Questions and Answers
What is the main function of the Von Ebner Glands?
Which type of lingual papillae is most common and has no taste buds?
What is the surface of the tongue that contains lingual papillae?
What is the function of the tongue during mastication and swallowing?
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What is the characteristic of the epithelium on the ventral surface of the tongue?
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What type of corticoids are mainly secreted by the Zona Fasiculata?
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What is the main function of the cells in the Zona Reticularis?
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What is the characteristic of chromaffin cells in the adrenal medulla?
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What is the function of the pineal gland?
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What is secreted by pinealocytes during the day?
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What is the main function of myelin sheaths in nerve fibers?
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What type of neuroglial cells are found in the PNS?
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What is the main function of ganglia?
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What type of neurons are found in Autonomic ganglia?
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What is the function of the Endoneurium?
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What is the primary function of Pneumocyte type II cells?
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What is the characteristic of the epithelium in the bronchioles?
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What is the effect of asthma on the bronchioles?
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What is the result of hyaline membrane disease?
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What is the result of emphysema?
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What is the main function of the ear pinna?
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What is the characteristic of the epithelium on the cornea?
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What is the function of the choroid?
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What is the characteristic of the ciliary body?
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What is the amount of melanin in the iris pigmented epithelium responsible for?
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What is the primary function of the Malpighian Renal corpuscles?
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Which of the following layers of Bowman's capsule is formed of modified simple squamous cells known as podocytes?
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What is the main function of Mesangial cells?
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What is the main difference between the proximal convoluted tubules and the distal convoluted tubules?
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What is the location of the Juxtaglomerular Complex?
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What type of epithelium lines the vagina?
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What is the function of the stereocilia in the epididymis?
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What type of epithelium lines the ejaculatory duct?
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What is the characteristic of the epithelium covering the penis?
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What is the function of the smooth muscles in the vas deferens?
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Study Notes
Digestive System
- The digestive system includes the gastrointestinal tract (alimentary canal)
- The digestive system consists of the oral cavity, digestive tract, and digestive glands
Oral Cavity
- The oral cavity includes the lips, tongue, palate, and cheeks
- The lips consist of 3 histological regions:
- Outer surface: thin hairy skin with hair follicles, sebaceous, and sweat glands
- Inner surface: mucous membrane with labial muco-serous glands that produce saliva
- Red margin (vermillion): partially keratinized stratified squamous epithelium
Tongue
- The tongue has 2 surfaces:
- Dorsal surface (rough): covered by partially keratinized stratified squamous epithelium with lingual papillae
- Ventral surface (smooth): covered by non-keratinized stratified squamous epithelium
- The tongue has 4 types of lingual papillae:
- Filiform papillae: most common, conical in shape, and have no taste buds
- Fungiform papillae: few in number, reddish in color, and have few taste buds
- Foliate papillae: present on each side of the tongue
- Vallate or circumvallate papillae: 8-12 in number, present in a V-shaped groove, and rich in taste buds
Esophagus
- The esophagus is a 25-cm long muscular tube that connects the oral cavity to the stomach
- The esophagus wall consists of 4 layers:
- Mucosa: non-keratinizing stratified squamous epithelium, lamina propria, and mucous glands
- Submucosa: contains mucous glands (esophageal glands)
