TABLE OF CONTENTS
KEY CONCEPTS IN THIS LECTURE 1. The "Cell Theory" states the basic unit of life is the cell and that all organisms consist of at least one cell. Some cells, such as neurons, are highly specialized for a specific function (=communication). Tissues are aggregations of cells with a certain function, and organs are structures made from multiple tissues. Several organs form a body system which serves a specific function, such as communication (nervous system) or movement (muscular system). 2. All cells and organisms are capable of regulating their internal environment to some extent. This is often achieved by various homeostatic mechanisms. Two common mechanisms are positive and negative feedback 3. Each cell has certain requirements for survival, such as catabolism of food and in most cases reproduction. The cell consists of a nucleus which houses the DNA and the cytoplasm where most cellular processing occurs. Each organelle in the cytoplasm has a specific function associated with synthesis/absorption/secretion (ER, lysosomes, Golgi, ribosomes), support/movement (microtubules, microfilaments), or energetics (mitochondrion). 4. Cellular work is achieved coupled reactions and the utilization of ATP, a high energy phosphate compound. Although some ATP is produced directly in a chemical reaction, most ATP are synthesized by electron transport in the mitochondrion. Nerve cells obtain ATP only through glucose catabolism in the presence of oxygen. LECTURE OUTLINE I. INTRODUCTION TO THE CELL
A. Levels of biological organization.
cell --> tissue --> organ --> body system --> individual
B. Cell and Cell Theory
1. The cell is the basic unit of life
2. Organisms consist of at least one cell
3. Some cells have a special function (neurons communicate information)
4. Cells come from preexisting cells
C. Some cellular requirements.
1. Example: The neuron is a cell
1) A neuron has dendrites, an axon, a soma, and a terminal
2) There are unipolar, bipolar and multipolar neurons (Figs. 2-1, 2-2)
D. TISSUES
1. General tissue types and their function.
2. There are four types of animal tissue. Two are important for this course.
a. Muscle (function is movement, excitable tissue, contains
actin & myosin which make contraction and behavior possible)
e. Nervous (excitable tissue, function is communication and
regulation, consists of fibers carrying information to a
distant site)
D. ORGANS
1. Various tissues cooperate to form an organ which has a particular
function in the body. Example: the brain
E. BODY SYSTEMS
1. A number of organs form an body system--each body system has a
specific function and most contribute to achieving homeostasis.
a. There are 11 body systems. Examples: Nervous system &
Endocrine System
b. Each body system helps maintain a homeostatic cellular state.
In what way?
II. GENERAL REGULATORY MECHANISMS
A. What general mechanisms regulate function at a constant level for the most part?
That is, what are the basic mechanisms which make HOMEOSTASIS a reality?
B. There are two general mechanisms.
1. NEGATIVE FEEDBACK (common)
Example: Control of hunger
2. POSITIVE FEEDBACK. What changes is the sign (from - to +)
a. Example: Movement of Na+ into the nerve
1) Positive feedback mechanisms quickly accelerate once started.
III. STRUCTURE/FUNCTION OF THE NERVE CELL
A. A nerve cell is composed of three major components:
1. Plasma membrane
2. Nucleus. Contains the DNA. This is the genetic code for all of the
traits expressed by the cell, including the codes for all of the enzymes
that drive cellular synthesis and metabolism.
3. Cytoplasm contains organelles.
B. Organelles in the cytoplasm of a nerve cell.
Cytoplasmic organelles can be grouped by cellular function:
--synthesis, absorption or secretion
--support or movement
--energetics
1. Organelles Associated with Synthesis, Absorption, or Secretion.
a. Endoplasmic reticulum (ER)
1) Rough ER verses Smooth ER
b. Golgi (= Cisterna in nerve terminal)
c. Secretion occurs by exocytosis (Animation)
1) Synaptic vesicle
a) Roles of docking proteins and Ca++
d. Absorption into a neuron occurs via a transporter or endocytosis
(LDL Animation)
2. Organelles associated with support or movement.
a. Microfilaments, such as actin
b. Microtubules
1) Large protein complexes made from units of tubulin.
2) Kinesin, a "motor molecule," travels along microtubules (Animation)
3. Organelle associated with cellular energetics
a. Mitochondria
IV. CELLULAR METABOLISM and ENERGETICS
Metabolism is the sum of the chemical processes that occur in a cell.
A. Some Basics of Energetics
1. At the cellular level this involves thousands of individual reactions
a. All of which are involved in 1) energy transfer and 2) some
energy loss
2. ATP = ADP + P + energy (-7kcal).
a. Energy transfer occurs by a coupled reaction
Example 1: ATP + inactive kinase -> ADP + Kinase-PO4
Example 2: Creatine phosphate stores high energy bonds in skeletal muscle
3. Cell Metabolism Overview: Food + O2 + ADP --> ATP + H2O + CO2 + Heat (entropy)
4. The ultimate source of energy is in the food we eat.
a. Carbohydrates (sugars, starches, and glycogen)
b. Fats (fatty acids and glycerol, an alcohol)
c. Protein (strings of amino acids)
B. Food catabolism provides the energy to synthesize ATP
1. Glycolysis, Kreb's Cycle & Electron Transport System (ETS)
2. Most of the ATP is formed in the mitochondria by the ETS but some is formed
from substrate phosphorylation
3. Some metabolism occurs in the absence of Oxygen (anaerobic metabolism)
a. Glycogen breakdown to lactic acid
b. Nerves only ultilize glucose and require Oxygen
Electron
Transport and
ATP synthesis animations from the University of Connecticut.
Tissues and Homeostasis. A slide show describing various tissues and a brief description of homeostasis.
Go to: |
