Homeostasis and Thermoregulation

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Questions and Answers

What effect does ejaculation into the vagina have in terms of sperm movement?

It stimulates contractions of the uterus, aiding the movement of sperm.

Why is the pituitary gland referred to as the 'master gland'?

Because it controls other endocrine glands, though its release of hormones is stimulated by the hypothalamus.

How does the anterior lobe of the pituitary gland differ from the posterior lobe?

The anterior lobe produces its own hormones, while the posterior lobe stores and releases hormones produced by the hypothalamus.

What role do prolactin and oxytocin play during pregnancy and after childbirth?

Prolactin contributes to the development of mammary glands and stimulates breast milk production after birth, while oxytocin aids in uterine contractions. Signup and view all the answers

What mechanisms help control hormone release from the hypothalamus?

Nervous system control and negative feedback systems help regulate how hormones are released by the hypothalamus. Signup and view all the answers

What distinguishes exocrine glands from endocrine glands?

Exocrine glands release secretions into ducts leading outside the body or into cavities, while endocrine glands release hormones directly into the bloodstream. Signup and view all the answers

Describe the primary difference in solubility between protein hormones and steroid hormones.

Protein hormones are hydrophilic and soluble in water, whereas steroid hormones are hydrophobic and insoluble in water. Signup and view all the answers

How do water-soluble hormones like insulin activate cellular functions?

Water-soluble hormones bind to receptors on the cell membrane, forming a hormone-receptor complex that activates adenylyl cyclase, resulting in the production of cyclic AMP to activate enzymes. Signup and view all the answers

Explain the process by which lipid-soluble hormones exert their effects on target cells.

Lipid-soluble hormones diffuse through membranes, bind to receptors in the cytoplasm, and the hormone-receptor complex then moves to the nucleus to activate or deactivate specific genes. Signup and view all the answers

What role do the hypothalamus and pituitary gland play in the endocrine system?

The hypothalamus produces releasing hormones that stimulate the pituitary gland to release various hormones, thus regulating key body functions. Signup and view all the answers

What is homeostasis and why is it important for living organisms?

Homeostasis is the maintenance of a steady internal state despite changes in the external environment, and it is crucial for the proper functioning of cells and overall health. Signup and view all the answers

Describe the three functional components involved in maintaining homeostasis.

The three functional components are receptors that receive stimuli, a control center that integrates information, and effectors that perform responses to restore balance. Signup and view all the answers

Explain the difference between negative and positive feedback systems.

Negative feedback systems restore conditions to their original state, while positive feedback systems amplify changes, moving the controlled variable further from a steady state. Signup and view all the answers

What is thermoregulation and how do ectotherms differ from endotherms in this process?

Thermoregulation is the maintenance of body temperature, where ectotherms rely on external temperatures for metabolic regulation, whereas endotherms maintain constant body temperatures internally. Signup and view all the answers

What role does the hypothalamus play in hormone regulation?

The hypothalamus releases hormones that stimulate or inhibit hormone production from the anterior pituitary, and it is controlled by the nervous system. Signup and view all the answers

Provide an example of a negative feedback mechanism in the human body.

An example of negative feedback is the regulation of blood glucose levels, where increased glucose triggers insulin release to lower blood sugar levels. Signup and view all the answers

Explain how negative feedback systems influence hypothalamic hormone release.

Negative feedback systems regulate the release of hypothalamic hormones by ensuring that hormone levels remain within a specific range, thereby preventing overproduction. Signup and view all the answers

List two hormones produced by the hypothalamus and their functions.

Antidiuretic hormone (ADH) regulates blood pressure and water reabsorption, while oxytocin stimulates uterine contractions during labor and milk release in females. Signup and view all the answers

What are gonadotropin-releasing hormone (GnRH) functions?

GnRH stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. Signup and view all the answers

Describe the pathway through which hypothalamic hormones reach the pituitary gland.

Hypothalamic hormones are secreted into the blood via nerve endings and transported through the portal vein to the pituitary gland. Signup and view all the answers

What are the two types of hyperglycemia, and how are they defined?

The two types of hyperglycemia are postprandial hyperglycemia, which is blood sugar higher than 180 mg/dL two hours after eating, and fasting hyperglycemia, which is blood sugar higher than 130 mg/dL after not eating for 8 hours. Signup and view all the answers

List at least three symptoms of hypoglycemia.