- Musculosa: skeletal in upper 1/3, mixed in middle 1/3, and smooth in lower 1/3
- Adventitia: connective tissue covering with blood vessels and lymphatic vessels
Stomach
- The stomach is a sac-like muscular structure extended for digestion
- The stomach is the first station for digestion
- The stomach can be used to detect some diseases:
- Pale red color: may indicate anemia
- Blue color: lack of oxygen in the blood leading to increase carbon dioxide and cyanosis
- Red color: indicates healthy
Taste Buds
- Taste buds are present on the tongue and contain 3 layers
- Each taste bud has:
- Receptor taste cells (sensory nerve-like microvilli for absorption)
- Supporting cells (act as bodyguards)
- Basal cells (act as stem cells for renewal of other 2 cells)
Pituitary Gland
- Consists of two glands: neurohypophysis and adenohypophysis
- Adenohypophysis has three parts: pars distalis, pars intermedia, and pars tuberalis
- Pars distalis has two types of cells: chromophils (acidophils and basophils) and chromophobes
Chromophils
- Acidophils (35%): have acidophilic granules in cytoplasm, produce growth hormone and prolactin
- Basophils (15%): have basophilic granules in cytoplasm, produce TSH, ACTH, MSH, FSH, LH, and ICSH
Chromophobes
- Poorly stained, make up 50% of cells, function as reserve or stem cells
Pars Nervosa
- Consists of unmyelinated nerve fibers, Herring bodies, fenestrated blood capillaries, and pituicytes
- Function: stores and releases oxytocin, involved in sexual reproduction
Thyroid Gland
- Has two lobes connected by a narrow isthmus
- Stroma consists of capsule, C.T septa, and reticular C.T
- Parenchyma consists of secretory cells, producing T3 and T4 hormones
Thyroid Hormone Production
- Follicular cells secrete T3 and T4 hormones
- Parafollicular cells (C cells) secrete calcitonin hormone, which decreases bone osteoclast activity and lowers blood calcium levels
Thyroid Disorders
- Thyrotoxicosis: increased follicular cells and thyroxine secretion
- Iodine deficiency goiter: hypothyroidism due to low iodine in diet
- Myxedema: hypothyroidism leading to fatigue, sleeping, muscular and mental sluggishness
- Graves' disease: autoimmune disease, exophthalmic goiter, and hyperthyroidism
Parathyroid Glands
- Four small glands, behind the thyroid gland
- Stroma consists of capsule, septa, and reticular C.T
- Parenchyma consists of chief cells (secrete parathyroid hormone) and oxyphil cells
Adrenal Glands
- Two glands, one above each kidney, formed of peripheral cortex and central medulla
- Stroma consists of capsule, septa, and reticular C.T
- Parenchyma consists of adrenal cortex and adrenal medulla
Adrenal Cortex
- Divided into three zones: zona glomerulosa, zona fasiculata, and zona reticularis
- Zona glomerulosa: secretes mineral corticoids, mainly aldosterone
- Zona fasiculata: secretes glucocorticoids, mainly cortisone and some aldosterone
- Zona reticularis: secretes androgens, produces all hormones in the ovary after menopause
Adrenal Medulla
- Consists of chromaffin cells and autonomic ganglion cells
- Chromaffin cells: modified sympathetic ganglia cells, secrete epinephrine (80%) or norepinephrine (20%)
- Autonomic ganglion cells: scattered between chromaffin cells, innervated by preganglionic sympathetic neurons
Pineal Gland
- Also known as the third eye, affected by light
- Stroma consists of capsule, septa, and reticular C.T
- Parenchyma consists of pinealocytes, secretes melatonin (at night) and serotonin (precursor of melatonin during the day)
Nervous Tissue
- The nervous system is divided anatomically into:
- Central Nervous System (CNS): Brain and spinal cord
- Peripheral Nervous System (PNS): Cranial, spinal nerves, and ganglia
- There are approximately 10 billion neurons in the nervous system
Neurons
- Neurons are the main cells of the nervous tissue, with stellate shape and long processes
- Neurons have three parts:
- Dendrites: multiple elongated processes that receive impulses
- Soma or cell body: contains single central active nucleus, basophilic cytoplasm, and neurofilaments
- Axon: single elongated process that transmits nerve impulses
- Classification of neurons according to their processes:
- Pseudounipolar: contains a common stem that divides into two branches (central and peripheral)
- Bipolar: contains two processes, an axon and a dendrite
- Multipolar: contains more than two processes
Classification of Neurons by Cell Body Shape
- Pyramidal: pyramidal cells in cerebral cortex
- Pyriform: purkinje cells of cerebellum
- Stellate: AHCs of spinal cord and autonomic ganglia cells
Classification of Neurons by Function
- Sensory neurons: receive stimuli from the environment and conduct them to CNS
- Motor neurons: originate in CNS and conduct impulses to effector organs (muscle and glands)
- Associated neurons (interneurons): connect sensory with motor neurons
Nerve Fibers
- Made up of the axons of neurons
- Most axons are enveloped by myelin sheaths, formed by oligodendrocytes in CNS and Schwann cells in PNS
- Myelin sheath increases nerve impulse conduction through saltatory conduction
- Connective tissue coats (sheaths) surround nerve fibers:
- Epineurium: surrounds the nerve trunk
- Perineurium: surrounds nerve bundles
- Endoneurium: surrounds individual nerve fibers
