5: How Cells Sense their Environment
- Page ID
- 165595
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 5.2: Passive Transport
- This page covers membrane permeability and factors affecting biological diffusion rates, emphasizing selective permeability in plasma membranes, passive transport mechanisms like diffusion and osmosis, and their dependence on concentration gradients and molecular properties. It highlights filtration in the kidneys, explaining how blood pressure affects solute movement, and details how osmosis specifically involves water movement driven by solute concentration.
- 5.3: Facilitated Transport
- This page explains facilitated diffusion as a passive transport mechanism enabling polar molecules and ions to traverse the plasma membrane via integral membrane proteins. It highlights the roles of channel proteins, which provide rapid pathways, and carrier proteins, which are slower and specific due to their conformational changes. This process influences cellular selectivity and efficiency, exemplified in renal glucose reabsorption.
- 5.4: Active Transport
- This page explains active transport in cells, emphasizing its energy requirement (ATP) for moving substances against concentration gradients. It covers primary and secondary active transport, integral proteins' roles, and processes like endocytosis (phagocytosis and pinocytosis) for intake, and exocytosis for waste expulsion. The discussion includes defects impacting health, such as familial hypercholesterolemia, and defines key terms for clarity.
- 5.5: Cell Communication
- This page covers cellular communication through signaling, vital for organism health, highlighting four types: autocrine, paracrine, direct, and endocrine. It explains how receptors detect ligands, influencing responses via internal or cell-surface receptors, including ion channel-linked, G-protein-coupled, and enzyme-linked receptors.
- 5.6: Cell Response
- This page covers the regulation of cellular processes by signaling pathways, including gene expression, metabolism, growth, and apoptosis. It describes how ligands activate signal transduction through intracellular entry or receptor binding, highlighting examples like ERK and cAMP. The section also discusses growth factors' role in cell division and the importance of apoptosis in eliminating unnecessary cells.
- 5.1: Components of Plasma Membranes
- This page discusses the plasma membrane, a vital structure that serves as a protective barrier for cells. Composed primarily of a phospholipid bilayer, proteins, and carbohydrates, it regulates substance movement and facilitates cell communication through various mechanisms, including passive and active transport. The dynamic nature of the membrane, described by the fluid mosaic model, highlights its complexity and functional asymmetry.