Biomolecules, Cells, Tissues, and Homeostasis
1.1 The Four Major Classes of Biomolecules
BIOMOLECULES: Building blocks for functional cells, tissues, and organs.
Biomolecule Types and Functions:
Protein:
Building Block: Amino acid
Function: Fundamental component of structure and dynamic metabolic function in the cell.
Lipid:
Building Block: No single building block for all lipids.
Functions:
Long-term energy molecule.
Structural component of the membrane bilayer (ex: phospholipid).
Integral extracellular membrane facilitator of cell–cell interactions (ex: glycolipid).
Carbohydrate:
Building Block: Monosaccharide
Functions:
Structural molecule.
Attachment on proteins for cell recognition.
Short- and long-term energy storage (ex: glycogen).
Nucleic Acids:
Building Block: Nucleotide
Functions:
Unit for hereditary information (DNA).
Protein biosynthesis (RNA).
1.2 Example of Structure/Function Relationship
Mitochondria:
CRISTAE:
Structure: Specialized folds of mitochondrial membrane.
Function: Increase surface area for proteins that carry out mitochondrial respiration.
1.3 Levels of Biological Organization
Chemical Level:
Hydrogen atoms.
Oxygen atom.
Water molecule.
Cellular Level:
Smooth muscle cell.
Tissue Level:
Smooth muscle tissue.
Smooth muscle.
Skeletal muscle.
Organ Level:
Kidney.
Organ System Level:
Ureter.
Organism Level:
Bladder.
Urethra.
Urinary tract system.
1.4 Characteristics of Life
EAT: Bringing nutrients into the body.
Humans' primary energy source: ATP.
Humans are heterotrophs.
Energy Production/Consumption:
Essential for growth/repair.
Growth/Repair:
Cells, tissue, and organs grow and change over time.
Tissues repair themselves after injury (transient and/or permanent).
Adaptation:
Changes based on the environment.
Reproduction:
Required for survival of the species, not the individual.
1.5 Cells as the Living Unit of Life
All cells comprise at least:
Membrane:
Lipid bilayer surrounding cell or organelle.
Genetic Material:
E.g. DNA.
Cytosolic Fluid:
Fluid component of the cell interior.
1.6 The Four Major Categories of Tissue
Connective Tissue:
Provides support/integrity for other tissues/organs.
Has varied cell arrangement/order.
Epithelial Tissue:
Lines walls of open tubes and provides secretory and absorptive surfaces.
Components: Basal and apical.
Muscle Tissue:
Generates mechanical force.
Includes skeletal (voluntary), smooth (involuntary), and cardiac (involuntary) muscle types.
Nervous Tissue:
Glia provide protection, nourishment, and support to nerve cells.
Nerves provide long-distance communication within the body.
1.7 Organs and Organ Systems
Organ System: Organ and tissue classification.
Integumentary System:
Organs: Skin, hair, nails, sweat, oil glands.
Function: Protection/defense/body temperature regulation.
Endocrine System:
Organs: Hormone-secreting glands (e.g. thyroid).
Function: Coordination of body functions.
Reproductive System:
Female: Ovaries, fallopian tubes, uterus, vagina, mammary tissue.
Male: Testes, penis, vas deferens, glands.
Function: Production of reproductive components and support for developing fetus (female).
Nervous System:
Organs: Brain, spinal cord, nerves.
Function: Detection and coordination of response.
Immune/Lymphatic System:
Organs: Lymphoid tissue, spleen, various cell types, thymus.
Function: Defense against pathogens; fluid balance.
Cardiovascular System:
Organs: Heart, blood vessels, blood.
Function: Movement of blood throughout the body.
Respiratory System:
Organs: Nasal passages, trachea, lungs.
Function: Oxygen and carbon dioxide regulation.
Urinary System:
Organs: Kidneys, ureters, bladder, urethra.
Function: Filtration of blood and removal of waste.
Musculoskeletal System:
Organs: Bone, skeletal muscle, cartilage, tendons, ligaments.
Function: Movement, support/protection, blood formation.
Digestive System:
Organs: Mouth, salivary glands, esophagus, stomach, liver, gall bladder, pancreas, intestines.
Function: Breakdown of food, nutrient absorption.
1.8 Anatomical Position as the Standard of Reference
The Body Is:
Standing upright.
Feet together.
Eyes facing forward.
Arms by the side.
Palms facing forward.
1.9 Body Cavities: Groups of Organs within a Specific Region
THORACIC CAVITY:
Pleural Cavity: Contains trachea, bronchi, lungs, esophagus, mediastinum, heart, thymus.
Pericardial Cavity: Contains the heart.
CRANIAL CAVITY:
Contains the brain.
SPINAL CAVITY:
Contains the spinal cord.
ABDOMINOPELVIC CAVITY:
Abdominal Cavity: Contains stomach, liver, gall bladder, pancreas, spleen, small intestine, most of the large intestine.
Pelvic Cavity: Contains end of large intestine, rectum, urinary bladder, reproductive organs.
VENTRAL CAVITY: Comprised of the thoracic cavity and the abdominal cavity.
