Biology: Metabolism, Hormones, and Cellular Processes Overview

Anabolism

Building larger molecules from smaller molecules; requires energy.

Anabolic Reactions

Protein synthesis, glycogen synthesis, triglyceride synthesis, and tissue growth.

Energy Requirement of Anabolism

Energy receiving (requires ATP).

Catabolism

Breaking larger molecules into smaller molecules; releases energy.

Catabolic Reactions

Breakdown of carbohydrates, fats, proteins, and glycogen.

Energy Requirement of Catabolism

Energy yielding (produces ATP).

Insulin

An anabolic hormone released by the pancreas that promotes glucose uptake and storage.

Insulin Target Tissues

Liver, skeletal muscle, and adipose tissue.

Growth Hormone (GH)

An anabolic hormone released by the anterior pituitary that stimulates growth and protein synthesis.

Glucagon

A catabolic hormone released by the pancreas that stimulates glycogen breakdown and glucose release.

Glucagon Target Tissue

Liver.

Epinephrine

A catabolic hormone released by the adrenal medulla that increases blood glucose and energy availability.

Epinephrine Target Tissues

Liver, skeletal muscle, and adipose tissue.

Cortisol

A catabolic hormone released by the adrenal cortex that promotes protein and fat breakdown.

Cortisol Target Tissues

Most body tissues, especially liver, muscle, and adipose tissue.

Carbohydrate Catabolism

Glucose → Pyruvate → Acetyl-CoA → Krebs Cycle → Electron Transport Chain → ATP.

Glycolysis

Breakdown of glucose into pyruvate.

Starting Chemical of Glycolysis

Glucose.

Ending Chemical of Glycolysis

Pyruvate.

Glycogenesis

Formation of glycogen from glucose.

Starting Chemical of Glycogenesis

Glucose.

Ending Chemical of Glycogenesis

Glycogen.

Glycogenolysis

Breakdown of glycogen into glucose.

Starting Chemical of Glycogenolysis

Glycogen.

Ending Chemical of Glycogenolysis

Glucose.

Gluconeogenesis

Formation of glucose from non-carbohydrate sources.

Starting Chemicals of Gluconeogenesis

Amino acids, glycerol, and lactate.

Ending Chemical of Gluconeogenesis

Glucose.

Oxidation

Loss of electrons.

Reduction

Gain of electrons.

Redox Reaction

A reaction involving both oxidation and reduction.

NAD and FAD

Electron carriers that transport high-energy electrons to the electron transport chain.

Lipolysis

Breakdown of triglycerides into glycerol and fatty acids.

Starting Chemical of Lipolysis

Triglyceride.

Ending Chemicals of Lipolysis

Glycerol and fatty acids.

Beta-Oxidation

Breakdown of fatty acids into acetyl-CoA.

Starting Chemical of Beta-Oxidation

Fatty acid.

Ending Chemical of Beta-Oxidation

Acetyl-CoA.

Lipid Catabolism Pathway

Triglyceride → Fatty Acids → Acetyl-CoA → Krebs Cycle → Electron Transport Chain → ATP.

Lipogenesis

Formation of triglycerides for storage.

Starting Chemical of Lipogenesis

Acetyl-CoA.

Ending Chemical of Lipogenesis

Triglyceride.

Protein Catabolism

Breakdown of proteins into amino acids.

Starting Chemical of Protein Catabolism

Protein.

Ending Chemical of Protein Catabolism

Amino acids.

Deamination

Removal of an amino group from an amino acid.

Protein Catabolism Pathway

Protein → Amino Acids → Deamination → Krebs Cycle Intermediates/Acetyl-CoA → ATP.

Urea

Nitrogen-containing waste product formed from amino acid metabolism.

Receptor

Specialized cell that detects a stimulus.

Sensory Receptor

Converts a stimulus into a nerve signal.

Sensation

Awareness of a stimulus.

Perception

Interpretation of sensory information.

Mechanoreceptor

Responds to touch, pressure, stretch, or vibration.

Thermoreceptor

Responds to temperature changes.

Chemoreceptor

Responds to chemicals.

Photoreceptor

Responds to light.

Nociceptor

Responds to tissue damage and pain.

Tonic Receptor

Continues firing as long as the stimulus is present.

Phasic Receptor

Adapts quickly and stops responding to constant stimuli.

Receptive Field

Area monitored by a sensory receptor.

Two-Point Discrimination

Ability to distinguish two nearby stimuli.

Receptor Density

Number of receptors in a given area.

Localization

Ability to identify where a stimulus occurs.

Free Nerve Ending

Simple sensory receptor that detects pain and temperature.

Merkel Disc

Touch receptor for fine detail.

Meissner Corpuscle

Receptor for light touch.

Pacinian Corpuscle

Receptor for deep pressure and vibration.

Ruffini Ending

Receptor for skin stretch.

Neural Reflex

Automatic response to a stimulus.

Reflex Arc

Neural pathway of a reflex.

Stimulus

Change that initiates a response.

Sensory (Afferent) Neuron

Carries information to the CNS.

Motor (Efferent) Neuron

Carries commands away from the CNS.

Interneuron

Neuron connecting sensory and motor neurons.

Somatic Reflex

Reflex involving skeletal muscles.

Autonomic Reflex

Reflex involving smooth muscle, cardiac muscle, or glands.

Visceral Reflex

Another name for autonomic reflex.

Spinal Reflex

Reflex integrated in the spinal cord.

Cranial Reflex

Reflex integrated in the brain.

Monosynaptic Reflex

Reflex with one synapse.

Polysynaptic Reflex

Reflex involving interneurons.

Proprioceptor

Receptor that detects body position and movement.

Muscle Spindle

Receptor that detects muscle stretch.

Golgi Tendon Organ (GTO)

Receptor that detects muscle tension.

Alpha Motor Neuron

Stimulates contraction of skeletal muscle fibers.

Gamma Motor Neuron

Maintains sensitivity of muscle spindles.

Stretch Reflex

Muscle contraction caused by muscle stretch.

Muscle Tone

Continuous low-level muscle contraction that helps maintain posture.