Neuroglial Cells (Nerve Glue)
- Support and protect neurons
- Divided into:
- Neuroglia of PNS: Schwann cells and satellite cells
- Neuroglia of CNS: Astrocytes, Oligodendroglia, Microglia, and Ependymal cells
Ganglia
- Ovoid structures containing neuronal cell bodies and glial cells (satellite cells) supported by connective tissue
- Types of ganglia:
- Sensory (Spinal) Ganglia: receive peripheral afferent impulses that go to the CNS
- Autonomic ganglia: receive efferent impulses to the effector organs (motor)
Respiratory System
- Nasopharynx connects the nose and mouth to the trachea and is lined by respiratory epithelium (pseudostratified ciliated with goblet cells)
- Oropharynx is continuous with the nasopharynx at the level of the soft palate
Larynx
- Connects the pharynx to the trachea and is supported by hyaline cartilage and striated muscle
- Vocal cords consist of skeletal muscle (vocalis muscle)
- Anterior glottis is covered with stratified squamous epithelium, while the posterior glottis is covered with pseudostratified ciliated epithelium
Epiglottis
- Prevents food from entering the respiratory system
- Made of elastic cartilage and closes off the trachea to prevent inhalation of solids or liquids
Trachea
- Mucosa is lined with respiratory epithelium (pseudostratified ciliated columnar epithelium with goblet cells)
- Submucosa contains many seromucous glands
- Hyaline cartilage is present in the trachea
- Adventitia contains dense connective tissue
Bronchus and Bronchiole
- Bronchus has a longer lumen and is lined with pseudostratified ciliated columnar epithelium
- Bronchiole has a shorter lumen and is lined with ciliated columnar cells and Clara cells
- Present plate of cartilage and mucoserous glands in bronchus, but not in bronchiole
Alveoli
- Pneumocyte type I represents 97% of alveolar wall cells and forms part of the blood gas barrier
- Pneumocyte type II represents 3% of alveolar wall cells and secretes surfactant to decrease surface tension of alveoli
Respiratory Diseases
- Hyaline membrane disease occurs in those who lack adequate pulmonary surfactant and can be prevented by glucocorticoids
- Asthma is caused by constriction of smooth muscle in bronchioles, leading to decreased diameter and treated with drugs that relax bronchiolar smooth muscle
- Emphysema is characterized by destruction of alveolar walls and formation of large cyst-like sacs, reducing the surface area available for gas exchange and decreasing elasticity of the lungs
Ear
- The ear is divided into three main parts: the external ear, the middle ear, and the inner ear.
- The external ear consists of:
- The ear pinna, formed of elastic cartilage covered by thin skin, which directs sound waves to the inside.
- The external auditory meatus, a flattened canal extending from the ear pinna to the tympanic membrane, lined with skin containing hair follicles, sebaceous glands, and ceruminous glands that secrete a brownish semisolid wax.
- The tympanic membrane (ear drum) is covered by simple cubical epithelium and transmits sound vibrations from the outer ear to the bony ossicles of the middle ear.
Eye
- The eye wall consists of three main layers:
- The outer fibrous layer, which is supporting, consisting of:
- Cornea, anterior (stratified squamous non-keratinized) epithelium.
- Sclera, posterior (formed of dense irregular connective tissue).
- The middle vascular layer, which is vascular and pigmented, consisting of:
- Iris.
- Ciliary body.
- Choroid.
- The inner nervous layer, consisting of:
- Retina.
- The outer fibrous layer, which is supporting, consisting of:
- Eye color is determined by the amount of melanin in the iris pigmented epithelium on the back of the iris.
- The ciliary body consists of:
- Two layers of epithelial cells: inner and outer cell layers.
- The inner layer is formed of non-pigmented cells.
- The outer layer is formed of pigmented cells.
- The choroid:
- Has a black color.
- Functions to nourish the outer part of the retina.
Urinary System
- The urinary system consists of two kidneys, two ureters, one urinary bladder, and one urethra.
- The kidneys are responsible for excreting urine (approximately 1500-2000 ml/24 hours) containing metabolic waste products such as urea, creatinine, and uric acid.
Functions of the Kidneys
- Regulate water and electrolyte balance and maintain acid-base balance.
- Produce renin hormone that helps regulate blood pressure.
- Produce erythropoietin hormone that stimulates the production of erythrocytes.
- Hydroxylate vitamin D3 to its active form.
Structure of the Kidney
- The stroma of the kidney consists of a capsule, reticular fibers, and few collagenous bundles.
- The kidney is divided into lobes and lobules.
- The parenchyma of the kidney is formed of urineferous tubules.
Urineferous Tubules
- The cortex (outer) is red in color and contains Malpighian Renal Corpuscles.
- The medulla (inner) is light grey in color and contains medullary rays and collecting tubules.
The Nephron
- The nephron is the functional and structural unit of the kidney.
- Each nephron consists of a Malpighian renal corpuscle, proximal and distal convoluted tubules, and the loop of Henle.
- The Malpighian renal corpuscle forms the glomerular filtrate by the process of dialysis.
