The Human Body chapter 1
Survival Needs
Atmospheric Pressure
Specific air pressure is needed for adequate breathing and gas exchange in the lungs
Normal Body Temperature
If body temp falls below or goes above 37°C, rates of chemical reactions are affected
Water
The most abundant molecule in the body: Provides the watery environment needed for chemical reactions
→ Also is the fluid base for secretions and excretions
Oxygen
Essential for release of energy from foods
→ The body can survive only a few minutes without oxygen
Nutrients
Chemicals for energy and cell building
→ Carbs: Major source of energy
→ Proteins: Needed for cell building and enzyme activity
→ Fats: Long-term energy storage
→ Minerals and vitamins: involved in chemical reactions as well as for structural purposes
Homeostasis
Homeostatic Imbalance
Normally smooth layers can become rough and even can stick together, resulting in excruciating pain
Serous membranes can become inflamed as a result of infection or other causes
Control systems become less efficient
→ If negative feedback mechanisms become overwhelmed, destructive positive feedback mechanisms lower
→ e.g heart failure
Disturbance of homeostasis
→ Increases risk of disease: pathology
→ Contributes to changes associated with aging
Homeostatic Controls
Positive Feedback
- Response enhances the original stimulus
- May exhibit a cascade or amplifying effect as feedback causes variable to continue in the same direction as the initial change
- Usually controls infrequent events that don’t require continuous adjustment
1. Enhancements of labor contractions by oxycontin
2. Platelet plug formation and blood clotting
Negative Feedback
- Most-used feedback mechanism in the body
- Response reduces or shuts off original stimulus
- Variable changes in opposite direction of initial change
1. Regulation of blood glucose by insulin
2. Regulation of body temperature
Regulation of blood glucose
– Receptors sense increased blood glucose (blood sugar)
– Pancreas (control center) secretes insulin into the blood
– Insulin causes body cells (effectors) to absorb more glucose, which decreases blood glucose levels
Effector
- Receivers output from the control center
- Provides the means to respond
Control Center
- Determines set point at which variable is maintained
- Receives input from receptor
Receptor (sensor)
- Monitors environment
- responds to stimuli
The body must constantly be monitored and regulated to maintain homeostasis
→ Nervous Systems
→ Variables
Homeostasis is the maintenance of relatively stable internal conditions despite continuous changes in environment
Any self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival
Anatomical Terms, Position and Direction
Regional Terms
Appendicular
→ Libs (legs and arms)
Axial
→ Head, neck, and trunk
Regional terms designate specific areas within body divisions
PICTURE https://medictests.com/units/standard-anatomical-terms-and-planes
Directional Terms describe one body structure in relation to another body structure
→ Direction is always based on standard anatomical position
→ Right and left refer to the body being viewed, not right and left of the observer
Standard Anatomical Position
→ Body erect, feet slightly apart, palms facing forward with thumbs pointing away from the body
Body planes and Sections
Sections
→ cuts of sections made along a body plane
surfaces along which body or structures may be cut for anatomical study
→ Three most common planes:
Sagittal Plane
Frontal (coronal) plane
Transverse Plane
Oblique Section
→ Result of cuts and angles other than 90° to a vertical plane
Transverse (Horizontal) plane
→ Divides body horizontally (90° to the vertical plane) into superior and inferior (top and bottom)
→ Produces a cross-section
Frontal (coronal) plane
→ Divides body vertically into anterior and posterior parts (front and back)
→ Produces a frontal or coronal section
Parasagittal Plane
→ The cut was off-centered, not on the midline
Midsagittal (median) plane
→ The cut was made perfectly on the midline
Sagittal Plane
→ Divides body vertically into right and left parts
→ Produces a sagittal section if cut along this plane
Body Cavities
Two sets of Cavities
Ventral Body Cavity
Membranes in the ventral body cavity
→ Serosa (also called serous membrane
Thin, double-layered membranes that cover surfaces in the ventral body cavity