Three symptoms of hypoglycemia include sweating, dizziness, and irritability. Signup and view all the answers

What triggers the release of epinephrine from the adrenal medulla?

Epinephrine is released from the adrenal medulla under nervous system control during stressful situations such as danger, emotional excitement, or physical injury. Signup and view all the answers

Describe one effect of epinephrine on the cardiovascular system.

Epinephrine increases heart rate, which enhances blood circulation during stress. Signup and view all the answers

How can hyperglycemia be caused by infection or illness?

Infection or illness can increase stress hormones in the body, leading to increased blood sugar levels. Signup and view all the answers

What is the threshold for hypoglycemia in terms of blood sugar level?

Hypoglycemia is defined as having a blood sugar level lower than 70 mg/dL. Signup and view all the answers

Mention two causes of hyperglycemia.

Two causes of hyperglycemia are forgetting to take insulin and consuming too many carbohydrates. Signup and view all the answers

What happens to blood vessels in the digestive system during stress response involving epinephrine?

During stress response, blood vessels in the digestive system constrict, reducing blood flow and slowing down digestion. Signup and view all the answers

What role do testes play in the male reproductive system?

The testes produce sperm cells and testosterone hormone. Signup and view all the answers

How do anabolic steroids affect growth potential?

Anabolic steroids cause premature bone fusing of growth plates, decreasing height potential. Signup and view all the answers

What is the function of the seminal vesicle?

The seminal vesicle secretes fructose into semen, providing energy for sperm. Signup and view all the answers

What physiological changes occur in response to stress related to blood flow?

There is increased blood flow to local tissues and relaxation of smooth muscles in passages leading to the lungs. Signup and view all the answers

What effect does erythropoietin (EPO) have on red blood cell production?

EPO increases red blood cell production, enhancing oxygen delivery to cells. Signup and view all the answers

Describe the role of the epididymis in sperm maturation.

The epididymis matures and stores sperm cells in coiled tubules. Signup and view all the answers

What is a primary consequence of using beta blockers in sports?

Beta blockers slow the heart rate to steady nerves and aim, benefiting sharpshooters and archers. Signup and view all the answers

What is the main function of the uterus?

The uterus is the organ where the embryo and fetus develop during pregnancy. Signup and view all the answers

Identify the function of the ovaries in the female reproductive system.

The ovaries produce estrogen and progesterone and are the site of ova development and ovulation. Signup and view all the answers

How does caffeine influence athletic performance?

Caffeine mimics epinephrine, increasing heart rate, blood pressure, and alertness. Signup and view all the answers

Study Notes

Homeostasis

Homeostasis is the maintenance of a steady internal state, despite changes in the external environment
Examples include blood pressure, body temperature, blood glucose, pH, and fluid balance
Balance is maintained by dynamic equilibrium
Achieved through three functional components:
- Receptor or sensor: receives the stimulus or information
- Control centre or coordinating centre: processes the information and determines the sequence of events
- Effector or regulator: performs the response
Feedback system: A cycle where a variable (e.g., body temperature) is monitored, assessed, and adjusted continually
Types of feedback systems:
- Negative feedback: A mechanism that restores conditions to their original state, e.g., blood glucose control
- Positive feedback: A process where a small effect is amplified, moving the controlled variable further from a steady state, e.g., childbirth contractions

Thermoregulation

Thermoregulation is the maintenance of body temperature within a range efficient for cell function
Ectotherms: organisms whose body temperature is dependent on external temperature, e.g. reptiles
Endotherms: organisms that maintain a constant internal body temperature, e.g mammals like humans
Core temperature: internal temperature includes organs like the liver, heart, and blood
Average Human core temperature is between 36.5 and 37.5°C
Peripheral temperature fluctuates; can be 4°C lower in cold days (e.g., fingers and toes)

Water Balance

Osmosis: movement of water across a selectively permeable membrane from high water concentration to low water concentration
Osmotic pressure: pressure resulting from the difference in water concentration
Hyperosmotic: solution with higher solute concentration (less water)
Hypoosmotic: solution with lower solute concentration (more water)
Isosmotic: solution with the same solute and water concentration
Osmoregulation: maintaining proper balance of water and solutes to ensure proper cell function

