Human Physiology and Endocrine Control: Chapters 8, 9, 22, 23, 26 Review

What are the classes of hormones?

Peptides/proteins, steroids, amines.

What hormones are classified as peptides/proteins?

Insulin, glucagon, GH, PTH, ACTH, TSH.

What hormones are classified as steroids?

Cortisol, aldosterone, sex steroids, calcitriol.

What is the pathway for cortisol release?

Stress and circadian rhythm → CRH → ACTH → zona fasciculata cortisol.

What are the effects of cortisol?

Gluconeogenesis, protein breakdown, lipolysis, immune suppression.

What is primary hypercortisolism?

High cortisol, low ACTH, low CRH.

What is Cushing disease?

Secondary hypercortisolism due to a pituitary ACTH tumor.

What is Addison disease?

Primary hypocortisolism with low cortisol and high ACTH.

What is the role of thyroid hormones?

Regulate metabolism, increase BMR, and support growth.

What is Graves disease?

An autoimmune disorder causing high T3/T4 and low TSH.

What is the effect of somatostatin on growth hormone?

Somatostatin inhibits growth hormone secretion.

What is the role of PTH?

Increases bone resorption and renal calcium reabsorption.

What is calcitriol?

The main hormone increasing intestinal calcium absorption.

What are the symptoms of hypocalcemia?

Cramps, tetany, seizures.

What is the main hormone during the anabolic phase?

Insulin.

What characterizes Type 1 diabetes?

Autoimmune destruction of β-cells leading to low insulin.

What is the function of glucagon?

Stimulates glycogenolysis and gluconeogenesis.

What is the role of the SRY gene?

Determines male sex by promoting testis development.

What is gametogenesis in males?

Spermatogonia produce sperm continuously after puberty.

What happens to primary oocytes in females?

Arrest until puberty; one egg per primary oocyte.

What does GnRH stimulate?

Release of FSH and LH from the pituitary.

What is the function of inhibin?

Lowers FSH levels.

What does the first polar body contain compared to the second?

The first polar body has twice the DNA of the second.

When does Meiosis II finish?

Meiosis II finishes only if fertilized.

What hormones are released by GnRH?

FSH and LH.

What does inhibin do?

Inhibin lowers FSH.

What happens to gonadotropins when steroid levels are low?

Low steroids raise gonadotropins.

What triggers the LH surge?

Sustained high estrogen switches to positive feedback.

What are the phases of the ovarian cycle?

Follicular phase, ovulation, luteal phase.

What are the phases of the uterine cycle?

Menses, proliferative phase, secretory phase.

What triggers ovulation?

The LH surge triggers ovulation and formation of the corpus luteum.

What is the dominant hormone of the secretory/luteal phase?

Progesterone.

What do the theca and granulosa cells do in estrogen production?

Theca cells make androgens; granulosa cells aromatize them to estrogen.

What happens if there is no pregnancy?

The corpus luteum dies, steroids fall, and menses occurs.

What primarily sets the resting membrane potential?

K+ leak channels.

What is the Nernst equation used for?

To calculate the equilibrium potential for one ion.

What does hyperkalemia do to the resting membrane potential?

Makes Vm less negative and closer to threshold.

What effect does hypokalemia have on resting membrane potential?

Makes Vm more negative.

What depolarizes the neuron?

Na+ or Ca2+ entry.

What hyperpolarizes the neuron?

K+ exit or Cl− entry.

What is the sequence of an action potential?

Threshold → Na+ activation gates open → Na+ inactivation gates close and K+ channels open → extra K+ efflux → reset.

What stops the rising phase of an action potential?

Closing of Na+ inactivation gates.

What is the major excitatory neurotransmitter in the CNS?

Glutamate.

What is the major inhibitory neurotransmitter in the CNS?

GABA.

What is the function of the thalamus?

Relay for sensory information to the cortex, except olfaction.

What is the role of the hypothalamus?

Homeostasis — temperature, thirst, hunger, reproduction, ANS, pituitary.

What does the cerebellum coordinate?

Movement and balance.

What does damage to Broca's area produce?

Expressive aphasia.

What is the primary function of the spinal cord?

Integrates sensory and motor commands.

What does secondary hypocortisolism produce?

Low cortisol, low ACTH, high CRH

What does iodine-deficiency hypothyroidism produce?

Low T3/T4, high TSH, high TRH, and a goiter

What is the difference between childhood GH excess and adult GH excess?

Gigantism versus acromegaly

What happens to the endometrium during menses?

It sloughs its surface layer

In males, what do FSH and LH mainly target?

Sertoli cells and Leydig cells, respectively

How does a graded potential differ from an action potential?

A graded potential can vary in size, can summate, and decays with distance

What occurs at the neuromuscular junction with ACh?

ACh is synthesized by choline acetyltransferase, binds nicotinic receptors, and is broken down by AChE

What is the most likely effect of CN VII damage (Bell palsy)?

Facial droop and impaired facial expression, with possible loss of taste

What is the hippocampus critical for?

Learning and memory

What causes glycosuria and polyuria in untreated type 1 diabetes?

Filtered glucose exceeds the renal threshold and osmotically holds water in the tubule

Why do both insulin and glucagon rise after a pure protein meal?

Glucagon prevents the hypoglycemia insulin would otherwise cause

What is the role of calcitonin?

It is released when plasma Ca2+ is high and decreases bone resorption

What is the metabolic pattern of fasted-state metabolism?

Catabolic, supports brain glucose, and can form ketones

Why does the absolute refractory period exist?

Voltage-gated Na+ channels are inactivated

What does damage to Wernicke area cause?

Receptive aphasia (cannot understand language)

What is the lesion in a patient with moon face, truncal obesity, striae, and high cortisol?

Secondary (pituitary ACTH), Cushing disease

What would a hypophysectomized animal show?

Low T3/T4 and low TSH, with high TRH and no TSH-driven goiter

What explains heat intolerance in hyperthyroidism?

Increased oxidative metabolism, with energy released as heat

What do AMH and DHT do in a male embryo?

Regress Müllerian ducts and masculinize external genitalia, respectively

How much DNA does the first polar body have relative to the second polar body?

The same

What is the difference between early and late follicular estrogen?

Moderate estrogen is negative feedback; sustained high estrogen becomes positive feedback

What happens when a neuron has a net Vm of -58 mV?

It does not fire

What effect does hypokalemia have on a neuron?

Makes it less likely to fire, because Vm is more negative

Where is conduction fastest?

In a large myelinated axon

What does a CN IX lesion most likely cause?

Difficulty swallowing and loss of posterior pharyngeal sensation

What is the difference between sleepwalking and sleep-talking?

Sleepwalking is typical of N3; sleep-talking is typical of light NREM, not REM

Which is NOT a main insulin target?

Renal glucose reabsorption

What do osteoblasts and osteoclasts do?

Osteoblasts deposit bone matrix; osteoclasts resorb it

What is cortisol's main metabolic pattern?

Gluconeogenesis, muscle protein breakdown, lipolysis, and immune suppression

What is true about CSF compared with plasma?

CSF has a lower concentration of glucose

Which statement about the blood-brain barrier is FALSE?

Endothelial cells are joined by gap junctions