Additional Deep Brain Additional Deep Brain StructuresStructures

Notes to be added after the Notes to be added after the ThalamusThalamus and and HypothalamusHypothalamus

Pages from “The Brain.”Pages from “The Brain.”

The Pituitary Gland

Often called the "Master Gland," the pituitary gland lies in a small pocket of bone at the skull base called the sella turcica. It is a small endocrine organ that is controlled by the hypothalamus, and directs other organs and endocrine glands to suppress or induce hormone production.

The Pituitary Gland

This small gland, also called the hypophysis, is divided into an anterior lobe, intermediate, and posterior lobe, all of which are involved in hormone production.

Intermediate Lobe

Function of the Anterior Lobe of the Pituitary

Also known as the adenohypophysis, this anterior lobe of the pituitary gland is responsible for secreting the following hormones:Growth hormone - (GH) for stimulating growth, as well as cell reproduction and regeneration.

Prolactin (PRL) for stimulating milk production in nursing mothers.

Function of the Anterior Lobe (continued):

Adrenocorticotropic hormone (ACTH), which is required for stimulating the adrenal cortex the adrenal glands.

Follicle-stimulating hormone (FSH) for taking care of the development, growth, pubertal maturation and reproductive processes of the body.

Function of the Anterior Lobe (continued):

Thyroid-stimulating hormone (TSH) which stimulates the thyroid gland.

Luteinizing hormone (LH) is secreted to stimulate the ovulation and corpus luteum development in female, and stimulates the production of testosterone in men.

Function of the Posterior Lobe of the Pituitary:

The posterior lobe is also known as neurohypophysis and it is responsible for the release of the following hormones:Antidiuretic hormone or Vasopressin (ADH) which regulates water balance by causing an increase in the absorption of water back into the blood at the kidneys, thus allowing water reabsorption and excretion of more concentrated urine.

Function of the Posterior Lobe (continued):

Oxytocin - This hormone is released during labor when the fetus stimulates the cervix and vagina. It enhances contraction of uterine smooth muscle to facilitate birth. It is also responsible for the stimulation of milk ejection (“let-down”) which facilitates breast-feeding (not to be confused with milk production facilitated by prolactin).

Intermediate Lobe

In adult humans, the intermediate lobe is just a thin layer of cells between the anterior and posterior pituitary. It can be regarded as the boundary between the other two lobes. Also known as the pars

intermedia, it is often considered part of the anterior pituitary. The main function of the intermediate lobe is to produce melanocyte-stimulating hormone (MSH).

Function of the Intermediate Lobe of the Pituitary:

Intermediate Lobe

Function of the Intermediate Lobe of the Pituitary:

Melanocyte-stimulating hormone (MSH) stimulates the production and release of melanin (melanogenesis) by melanocytes in skin and hair. MSH also signals the brain to have effects on appetite and sexual arousal.

An Interesting Extra:Different levels of MSH are not the major cause of racial variation in skin color. However, in many red-headed people, and others who do not tan well, there are variations in their hormone receptors, causing them to not respond to MSH in the blood.

Pineal Gland

The Pineal Gland

The pineal gland (also called the epiphysis) is a small, pine cone shaped gland of the endocrine system located between the two cerebral hemispheres in the groove where the two halves of the thalamus join. The pineal gland is a partof the diencephalon of the brain, and it produces several important hormones:

Functions of the Pineal Gland

The pineal gland produces the serotonin derivative melatonin, which influences sexual development, sleep-wake cycles, and seasonal functions – which means melatonin helps regulate the body’s internal clock and circadian rhythms.

Pineal Gland

Thalamus

Pineal Gland

Functions of the Pineal Gland

The pineal gland also connects the endocrine system with the nervous system in that it converts nerve signals from the sympathetic system of the peripheral nervous system (two subjects of a future lecture) into hormone signals.

Pineal Gland

Thalamus

Pineal Gland

The Limbic System

The limbic system, often referred to as the "emotional brain," is a set of brain structures located on top of the brainstem and under the cerebral cortex that are involved in many of our emotions and motivations, particularly thosethat are related to survival. Suchemotions include fear, anger, and the emotions related to sexual behavior.

The Limbic System

The limbic system is also involved in feelings of pleasure that are related to our survival, such as those experienced from eating and sex. Certain structures of the limbic system are involved in memory as well. Thus, overall the limbicsystem is the center of our emotions, learning, and memory.

The Limbic System

Included in this system are the hypothalamus, thalamus, amygdala, and hippocampus. Other structures near to the limbic system that are intimately connected to it are the cingulate gyrus, olfactory bulbs & olfactory cortex, fornix and the pre-frontal cortex.

Hypothalamus

The Hypothalamus – expanded notes

The hypothalamus is responsible for regulating hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger and aggressive behavior, and more. It controls these things by being neurally and chemically connected to thepituitary gland.  As was discussed earlier, the pituitary is called the “master gland,” and that which controls the pituitary, controls all its functions.

The Hypothalamus – expanded notes

Hypothalamus

The hypothalamus also regulates the functioning of the autonomic nervous system (notes to come), which in turn means it regulates things like pulse, blood pressure, breathing, and arousal in response to emotional circumstances. Control of all these means that the main, overall function of the hypothalamus is the maintenance of the body’s homeostasis. 

Thalamus - serves as a central relay station for all sensory information (except smell) that goes into and comes out of the cerebral cortex. It plays a key role in pain, touch, and temperature sensation, as well as in attention, alertness and memory.

Thalamus

The amygdala is an almond shaped mass of nuclei located deep within the temporal lobe of the brain. It is the heart of the emotional system. It processes and interprets all sensory data and is involved in many of our emotions and motivations, particularly those that are related to survival.

The amygdala is involved in the processing of emotions such as fear, anger and pleasure. It processes and stores memories of emotional events and is responsible for determining what memories are stored and where those memories are stored in the brain.

Amygdala

The amygdala regulates the flow of emotional information between the cerebral cortex and the hypothalamus, and in doing that, it helps control autonomic, endocrine, and emotional responses.

An Interesting Extra:Researchers also find that the amygdala in men and women respond differently to emotional situations. Go figure, men and women display different emotions under equal circumstances!

The hippocampus is the part of the brain that is involved in memory formation, organization, and storage, as well as spatial navigation. It is important in forming new memories – especially episodic memories relating to personal events and their related emotions – and connecting emotions and senses to memories. The hippocampusacts as a memory sorter by sending memories out to the appropriate part of the cerebral hemisphere for long-term storage and by retrieving them when necessary.

The cingulate gyrus is a fold in the brain which lies just above the corpus collosum and is involved with sensory input concerning emotions and the regulation of aggressive behavior.  It provides a pathway from the thalamus to the hippocampus, helps focus attention on emotionally significant events, and associates memories to smells and to pain.

Cingulate Gyrus Cingulate Gyrus