SA 1105 Intro to Small Animal Management: Anatomy & Physiology Study Notes
Course Information
Course Code: SA 1105
Title: Introduction to Small Animal Management: Overview of Anatomy & Physiology
Instructor: Keith J. Ou, Ph.D.
Date: September 16, 2025
Announcements
Office hours have been adjusted today from 12:00-1:30 PM to 1:00-2:30 PM.
Learning Outcomes
At the conclusion of this lecture, students should be able to:
Define homeostasis and understand its significance in maintaining normal physiological states.
Identify the major systems of the body and their respective functions.
Recognize how anatomical forms and structures correlate with physiological functions.
Levels of Organisation
Cell
Tissue
Organ
Organ System
Homeostasis
Definition:
The maintenance of a narrow range of internal conditions within which an organism can live and function beneficially.
Examples of homeostasis:
Body temperature regulation (e.g., in endotherms)
Blood pH levels
Oxygen levels in the blood
Disruption of Homeostasis:
Can lead to illness or death.
Mechanisms of maintaining homeostasis:
Negative Feedback:
Involves a response that counteracts a stimulus (e.g., body temperature regulation).
Positive Feedback:
Amplifies a bodily process or increases the output (e.g., oxytocin release during childbirth).
Examples of Feedback Mechanisms
(a) Negative Feedback Loop
Stimulus: Body temperature exceeds 37°C
Sensor: Nerve cells in the skin and brain detect the increase.
Control Center: Temperature regulatory center in the brain.
Effector: Sweat glands throughout the body increase sweat production.
Response: Increased heat loss.
(b) Example of Positive Feedback
Stimulus: Head of the baby pushes against the cervix during childbirth.
Sensor: Nerve impulses from the cervix are sent to the brain.
Control Center: Brain stimulates the pituitary gland to secrete oxytocin.
Effector: Uterine contractions are intensified due to oxytocin's effects.
Skeletal System
Functions of the skeletal system include:
Support: Provides structure to the body.
Protection: Shields vital organs (e.g., rib cage protecting the heart).
Leverage: Acts as levers for muscles.
Storage: Reservoir for minerals and lipids.
Hematopoiesis: The formation of blood cells occurs within certain bones.
Bone Classification
Long Bones:
Function: Movement and support.
Short Bones:
Function: Stability, support, and movement.
Flat Bones:
Function: Points of attachment and protection of organs.
Irregular Bones:
Function: Various roles including protection, movement, and support.
Sesamoid Bones:
Function: Protection and facilitation of muscle action.
Long Bone Structure
Epiphysis vs. Diaphysis:
Epiphysis: Ends of the bone, often spongy.
Diaphysis: Shaft of the bone, primarily made of compact bone.
Cancellous Bone:
Characteristics: Porous, light, and sponge-like in appearance. Houses red bone marrow.
Compact Bone:
Characteristics: Heavy, dense, and very strong, providing weight-bearing support.
Bone Remodeling
Definition: Continuous regeneration of bones to maintain homeostasis.
Bone Cell Types:
Osteocyte: Mature bone cells that maintain bone structure.
Osteoblast: Cells responsible for bone formation.
Osteoclast: Cells responsible for bone resorption, breaking down bone tissue.
Anatomical Variations and Adaptations
Differences in human and animal skeletal structures (e.g., forelimb variations across species):
Human: Humerus, Radius & Ulna, Carpals, Metacarpals, Phalanges.
Horse: Special adaptations for speed and mobility.
Various other animal species (Frog, Cat, Mole, Whale, Bird) exhibit adaptations suitable for their environments and behaviors.
Muscular System
Importance:
Facilitates movement and stability.
Generates heat through contraction.
Types of Muscle:
Skeletal Muscle:
Characteristics: Under voluntary control, striated, tubular, and multinucleated.
Function: Executes voluntary movements.
Cardiac Muscle:
Found only in the heart; involuntary, striated, branched, and uninucleated.
Function: Pumps blood throughout the body.
Smooth Muscle:
Involuntary, non-striated, and spindle-shaped.
Function: Covers walls of internal organs (e.g., intestines).
Muscle Attachments
Tendons:
Definition: Fibrous connective tissue connecting muscle to bone.
Ligaments:
Definition: Fibrous tissue connecting bone to bone.
Joints:
Definition: Articulations where two or more bones meet.
Movement Mechanism:
Contraction of skeletal muscles facilitates movement and provides stability.
Respiratory System
Functions:
Provides oxygen (O₂) to tissues.
Removes waste product (CO₂).
Maintains acid-base balance.
Sensory: Odor detection.
Facilitates speech production.
Oxygen Transport in Blood
Process of Oxygen Binding:
Oxygen enters the lungs.
Binds to hemoglobin within red blood cells.
Released to tissue cells as needed.
Case Study on Oxygen Affinity:
Lugworm: Has hemoglobin with high oxygen affinity for low-oxygen habitats.
Cheetahs: Have hemoglobin with a low affinity to meet high oxygen demands during intense activities.