-Parietal serosa lines internal body cavity walls
-Visceral serosa covers internal organs (viscera)
Double layers are separated by a slit-like cavity filled with serous fluid
Fluid secreted by both layers of membrane
Pleural Cavity
Abdominal Pelvic Cavity
Dorsal Body Cavity
Vertebral Cavity
Cranial Cavity
A body cavity is a fluid-filled space inside the body that holds and protects internal organs
Body contains internal cavities that are closed to an environment
Cavities provide different degrees of protection to organs within them
The Body’s Organ Systems and Their Major Functions
Female Reproductive System
Mammary glands, Ovary, Uterus, Vagina, Uterine tube
Overall function is offspring. Ovaries produce eggs and female sex hormones
Male Reproductive System
Prostate, Penis, Testis, Scrotum, Ductus deferens
Overall function is production of offspring. Testes produce sperm and male sex hormones
Urinary System
Urinary Bladder, Kidney, Urethra
Eliminates nitrogenous wastes from the body. Regulates water, electrolyte, and acid-base balance of the blood
Digestive System
Liver, Stomach, Large/Small Intestine
Breaks down food into absorbable units that enter the blood for distribution to body cells. Indigestible food are eliminated as feces
Respiratory System
Lungs, Nasal Cavity, Pharynx, Trachea, Bronchus
Keeps blood constantly supplied with oxygen and removes carbon dioxide. Occurs within the walls of the lungs
Lymphatic system
Redbone Marrow, Thymus, Spleen, Lymph nodes
Picks up fluids leaked from blood vessels and returns it to blood. Houses white blood cells (involved with immunity).
Cardiovascular System
Blood Vessels, Heart
Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. The heart pumps blood
Endocrine System
Ovary, Testis, Adrenal gland, Pancreas
Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use
Nervous System
Nerves, Brain, Spinal cord
Responds to internal and external changes by activating appropriate muscles and glands
Muscular System
Muscles in body: Obliques, Biceps, Pec
Allows manipulation of the environment, locomotion, facial expression, etc
Skeletal system
Bones, Joints
Protects and supports body organs. Blood cells are formed within bones
Integumentary System
Hair, Skin, Nails
Synthesizes vitamin D and houses pain, pressure, etc receptors along with sweat and oil glands
Requirements for life
Growth
Increase in size of a body part or of the organism
Reproduction
At the cellular level, reproduction involves the division of cells for growth or repair
At the organismal level, reproduction is the production of offspring
Excretion
Removal of wastes from metabolism and digestion E.g
Urea (from breakdown of proteins), carbon dioxide (from metabolism), feces (unabsorbed food)
Metabolism
All chemical reactions that occur in body cells. Sum of all catabolism (breakdown of molecules) and anabolism (synthesis of molecules)
Digestion
Mechanical and enzymatic breakdown of ingested food, followed by absorption of simple molecules (monomers) into blood/lymphatics
Responsiveness
Ability to sense and respond to stimuli
Movement
The muscular System allows movement
of body parts via skeletal muscles and of substances via cardiac muscle (blood) and smooth muscle (digestion, urination)
Maintaining Boundaries
Separation between internal and external environments
(E,g Plasma membranes, Skin separates organism from environment)
Structural Organization
Organismal Level
All Organ Systems Combined to Make the Whole Organism
Organ System
Organs That Work Closely Together
Organ Level
Contains 2+ Types of Tissues
Tissue Level
Groups of Similar Cells
Cellular Level
Single Cell
Chemical Level
Atoms, Molecules, Organelles
Anatomy and Physiology
The two are Inseprable
- Function always reflects structure
- What a structure can do depends on its specific form
- Known as the principle of complementarity of structure and function
Physiology
Looks at how the body’s abilities are dependent on chemical reactions in individual cells
Often focuses on cellular and molecular levels of the body
Based on organ systems
Study of the function of body parts; how they work to carry out life-sustaining activities
Anatomy
Developmental
Embryology
Microscopic
Cytology, Histology
Gross/Macroscopic
Reigonal, System, Surface
Study of the structure of body parts and their relationship to one another
