Core Concepts in Anatomy & Physiology: Study Guide

Study Guide - Smart Notes

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Homeostasis

Definition and Mechanisms

Homeostasis refers to the maintenance of a stable internal environment within an organism, despite changes in external conditions.

Feedback loops are essential for homeostatic control, especially negative feedback loops that counteract deviations from a set point.
Homeostasis does not keep conditions static, but rather regulates internal variables within a narrow range.
Adaptation through the nervous system is a key aspect, but not the sole mechanism.

Example: Regulation of body temperature via sweating or shivering.

Biomolecules

Hydrocarbons and Biological Examples

Hydrocarbons are organic compounds consisting entirely of hydrogen and carbon.

Amino acids are not hydrocarbons; they contain additional functional groups such as amine and carboxyl.
Common biological hydrocarbons include cholesterol and other lipids.

Example: Fatty acids are long hydrocarbon chains.

Cell Junctions

Types and Functions

Cell junctions are specialized structures that connect adjacent cells and facilitate communication and structural integrity.

Gap junctions are composed of connexins and allow direct cytoplasmic exchange of ions and small molecules, enabling coordinated cellular responses.
Tight junctions (claudins, occludins) prevent passage of molecules between cells.
Desmosomes (desmogleins, desmocollins) anchor cells and transmit mechanical signals.
Adherens junctions (cadherins) maintain adhesion and signal transduction.

Example: Gap junctions in cardiac muscle allow synchronized contraction.

Cytoskeletal Elements

Intermediate Filaments

Intermediate filaments are one of the three main types of cytoskeletal fibers, providing mechanical support to cells.

Structural support is their primary function, maintaining cell shape and integrity.
They do not play a direct role in signaling, waste transport, or energy production.

Example: Keratin in epithelial cells.

Enzymes and Activation Energy

Role in Chemical Reactions

Enzymes are biological catalysts that accelerate chemical reactions by lowering the activation energy required.

Activation energy () is the minimum energy needed for a reaction to occur.
Enzymes decrease the activation energy, making reactions proceed faster.

Equation:

Membrane Transport

Active and Passive Mechanisms

Cells transport substances across membranes using various mechanisms.

Carrier-mediated active transport uses energy (often ATP) to move substances against their concentration gradient.
Passive transport does not require energy.
Bulk transport includes endocytosis and exocytosis.

Example: Sodium-potassium pump ( ATPase).

Signal Transduction Pathways

Phosphoinositide Pathway

This pathway involves the activation of phospholipase C (PLC), leading to the production of second messengers.

IP3 (inositol trisphosphate) and DAG (diacylglycerol) are produced, not GTP/GDP.
These messengers regulate calcium release and protein kinase C activation.

Equation:

Neuronal Physiology

Action Potential Initiation

An action potential typically starts at the axon hillock of a neuron.

This region has a high density of voltage-gated sodium channels.
Action potentials propagate along the axon to synaptic terminals.

Example: Initiation of nerve impulses in motor neurons.

Cerebrum Functions

Major Roles

The cerebrum is responsible for higher brain functions.

Sensory processing, memory, and language are key functions.
Sleep-wake cycle is regulated by other brain regions.

Example: Language centers in Broca's and Wernicke's areas.

Sensory Receptors

Taste and Smell

Chemoreceptors detect chemical stimuli and are essential for taste and smell perception.
Photoreceptors detect light; mechanoreceptors detect pressure; nociceptors detect pain.

Example: Olfactory receptors in the nasal cavity.

Neurotransmitters

Postsynaptic Effects

Neurotransmitters that cause hyperpolarization are considered inhibitory neurotransmitters.
Hyperpolarization makes the postsynaptic neuron less likely to fire an action potential.

Example: GABA is a major inhibitory neurotransmitter.

Muscle Types

Movement in the Intestines

Smooth muscle is responsible for involuntary movement of substances through the intestines (peristalsis).
Cardiac muscle is found in the heart; skeletal muscle is voluntary.

Example: Peristaltic waves in the digestive tract.

Peripheral Nervous System

Nerve Classification

The optic nerve is part of the central nervous system, not the peripheral nervous system.
Peroneal, femoral, and sciatic nerves are peripheral.

Example: Sciatic nerve innervates the lower limb.

Endocrine System

Adenohypophysis Hormones

The adenohypophysis (anterior pituitary) releases hormones such as growth hormone, prolactin, and luteinizing hormone.
Antidiuretic hormone is released by the posterior pituitary.

Example: Growth hormone stimulates tissue growth.

Cardiovascular System

Major Veins

The superior vena cava returns deoxygenated blood from the upper body to the heart.
Other major veins include the cephalic and basilic veins.

Example: Blood flow from the arms to the heart.

Hemoglobin and Sickle Cell Anemia

Structural Changes

In sickle cell anemia, hemoglobin undergoes polymerization when deoxygenated, causing red blood cells to become sickle-shaped.
Normal hemoglobin remains unaffected when oxygen is unloaded.

Example: Sickle-shaped cells can block blood vessels.

Renal System

Urine Collection Structures

The renal pelvis is the funnel-shaped structure that collects urine from the kidney and channels it to the ureter.
Renal medulla is the inner part of the kidney; renal capsule is the outer covering.

Example: Urine flow from nephrons to the bladder.

Cellular Energy Currency

Important Anions

Phosphate ions are crucial for ATP, the cell's primary energy currency.
ATP: (where is inorganic phosphate)

Example: ATP hydrolysis during muscle contraction.

Electrocardiogram (ECG)

QRS Complex Waves

In the QRS complex, any negative wave following a positive wave is called the S wave.
Q wave is the initial negative deflection; R wave is the positive deflection; T wave follows the QRS complex.

Example: S wave indicates ventricular depolarization. Additional info: Some answer choices in the original questions may have been incorrect; academic context and corrections have been provided for clarity.