Malpighian Renal Corpuscle
- Each corpuscle is formed of Bowman's Capsule, glomerular capillaries, supporting mesangial cells, and afferent and efferent arterioles.
- Bowman's Capsule is a double-walled capsule surrounding the glomerular blood capillaries, formed of two continuous layers of epithelium separated by capsular space.
- The parietal layer is formed of simple squamous epithelium, and the visceral layer is formed of modified simple squamous cells known as podocytes.
Podocytes
- Podocytes have small foot-like processes (pedicles) that form a fenestrated epithelium around the fenestrated capillaries of the glomerulus.
Mesangial Cells
- They are branched cells adherent to the surface of glomerular blood capillaries and act as structural support to podocytes and vessels.
Juxtaglomerular Complex
- Present under the distal convoluted tubule (DCT), fitting between the afferent and efferent arterioles.
Proximal Convoluted Tubules vs. Distal Convoluted Tubules
- Proximal convoluted tubules have a larger diameter, more apical microvilli, and reabsorb water, NaCl, Ca, phosphate, glucose, amino acids, and plasma proteins, while excreting creatinine, iodine, and penicillin.
- Distal convoluted tubules have a smaller diameter, less apical microvilli, and reabsorb water and sodium while excreting sodium, potassium, and ammonium.
Female External Genitalia
- Ovaries are covered by germinal epithelium and divided into cortex and medulla.
- The ovarian cortex is composed of ovarian follicles in various stages of development.
- The ovarian medulla is a richly vascularized fibroelastic connective tissue and hilus cells that secrete androgens.
- If androgens increase in males, it will lead to sterility.
Ovarian Follicles
- Ovarian follicles evolve through four developmental stages: primordial, primary, secondary, and Graafian follicles.
- Primordial follicles are composed of a single layer of flattened follicular cells that surround the primary oocyte.
- Primary follicles have two types: unilaminar and multilaminar, depending on the number of layers of follicular cells that surround the primary oocyte.
- Multilaminar follicles secrete progestron and estrogen under FSH and lipids produce estrogen after menopause.
- Secondary follicles are similar to primary follicles except for the presence of accumulations of liquor folliculi among the granulosa cells.
- Graafian follicles, also known as mature follicles, undergo ovulation and may be as large as the entire ovary.
Ovulation
- Ovulation is the process of releasing the secondary oocyte from the graafian follicle.
- The corpus luteum is formed from the remnants of the graafian follicle and is a temporary endocrine gland that manufactures and releases hormones that support the uterine endometrium.
Oviducts (Fallopian Tubes)
- The oviducts act as a conduit for spermatozoa to reach the primary oocyte and to convey the fertilized egg to the uterus.
- The mucosa of oviduct is simple columnar epithelium partially ciliated and has two types of cells: columnar ciliated cells and peg cells.
Uterus
- The uterus is a muscular organ consisting of a fundus, body, and cervix.
- The uterine wall of the body and the fundus is composed of endometrium, myometrium, and adventitia or serosa.
- The endometrium consists of two layers: a superficial functional layer (shed during menstruation) and a deeper basal layer.
- The myometrium is composed of three smooth muscle layers: inner and outer longitudinal layers, and a middle circular (stratum vascularis) layer.
Cervix
- The cervix is the terminal end of the uterus that protrudes to the vagina.
- The upper cervix (endocervix) is lined by a simple columnar epithelium that contains mucous-secreting cells.
- The lower cervix (ectocervix) is lined by a stratified squamous non-keratinizing epithelium.
Vagina
- The vagina is lined by a stratified squamous non-keratinizing epithelium.
Male External Genitalia
- The male external genitalia include the penis, urethra, and scrotum.
- The internal male genitalia include the testes, epididymis, vas deferens, seminal vesicles, prostate, bulbo-urethral glands, and ejaculatory ducts.
Duct of Epididymis
- The duct of epididymis is lined with pseudo-stratified columnar epithelium with stereocilia that increase the apical surface area.
- The function of the duct of epididymis is absorption and storage of spermatozoa.
Vas Deferens
- The vas deferens is formed of smooth muscles that convey spermatozoa to the ejaculatory duct during ejaculation.
Ejaculatory Duct
- The ejaculatory duct is lined by folded simple columnar epithelium surrounded by connective tissue.
- There is no muscle in the wall of the ejaculatory duct.
Penis
- The penis is surrounded by erectile tissue and covered by keratinized stratified squamous epithelium.
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Description
This quiz covers the different parts of the digestive system, including the oral cavity, digestive tract, and digestive glands. Learn about the functions of the lips, tongue, palate, and cheeks in the digestive process.