Excretion

Excretion: elimination of waste products and foreign matter from the body
Maintains ionic and osmotic equilibrium
Kidneys play a key role in:
- Eliminating waste products
- Balancing blood pH
- Maintaining water balance
Proteins are used to build and maintain tissues, when in excess, protein is converted to carbohydrates, amino acid group is removed (deamination) producing extremely harmful ammonia
Human excretory system (urinary system) consists of kidneys, ureters, bladder, and urethra
Kidneys filter waste from the blood
Kidneys weigh 170g, bean shaped, reddish-brown colour

Nephron and Urine Formation

Nephron: functional unit of the kidney that filters wastes from the blood
Blood flows from the aorta → renal arteries → afferent arterioles → glomerulus → efferent arterioles → peritubular capillaries → venules → renal vein → vena cava
Filtration: fluids move from blood to Bowman's capsule
Reabsorption: transferring essential solutes and water from the nephron back into the blood
Secretion: transferring materials from blood back into the nephron

Urine Output and Water Balance

Water balance: increased water intake equals increased urine output, vice versa
Exercise increases water loss through cellular respiration

Hormones

Endocrine system: uses hormones/chemical messengers carried in the bloodstream to control functions in various parts of the body
Hormones: Chemical messengers that control and regulate specific bodily functions, often in a long-term manner
Protein hormones: made of amino acid chains generally soluble in water, have receptors on the surface of cells (e.g. insulin, growth hormones)
Steroid hormones: derived from cholesterol, generally soluble in fat, have receptors inside cells (ex. sex hormones)
Hormones are produced by endocrine glands, including the pituitary, thyroid, adrenal glands, pancreas, testes in males and ovaries in females.
Hypothalamus: a part of the brain that monitors many conditions in the body and regulates hormone production in the pituitary gland
Pituitary gland: master gland secretes many different anterior hormones, regulate production of other endocrine glands. Two main lobes (anterior and posterior), each with difference functions.
Posterior pituitary (neurohypophysis): stores ADH, Oxytocin
Anterior pituitary (adenohypophysis): produces growth hormone (GH),thyroid stimulating hormone(TSH), adrenocorticotropic hormone (ACTH), follicle stimulating hormine (FSH), luteinizing hormone (LH), prolactin (PRL), releasing hormones that stimulate the release of other hormones.

Hormones Affecting Metabolism

Thyroid gland, located in the neck, produces thyroxine (T4) and triiodothyronine (T3), which regulate metabolic rate.
- Hypothyroidism (underactive thyroid): low thyroid output leading to decreased metabolic rate and symptoms like weight gain, sluggishness, intolerance to cold
- Hyperthyroidism (overactive thyroid): excessive thyroid hormone leading to increased metabolic rate and symptoms such as weight loss, anxiety and rapid heartbeat
Pancreas produces insulin and glucagon, which regulate blood glucose levels.
- Diabetes mellitus (high blood glucose): results from insufficient or unresponsive insulin, leading to high blood glucose levels. Causes symptoms like frequent urination, increased thirst, increased hunger, and fatigue

Adrenal Gland and Stress Response

Adrenal glands sit atop the kidneys; two parts to the adrenal glands:
- Adrenal medulla: releases epinephrine (adrenaline) and norepinephrine (noradrenaline) in response to short-term stress – prepares the body for "fight or flight," increasing heart rate, blood pressure, and blood glucose.
- Adrenal cortex: produces corticosteroids, like cortisol, in response to long-term stress. Cortisol raises blood glucose and regulates body fluids.

Male and Female Reproductive Hormones

Male reproductive system: testes produce sperm and testosterone, and the seminal vesicles, prostate gland and Cowper's gland produce fluids to nourish sperm.
Female reproductive system: ovaries produce eggs and estrogen/progesterone, fallopian tubes carry eggs, and the uterus supports development of a fetus.
Hormonal control regulates the development and function of reproductive organs.

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Description

Explore the fascinating processes of homeostasis and thermoregulation, focusing on how the body maintains internal stability despite external changes. This quiz covers key components like feedback systems, receptors, and the balance of bodily functions. Test your understanding of both negative and positive feedback mechanisms.