Human Biology: Brain Functions, Mitosis, and Hormones

Brain Anatomy and Functions

• Spinal bulb/medulla: Controls heartbeat, sneezing, coughing, and other vital functions.
• Cerebellum: Intervenes in the control of muscles, posture, and balance of the body.
• Thalamus: Acts as a filter of information.
• Hypothalamus: Controls body temperature and blood pressure.
• Limbic system: Controls behaviors related to feeding, aggression, and sexuality.
• Additional Structures: Frontal lobe, pituitary gland, temporal lobe, pons, and pleura.

Types of Sensory Receptors

• Mechanoreceptors: Detect changes in pressure in muscles, articulations, and ears.
• Thermoreceptors: Inform us about heat and cold through the skin.
• Chemoreceptors: Detect chemical substances in the air and food via the nose and tongue.
• Photoreceptors: Capture luminous energy through the eyes.
• Nociceptors: Detect dangerous stimuli and pain; the skin also captures heat, cold, and pressure.

Human Sexual Hormones

Female Hormones

• Estrogens: Responsible for secondary characteristics, the growth of the uterus, the development of the ducts of the breast, and the maturity of the ovaries.
• Progesterones: Preparing the uterine wall for the embryo.

Male Hormones

• Androgens: Responsible for secondary sexual characteristics.
• Testosterones: Responsible for the production and maturation of spermatozoa.

Energy and the Renal System

Calorie Definition

A calorie is the amount of heat required to increase the temperature of a gram of water by 1 degree Celsius.

Renal Anatomy

• Renal cortex: Contains the Bowman's capsule.
• Renal medulla: Contains the loops of Henle.
• Renal pelvis: Where urine produced from nephrons is collected.

The Stages of Mitosis

• Interphase: Chromosomes are copied. They appear as threadlike coils and change to sister chromatids at the end of this phase.
• Prophase: Mitosis begins. Centrioles appear and begin to move to opposite ends of the cell. Spindle fibers form between the poles.
• Metaphase: Chromatids attach to the spindle fibers.
• Anaphase: Chromatids separate and begin to move to opposite ends of the cell.
• Telophase: Two new nuclei form. Chromosomes appear as chromatin, and mitosis ends.
• Cytokinesis: The cell membrane moves inward to create two daughter cells, each with its own nucleus and identical chromosomes.

Cell Movement and Digestion

Movement of Cells

Cellular movement occurs via cilia, flagella, amoeboid movement, and contractions.

Types of Digestion

• Mechanical Digestion: Consists of cutting, crushing, removing, and diluting foods, bringing about physical changes in the food.
• Chemical Digestion: Done through the action of substances which attack the foods and bring about chemical changes in them, breaking them down into smaller substances.