DORSAL CAVITY: Contains the skull and vertebral column.
1.10 Subdivision of Body Cavities into Sub-regions and Quadrants
Regions:
Right Hypochondriac
Left Hypochondriac
Epigastric
Right Lumbar
Left Lumbar
Umbilical
Right Iliac
Left Iliac
Hypogastric
Quadrants:
Right Upper Quadrant
Left Upper Quadrant
Right Lower Quadrant
Left Lower Quadrant
1.11 Terms of Relative Position Define Location of Body Parts with Respect to Each Other
Terminology and Examples:
Anterior (Cranial): Toward the front of the body.
Example: "The sternum is anterior to the spine."
Posterior: Toward the back of the body.
Example: "The buttocks are posterior and the umbilicus is anterior."
Medial: Closer to the midline dividing the body into right and left halves.
Example: "The heart is medial to the shoulder."
Lateral: Further away from the midline and more towards the side of the body.
Example: "The ears are lateral to the nose."
Superior: Closer to the head.
Example: "The shoulder is superior to the hip."
Inferior: Towards the feet.
Example: "The ankle is inferior to the knee."
Proximal: Closer to the trunk or to another specified point of reference (used when referring to limbs).
Example: "The elbow is proximal to the wrist."
Distal: Opposite of proximal.
Example: "The toes are distal to the ankle."
Superficial: Closer to the surface of the body.
Example: "The epidermis is the most superficial layer of skin."
Deep: Parts that are more internal and farther from the surface of the body.
Example: "The liver is deep to the skin."
1.12 Planes of Section and Compartmentalization
Types of Planes:
Transverse Section (horizontal): Divides body into upper and lower sections.
Coronal Section (frontal): Divides body into anterior and posterior sections.
Sagittal Section: Divides body into left and right sections.
Midsagittal Section: Divides body into left and right sections at the midline.
1.13 Feedback Control Systems Maintain Homeostatic Set Points
Homeostasis:
The processes that maintain steady conditions within the human body.
Homeostatic Set Points: Established thresholds required for physiological processes to maintain balance.
1.14 Temperature Regulation as an Example of Homeostatic Set Point
Negative Feedback Mechanism:
Stimulus: Body temperature increases.
Receptors: Thermoreceptors in skin detect the change in temperature.
Controller: Hypothalamus detects change and sends signals.
Effectors: Sweat glands increase secretion and blood vessels in skin dilate.
Response: Cooling effect (sweating) and increased heat loss.
Normal Body Temperature: Returns to set point of 98.6°F.
1.15 Insulin Regulation as an Example of a Negative Feedback Control System
Insulin Regulation Process:
STIMULUS 1: Blood glucose level rises.
Beta cells in the pancreas release insulin into the blood.
Liver takes up glucose and stores it as glycogen.
STIMULUS 2: Blood glucose level falls.
Alpha cells in the pancreas release glucagon.
Liver breaks down glycogen and releases glucose.
Body cells take up glucose.
Homeostasis Set Point: Glucose levels maintain at approximately 90 mg/100mL.
1.16 Positive Feedback Control Systems
Definition of Negative Feedback:
The outcome of the feedback loop is a return to the homeostatic set point.
Definition of Positive Feedback:
The physiological response elicited by the stimulus acts to increase the original stimulus.
Example of Positive Feedback:
Childbirth: A self-amplifying cycle leading to greater physiological change.
Other Positive Feedback Loops:
Blood clotting.
Protein digestion.
Generation of nerve signals.
1.17 Blood Clotting Positive Feedback Loop
Process:
Released chemicals attract more platelets to the break or tear in the blood vessel wall.
Clotting occurs as platelets adhere to the site and release chemicals.
Clotting proceeds until the break is sealed by a newly formed clot.
Feedback cycle ends when the clot is secure.
1.18 Harmful Positive Feedback Process
High Fever Example:
If temperature rises above 108°F:
Metabolic rate increases causing the body to produce heat faster.
This causes temperature to continue rising, resulting in a cycle that repeats again.
Seizures and potential neurological damage can occur.
Fatality can result at temperatures around 113°F.
1.19 Maintenance of Proper Fluid Compartment Volumes Necessary for Life
ICF: Fluid inside cells.
ECF: Fluid outside/around cells.
Fluid Imbalance Can Lead To:
Dehydration of cells.
Imbalance in ion concentrations.
Cell death (if prolonged).
Fluid Movement:
Occurs by osmosis.
Is impacted by ion concentrations.
1.20 Feedback Mechanisms Maintain Fluid Compartment Volumes
Mechanisms of Fluid Movement:
Hydrostatic Pressure:
Pressure exerted on the wall of a vessel due to fluid volume.
Colloid Osmotic Pressure:
Pressure exerted by proteins (e.g., albumin) on a vessel’s plasma.
Capillary Filtration Process:
Arterial End: Hydrostatic pressure and colloid osmotic pressure push plasma and nutrients out.
Venous End: Hydrostatic pressure and colloid osmotic pressure pull fluid in.