Homeostasis and Body Organization

Terminology

  • Study guide includes all the learning outcomes.

An Introduction to Anatomy and Physiology

What is Anatomy and Physiology?

Anatomy

  • Describes the structures of the body, including:
    • What they are made of
    • Where they are located
    • Associated structures

Physiology

  • Is the study of:
    • Functions of anatomical structures, both individual and cooperative functions

Key Concept

  • All physiological functions are performed by specific anatomical structures.
  • Anatomy and physiology are inseparably linked:
    • Anatomy leads to physiology.
    • Physiology leads to anatomy.

Organization of Living Things

Hierarchy of Complexity

  • Organism is composed of organ systems.
  • Organ systems are composed of organs.
  • Organs are composed of tissues.
  • Tissues are composed of cells.

Further Breakdown

  • Cells contain organelles.
  • Organelles are composed of molecules.
  • Molecules are composed of atoms.

List of Organizational Levels

  • System
  • Organism
  • Tissue
  • Organ
  • Macromolecule
  • Organelle
  • Atom
  • Molecule
  • Cell

The 11 Organ Systems

  1. Integumentary
  2. Skeletal
  3. Muscular
  4. Nervous
  5. Endocrine
  6. Reproductive
  7. Cardiovascular
  8. Blood and Lymphatic
  9. Respiratory
  10. Urinary
  11. Digestive

Key Concepts

  • The body is divided into 11 organ systems which work together.
  • Many organs function in more than one organ system.
  • 4 Organ Systems covered in BIO 168; the rest in BIO 169.

Organ Systems Covered in BIO 168

  1. Integumentary system
  2. Skeletal system
  3. Muscular system
  4. Nervous system

The Integumentary System

Major Organs:

  • Skin
  • Hair
  • Sweat glands
  • Nails

Functions:

  • Protects against environmental hazards
  • Helps regulate body temperature
  • Provides sensory information

The Skeletal System

Major Organs:

  • Bones
  • Cartilages
  • Associated ligaments
  • Bone marrow

Functions:

  • Provides support and protection for other tissues
  • Stores calcium and other minerals
  • Forms blood cells

The Muscular System

Major Organs:

  • Skeletal muscles and associated tendons and aponeuroses (tendinous sheets)

Functions:

  • Provides movement
  • Provides protection and support for other tissues
  • Generates heat that maintains body temperature

The Nervous System

Major Organs:

  • Brain
  • Spinal cord
  • Peripheral nerves
  • Sense organs

Functions:

  • Directs immediate responses to stimuli
  • Coordinates or moderates activities of other organ systems
  • Provides and interprets sensory information about external conditions

Homeostasis

  • Homeostasis is the state of steady internal conditions necessary for survival and optimal functioning for the body, maintained by living things.
  • It is a self-regulating process that allows an organism to maintain internal stability while adjusting to changes.

Key Concepts

  • Homeostasis means maintaining a stable internal environment.
  • Systems respond to external and internal changes to function within a normal range (e.g., body temperature, fluid balance).

Maintaining Normal Limits

  • Receptor: Receives the stimulus.
  • Control Center: Processes the signal and sends instructions.
  • Effector: Carries out the instructions.

Example of Maintaining Normal Limits

Body Temperature Regulation

  • Stimulus: Body temperature exceeds 37°C
  • Sensor: Nerve cells in skin and brain
  • Control Center: Temperature regulatory control center in the brain
  • Effector: Sweat glands throughout the body

Diagram Describing Negative Feedback Loop

  • (a) Regulation: Negative feedback loop

Negative Feedback

  • The body senses a change and activates mechanisms to reverse (negate) the stimulus.

Examples of Negative Feedback:

  • Regulation of blood glucose
  • Regulation of body temperature
  • Most other physiological mechanisms

Negative Feedback, Set Point

  • Room temperature does not stay at a set point of 68 degrees—it only averages 68 degrees.

Human Thermoregulation

  • Brain senses change in blood temperature:
    • If overheating, blood vessels dilate in the skin, and sweating begins.
    • If too cold, vasoconstriction in the skin and shivering begins.

Life-Threatening Fever

  • Temperature > 108 degrees F significantly increases metabolic rate, causing the body to produce heat faster.
    • This cycle reinforces itself and becomes fatal at 113 degrees F.

Positive Feedback Loops

  • Self-amplifying changes that lead to change in the same direction; the effector reinforces the stimulus.
  • Normal way of producing rapid changes; examples include:
    • Childbirth
    • Blood clotting
    • Protein digestion
    • Generation of nerve signals
  • Most responses are to special conditions, resulting in a new, temporary physiological state.

