layer and pigment epithelium
  • Night vision

Ciliary Body

  • Anterior continuation of the choroid
  • Zonular fibers extend to lens
102
Q

Ciliary Body

A
  • Classified as bistratified columnar
103
Q

Ciliary Muscle Controls Lens Thickness

A
  • Under parasympathetic innervation
  • When it contracts it removes tension from zonules, lens “round up” to accomate for near vision
104
Q

Iris

A
  • Circular diaphragm in front of lens (extension of choroid)
  • Heavily pigmented myoepithelial cell lining

2 types of muscles

  • Pupillary sphincter muscle (constriction) - parasympathetic innervation
  • Pupillary dialator muscle - sympathetic innervation

Corpora nigra (iris granules)

  • Found in the horse and ruminants
105
Q

Aqueous Humor

A
  • Drained away at filtration angle into endothelial spaces between trabeculae and then to the Canal of Schlemm
106
Q

Retina

A

Ora serrata

  • Transition from optic to blind part of retina, closer to lens

Pigmented Epithelium

  • Has phagocytic ability
  • Dehydrate retina
  • Creat immune privilege space of inner eye

Layers of Rods and Cones

  • Contains membranous vesicles stacked like coins in the processes of rods and cones

In rods these membranous stacks contain a pigment called rhodopsin

  • In cones there is a pigment called iodospin
  • Rhodopsin and iodopsin are photoreceptor proteins
107
Q

Retinal Photoreceptors

A

Two visual system: scotopic & photopic

  • Dark adapted (night) vision is called scotopic and is ruled by rods
  • Rods have rhodopsin
  • Light adapted (daylight) is called photoic and uses cones (color vision)
  • Cones have iodopsin
108
Q

Three Neuron System of Nuclear Layers of the Retina

A

1st neuron

  • Nuclei of rods and cones

2nd neuron

  • Inner nuclear layer of bipolar cells, horizontal cells, and amacrine cells

3rd neuron

  • Layer of ganglion cells

Plexiform layers are seen between these nuclear layers as lighter areas not containing many nuclei

109
Q

Fovea

A
  • The foveal retina is modified to obtain the maximum photoreceptor sensitivity and the greatest visual discrimination.
  • Surrounding the fovea is an ovid yellow area about 1 mm wide called the macula lutea.
  • Retinal blood vessels are absent at the fovea. AT the fovea, the photoreceptors are almost exclusively cones which are elongated an closely packed.
110
Q

Optic Nerve

A

The afferent fibers from the retina converge at a point medial to the fovea, at the optic disc. The fibers then penetrate the sclera through the lamina cribosa to form the optic nerve.

Retina blind spot: Absence of photoreceptor cells from the optic nerve

The afferent fibers are not myelinated

The main blood supply of the retina is provided by the central artery of the retina

111
Q

Lens

A

Lens Capsule

  • Thick basement membrane
  • Produced by epithelial lens cells
  • Is on the very outside of the lens

Lens Epithelium

  • Cuboidal, present only on anterior aspect in the adult lens
112
Q

Eyelids

A

Palpebral conjunctiva

Tarsal glands

  • Large sebaceous glands that produce an oily film which covers the tear film and prevents evaporation

Orbicularis oculi muscle

Third Eyelid: Nictating memrane

  • Protection and moisten the eye while keeping visibility
113
Q

Glands of the Eyes

A

Lacrimal glands

  • Contain serous antibacterial enzymes

Superficial glands of the 3rd eyelid

  • Help produce lacrimal secretion
  • Cherry eye is a prolapse of this gland

Deep Gland of 3rd Eyelid

  • Lacrimal gland
114
Q

Ear Organization

A

External Ear

Middle Ear

  • Tympanic membrane transmits vibrations to oval window via ossicles

Inner Ear

  • Impulses generated, transmitted to brain by cochlear nerve for hearing; by vestibular nerve for equilibrium
115
Q

External Ear

A

Ceruminous glands

  • Modified apocrine sweat glands that make cerumen.
116
Q

Middle Ear

A

Tympanic cavity

  • Simple squamous epithelium

Ossicles: 3 small bones in the midle ear

Malleus

Incus

Stapes

Auditory (Eustachian) Tube

  • Line by pseudo stratified columnar epithelium with goblet cells
  • Connects tympanic cavity and pharynx
  • Guttural pouches: In equine, are large diverticuli of the auditory tubes which functon to cool brain during exercise
117
Q

Inner Ear

A

A system of canals and cavities in the petrous temporal bone (osseous labyrinth).

Inside this system is a membranous system (membranous labyrinth)

Osseous Labrynth: 3 Compartments

  1. Vestibule
  2. Utricle (horizontal linear acceleration)
  3. Saccule (vertical linear accleration)
  4. Semicircular canals
    - 2 verticle and 1 horizontal
    - Each canal has a bulge at one extremility “ampulla” where sensory epithelium is located
  5. Cochlea
118
Q

Sensory Epithelium

A

Accleration

rotational accleration - cristae ampullares

Cupula - gelatinous body

horizontal liner accleration - macula utriculus

vertical linear accleration - macula sacculus

  • Otoliths - calcium protein

Vibration

Organ of Corti

119
Q

Cochlea

A

Dorsal - contains perilymph

Middle (scala media) - contains endolymph

Ventral - contains perilymph

120
Q

Scala Media

A

Stria vascularis produces endolymph

Organ of Corti - Has supporting cells and sensory “hair cells”

Tectorial memrane - gelatinous body structure

AP 710 - Microanatomy (2 decks)

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