Animal Structure, Function, and Physiology: Study Guide

Chapter 39: Animal Structure and Function

Adaptations, Traits, and Fitness

• Adaptation: A heritable trait that increases an organism's fitness in a particular environment.

• Trait: Any observable characteristic of an organism, such as morphology, physiology, or behavior.

• Fitness: The ability of an organism to survive and reproduce, passing its genes to the next generation.

• Example: Thick fur in arctic animals is an adaptation for cold climates.

Trade-Offs in Structure and Function

• Trade-off: A compromise between two traits that cannot be optimized simultaneously.

• Trade-offs often occur between energy allocation to growth, reproduction, and survival.

• Example: Birds with larger eggs may produce fewer eggs overall.

Cricket Immune Function Experiment

• Strengths: Controlled variables, measurable immune response.

• Weaknesses: May not account for all environmental factors or long-term effects.

Animal Tissue Types

• Epithelial Tissue: Covers body surfaces and lines cavities; functions in protection, absorption, and secretion.

• Connective Tissue: Supports, binds, and protects other tissues; includes bone, blood, and adipose tissue.

• Muscle Tissue: Responsible for movement; includes skeletal, cardiac, and smooth muscle.

• Nervous Tissue: Conducts electrical impulses; found in the brain, spinal cord, and nerves.

Digestive System Anatomy and Function

• Mouth: Mechanical and chemical digestion begins.

• Esophagus: Transports food to the stomach.

• Stomach: Protein digestion and food storage.

• Small Intestine: Major site of nutrient absorption.

• Large Intestine: Water absorption and feces formation.

Surface Area, Volume, and Basal Metabolic Rate (BMR)

• BMR is the rate at which an organism uses energy at rest.

• As animals increase in size, volume increases faster than surface area.

• Surface area to volume ratio affects heat and material exchange.

• Equation: $\text{Surface Area} \propto L^2$, $\text{Volume} \propto L^3$

Organ Features Increasing Surface Area

• Folds, villi, and microvilli in the intestine increase surface area for absorption.

• Alveoli in lungs increase surface area for gas exchange.

Negative Feedback and Homeostasis

• Negative Feedback Loop: A process that detects and reverses deviations from a set point to maintain homeostasis.

• Components: Sensor, integrator, effector.

• Example: Regulation of body temperature.

Chapter 40: Osmoregulation

Osmolarity and Solutions

• High Molarity: Solution with a high concentration of solutes.

• Low Molarity: Solution with a low concentration of solutes.

Ion Pumps and Electrochemical Gradients

• Pumps (e.g., Na+/K+ ATPase) use energy to move ions, creating gradients.

• Gradients drive passive movement of ions and water.

Excretion of Urea in Humans

• Humans convert toxic ammonia to urea in the liver for safer excretion.

• Urea is excreted by the kidneys in urine.

Anatomy and Flow of the Kidney and Nephron

• Kidney: Filters blood, regulates water and solute balance.

• Nephron: Functional unit; includes renal corpuscle, proximal tubule, loop of Henle, distal tubule, and collecting duct.

• Filtrate flows from Bowman's capsule → proximal tubule → loop of Henle → distal tubule → collecting duct.

Filtrate Formation and Na+ Reabsorption

• Filtrate Formation: Blood pressure forces fluid into Bowman's capsule (renal corpuscle).

• Na+ Reabsorption: Occurs in the proximal tubule via active transport.

Countercurrent Osmotic Gradient in the Loop of Henle

• Descending limb: Permeable to water, not solutes; water exits, concentrating filtrate.

• Ascending limb: Impermeable to water; solutes are actively transported out, diluting filtrate.

• Creates an osmotic gradient for water reabsorption.

Antidiuretic Hormone (ADH)

• ADH increases water reabsorption in the collecting duct, reducing urine volume.

Chapter 42: Gas Exchange and Circulation

Endotherms vs. Ectotherms

• Endotherms: Generate heat metabolically (e.g., mammals, birds).

• Ectotherms: Rely on external sources for heat (e.g., reptiles, amphibians).

Countercurrent Exchangers

• Require two fluids flowing in opposite directions.

• Maximize exchange efficiency (e.g., fish gills, loop of Henle).

Steps in Gas Exchange

• Ventilation → Diffusion at respiratory surface → Circulation → Diffusion at tissues → Cellular respiration.

Partial Pressure and Fick's Law

• Partial Pressure: The pressure exerted by a single gas in a mixture.

• Fick's Law:

$J = D \frac{A (P_1 - P_2)}{d}$

• Where J is the rate of diffusion, D is the diffusion coefficient, A is area, P1 - P2 is the partial pressure difference, and d is the distance.

Blood and Its Components

• Plasma: Liquid matrix.

• Red Blood Cells: Carry oxygen via hemoglobin.

• White Blood Cells: Immune defense.

• Platelets: Blood clotting.

Hemoglobin, Cooperative Binding, and the Bohr Shift

• Cooperative Binding: Binding of one O2 increases affinity for more O2.

• Bohr Shift: Lower pH or higher temperature reduces hemoglobin's O2 affinity, aiding O2 release during exercise.

CO2 Transport and pH Buffering

• CO2 is transported as bicarbonate ions in plasma.

• Hemoglobin and plasma proteins buffer blood pH.

Blood Vessel Types and Characteristics

Vessel	Structure	Function
Arteries	Thick, muscular walls	Carry blood away from heart; high pressure
Veins	Thinner walls, valves	Carry blood to heart; low pressure
Capillaries	Single-cell thick	Exchange of gases and nutrients

Partial Pressures in Circulation

• O2 partial pressure is highest in alveoli, decreases in tissues.

