BIOL 1103 Week 4 - Body Structure & Homeostasis

Integumentary system function

Responsible for the body’s outermost layer, which functions as a protective barrier against the external environment

Skeletal system function

The body's support structure, composed of bones, cartilage, ligaments, and tendons.

Muscular system function

Permits movement of the body, maintains posture, and circulates blood throughout the body

Respiratory system function

Inhaling and exhaling + exchange of gas within the body and with the external environments

Cardiovascular system function

Transport of nutrients, gases, etc. throughout the body

Lymphatic system function

Return of fluid from the interstitial compartment to the cardiovascular system

Digestive system function

Eating, absorption of nutrients, removal of wastes through defecation

Urinary system function

Filtration of blood and removal of wastes through micturition

Nervous system function

Voluntary and involuntary control of the body

Endocrine system function

Hormonal regulation of the body

Reproductive system function

Formation of gametes and development of reproductive organs

Superior

Referring to a position that is above or higher than another part of the body

Inferior

Referring to a position that is below or lower than another part of the body

Medial

Referring to a position that is closer to the midline of the body.

Lateral

Referring to a position that is farther from the midline of the body.

Anterior

Referring to a position that is toward the front of the body.

Posterior

Referring to a position that is toward the back of the body

Proximal

Referring to a position that is closer to the point of attachment of a limb or other body structure

Distal

Referring to a position that is farther from the point of attachment of a limb or other body structure

Saggital

A vertical plane that divides the body into right and left parts

Transverse plane

A horizontal plane that divides the body into superior (upper) and inferior (lower) parts

Frontal/coronal plane

A vertical plane that divides the body into anterior (front) and posterior (back) parts

Intermediate

A position between the two other structures

Parietal

Pertaining to or forming the outer wall of the body cavity

Visceral

Pertaining to the covering of an organ or inner layer

Peripheral

Referring to a position away from the centre

Central

Referring to a position away from the centre

Deep

Refers to something further away from the surface

Superficial

Refers to something near the outer surface

Median

Refers to the middle of a structure (not the same as medial)

Cranial cavity

Space within the skull that accommodates the brain

Vertebral cavity

Anatomical space formed by the vertebral column that accommodates the spinal cord and nerve roots

Thoracic cavity

Space within the chest enclosed by the rib cage, containing the heart and lungs

Abdominal cavity

Large body space located below the chest and above the pelvis, containing the intestines and stomach

Pelvic cavity

Space within the pelvic bones that houses the bladder and internal reproductive organs

Serous membrane

Smooth epithelial membrane lining the contents and inner walls of body cavities, secreting serous fluid

Pleura

Membrane lining the pleural cavity, which covers the lungs in the thoracic cavity

Pericardium

Membrane lining the pericardial cavity, covering the heart in the mediastinum

Mediastinum

Middle part of the thoracic cavity

Peritoneum

Membrane lining the peritoneal cavity, covering the organs that fill the abdominopelvic cavity

Abdominopelvic cavity

Body cavity consisting of the abdominal cavity and pelvic cavity

Peritoneal cavity

Potential space between the parietal and visceral peritoneum that contains. mall amount of peritoneal fluid to lubricate organs

Three conditions for homeostasis:

1. Proper concentration of gases (eg. O2, CO2),
nutrients (eg. glucose), salts (eg. NaCl), water
2. Optimum temperature (37C)
3. Optimum pressure (eg. blood pressure)

What percentage of extracellular fluid is interstitial fluid?

80%

What percentage of extracellular fluid is plasma?

20%

How much of our bodily fluid is intracellular fluid?

2/3

How much of our bodily fluid is extracellular fluid?

1/3

How does plasma exchange materials with intracellular fluid?

Through the circulatory system

How does interstitial fluid exchange materials with intracellular fluid?

Direct exchange with cells

Can extracellular compartments exchange fluid?

Yes, fluid is exchanged between extracellular compartments

How does interstitial fluid return to the circulatory system?

Through the lymphatic system (about 15%)

Stress (stressor)

Any stimulus that causes an imbalance in the internal environment

Changes in blood pressure is an example of an _____________ stress

Internal

Extreme temperatures are an example of an _____________ stress

Internal

Feedback loop

A circular situation where the status of a body condition is
monitored and then reported back to a control centre which causes an action that changes the status, in order to regain homeostasis

First step of a feedback loop

Input: A stimulus that causes change

Second step of a feedback loop

Sensor: Sensory structures called receptors that detect change and sends signal to control centre

Third step of a feedback loop

Control centre: Most often is the hypothalamus which receives the signal and sends an appropriate signal to target tissues

Fourth step of a feedback loop

Effector: Targets tissues that receive signal and adjust the
condition

Fifth step of a feedback loop

Output: The resulting change from the effector(s) that then
brings condition back to homeostatic level

Negative feedback loop

Common feedback loop where a particular body
condition is constantly monitored to ensure
homeostasis is maintained. The output is the opposite of the input

Blood pressure rising is an example of a _______________ feedback loop

Negative

Baroreceptors

A receptor sensitive to changes in blood pressure

When the brain processes an increase in blood pressure, what happens?

It sends a message to the effectors which are the heart to slow down heart rate and blood vessels to vasodilate

When it’s too cold, what signals does the brain send to the body?

• Contraction of skeletal muscle
  (shivering)

• Vasoconstriction

• Release of hormones (to
  increase thermogenesis)

• Increase in muscle tone

When it’s too hot, what signals does the brain send to the body?

• Release of sweat by sweat glands

• Vasodilation

• Fewer hormones released (decrease thermogenesis)

• Decrease in muscle tone

Positive feedback loop

Rare feedback loop where the output is stronger, more amplified than the input

How is childbirth an example of a positive feedback loop?

Pressure from the baby’s head on the cervix stimulates the release of oxytocin, which causes stronger and more frequent uterine contractions

Dorsal cavity

Large posterior body cavity that protects the central nervous system

Ventral cavity

Large anterior body cavity, comprised of the thoracic and abdominal cavity