UNIT 2, SLIDES 1. homeostasis

Understanding of homeostatic mechanisms as dynamic processes.
- Distinction between acclimatization and adaptation.
Comprehension of positive feedback mechanisms.
Familiarity with general anatomic terminology.
- Terms of relative direction/position.
- Body planes.
- Body surface regions (covered mainly in lab).
Knowledge of body cavities and the membranes lining these cavities.
Understanding of abdominopelvic regions and quadrants.

No over/undershoot in physiological variables in healthy individuals.
- After change from the set point, the variable returns exactly back to the set point.
- Absence of overshoot indicates proper function of homeostatic mechanisms.
- An overshoot can indicate inappropriate increase in sensitivity of homeostatic mechanisms due to a disease state.

A form of respiration that occurs during sleep following a significant cardiac event.
- Characterized by alternating periods of apnea (temporary halt in breathing) and hyperpnea (increased breathing).
- This pattern arises due to heightened responsiveness of the respiratory system.
Main physiological stimulus for breathing is the levels of CO2 in blood.
- CO2 levels are maintained through a negative feedback loop:
- Too high CO2: leads to rapid breathing.
- Too low CO2: can lead to cessation of breathing.

Acclimatization:
- Refers to long-term changes in the environment, leading to improved homeostatic control.
- Example: In heavy drinkers, repeated increases in Blood Alcohol Concentration (BAC) trigger an upregulation of alcohol dehydrogenase, helping to mitigate increases in BAC over time.
Drugs and Homeostatic Plasticity:
- Example: THC use increases endorphin release.
- The body responds by decreasing the expression of endorphin receptors, normalizing neuronal activity despite high levels of endorphins.
- Consequence: When endorphin levels normalize, reduced receptors can lead to withdrawal symptoms.
Adaptations:
- Changes in homeostatic mechanisms that can be inherited.
- These changes improve survival in particular environments.

Positive feedback loops are uncommon in the body.
Function by intensifying the stimulus rather than negating it.
- They are typically short-lived and can lead to unstable conditions.
- Eventually results in restoration of homeostasis.
Examples include:
- Blood clotting processes.
- Uterine contractions during childbirth.
- Learning processes.

Anatomical Position: Standard position of reference in anatomy where the individual stands erect, faces forward, arms at their sides, and palms facing forward.
Importance of anatomical terms reviewed in lectures and labs for understanding of structures and regions:
- Surface Body Regions:
- Otic (ear).
- Nasal (nose).
- Oral (mouth).
- Cervical (neck).
- Acromial (point of shoulder).
- Axillary (armpit).
- Mammary (breast).
- Brachial (arm).
- Cephalic (head).
- Frontal (forehead).
- Orbital (eye cavity).
- Buccal (cheek).
- Mental (chin).
- Sternal (chest).
- Inguinal (groin).
- Coxal (hip).
- Occipital (back of head).
- Vertebral (spinal column).
- Dorsal (back).
- Cubital (elbow).
- Lumbar (lower back).
- Sacral (between hips).
- Gluteal (buttocks).
- Perineal (between reproductive organs and anus).
- Umbilical (navel).
- Antecubital (front of elbow).
- Abdominal (abdomen).
- Antebrachial (forearm).
- Carpal (wrist).
- Palmar (palm).
- Digital (finger).
- Genital (external reproductive organs).
- Patellar (front of knee).
- Crural (leg).
- Tarsal (ankle).
- Digital (toe).
- Femoral (thigh).
- Popliteal (back of knee).
- Pedal (foot).
- Sural (calf).
- Calcaneal (heel).
- Plantar (sole).

Sagittal section:
- Cut dividing the body into left and right portions.
- Mid-sagittal/Median section: divides body into equal left and right portions.
- Parasagittal section: sagittal section lateral to midline, divides body into unequal left and right portions.
Transverse or Horizontal section: divides the body into superior and inferior portions.
Coronal or Frontal section: divides the body into anterior and posterior portions.
Importance of understanding these body planes in evaluating medical imaging.

Human body consists of two main portions:
- Axial portion: includes the head, neck, and trunk.
- Appendicular portion: includes the upper and lower limbs.

Thoracic Cavity components:
- Left/Right Pleural Cavity: each contains a lung.
- Mediastinum: contains trachea, esophagus, and major vessels, separates each lung cavity.
- Pericardial cavity: surrounds the heart.
Abdominopelvic Cavity components:
- Separated from the thoracic cavity by the diaphragm.
- Abdominal Cavity: houses digestive organs.
- Pelvic Cavity: contains bladder, reproductive organs, and rectum.

Lined by double-layered serous membranes that secrete serous fluid to prevent friction between layers:
- Visceral layer: inner layer that directly covers an organ.
- Parietal layer: outer layer that lines the wall of the cavity.
There is a small fluid-filled space between the two layers of serous membranes; excess fluid can indicate a disease state.

Refers to the inflammation or buildup of fluid inside the pericardium (serous membranes surrounding the heart).
Can be caused by various conditions such as pneumonia, viral infections, or chest surgery.
Increased pressure from the fluid can decrease heart function.

Serous membranes are named based on the cavities they line:
- Thoracic Cavity: Pleural cavities are lined with the Pleural Membranes.
- Abdominopelvic Cavity: referred to as the Peritoneum, lined with peritoneal membranes:
- Visceral peritoneum: covers the organs.
- Parietal peritoneum: lines the cavity walls.