• CO2 partial pressure is lowest in alveoli, increases in tissues.

Heart Anatomy and Blood Flow Path

• Blood flows: Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium → Left ventricle → Aorta → Body.

Electrical Activation and Blood Pressure

• Sinoatrial (SA) node initiates heartbeat; signal spreads to atrioventricular (AV) node and ventricles.

• Contraction increases blood pressure; relaxation decreases it.

Blood Flow Equation and Vessel Pressure

• Blood Flow Equation:

$F = \frac{\Delta P}{R}$

• Where F is flow, \Delta P is pressure difference, R is resistance.

• Arteries have the highest pressure.

Chapter 43: Neurons and Electrical Signaling

Central Nervous System (CNS) and Neurons

• CNS: Brain and spinal cord; integrates information.

• Neurons: Functional units; transmit electrical signals.

Neuron Structure and Information Flow

• Dendrites: Receive signals.

• Cell Body (Soma): Integrates signals.

• Axon: Transmits signals to other cells.

Neuron Categories

• Sensory Neurons: Detect stimuli.

• Interneurons: Connect neurons within CNS.

• Motor Neurons: Stimulate effectors (muscles/glands).

Membrane Potential Calculation

• Generated by ion gradients and selective permeability.

• Resting Potential: Typically -70 mV in neurons.

• Nernst Equation:

$E_{ion} = \frac{RT}{zF} \ln \frac{[\text{ion}]_{out}}{[\text{ion}]_{in}}$

• Where Eion is equilibrium potential, R is gas constant, T is temperature, z is ion charge, F is Faraday's constant.

Action Potentials

• All-or-none electrical impulses.

• Rapid depolarization (Na+ influx), repolarization (K+ efflux).

Neuronal Communication Steps

• Action potential travels down axon.

• Triggers neurotransmitter release at synapse.

• Neurotransmitter binds postsynaptic receptors, generating postsynaptic potential.

Chapter 44: Sensory Mechanisms

Synapse Components

• Presynaptic Terminal: Releases neurotransmitter.

• Synaptic Cleft: Gap between neurons.

• Postsynaptic Membrane: Receives signal.

EPSPs and IPSPs

• EPSP (Excitatory Postsynaptic Potential): Depolarizes membrane, increases firing likelihood.

• IPSP (Inhibitory Postsynaptic Potential): Hyperpolarizes membrane, decreases firing likelihood.

Divisions of the Nervous System

• CNS: Brain and spinal cord.

• PNS: All nerves outside CNS.

• Somatic Nervous System (SNS): Controls voluntary muscles.

• Autonomic Nervous System (ANS): Controls involuntary functions; includes sympathetic and parasympathetic divisions.

Brain Functional Specialization

• Frontal Lobe: Decision making, movement.

• Parietal Lobe: Sensory processing.

• Temporal Lobe: Hearing, memory.

• Occipital Lobe: Vision.

Learning and Memory Encoding

• Thought to involve synaptic plasticity and changes in neural circuits.

SNS and PNS Actions

• SNS: "Fight or flight" responses; increases heart rate, dilates pupils.

• PNS: "Rest and digest" responses; slows heart rate, stimulates digestion.

• Somas of SNS neurons are mostly in the spinal cord; PNS in the brainstem and sacral spinal cord.

Encoding Sound in the Inner Ear

• Sound waves vibrate the cochlea, stimulating hair cells.

• Hair cells convert vibrations to electrical signals sent to the brain via the auditory nerve.

Visual Information Pathway

• Photoreceptors in the retina detect light.

• Signals travel via optic nerve to the visual cortex in the occipital lobe.

Gustatory System Anatomy and Path

• Taste buds detect chemicals; signals sent via cranial nerves to the gustatory cortex.

Chapter 47: Animal Reproduction

Asexual vs. Sexual Reproduction

• Asexual Reproduction: Offspring genetically identical to parent; common in stable environments.

• Sexual Reproduction: Involves gamete fusion; increases genetic diversity.

• Daphnia: Switches between modes based on environmental cues.

Gamete Production and Structure

• Gametes: Haploid cells (sperm and egg) produced by meiosis.

• Sperm: Small, motile; Egg: Large, nutrient-rich.

Oogenesis and Fertilization Types

• Oogenesis: Egg formation; produces one mature egg and polar bodies.

• Internal Fertilization: Fertilization inside the body (e.g., mammals).

• External Fertilization: Fertilization outside the body (e.g., fish, amphibians).

Steps of Internal Fertilization and Polyspermy Prevention

• Sperm penetrates egg; cortical reaction prevents entry of additional sperm (polyspermy).

Germ Layers and Gastrulation

• Germ Layers: Ectoderm, mesoderm, endoderm; form during gastrulation.

• Gastrulation reorganizes the embryo into these layers, setting up organ development.

Human Reproductive System Functions

• Male: Produces and delivers sperm.

• Female: Produces eggs, supports fertilization and development.

Sex Hormones and Regulation

• Major Hormones: Testosterone (testes), estrogen and progesterone (ovaries).

• Regulated by hypothalamic-pituitary-gonadal axis.

Ovulation Phases and Hormones

• Follicular phase (FSH, estrogen), ovulation (LH surge), luteal phase (progesterone).

Function of hCG

• hCG (human chorionic gonadotropin): Maintains corpus luteum and progesterone production in early pregnancy.