Example of Positive Feedback Loop

  1. Brain stimulates pituitary gland to secrete oxytocin.
  2. Nerve impulses from cervix transmitted to brain.
  3. Oxytocin stimulates uterine contractions and pushes fetal head toward cervix.

Key Concept

  • Homeostasis is a state of equilibrium where opposing forces are in balance.
  • Physiological systems work to restore balance; failure results in disease or death.

Anatomical Terms for Body Sections

Positions

  • Anatomical position: Hands at sides, palms forward
  • Supine: Lying down, face up
  • Prone: Lying down, face down

Anatomical Position Defined

  • Person stands erect
  • Feet flat on the floor
  • Arms at sides
  • Palms, eyes & face facing forward
  • Standard frame of reference for anatomical descriptions & dissection

Forearm Positions

  • Supine: Palms face forward or upwards; radius and ulna are parallel.
  • Prone: Palms face rearward or downward; radius and ulna are crossed.

Anatomical Planes and Sections

Description

  • Planes are imaginary flat surfaces passing through the body. - Sections are anatomical views if the body is cut on a plane.

Types of Planes

  • Sagittal Plane: Divides body into right and left halves; median plane creates equal halves.
  • Frontal (Coronal) Plane: Divides body into front & back portions.
  • Transverse (Horizontal) Plane: Divides the body into upper & lower portions.

Typical Sectional Views of the Body

১. (a) Sagittal section
২. (b) Frontal section
৩. (c) Transverse section

Body Regions

  • Axial Region: Head, neck & trunk
  • Appendicular Region: Upper & lower limbs

Directional Terms

  • Allow us to explain where one body structure is in relation to another.
  • Different meanings for humans and animals:
    • Anterior (ventral) surface of a human is the chest & belly; anterior (cranial, cephalic) in a four-legged animal is head end.
    • Posterior (dorsal) surface of a human is the back side; posterior (caudal) in a four-legged animal is the tail end.

Anatomical Directions (Relative Positions):

  • Superior (cranial)
  • Inferior (caudal)
  • Anterior (ventral)
  • Posterior (dorsal)
  • Medial
  • Lateral
  • Ipsilateral
  • Contralateral
  • Proximal
  • Distal
  • Superficial
  • Deep

Intermediate Directions can combine:

  • Dorsolateral
  • Superiomedial

Abdominal Quadrants and Regions

Quadrants

  • Right Upper Quadrant (RUQ)
  • Left Upper Quadrant (LUQ)
  • Right Lower Quadrant (RLQ)
  • Left Lower Quadrant (LLQ)

Abdominal Quadrants Structures

  • RUQ : Liver, Gallbladder, Ascending colon of large intestine.
  • LUQ : Diaphragm, Spleen, Stomach, Transverse colon of large intestine.
  • RLQ : Cecum, Appendix, Initial part of sigmoid colon, Urinary bladder.
  • LLQ : Descending colon of large intestine.

Nine Abdomino-pelvic Regions

Regions Are

  1. Right hypochondriac region
  2. Epigastric region
  3. Left hypochondriac region
  4. Right lumbar region
  5. Umbilical region
  6. Left lumbar region
  7. Right iliac region (inguinal)
  8. Hypogastric (pubic) region
  9. Left iliac region (inguinal)

Appendicular Region

Upper Limb:

  • Brachium (arm)
  • Antebrachium (forearm)
  • Carpus (wrist)
  • Manus (hand)
  • Digits (fingers)

Lower Limb:

  • Thigh
  • Crus (leg)
  • Tarsus (ankle)
  • Pes (foot)
  • Digits (toes)

Anatomical Terminology (Ventral)

Upper Extremity

  • Acromial region (shoulder)
  • Axillary region (armpit)
  • Brachial region (arm)
  • Cubital region (elbow)
  • Antebrachial region (forearm)
  • Carpal region (wrist)
  • Palmar region (palm)

Lower Extremity

  • Coxal region (hip)
  • Patellar region (knee)
  • Femoral region (thigh)
  • Crural region (leg)
  • Tarsal region (ankle)
  • Pedal region (foot)
  • Dorsum of foot
  • Plantar surface (sole)

Anatomical Terminology (Dorsal)

Regions Include

  • Cranial region
  • Nuchal region (back of neck)
  • Interscapular region
  • Scapular region
  • Vertebral region
  • Lumbar region
  • Sacral region
  • Gluteal region (buttock)
  • Perineal region

