Download presentation
Presentation is loading. Please wait.
1
Chapter 3: Cell Anatomy and Cell Junctions
Pages 62-75 © 2015 Pearson Education, Inc.
2
Anatomy and Physiology of Cells
It is important to know the organelles within the cell and to understand the general functions of each Organelles > cell Organs > system Organ systems > human body © 2015 Pearson Education, Inc.
3
Summary of Organelles and their Functions
Nucleus = control center; houses DNA Plasma Membrane = selective; boundary Ribosomes = site of protein synthesis Mitochondria = site of cellular respiration Endoplasmic Reticulum = transportation network Rough = finalizing protein synthesis - folding Smooth = fat metabolism and detoxing Golgi Bodies =protein packaging; become vesicles Vesicles = move products via endocytosis/exocytosis Lysosomes = garbage crew Peroxisomes = detoxification/neutralizers Cytoskeleton = structural organelle Centrioles =direct cell division via mitotic spindle
4
Figure 3.4 Structure of the generalized cell.
Chromatin Smooth endoplasmic reticulum Nuclear envelope Nucleolus Nucleus Plasma membrane Lysosome Mitochondrion Rough endoplasmic reticulum Centrioles Ribosomes Golgi apparatus Secretion being released from cell by exocytosis Peroxisome
5
“How do cells stick together?”
Plasma Membrane Junctions Cells are bound together in three ways: Glycoproteins act as an adhesive or cellular glue Wavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion Special membrane junctions are formed, which vary structurally depending on their roles 3 different junctions © 2015 Pearson Education, Inc.
6
Figure 3.2 Structure of the plasma membrane.
Extracellular fluid (watery environment) Glycoprotein Glycolipid Cholesterol Sugar group Polar heads of phospholipid molecules Bimolecular lipid layer containing proteins Channel Nonpolar tails of phospholipid molecules Proteins Filaments of cytoskeleton Cytoplasm (watery environment)
7
Tight (impermeable) junction
Figure 3.3 Cell junctions. Microvilli Tight (impermeable) junction Desmosome (anchoring junction) Plasma membranes of adjacent cells Connexon Underlying basement membrane Extracellular space between cells Gap (communicating) junction
8
TIGHT JUNCTIONS Tight junctions
Impermeable junctions made up of the plasma membrane Bind cells together into leakproof sheets Prevent substances from passing through extracellular space between cells © 2015 Pearson Education, Inc.
9
DESMOSOMES Desmosomes
Anchoring junctions that prevent cells from being pulled as a result of mechanical stress Created by “buttonlike” thickenings of adjacent plasma membranes kind of like the rivets in the pockets of your jeans- they keep the material together © 2015 Pearson Education, Inc.
10
GAP JUNCTIONS Gap junctions
allow direct diffusion of ions and small molecules between adjacent cells Hollow cylinders of proteins (connexons) function like tunnels to send messages Molecules can travel directly from one cell to the next through these channels © 2015 Pearson Education, Inc.
11
Tight (impermeable) junction
Figure 3.3 Cell junctions. Microvilli Tight (impermeable) junction Desmosome (anchoring junction) Plasma membranes of adjacent cells Connexon Underlying basement membrane Extracellular space between cells Gap (communicating) junction
12
Exocytosis/Endocytosis review
Active Transport of bulk materials Endocytosis: Plasma membrane engulfs product from extracellular space to bring into cell Becomes travelling vesicle inside cell Exocytosis: Vesicle from inside the cell fuses with plasma membrane to dump contents outside of cell
13
Plasma membrane SNARE (t-SNARE)
Figure 3.12 Exocytosis. Extracellular fluid Plasma membrane SNARE (t-SNARE) 1 The membrane- bound vesicle migrates to the plasma membrane. Vesicle SNARE (v-SNARE) Molecule to be secreted Secretory vesicle Cytoplasm Fusion pore formed 2 There, v-SNAREs bind with t-SNAREs, the vesicle and plasma membrane fuse, and a pore opens up. Fused SNAREs Vesicle contents are released to the cell exterior. 3 (b) Electron micrograph of a secretory vesicle in exocytosis (190,000×) (a) The process of exocytosis
14
Figure 3.13a Events and types of endocytosis.
Extracellular fluid Cytosol Plasma membrane Vesicle Lysosome Vesicle fusing with lysosome for digestion 1 Release of contents to cytosol 2 Transport to plasma membrane and exocytosis of vesicle contents Detached vesicle Ingested substance 3 Membranes and receptors (if present) recycled to plasma membrane Pit (a)
15
Cell Extensions Cilia: whiplike extensions
Propels substances along passageways Found in respiratory passageways, uterine tubes, kidneys, inner ear Flagella: longer whiplike extensions Propels the cell The sperm is the only flagellated cell in the human Microvilli: extensions of cell membrane Increases cell surface area (often for absorption) Found along entire small intestine; large numbers along the proximal convoluted tubule in the nephron
16
Figure 14.7 Structural modifications of the small intestine.
Blood vessels serving the small intestine Microvilli (brush border) Muscle layers Lumen Circular folds (plicae circulares) Villi Absorptive cells Lacteal (c) Absorptive cells Villus (a) Small intestine Blood capillaries Lymphoid tissue Intestinal crypt Muscularis mucosae Venule Lymphatic vessel Submucosa (b) Villi
17
Figure 3.8g Cell diversity.
Nucleus Flagellum Sperm (g) Cell of reproduction
18
Cell Diversity Cells can vary in structure and function
Variations include: Modified shape More of a particular organelle Modified organelles
19
Specialized Function of cells
Cells are classified based on their structure and function This is known as Histology the study of the structure of cells and their formation into tissues and organs An Histologist can identify abnormalities in tissues obtained from cultures/biopsies
20
Body Tissues Epithelial Connective Muscular Nervous Secrete and aborb
Hold structures together, store nutrients Muscular Movement Nervous communication
21
Figure 3.8b Cell diversity.
EPITHELIAL Nucleus Epithelial cells Intermediate filaments
22
Figure 3.8c Cell diversity.
MUSCULAR Skeletal muscle cell Nuclei Contractile filaments Smooth muscle cells
23
Figure 3.8a Cell diversity.
CONNECTIVE Fibroblasts Rough ER and Golgi apparatus No organelles Nucleus Erythrocytes
24
Figure 3.8f Cell diversity.
NERVOUS Processes Rough ER Nerve cell Nucleus
Similar presentations
