The Cell Membrane

The cell membrane:

1. Phospholipid Bilayer
2. Membrane Proteins

Types of Membrane Proteins

1. Transport Proteins
2. Receptor Proteins
3. Enzymes
4. Joining Proteins
5. Identifying Proteins

Carrier

 A transmembrane protein that changes shape to envelop and transport a polar substance across the cell membrane

Channel

A transmembrane protein that helps form aqueous channels that transport substances from one side of the membrane to the other

Receptor Protein

A protein that binds specifically with other molecules, e.g., neurotransmitters, hormones, paracrines, antigens

Enzyme

Facilitated Diffusion

Osmosis

Simple Diffusion

Osmotic Pressure

Tonicity

Hypertonic Solution

Hypotonic Solution

Isotonic Solution

Gated Ion Channels

Gated ion channels can open in response to:

1. Membrane voltage changes
2. Chemical changes
3. Other stimuli

Active Transport

Membrane transport processes for which ATP is provided, e.g., solute pumping and endocytosis.

Vesicular Transport

Endocytosis

Exocytosis

Pinocytosis

Phagocytosis

Resting Membrane Potential

Concentration Gradient

Electrochemical Gradient

Membrane Potential

Primary Active Transport

Sodium-Potassium Pump

Hyperpolarization

Depolarization

Where do Graded Potentials usually occur?

Graded Potential

Where are action potentials generated?

Action Potentials

A large transient depolarization event, including polarity reversal, that is conducted along the membrane of a muscle cell or a nerve fiber.

A long-distance regenerative electrical signal transmitted along an axon. The action potential is an all-or-none event. Also called a nerve impulse, spike, or discharge.

Where are Action Potentials generated?

Threshold

A critical level of membrane potential at which the depolarization process becomes regenerative and the cell generates an action potential.

Absolute Refractory Period

The period of time following an action potential when an excitable cell cannot generate another action potential no matter how large a stimulus it receives.

Relative Refractory Period

The period of time following an action potential when an excitable cell can generate another action potential only if it receives a stimulus stronger than normal (i.e., more positive than its normal threshold).

Propagation

In physiology, the process of reproducing and spreading the action potential along the sarcolemma and down the T tubules.

Determinants of the Rate of Propagation

1. Fiber Diameter
2. Whether the fiber is myelinated or unmyelinated

Saltatory Conduction

The process by which an action potential appears to jump from one node of Ranvier to the next along a myelinated axon.

Excitatory PSPs

A local, graded, depolarization of an excitable cell. Function is to generate an action potential in the postsynaptic cell.

Inhibitory PSPs

A local, graded, hyperpolarization of an excitable cell. Functions to prevent generation of an action potential in a postsynaptic cell.

Somatic Reflex

Visceral Reflex

Ipsilateral

Monosynaptic

Polysynaptic

Contralateral

Neuromuscular Junction

Phasic Receptors

These show adaptation.

Receptor Potential

Functions of: Midbrain

• Auditory and Visual Reflexes
• Movement of eyes, head, or neck in response to visual or auditory stimuli

Functions of: Pons

• Functions with the medulla oblongata to regulate breathing
• Sets the rhythm of breathing

Functions of: Medulla Oblongata

• Vital Reflex centers: respiratory area, vasomotor area, cardiac centers
• Non-Vital Reflex centers: swallowing, vomiting, coughing, sneezing

Overall Function of the Brainstem

• It controls life-sustaining processes, for example, breathing and circulation

Functions of the Hypothalamus

• 1) Regulates the ANS (Smooth, cardiac muscle, and glands)
• 2) Regulates Endocrine System
• 3) Regulates Temperature
• 4) Regulates Eating and Drinking
• 5) Part of the Limbic System (emotional brain)
• 6) Coordinates the reticular Activating System
• 7) Recieves sensory input from cutaneous receptors of the nipples and external genitalia

Sympathetic Nervous System

Autonomic Nervous System (ANS)

Efferent division of the peripheral nervous system that innervates cardiac and smooth muscles and glands; also called the involuntary or visceral motor system.

Sympathetic Nervous System Neurons

Preganglionic Neurons: Cholinergic

Postganglionic Neurons: Anrenergic or Cholinergic

Parasympathetic Nervous System Neurons

Somatic Nervous System

Three Types of Movement in Somatic Nervous System

1) Reflexes: Spinal & Postural

2) Voluntary

3) Rhythmic

Prefrontal Cortex

Wernicke's Area

Broca's Area

Second Messenger

cAMP (Cyclic AMP)

Intracellular second messenger that mediates the effects of the first (extracellular) messenger (hormone or neurotransmitter), formed from ATP by a plasma membrane enzyme (adenylate cyclase)

G Protein

Luteinizing Hormone

Follicle-Stimulating Hormone (FSH)

Hormone produced by the anterior pituitary that stimulates ovarian follicle production in females and sperm production in males.

