Flower Anatomy: Sepals, Petals, Stamens, and Pistils
Flower Anatomy
First, there is a stalk (pedicel) which supports the flower. Some flowers may be without a stalk (sessile). The tip of the stalk may also be enlarged to form a cup-shaped receptacle or thalamus.
A flower is a specialized shoot in which the leaves are modified into floral structures.
The floral parts are borne on the thalamus in four whorls:
- First Whorl: Green sepals (collectively called calyx)
- Second Whorl: Large, brightly-colored petals (collectively called corolla).
- Third Whorl: Male
Cerebrovascular Accident (CVA): Types, Causes, and Mechanisms
Cerebrovascular Accident (CVA)
A Cerebrovascular Accident (CVA), also known as a stroke, has an impact characterized by a sudden focal neurological deficit that persists for at least 24 hours. It normally occurs in the encephalic circulation due to a lack of blood flow, and cells die, causing permanent damage to structures.
Risk Factors: Hypertension, hypercholesterolemia, diabetes, smoking, heavy drinking, and the use of oral contraceptives.
Pathophysiology
Vascular supply is related to the signs and
Read MoreMeiosis: Understanding Cell Division and Genetic Diversity
Meiosis involves two consecutive cell divisions, resulting in four haploid cells per diploid mother cell. These divisions occur in prophase, metaphase, anaphase, and telophase.
Meiotic Division 1
The fundamental difference between meiosis and mitosis takes place in prophase. Homologous chromosomes pair up and exchange hereditary material.
Prophase 1
- DNA filaments begin to condense, chromosomes become visible, and each chromosome is replicated into two chromatids.
- Homologous chromosomes pair lengthwise
Understanding Blood Vessels, Heart Function, and ECG
Blood Vessels: Structure and Function
There are three main classes of blood vessels: arteries, veins, and capillaries. Their primary function is to transport blood throughout the body. They are distinguished by the amount of muscle and elastic tissue in their walls.
Arteries
Arteries have stronger and thicker walls and are formed of three layers:
- Endothelium: Formed by epithelial tissue, it contains smooth muscle and elastic tissue.
- Outer layer: Composed of elastic tissue.
- Lumen: Fairly small but increases
Human Body: Nutrient Absorption and Respiratory System
Nutrient Absorption
Absorption is the process by which nutrients, obtained through digestion, cross the intestinal wall into the circulatory system. From there, they are distributed to all of the body’s cells.
How Absorption is Carried Out
- Most organic nutrients are absorbed in the small intestine. They cross the plasma membrane of the cells in the intestinal mucosa and travel towards the intestinal villi, which are made up of a network of capillaries. Nutrients then pass through these capillaries
Human Sensory and Coordination Systems: A Deep Dive
Sensory Receptors in Humans
Receptors are the structures human beings use to detect stimuli.
- Interoceptors: Also known as internal receptors, collect information about the human body’s internal conditions. These receptors, located in the internal environment, mostly respond to chemical stimuli (e.g., oxygen in blood).
- Exteroceptors: Also known as external receptors, provide information from the body’s outside environment and are therefore located on the surface of the body. Sense organs are exteroceptors.