Nervous and Endocrine Systems Quiz

Nervous System

• Marked as 5 marks, 1NR (5 marks, 1 non-responsive question).
• Includes Neuron (2 marks)
• Includes Impulse (1 mark)
• Includes Synaptic transmission (2 marks)
• Includes Brain (2 marks)
• Includes Eye & Ear (2-3 marks).

Endocrine System

• Marked as ~6-7 marks.
• Includes Glands & hormones (2 marks)
• Includes Specific hormone functions (2 marks)
• Includes Negative feedback loops (ie TSH, ACTH) (1 mark)
• Includes What if (1 mark)
• Includes Disorder (1 mark)

Nervous System vs Endocrine System

• Nervous System acts via electrochemical impulses (action potentials & neurotransmitters).
• Endocrine system acts via chemical messengers (hormones).
• Nervous system communication is cell-to-cell (neurons to neurons or neurons to effector cells).
• Endocrine system communication is via bloodstream to target cells.
• Nervous system response is fast, short-term.
• Endocrine system response is slow, long-lasting.

Endocrine System: Feedback Loops

• Positive feedback increases the initial stimulus and moves the body away from homeostasis.
• Examples include oxytocin release during parturition.
• Negative feedback inhibits the initial stimulus and returns the body to homeostasis.
• Examples include regulation of estrogen, progesterone, and testosterone.

Key Endocrine Glands

• Hypothalamus
• Pituitary gland
• Thyroid gland
• Parathyroid gland
• Thymus
• Adrenal gland
• Pancreas
• Ovary
• Testis

Hypothalamus & Pituitary Gland

• Hypothalamus regulates the pituitary gland.
• Hypothalamus releases tropic hormones (stimulates other glands).
• Pituitary gland is considered the "master gland".
• Pituitary gland releases hormones involved in growth, development, metabolism, and reproduction.

Pituitary Hormones

• Posterior pituitary releases hypothalamic hormones oxytocin and ADH.
• Anterior pituitary releases hormones synthesized by the pituitary including hGH, prolactin, TSH, ACTH, FSH, and LH.

Adrenal Gland

• Adrenal medulla (inner layer) secretes Epinephrine and norepinephrine, responsible for short-term stress response.
• Adrenal cortex (outer layer) secretes Glucocorticoids (e.g., cortisol) and mineralocorticoids (e.g., aldosterone), responsible for long-term stress response.

Pancreas

• Pancreas secretes digestive enzymes into the small intestine.
• Islets of Langerhans = specialized pancreatic cells secreting hormones to regulate glucose retention.
• Alpha cells secrete glucagon.
• Beta cells secrete insulin.

Water Soluble & Fat Soluble Hormones

• Water-soluble hormones (proteins, peptides, and amino acids) cannot cross the lipid membrane and bind to external receptor sites.
• Examples include hGH and epinephrine.
• Fat-soluble hormones (steroids) diffuse across the lipid membrane and bind to receptor sites within the cytoplasm .
• Examples include sex hormones.

Hormone Responses

• Growth and metabolism - hGH, TSH, thyroxine, calcitonin, and PTH.
• Stress - epinephrine, norepinephrine, cortisol, ACTH, and aldosterone.
• Blood glucose - glucagon and insulin.
• Water and ion balance - ADH.

Human Growth Hormone (hGH)

• Secreted by the anterior pituitary gland.
• Targets almost all body tissues: increases protein synthesis, cell division, metabolic release, and promotes cartilage, bone and muscle tissue growth.
• Important in childhood development.

Thyroxine (T4)

• Secreted by the thyroid gland.
• Targets almost all body tissues: increases metabolism of fats, proteins, and carbohydrates.
• High T4 = hyperthyroidism (symptoms?)
• Low T4 = hypothyroidism (symptoms?).

T4 Regulation

• T4 (thyroxine) is controlled via negative feedback by TSH (thyroid-stimulating hormone).
• When thyroxine levels fall, TSH is released from the anterior pituitary, stimulating thyroxine production.
• When thyroxine levels rise, TSH production is suppressed by the hypothalamus.

Thyroid and Iodine

• Thyroid requires iodine to produce thyroxine.
• Lack of iodine inhibits thyroxine production and can lead to goiter (thyroid gland enlargement).

Calcitonin

• Secreted by the thyroid gland.
• ↑ [Ca²⁺] in blood = calcitonin stimulates calcium uptake from blood into bones.
• Lowers blood Ca²⁺ levels.

Parathyroid Hormone (PTH)

• Secreted by the parathyroid glands.
• ↓ [Ca²⁺] in blood = PTH released, stimulating breakdown of bones into calcium phosphate.
• Increases blood Ca²⁺ levels. Vitamin D activation and increased calcium reabsorption in intestines are also stimulated by PTH.

Calcitonin and PTH

• Calcitonin and PTH work antagonistically to regulate blood Ca²⁺.

Stress Hormones

• Stress hormones are secreted by the adrenal glands.
• Epinephrine and norepinephrine (secreted by the adrenal medulla) regulate short-term stress response ("fight or flight").
• Cortisol (secreted by the adrenal cortex) regulates long-term stress response.
• Adrenal medulla hormones trigger rapid response via nerve impulses from the hypothalamus. Increase breathing and heart rate to prepare for action.

Cortisol

• Secreted by adrenal cortex
• Regulated by ACTH (released by anterior pituitary).
• Regulates long-term stress response. Increases muscle breakdown into amino acids.
• Promotes breakdown of fat cells.

Aldosterone

• Secreted by the adrenal cortex.
• Regulates long-term stress response by promoting elevated oxygen and nutrient delivery to cells.
• Increases sodium absorption in nephrons (kidneys).
• Increased solute in blood = increased water absorption, increasing blood pressure.

Insulin & Glucagon

• Secretion by Pancreatic cells.
• Insulin: lowers blood [glucose]. Secreted by beta cells of islets of Langerhans in the pancreas, increases permeability to glucose in skeletal muscle and liver cells, leading to storage as glycogen.
• Glucagon: increases blood [glucose]. Secreted by alpha cells of islets of Langerhans in the pancreas. Breakdown of glycogen in liver cells and fat in adipose tissue to release glucose into the bloodstream.

Insulin & Glucagon Regulation

• Insulin and glucagon work antagonistically to maintain blood glucose levels. In other words, insulin reduces blood glucose, glucagon increases it.

Diabetes Mellitus

• Type 1 diabetes is diagnosed in childhood. The immune system attacks beta cells, decreasing insulin production. Requires daily insulin injections.
• Type 2 diabetes develops over time. Cell receptors stop responding to insulin, or beta cells produce less insulin. Requires diet, exercise and sometimes medication to regulate.

Antidiuretic Hormone (ADH)

• Secreted by posterior pituitary when blood osmotic pressure is high (↓ [water]).
• Target: nephrons in kidneys. Inhibits water loss.
• Regulation of water reabsorption, making nephron tubules more permeable to water in order to form concentrated urine. Decreased osmotic pressure signals negative feedback to the hypothalamus which reduces ADH production.

Diabetes Insipidus

• Inability to produce, store, or properly respond to ADH.
• Characterized by large urine output.
• Can occur during pregnancy. Can be treated with ADH administration.

Likely Disorder Questions:

• Diabetes (Mellitus type I, Mellitus type II, Insipidus)
• Growth (Too much or too little hGH → gigantism or dwarfism)
• Thyroxine (too much → high metabolism (Grave's disease) or too little → low metabolism (goiter))

Other

• Additional details and potential questions about the different glands and hormone responses for the human body and the associated diseases.