Tissues Flashcards
Epithelial tissues in general
Epithelial cell layer on surface (avascular)
Basal lamina (ECM) and a reticular lamina compose the basement membrane.
Connective tissue
Little ECM and often junctional specialization (tight junctions, desmosomes and gap junctions)
Frequent cell division because of exposure to exterior/lumen (called free surface)
Simple squamous
Thin = adapted for diffusion (gas, blood, waste, nutrients), filtration (urine in kidney glomeruli) and secretion (lubricating of lining body cavities)
Alveoli lungs, kidney glomeruli (bowman’s capsule), lining heart, blood/lymphatic vessels.
Simple cuboidal
Secretion and absorption
Kidney tubules, small glands, ovary
Simple columnar
Ciliated= secretion/moving of mucus.
Small bronchi, uterine tubes, uterus.
Non-ciliated= contain microvilli = high absorption. Absorption and secretion in GI tract
Simple pseudostratified
Ciliated= Secretion and propulsion of mucus
Trachea, bronchi, respiratory tract.
Non-ciliated= Lining of male urethra
Stratified squamous
Thickest of all epithelia = protection
Keratinized= retains water, protects against friction and bacteria. Skin epidermis
Non-keratinized= Lining of wet surfaces like epiglottis, vestibule of mouth, tongue, esophagus, vagina
Stratified cuboidal
Protection
Largest ducts of sweat glands, mammary glands, salivary glands and urethra.
Stratified columnar
Protection and secretion
Very rare! Lines urethra, Large ducts of some glands and portion of conjunctiva of the eye
Stratified transitional
Lining of organs that stretch like bladder, ureters and urethra. Urinary organs
Stratified epithelium will be called accordingly
To the layer closest to free surface (lumen)
Glandular epithelium
Endocrine: No free surface, secrete Hormones into Blood, most of endocrine glands are epithelial derivatives formed by invagination and during embryo development they lose their ducts.
Exocrine: Release products onto free surface (skin or lumen) like GI, respiratory or reproductive tract.
1. Merocrine: no part of cell is lost (salivary)
2. Apocrine: top of cell is lost with secretion (mammary)
3. Holocrine: whole cell detaches with secretion (sebaceous)
Hypothalamus
Endocrine Master gland: Control center, controls anterior pituitary gland hormones
Anterior pituitary
Endocrine gland.
TSH: thyroid stimulating hormone: stimulate thyroid to produce Thyroxine (T4) and triiodothyronine (T3): brain development, metabolism, reproduction.
ACTH: adrenocorticotropic hormone: stimulates cortisol secretion from adrenal cortex
GH: growth hormone
FSH: follicle stimulating hormone and LH luteinizing hormone: act on gonads, growth of follicle, ovulation, stimulation of testosterone, fsh in male, androgen binding protein expression BREF sexual cell stimulation!
PRL: prolactin: milk synthesis from mammary glands
MSH: melanocyte stimulating hormone
Posterior pituitary
ADH/vasopressine: acts on kidney, water retention
Oxytocin- milk let down and uterine contraction during delivery
Smaller endocrine glands (other glands)
Pineal gland: produces melatonin, sleep
Thyroid gland: produces T3,T4, calcitonin. To decrease plasma, controls energy metabolism.
Adrenal cortex: mineralocorticoid like aldosterone (water retention), corticosteroids (increases bp and blood sugar and reduces immune responses, case of stress) and androgens for sex steroids
Adrenal medulla epinephrine and norepinephrine: stress adaptation
Pancreas: insulin, glucagon, somatostatin: nutrient utilization
Gonads: produces testosterone estrogen and progesterone.
General functions of connective tissues.
- Support, binding. ex: Bone, cartilage, ligaments, tendons, connective tissue around other types of tissues.
- Protection, defense, repair. Ex: Scar tissue, skull.
- Insulation: fat cells (adipocytes).
- Transportation. Blood cells.
ECM is made of
Ground substance: mineralized (bone), gelatinous(loose,dense, cartilage, adipose), watery (blood). Made of proteoglycans (polysaccharide groups on proteins allow to trap more or less water) and cell adhesion proteins (attach cells to ECM)
Protein fibers: fibronectin reticular (connect cells to ECM and support organs), fibrilin reticular (forms filaments and sheets to support organs), elastin (strech, yellow), collagen (stif but flexible, shiny white)
Fibroblasts
cells that secrete ECM in connective tissue proper
Chondroblasts
cells that secrete ECM in cartilage. 3 types of cartilage: hyaline (most common,looks like shiny eyes looking at us oo), elastic(elastic fibers), fibrocartilage(collagen fibers). Hyaline cartilage is repaired by fibrocartilage scar tissues.
Osteoblasts
cells that secrete ECM in bone
Hemocytoblasts
cells that secrete ECM in blood
Blood composition
Cells: RBCs (no nucleus), monocyte(neutrophils, moonshaped shadow), lymphocytes (type of WBCs, smaller), eosinophils (2 nuclei)
ECM: water
Loose connective tissue
Cells: fibroblasts.
ECM: more ground substance than fibers (collagen, elastic, reticular)
Skin, around blood vessels, organs, under eptithelia
Dense irregular connective tissue
Cells: fibroblasts
ECM: more fibers (random collagen) than ground substance
Muscle, nerve sheats
Dense regular connective tissue
Cells: fibroblasts
ECM: more fibers (parallel collagen) than ground substance
Tendons, ligaments
Adipose tissue
Cells: adipocytes (brown and white)
ECM: little ground substance and no fiber
Cartilage
Cells: chondroblasts
ECM: ground substance is hyaluronic acid (firm/flexible) and fibers are collagen
Bone
Cells: osteoblasts and osteocytes
ECM: ground substance is mineralized (calcium salts) and fibers are collagen
In general, ECM is made of
proteoglycans, fibrous proteins, glycosoaminoglycans
What is transcytosis
Transcytosis= endocytosis followed by exocytosis of the same substance.
Common muscle tissue characteristics
- Well vascularized
- Many cells close together
- Elongated
- Contains myofilaments (contractile proteins)
Skeletal muscle tissue
Rod-like cells. Striations perpendicular to axis of cells. Several nuclei on periphery of cell. Always generate heat (imp for body temperature)
Cardiac muscle tissue
one of many nuclei but always in middle of cell. Striations perpendicular to cell. Intercalated discs for impulse. Found in heart only
Smooth muscle tissue
One nucleus in middle of cell. No striation. Spindle shaped-cells. Found in hollow organs
Nervous tissue
Made of
Neurons: conduct electrical impulse. Only in grey matter. Made of cell body, dendrites (receive stimuli) and axons (generate nerve impulse and transmit).
Glial cells: support neurons. In grey and white matter.
Nervous tissue are found in brain, spinal cords and nerves.
