Hormones, Nervous System, and Brain Functions

Posted on Jan 22, 2025 in Biology

Hormonal Regulation of Blood Glucose

Insulin: Released when blood glucose levels are high.

Glucagon: Released when blood glucose levels are low, stimulating the liver to release glucose, thus increasing blood glucose levels.

Antidiuretic Hormone (ADH)

Function: Inhibits urine production by promoting water reabsorption by the kidneys. In large amounts, it causes vasoconstriction of arterioles, leading to increased blood pressure.

Production: Produced by the hypothalamus.

Female Reproductive Hormones

Estrogens:

  • Stimulate the development of secondary female characteristics.
  • Mature female reproductive organs.

Estrogen & Progesterone:

  • Promote breast development.
  • Regulate the menstrual cycle.

Progesterone:

  • Helps in the implantation of an embryo in the uterus.
  • Helps prepare breasts for lactation.

Characteristics of the Nervous System

The nervous system:

  1. Requires information received from our senses.
  2. Integrates information, making it all make sense.
  3. Is very fast to receive, integrate, and produce a response.

Information Flow:

  1. Sensory Input: Monitors changes occurring inside and outside the body (stimuli).
  2. Integration: Processes and interprets sensory input and decides whether action is needed.
  3. Motor Output: A response to integrated stimuli, activating muscles or glands.

Somatic vs. Autonomic Nervous System

Somatic Division

Functions:

  • Voluntary: conscious control of skeletal muscles.
  • Involuntary: spinal reflexes (flexor, crossed extensor, stretch).

Neurotransmitter: Uses Acetylcholine.

Autonomic Division

Controls automatic body functions.

Sympathetic Division

Origin: Thoracic or lumbar regions.

Function: Releases norepinephrine for fight-or-flight reaction; opposes parasympathetic division; arouses the body.

Parasympathetic Division

Origin: Brain or sacral region.

Function: Releases acetylcholine to relax the body; opposes sympathetic division; predominates during relaxation.

Neuroglia and Brain Tumors

Neuroglia divide, and most brain tumors involve neuroglia cells, not neurons. Tumors are based on cell division.

Oligodendrocytes vs. Schwann Cells

Both produce myelin. Schwann cells wrap around the axon, while oligodendrocytes create the myelin sheath.

  • CNS: Oligodendrocytes
  • PNS: Schwann cells

Cerebral Lobe Functions

  • Occipital: Visual area
  • Temporal: Auditory area, Olfactory area
  • Parietal: Somatic sensory
  • Frontal: Somatic motor

Functions of the Cerebellum

The cerebellum:

  • Coordinates basic movement.
  • Controls balance and equilibrium.
  • Provides timing for skeletal muscle activity.
  • Coordinates body movements.

Gray vs. White Matter in the CNS

  • Internal Gray Matter: Mostly cell bodies of neurons.
  • External White Matter: Conduction tracts.