[2] Biology Q1L2 - Human Endocrine System

Endocrine system

Group of specialized organs and body tissues. It produces, store, and secrete chemical substances known as hormones. It works simultaneously with the nervous system.

Endocrine Organs

Sometimes called “ductless glands” because they have no ducts connecting them to specific body parts. The hormones they secrete are released directly into the bloodstream.

Exocrine glands

Releases their secretions to target areas

Endo-exocrine

They secrete hormones and other substances

Hypothalamus

Found deep within the brain and controls the pituitary gland. Coordinator of the endocrine system. Primary link between the endocrine and nervous systems.

Pituitary gland

This is the most important endocrine gland and most often called as the “master gland”.

Anterior and Posterior lobes.

Two parts of the Pituitary gland.

Anterior lobe

This regulates the activity of thyroid, adrenal and reproductive glands. It also holds the body’s growth and stimulates milk production in women.

Posterior lobe

Contains the nerve endings (axons) from the hypothalamus, which stimulate or suppress hormone production. This also secretes antidiuretic hormones (ADH), which control the water balance in the body and the oxytocin. This also controls muscle contractions in the uterus.

Adrenocorticotropic Hormone

Stimulates growth and secretions of the adrenal gland’s cortex.

Thyroid-stimulating Hormone

This triggers the secretion of thyroid hormones. It controls the amount of thyroglobulin secreted by the thyroid.

Luteinizing Hormone

This attaches an embryo to its mother’s womb. Stimulates female ovulation and male secretion of testosterone.

Follicle-stimulating Hormone

Stimulates female egg maturation and male sperm production

Growth Hormone

Promotes the growth of the skeleton and the body as a whole

Prolactin

Stimulates milk production in the breast after childbirth

Melanocyte-stimulating Hormone

Stimulates to melanocytes, the cells of the skin, which contain the black pigment. This is responsible for moles, freckles, and birthmarks.

Antidiuretic Hormone (Vasopressin)

This regulates the water retention and blood pressure

Oxytocin

Triggers contractions of the uterus during labor. This stimulates milk letdown for breastfeeding.

Thyroid gland

Located in the front of the neck. It has two lobes on each side of the trachea (windpipe). It takes iodine from the blood and uses it to make hormones.

Thyroid hormones

This control the body’s cell metabolism. Cells increase the rate at which they convert oxygen and nutrients into energy and heart.

Thyroxin

This influences the growth and development of the body.

Calcitionin

Produced in response to high calcium levels in the blood. It causes the kidneys to discharge more calcium into the urine and raises the amount of calcium stored in the bones.

Parathyroid gland

This secretes parathormone.

Parathormone

This controls the concentration of calcium (calcium ion) and phosphorus (phosphate) in the blood

Adrenal glands

This is a small, pyramid-shaped organs that secrete many vital hormones. We have two of these in our bodies, placed on top of each kidney.

Medulla (inner core) and a cortex (outer core)

Each adrenal gland comprises these two.

Adrenaline, Noradrenaline

Nerve signals stimulate the medulla to secrete epinephrine and norepinephrine into the blood. What is another term for Epinephrine and Norepinephrine?

Epinephrine and Norepinephrine

Hormones within the medulla (inner core) of the Adrenal glands

Aldosterone and Hydrocortisone

Hormones within the cortex (outer core) of the Adrenal glands

Epinephrine

Increases blood pressure, heart and metabolic rate, and blood sugar levels; dilates blood vessels released during exercise—the emergency hormone of the body that facilitates the utilization of glucose.

Norepinephrine

Increases blood pressure and heart rate and constricts blood vessels.

Aldosterone

It regulates sodium and potassium levels in the blood to control blood pressure.

Hydrocortisone

It plays a crucial role in stress response, increases blood glucose levels, mobilizes fat, and reduces inflammation.

Pineal body

It is in the middle of the brain. It can also be called the pineal gland.

Melatonin

The Pineal body secretes this hormone that regulates the wake-sleep cycle.

Melatonin

The hormone that was responsible for experiencing jet lag during long-distance air travel.

Gonads

The reproductive components of the endocrine system. This secretes sex hormones in response to stimulation of the pituitary gland.

Ovaries

These are the female gonads that produce eggs. These are located in the pelvis.