Progesterone

Anabolism

Catabolism

DNA Transcription

One of the two major steps in the transfer of genetic code information involving the transfer of information from a DNA gene's base sequence to the complementary base sequence of an mRNA molecule.

Translation

Lysosomes

ATP

Organic molecule that stores and releases chemical energy for use in body cells.

Cellular Respiration

Glycogen

Skeletal System Functions

1. Support
2. Protection of vital organs
3. Attaches muscles allowing movement
4. Contains bone marrow (red & white blood cell production)
5. Store calcium

Fontanels

Endochondral Ossification

Factors Affecting Bone Growth and Remodelling

1. Mechanical Stress
2. Nutrition

Callus

Muscular Characteristics

• A) Excitable - respond to stimuli
• B) Contractile - can shorten and tigthen
• C) Extensible - stretch when they are pulled
• D) Elastic - return to original shape after contraction or extension

Motor Unit

A motor neuron and all of the muscle cells it stimulates.

Neuromuscular junction

Synapse between a motor neuron and skeletal muscle fiber. The muscle cell and motor neuron do not actually touch, but are separated by the synaptic cleft.

Motor end plate

The folded portion of the sarcolemma in close contact with the synaptic ending of the axon terminal.

Sliding Filament Theory

The current theory of how a muscle cell contacts. This theory states that the contraction of a muscle cell occurs as the thin filaments slide past the thick filaments. The sarcomere shortens as the thin and thick filament overlap to a greater degree.

Five molecules involved in sliding filament theory

1. Myosin
2. Tropomyosin
3. Actin
4. ATP
5. Troponin
6. Also calcium ions

Crossbridge

A structure formed by the globular head of the myosin protein of the thick filament when it attaches to the thin filament during muscle contraction. Flexing the cross bridge moves the thin filament toward the center of the sarcomere.

Power Stroke

The flexing movement of the myosin cross bridge that pulls the thin filament inward toward the center of the sarcomere.

Role of ATP in Muscle Contraction

1. Activation of Myosin
2. Crossbridge Release
3. Pumping Ca+2 into SR
4. Maintaining the Na+/K+ - ATPase activity in muscle cell (Na+/K+ gradients)

Tension

The force produced by a muscle in order to perform work.

Negative Feedback Mechanisms

Factors Effecting Muscle Tension in Muscle Fibers

1. Effect of Frequency of Stimulation on Muscle Fiber
2. Fiber types in a muscle differ
3. Effects of Fiber length on tension development
4. The size of the fiber
5. Fatigue

Muscle Twitch

A single, rapid contraction of a muscle in response to a stimulus of adequate strength. In vivo, a muscle’s contraction is usually in response to multiple stimulations rather than a single impulse.

Wave Summation

Phenomenon seen when another stimulus is applied to a muscle before the previous relaxation period is complete, resulting in a stronger contraction. In muscle physiology, also called wave summation. May be due to more calcium in stimulated muscle cells.

Treppe

At first when a muscle is stimulated frequently, each muscle twitch shows a slight increase in strength of contraction and complete relaxation. The increase is not due to summation but may due to increased muscle warming and efficiency of enzymes.

Incomplete Tetanus

A condition of rapid, shortened contraction/relaxation cycles resulting from increased frequency of stimulation. Some degree of cyclical relaxation is visible. Also called unfused tetanus.

Complete Tetanus

The condition in which rapid multiple stimulations cause the contraction/relaxation cycles to fuse into a total contraction without evidence of any cyclical relaxation.

Fast Fibers

White muscle fibers. Large in diameter; light in color due to reduced myoglobin; surrounded by few capillaries; relatively few mitochondria; mainly use glycolysis to synthesize ATP; quick and powerful but fatigue rapidly; fast cross bridge cycling.

Slow Fibers

Red muscle fibers. Half the diameter of white muscle fibers; red due to myoglobin; many capillaries; numerous mitochondria; mainly uses Krebs cycle and oxidative phosphorylation to make ATP; fatigue resistant; high-endurance; slow cross bridge cycling.

Isometric

A muscle contraction in which cross bridge cycling is activated and tension is developed, but the length of the muscle does not change.

Physiology

is the study of how the body functions

Homeostasis

A state of body equilibrium or stable internal environment of the body.

Regulation of Homeostasis

1. Change in internal environment must be detected (or anticipate)
2. Nervous system and/or endocrine response alters a system(s) that are responsible for that condition.

Proprioceptors

Sensory receptors located in muscles and joints that respond to changes in body position and movement.

Positive Feedback Mechanism