Fungi and Parasites Chapter 13 & 14 PDF

Chapter 13 & 14 of - Fungal diseases human - Parasitic diseases of human Dr. Abdulaziz Hakami Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Fungi Mycology: the study of fungi Chemoheterotrophs –...

Chapter 13 & 14 of - Fungal diseases human - Parasitic diseases of human Dr. Abdulaziz Hakami Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Fungi Mycology: the study of fungi Chemoheterotrophs – Decompose organic matter Aerobic or facultative anaerobic Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Vegetative Structures Molds and fleshy fungi – The fungal thallus (body) consists of hyphae filaments; a mass of hyphae is a mycelium – Septate hyphae: contain cross-walls – Coenocytic hyphae: do not contain septa – Vegetative hyphae obtain nutrients while aerial hyphae are involved with reproduction Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure : Characteristics of Fungal Hyphae Cell wall Pore Nuclei Spore Septum Septate hypha Coenocytic hypha Growth of a hypha from a spore Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Vegetative Structures Yeasts – Nonfilamentous and unicellular – Budding yeasts divide unevenly – Fission yeasts divide evenly Dimorphic fungi – Yeastlike at 37°-C and moldlike at 25°-C Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure : A Budding Yeast Parent cell Bud Bud scar Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Life Cycle Fungi reproduce sexually and asexually via the formation of spores that detach from the parent and germinate into a new mold. Asexual spores – Produced via mitosis and cell division; formed by the hyphae of one organism Sexual spores – Fusion of nuclei from two opposite mating strains Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Fungal Diseases Mycosis: fungal infection Systemic mycoses: deep within the body Subcutaneous mycoses: beneath the skin Cutaneous mycoses: affect hair, skin, and nails Superficial mycoses: localized (e.g., hair shafts) Opportunistic mycoses: fungi harmless in normal habitat but pathogenic in a compromised host Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Protozoa Unicellular eukaryotes Inhabit water and soil Animal-like nutrition Complex life cycles Feeding and growing form is a trophozoite Asexual reproduction is by fission, budding, or schizogony (multiple fission) Sexual reproduction is by conjugation Some produce a cyst to survive adverse conditions Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure : Conjugation in the Ciliate Protozoan Paramecium Macronucleus Micronucleus Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Medically Important Protozoa Feeding grooves (Excavata) – Diplomonads – Parabasalids – Euglenozoa Amebae Apicomplexa Ciliates Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Amebae Move by extending pseudopods Entamoeba histolytica—causes amebic dysentery Acanthamoeba—infects corneas and causes blindness Balamuthia—granulomatous amebic encephalitis Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Food vacuole Pseudopods Figure : Amebae Nucleus Amoeba proteus Red blood cells Nucleus Entamoeba histolytica Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Apicomplexa Nonmotile Obligate intracellular parasites Complex life cycles Toxoplasma gondii—transmitted by cats; causes fetal infections Cryptosporidium—transmitted via feces; causes waterborne illness Copyright © 2021 Pearson Education Ltd. All Rights Reserved Clinical Focus Sporozoite Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Apicomplexa Plasmodium—causes malaria – Sexually reproduces in the Anopheles mosquito – A mosquito injects a sporozoite into its bite, and the sporozoite undergoes schizogony in the liver; merozoites are produced – Merozoites infect red blood cells, forming a ring stage inside the cell – Red blood cells rupture, and merozoites infect new red blood cells Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Ciliates Move by cilia arranged in precise rows Balantidium coli is the only human parasite; causes dysentery Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Pellicle Cytostome Food vacuoles Cilia Figure : Ciliates Contractile vacuole Macronucleus Micronucleus Anal pore Paramecium Cytostome Cilia Stalk Vorticella Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Helminths Parasitic worms Two phyla: – Platyhelminthes (flatworms) – Nematoda (roundworms) Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Platyhelminths Trematodes (flukes) – Flat, leaf-shaped – Ventral and oral sucker – Absorb food through cuticle covering – Paragonimus spp.—lung fluke – Schistosoma—blood fluke Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Platyhelminths Cestodes (tapeworms) – Scolex—head that has suckers for attachment – Absorb food through cuticle – Proglottids—body segments; contain male and female reproductive organs Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Scolex Figure : General Hooks Anatomy of an Adult Tapeworm Sucker Neck Testis Genital pore Ovary Mature proglottid will disintegrate and release eggs Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Cestodes Humans as definitive hosts – Eggs from proglottids are ingested, hatch into larvae, and bore into the intestinal wall – Produce cysticerci – Taenia solium—pork tapeworm Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Cestodes Humans as intermediate hosts – Eggs are ingested and hatch in the intestine – Larvae migrate to the liver or lungs and develop a hydatid cyst – Echinococcus granulosus Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Nematodes Roundworms – Cylindrical; complete digestive system – Dioecious; males contain spicules – Free-living and parasitic Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Nematodes Eggs infective for humans – Ascaris lumbricoides—infects human intestines – Baylisascaris procyonis—raccoon roundworm – Trichuris trichiura—whipworm – Enterobius vermicularis—pinworm Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure :The Pinworm, Enterobius vermicularis Mouth Intestine Mouth Ovary Genital pore Anus Intestine Testis Egg Spicules (55µm Genital long) pore Anus Female Male Larva Adult pinworm (8–13 mm long) (2–5 mm long) Pinworm egg Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Nematodes Larvae infective for humans – Strongyloides—reemerging infection – Necator americanus and Ancylostoma duodenale— hookworms; enter the skin and are carried to the intestines – Dirofilaria immitis—spread by mosquitoes; causes heartworm Copyright © 2021 Pearson Education Ltd. All Rights Reserved Thank you Copyright © 2021 Pearson Education Ltd. All Rights Reserved