Estrogen and Progesterone

These are the female sex hormones that the ovaries secrete, which control the development of the reproductive organs, stimulate the appearance of female secondary sex characteristics and regulate menstruation and pregnancy.

Testicles (Testes)

These are the male gonads that is located in the scrotum. The male gonad produces sperm and secrete several male sex hormones or androgens.

Testosterone

This is the most important androgen. It regulates the development of the reproductive organs and stimulates the male secondary sex characteristics and muscle growth.

Pancreas

This is positioned in the upper abdomen, just under the stomach.

Exocrine Pancreas

This is the central part of the pancreas. It functions as an exocrine gland and secretes digestive enzymes into the gastrointestinal tract.

Erythropoietin

This is what the kidney secretes when the kidney detects that the number of red blood cells in the body is declining. This hormone travels in the bloodstream to the bone marrow and stimulates the production of red blood cells.

Homeostasis

This is what the endocrine system work and maintain by regulating negative feedback mechanisms.

Nervous system

This coordinates the activities of all body organ systems. It enables the body to adjust to changes within itself and its surroundings. This is made up of countless nerve cells or neurons.

Neurons

This is the basic unit of structure and function of the nervous system. These form a communication network extending to all body parts. It has a cell body. It is oldest and longest cells in the body.

Nucleus

This is what the cell body contains.

Dendrites

This carries the messages from one neuron to other neurons.

Axon

This is almost a meter in length and microscopically thin. A message carried away from the cell body is transferred through this.

Myelin sheath

This is a fatty white substance that surrounds the axon of some nerve cells, forming an electrically insulating layer.

Nodes of Ranvier

This occur along a myelinated axon where the axolemma is exposed to the extracellular.

Axon terminal

Contains synapses, specialized structures where neurotransmitter chemicals are released to communicate with target neurons.

Schwann cells

This is known for the roles in supporting nerve regeneration.

Coordination of the different actions of the body

This is one of the two major functions of the nervous system.

Coordinates of the body’s response to the outside world.

This is the second major function of the nervous system.

Receptors

The information and messages are in the form of electrical signals. This is the structure that receives information from the environment.

The central nervous system and the peripheral nervous system.

The two divisions of the nervous system.

Central nervous system

This is composed of the brain, the spinal cord, and the nerves.

Control center of the body

The coordination of different body parts is one of the main functions of the nervous system. All the information about what is happening in the outside world or within the body itself is brought to the ___.

Brain

The center of the nervous system. This is composed of the brainstem, the cerebellum, and the cerebrum.

Brainstem

This controls basic functions such as breathing rate and heartbeat. It contains nerve centers involved in hearing and vision.

Cerebellum

Controls balance or equilibrium and locomotion.

Hypothalamus

Monitors your body’s internal temperature.

Hippocampus

This helps you remember things that happened recently.

Pituitary gland

This releases hormones, special chemicals that trigger specific actions.

Spinal cord

This extends from the brain into the spine though a canal encased in a bone. This is a collection of nerve fibers and cells that carry sensory impulses from the outer parts of the body up to the brain. The brain responds by sending impulses down through other spinal cord never fibers to stimulate muscles under voluntary control.

Peripheral nervous system

This includes all neural tissues outside the central nervous system. Comprises the nerves connecting the central nervous system with every body part. Provides sensory or afferent info to the central nervous system and carries the command to the body.

Sensory Neurons

Carry information from special receptors to the central nervous system

Motor neurons

This relay instructions from the central nervous system. It carries messages from the central nervous system to the effectors.

Effectors

Parts of the body that carry out instructions of the nervous system. This is the muscles in our fingers, hand, and arms.

The somatic nervous system

This controls voluntary motor commands, such as moving the muscles to walk or talk.

Autonomic nervous system

Governs involuntary motor commands, such as digestion and heartbeat. This is a particular part of the peripheral nervous system. It carries messages from the subconscious level of the brain to the internal organs.

Parasympathetic nervous system and Sympathetic nervous system

The autonomic nervous system is divided into two subdivisions, which are the ___ and ___.

Parasympathetic nervous system

Controls the internal organs during routine conditions.

Sympathetic nervous system

Controls the internal organs, primarily during stressful situations.

Cerebrum

It regulates mental functions such as understanding, remembering, speaking, learning, reasoning, and feeling emotions.