Common Regional Descriptive Terms

  • Examples Include:
    • Acromial
    • Axillary
    • Brachial
    • Antecubital
    • Antebrachial
    • Carpal
    • Digital
    • Radial
    • Ulnar
    • Inguinal
    • Femoral
    • Gluteal
    • Popliteal
    • Plantar
    • Cervical
    • Lumbar
    • Sacral
    • Costal
    • Pectoral
    • Mammary
    • Buccal
    • Lingual
    • Orbital
    • Mental
    • Occipital
    • Temporal
    • Somatic
    • Viscera

Body Cavities and Membranes

Major Body Cavities

  • Dorsal Body Cavity:
    • Cranial cavity
    • Vertebral canal
  • Ventral Body Cavity:
    • Thoracic cavity (diaphragm separates them)
    • Abdominopelvic cavity:
    • Abdominal cavity
    • Pelvic cavity
  • Lined by membranes
  • Filled with viscera

Body Cavities

Dorsal Body Cavity

  1. Cranial cavity
  2. Vertebral canal

Ventral Body Cavity

  • Thoracic cavity:
    • Superior mediastinum
    • Pleural cavity
    • Pericardial cavity within the mediastinum
  • Diaphragm separates thoracic and abdominopelvic cavities.
  • Abdominal cavity
  • Pelvic cavity

Serous Membranes

  • Line cavities not open to the outside (ventral body cavities).
  • Are thin but strong.
  • Have a double-layered structure.

Types of Serous Membranes

  • Pericardial membrane:
    • Lines pericardial cavity containing the heart.
    • Covers the heart.
  • Pleural membrane:
    • Two pleural cavities filled with lungs.
    • Lines pleural cavities and covers lungs.
  • Peritoneum:
    • Lines the abdominopelvic cavity containing many organs.
    • Covers abdominal organs.

Serous Membrane Structure

  • Visceral layer:
    • Covers the organ.
  • Parietal layer:
    • Lines the cavity.
  • Serous fluid:
    • Watery fluid in the potential space in between layers to reduce friction.

Potential Spaces

  • Found between two tissue layers such as visceral & parietal membranes.
  • Normally, these layers are pressed firmly together and contain only a thin film of serous fluid.
  • In unusual situations, they may separate and fill with fluid.

Example

  • Pleural cavity: Air or fluid can accumulate between parietal and visceral pleura, forming a space.

Summary

Coverage Includes

  • Structure and function in anatomy and physiology
  • Vocabulary and anatomical terms
  • Levels of physical organization
  • Homeostasis and feedback
  • Systems integration and equilibrium
  • Dividing and describing the body
  • Locations and functions of major organ systems

Lecture 1 Handout

Body Regions

Anterior View

  • Nasal (nose)
  • Oral (mouth)
  • Cervical (neck)
  • Acromial (shoulder)
  • Axillary (armpit)
  • Brachial (arm)
  • Antecubital (front of elbow)
  • Antebrachial (forearm)
  • Coxal (hip)
  • Carpal (wrist)
  • Palmar (palm)
  • Cephalic (head)
  • Frontal (forehead)
  • Orbital (eye)
  • Buccal (cheek)
  • Mental (chin)
  • Sternal (sternum)
  • Pectoral (chest)
  • Mammary (breast)
  • Costal (ribs)
  • Abdominal (abdomen)
  • Pelvic
  • Inguinal (groin)
  • Pubic
  • Digital (fingers)
  • Femoral (thigh)
  • Patellar (knee)
  • Crural (leg)
  • Pes (foot)
  • Tarsal (ankle)
  • Dorsum of the foot

Posterior View

  • Cranial (surrounding the brain)
  • Otic (ear)
  • Temporal
  • Occipital (back of head)
  • Lumbar (lower back)
  • Sacral (between hips)
  • Gluteal (buttock)
  • Dorsum (back)

Abdomen Nine Regions

  • Right hypochondriac region
  • Left hypochondriac region
  • Epigastric region
  • Right lumbar region
  • Left lumbar region
  • Umbilical region
  • Right iliac (inguinal) region
  • Hypogastric (pubic) region

Major Body Cavities

  • Dorsal body cavity:
    • Cranial cavity
    • Vertebral canal
  • Ventral body cavity:
    • Thoracic cavity
    • Abdominopelvic cavity

Example of Cavity Layers

  • Pleural Membrane: Covers lungs and lines pleural cavity.
  • Pericardial Membrane: Lines the heart cavity.
  • Peritoneum: Covers the organs in the abdominal cavity.