Week 11 (Endocrine Physiology) Flashcards
Endocrine System
Regulates the body’s activities by secreting hormones (chemical messengers) into the bloodstream, lymph, and interstitial fluid, where they are carried throughout the entire body.
Responsible for sending and receiving sensory information and coordinating body responses.
The Nervous System also does this; the two systems work together and are sometimes referred to as the Neuroendocrine System.
Influences metabolism of specific target cells/organs.
Regulated by negative feedback.
The goal is to preserve homeostasis.
Endocrine glands produce and secrete hormones.
*These are ductless glands.
Major Endocrine Glands
Hypothalamus
Pituitary gland
Pineal gland
Thyroid gland
Thymus
Parathyroid glands
Pancreas
Adrenal glands
Ovaries
Testes
Other Cells, Tissues, or Organs That Secrete Hormones
Heart (atria)
Kidney
Stomach
Liver
Small intestine (duodenum)
Platelets
Lymphocytes
Skin (epidermal cells)
Adipose tissue
Placenta
Skeleton
Classification of Endocrine Glands
Classical (classic) endocrine glands – organs whose primary function is hormone secretion.
Non-classical (traditional) endocrine glands – organs that produce hormones as a secondary function.
Components Of The Endocrine System
- Glands
Release hormones directly into the bloodstream, lymph, or interstitial fluid. - Hormones
Deliver messages to the body. - Target Cells
Specific cells affected by a hormone.
Have specific receptors for specific hormones. - Receptors
Proteins or glycoproteins in the plasma membrane of a target cell.
Recognize specific hormones and trigger responses in the cell.
Regulated Through Negative Feedback
Maintains hormone levels by reducing further hormone release once the desired effect is achieved.
Hormones
Chemical messengers secreted into the bloodstream, lymph, or interstitial fluid by endocrine glands.
Facilitate cell-to-cell communication.
Regulate the metabolic functions of target cells.
Elicit specific physiological responses.
Responses may be instantaneous or delayed by days.
Hormones have a wide variety of effects on the body.
Classification of Hormones
Endocrine – Hormones travel through the blood to act at a distant site.
Paracrine – Hormones act on nearby cells.
Autocrine – Hormones act on the secreting cell itself.
Neurocrine – Secreted by neural cells (includes neurotransmitters and neurohormones).
Classification of Hormones By Chemical Structure
Steroid Hormones:
Testosterone, estrogen, progesterone, cortisol, aldosterone.
Peptide/Protein Hormones:
Peptide Hormones: Antidiuretic hormone (ADH), oxytocin, adrenocorticotropic hormone (ACTH), calcitonin, parathyroid hormone (PTH).
Protein Hormones: Growth hormone (GH), insulin, glucagon, prolactin.
Glycoprotein Hormones: Follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH).
Amine/Amino Acid Hormones
Epinephrine, norepinephrine, melatonin, thyroxine (T4), triiodothyronine (T3).
Pituitary Gland
Pea-sized gland located at the base of the brain, attached to the hypothalamus.
Often referred to as the “master gland” because it regulates the hormonal secretions of several other endocrine glands (e.g., thyroid gland, testes).
Divided into two parts:
-Anterior Pituitary – Regulates a wide variety of body functions and activities.
-Posterior Pituitary – Releases hormones controlled by the hypothalamus.
Hypothalamus
Major Hormones Secreted: Regulatory hormones
Primary Target Organs: Pituitary gland
Primary Effects: Controls pituitary secretion
Pineal Gland
Major Hormones Secreted: Melatonin
Primary Target Organs: Brain
Primary Effects: Regulates sleep-wake cycles
Thyroid Gland
Major Hormones Secreted: Thyroxine (T4), Triiodothyronine (T3)
Primary Target Organs: Various tissues
Primary Effects: Regulates metabolism
Thymus
Major Hormones Secreted: Thymosins
Primary Target Organs: Immune system
Primary Effects: Stimulates T-cell production
Parathyroid Glands
Major Hormones Secreted: Parathyroid hormone (PTH)
Primary Target Organs: Bones, kidneys, intestines
Primary Effects: Regulates calcium levels
Pancreas
Major Hormones Secreted: Insulin, Glucagon
Primary Target Organs: Liver, muscles
Primary Effects: Regulates blood sugar levels
Adrenal Glands
Major Hormones Secreted: Cortisol, Aldosterone, Epinephrine
Primary Target Organs: Various organs
Primary Effects: Stress response, metabolism
Ovaries
Major Hormones Secreted: Estrogen, Progesterone
Primary Target Organs: Female reproductive system
Primary Effects: Regulates menstrual cycle, pregnancy
Testes
Major Hormones Secreted: Testosterone
Primary Target Organs: Male reproductive system
Primary Effects: Supports sperm production, secondary sex characteristics
