Physiology
Endocrine
Question 131 of 180
Adrenocorticotropic hormone (ACTH) primarily acts on which of the following target organs:
Answer:
Adrenocorticotropic hormone (ACTH) primarily acts on the adrenal cortex to stimulate release of glucocorticoids which regulate metabolism and the stress response.Hypothalamic-Pituitary Axis
Physiology / Endocrine / Pituitary Function
Last Updated: 26th July 2024
| Pituitary Hormone | Hypothalamic Releasing/Inhibiting Factors | Target Organ | Effect |
|---|---|---|---|
| Growth hormone (GH) |
|
Liver, bone, muscles | Direct effect (regulates growth and metabolic rate) |
| Adrenocorticotropic hormone (ACTH) |
|
Adrenal gland | Stimulates release of cortisol |
| Follicle-stimulating hormone (FSH) and luteinising hormone (LH) |
|
Gonads | Stimulates release of testosterone/oestrogen and production of eggs/sperm |
| Thyroid-stimulating hormone (TSH) |
|
Thyroid gland | Stimulates release of thyroid hormones (T4/T3) |
| Prolactin |
|
Mammary glands | Direct effect (stimulates lactation) |
| Antidiuretic hormone (ADH) |
|
Kidneys | Direct effect (regulates water balance) |
| Oxytocin |
|
Female reproductive system | Direct effect (stimulates milk ejection in suckling and uterine contractions in childbirth) |
Hypothalamus-Pituitary Axis. (Image by OpenStax College [CC BY 3.0 , via Wikimedia Commons)
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