Cardiovascular System
Core Components:
Consists of the heart and blood vessels.
Functions:
Acts as a major transportation mechanism for:
Nutrients (via the digestive system).
Hormones (via the endocrine system).
White blood cells (via the lymphatic/immune system).
Gases (O₂ and CO₂ via the respiratory system).
Metabolic wastes (via the urinary system).
Heart Anatomy
Chambers:
Left and Right Atrium and Left and Right Ventricles.
Circulatory Routes:
Pulmonary Circuit:
Transports deoxygenated blood to the lungs and returns oxygenated blood to the heart.
Systemic Circuit:
Distributes oxygenated blood throughout the body and returns deoxygenated blood to the heart.
Blood Composition
Components of Blood:
Red Blood Cells (Erythrocytes): Carry oxygen.
White Blood Cells (Leukocytes): Immune defense, including subtypes like neutrophils, eosinophils, basophils, lymphocytes, and monocytes.
Platelets: Role in clotting.
Plasma: Contains transport proteins, immunoglobulins, and other solutes.
Functions of Blood:
Oxygen and nutrient delivery.
Waste removal.
Blood Types:
Type A: Contains A antigens and anti-B antibodies.
Type B: Contains B antigens and anti-A antibodies.
Type AB: Universal recipient, contains both A and B antigens; no antibodies.
Type O: Universal donor; no antigens, both anti-A and anti-B antibodies present.
Immune/Lymphatic System
Importance:
Provides barrier defenses (e.g., skin, mucous membranes).
Engages in two immune responses:
Innate response: Rapid, non-specific defenses.
Adaptive response: Slower, specific defenses controlled by lymphocytes.
Immune Cell Types
Hematopoiesis:
Process by which blood cells are formed from multipotent stem cells.
Lymphocytes:
Types include B lymphocytes (generate antibodies), T lymphocytes (destroy infected cells), plasma cells, etc.
Digestive System
Components:
Alimentary Canal: Mouth, Esophagus, Stomach, Small Intestine, Large Intestine, Anus.
Accessory Organs: Salivary Glands, Liver, Gallbladder, Pancreas.
Nutritional Processes
Process Steps Include:
Prehension: Grasping food.
Ingestion: Intake of food.
Mastication: Mechanical breakdown of food.
Digestion: Both mechanical/chemical breakdown (including enzymatic action).
Absorption: Transport of nutrients into the body.
Metabolism: Biochemical processes within cells.
Excretion: Removal of waste products.
Nutritional Components
Carbohydrates: Including starches, sugars, and fibers.
Proteins: Required for cellular structure and function.
Lipids: Fats and oils important for energy storage.
Minerals and Vitamins: Essential for various metabolic functions.
Water: Vital for cellular processes and as a solvent.
Energy: Derived mainly from carbohydrates, fats, and proteins.
Urinary System
**Function: **
Removal of nitrogenous wastes.
Recycling of nutrients (like electrolytes and calcium).
Components:
Kidneys, Ureters, Bladder, Urethra.
Nephron
Definition: Functional unit of the kidney responsible for:
Filtration, reabsorption and secretion.
**Key Processes: **
Glomerular capsule: Site for initial filtration.
Waste Products in Urine
Includes urea, uric acid, creatinine, and excess ions.
Nervous System
Functions:
Sensation: Detecting environmental stimuli.
Response: Producing reactions to stimuli.
Nervous System Organization
Central Nervous System (CNS):
Comprises the Brain and Spinal Cord.
Peripheral Nervous System (PNS):
Comprises all other nerves; transmits impulses to/from the CNS.
Endocrine System
Importance:
Regulates body functions through hormone communication.
Mechanism of Action:
Hormones released by endocrine glands travel through the bloodstream to target tissues/cells.
Endocrine Glands and Their Hormones
Pituitary Gland:
Releases Growth Hormone (GH), Prolactin, Thyroid-Stimulating Hormone (TSH).
Parathyroid Glands:
Secrete Parathyroid Hormone (PTH) influencing calcium levels.
Adrenal Glands:
Produce cortisol and adrenaline (epinephrine).
Pineal Gland:
Produces melatonin, regulating sleep-wake cycles.
Pancreas:
Secretes insulin and glucagon for blood sugar regulation.
Gonads (Testes/Ovaries):
Produce sex hormones: testosterone and estrogens.
Reproductive System
Overview:
Regulates hormonal cycles associated with reproduction.
Hormonal Concentrations:
Varies during different phases of the estrous cycle (e.g., FSH, LH, E2 levels).
Types of Estrous Cycles:
Polyestrous: Multiple reproductive cycles throughout the year.
Seasonal Polyestrous: Cycles occur at specific seasons.
Induced: Ovulation occurs in response to mating.
Conclusion
The anatomy (structure/shape/form) is closely related to its functions/purposes (what it does). Examples include the differing anatomical structures in humans, horses, whales, turtles, frogs, and birds, particularly focusing on adaptations such as the lumen of the small intestine and various specialized morphological features that enhance their physiological roles.